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Aim: The study aims to investigate the clinical implication of nonfunctional poor metabolizer (PM) alleles and intermediate metabolizer (IM) alleles of CYP2D6 , including the CYP2D6*10 allele which shows substrate-dependent decrease in enzymatic activity, in antiarrhythmic therapy using propafenone. Materials & methods: We examined serum propafenone concentrations and metabolic ratio, which was expressed as serum concentrations of propafenone to 5-hydroxypropafenone, in 66 Japanese patients with tachyarrhythmias. Results: The peak propafenone concentration and metabolic ratio in CYP2D6 PM allele carriers were higher than those in extensive metabolizer (EM)/EM, EM/IM and IM/IM genotype groups. Conclusion: Results suggest that CYP2D6 PM alleles affect peak propafenone concentration, but the CYP2D6 IM allele CYP2D6*10 has no clinical implication in propafenone dosing.

Therapeutic drug monitoring (TDM) is necessary for the optimal administration of anti-arrhythmic drugs in the treatment of heart arrhythmia. The present study aimed to develop and validate a direct analysis in real time tandem mass spectrometry (DART-MS/MS) method for the rapid and simultaneous determination of five anti-arrhythmic drugs (metoprolol, diltiazem, amiodarone, propafenone, and verapamil) and one metabolite (5-hydroxy(OH)-propafenone) in human serum. After the addition of isotope-labeled internal standards and protein precipitation with acetonitrile, anti-arrhythmic drugs were ionized by DART in positive mode followed by multiple reaction monitoring (MRM) detection. The use of DART-MS/MS avoided the need for chromatographic separation and allowed rapid and ultrahigh throughput analysis of anti-arrhythmic drugs in a total run time of 30 s per sample. The DART-MS/MS method yielded satisfactory linearity (R 2  ≥ 0.9906), accuracy (86.1-109.9%), and precision (≤ 14.3%) with minimal effect of biological matrixes. The method was successfully applied to analyzing 30 clinical TDM samples. The relative error (RE) of the concentrations obtained by DART-MS/MS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was within ± 13%. This work highlights the potential usefulness of DART for the rapid quantitative analysis of anti-arrhythmic drugs in human serum and gives rapid feedback in the clinical TDM practices.

First-episode psychosis (FEP) patients are more sensitive to neuroleptic side-effects such as hyperprolactinemia. We examined the prolactin levels of previously minimally treated patients with first episode schizophrenia over their first year of treatment with flupenthixol decanoate and the relationship between prolactin levels, gender and clinical features of schizophrenia. Prolactin levels were assessed at three monthly intervals in 126 patients with first-episode schizophrenia in a single-site study conducted over 12 months during treatment with flupenthixol decanoate according to a fixed protocol. The mean prolactin level for the total sample was 11.91 ng/ml (standard deviation [SD]15.52) at baseline. Women had higher levels of prolactin than men at month 3, 6 and 12, reaching statistical significance at month 12 (p = 0.02). At 12 months more women than men had hyperprolactinemia (defined as more than 20 ng/ml for males, and as more than 25 ng/ml for females (p = 0.007). Using a mixed effect model, there was a significant association between prolactin change scores over 12 months and gender (p = 0.025) as well as Positive and Negative Syndrome Scale (PANSS) total scores (p = 0.001). In addition female gender (p = 0.04) and age (p = 0.02) correlated with the risk of hyperprolactinemia as categorical variable. In this study treatment with flupenthixol decanoate was associated with relatively low levels of hyperprolactinemia, likely owing to flupenthixol's relatively atypical mode of action, as well as to the low doses used in our study. We found an inverse correlation between total PANSS scores and prolactin levels, which could support the suggested theory of prolactin having antipsychotic properties. Our study confirms the importance of gender on the prolactin raising effects of antipsychotic treatment.

Purpose: The clinical usefulness of therapeutic drug monitoring (TDM) of propafenone, a sodium channel blocker, has been unclear due to the lack of information regarding optimal blood sampling time and therapeutic concentration range. Antiarrhythmic effects of sodium channel blockers are affected by the activity of the cardiac sodium channel (SCN5A). We investigated the optimal sampling time and the clinical implication of the SCN5A promoter haplotype in propafenone TDM., Methods: We evaluated serum concentrations of propafenone, the SCN5A promoter haplotype, and antiarrhythmic efficacy in 55 patients with supraventricular tachy-arrhythmias. Blood samples obtained 1.5-6 and 10-24 h after the last dose were categorized as peak and trough samples, respectively., Results: The peak propafenone concentration was significantly higher in effectively treated patients than that in patients showing insufficient response (337 ± 213 vs. 177 ± 93 ng/mL, P = 0.005), but the trough propafenone concentration was not significantly different between the two groups (68 ± 48 vs. 42 ± 36 ng/mL). Clinically relevant propafenone efficacy was achieved significantly more often in SCN5A haplotype B carriers than in wild-type haplotype A homozygotes (90 vs. 60%, P < 0.05). Among the haplotype A homozygotes, peak propafenone concentration was higher in effectively treated patients than that in patients showing insufficient response (299 ± 177 vs. 177 ± 93 ng/mL, P = 0.061)., Conclusion: The present study found that antiarrhythmic efficacy of propafenone was associated with peak propafenone concentration rather than trough concentration and was affected by the SCN5A promoter haplotype.

Propafenone is an antiarrhythmic drug applied to ventricular arrhythmias, initially recognized as a sodium channel blocker. This study aims to evaluate the bioequivalence of two propafenone formulations (300 mg tablet) in healthy subjects under non-fasting conditions. The study was conducted as an open, randomized, 2-period design with a 2-sequence (RT, TR) with a 1-week washout interval. The subjects were selected for the study after having their health status previously assessed by a clinical evaluation and laboratory tests (biochemical and hematological parameters, and urinalysis). Debrisoquine phenotype of healthy subjects was determined by analysis of urinary excretion of debrisoquine and its major metabolite, 4-hydroxydebrisoquine. A single propafenone tablet (300 mg) was given in each occasion. Plasma propafenone concentrations were analyzed by liquid chromatography coupled to tandem mass spectrometry (HPLC/MS/MS) with positive ion electrospray ionization using multiple reactions monitoring (MRM). The geometric mean and 90% confidence intervals (CI) of propafenone/Ritmonorm ® (T/R) percent ratio were 100.44% (88.39 - 114.13%) for AUC last , 99.84% (90.31 - 110.36%) for AUC inf , and 99.30% (90.08 - 109.47%) for C max . Since the 90% CI for C max , AUC last , and AUC inf ratios were all inside the 80 - 125% interval proposed by the US Food and Drug Administration Agency, it was concluded that the propafenone formulation elaborated by Biolab Sanus Farmacêutica Ltda. is bioequivalent to Ritmonorm ® formulation for both the rate and the extent of absorption. The drug was well tolerated by the subjects, indicating that it is safe to perform propafenone bioequivalence studies in healthy subjects with intermediate/extensive metabolism.
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Propafenone, a class Ic antiarrhythmic agent, is metabolized to 5-hydroxypropafeone (5-OHP) and N-depropylpropafenone (NDPP). Simultaneous determination of serum propafenone and its metabolites was performed using HPLC equipped with a conventional octadecylsilyl silica column and ultraviolet detector. The wavelength was set at 250 nm. Propafenone and its metabolites in the serum were extracted using diethyl ether. The mobile phase solution, comprising 1-pentanesulfonic acid sodium salt (0.1 m), acetonitrile and acetic acid (280:185:2.5, v/v/v), was pumped at a flow rate of 1 mL/min. The recoveries of propafenone, 5-OHP and NDPP were greater than 85, 82 and 60%, respectively, with the coefficients of variation (CVs) less than 5.4, 1.9 and 2.9%, respectively. The calibration curves were linear for a concentration range of 12.5-1500 ng/mL for propafenone and 2-500 ng/mL for 5-OHP and NDPP (r > 0.999). CVs in the intraday assays were 1.0-3.8% for propafenone, 0.6-2.0% for 5-OHP and 0.6-1.7% for NDPP. CVs in interday assays were 1.3-7.7% for propafenone, 1.1-6.5% for 5-OHP and 5.4-8.0% for NDPP. The present HPLC method can be used to assess the disposition of propafenone and its metabolites for pharmacokinetic studies and therapeutic drug monitoring of propafenone., (Copyright © 2017 John Wiley & Sons, Ltd.)

A simple and rapid high-performance liquid chromatography tandem mass spectrometry method for the determination of propafenone (PPF) and its active metabolite 5-hydroxypropafenone (5-OHP) in human plasma was developed and validated. This new method was linear and allowed simultaneous quantification of PPF and 5-OHP at a lower level of 0.5 ng/mL. The aliquot of 200 μL plasma sample was simply treated with 4-fold methanol to deproteinize the plasma. The chromatographic separation was achieved on a Hedera ODS-2C18 analytical column with the mobile phase of methanol and 5 mM ammonium acetate solution containing 0.2% formic acid (pH 3.2) (68:32, v/v) at a flow rate of 0.4 mL/min. Quantitation of the analytes was achieved by multiple reaction monitoring under positive ionization mode. The method was successfully applied to a pharmacokinetic study of PPF and 5-OHP in healthy Chinese volunteers. After oral administration of a single dose of 425 mg PPF hydrochloride sustained-release capsule, the maximum peak plasma concentration (Cmax) of PPF was 210.9 ± 141.9 ng/mL with a Tmax of 6 ± 1 h, the Cmax of 5-OHP was 129.6 ± 65.4 ng/mL with a Tmax of 7 ± 2 h. The area under plasma concentration-time curve (AUC0-36) of PPF was 1610 ± 1309 ng·h/mL with a t1/2 of 4.6 ± 1.1 h, the AUC0-36 of 5-OHP was 1446 ± 754 ng·h/mL with a t1/2 of 7.6 ± 1.6 h., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Propafenone is a potent antiarrhythmic agent; clinically propafenone has been used for a number of cardiac arrhythmias because it possesses multiple modes of action, via beta adrenergic receptor blockade and calcium antagonistic activity. Propafenone (PPF) exhibits extensive saturable presystemic biotransformation (first-pass effect) resulting in two active metabolites: 5-hydroxypropafenone (5-OH PPF) formed by CYP2D6 and N-depropylpropafenone (NDP) formed by both CYP3A4 and CYP1A2 enzymes. A specific and sensitive LC-MS/MS method was developed and validated for quantitation of PPF, 5-OH PPF and NDP using turboion spray in a positive ion mode. A solid-phase extraction was employed for the extraction from human plasma. Chromatographic separation of analytes was achieved using an ACE-5 C 8 (50 × 4.6 mm) column with a gradient mobile phase comprising ammonium acetate containing 0.01% TFA in purified water and acetonitrile. The retention times achieved were 1.36, 1.23, 1.24 min and 1.34 min for PPF, 5-OH PPF, NDP and IS (carbamazepine), respectively. Quantitation was performed by monitoring multiple reaction monitoring transition pairs of m/z 342.30 to m/z 116.20, m/z 358.30 to m/z 116.20, m/z 300.30 to m/z 74.20 and m/z 237.20 to m/z 194.10, respectively. The developed method was validated for various parameters. The calibration curves of PPF and 5-OH PPF showed linearity from 1 to 500 ng/mL, with a lower limit of quantitation of 1.0 ng/mL and for NDP linearity from 0.1 to 25 ng/mL with a lower limit of quantitation of 0.1 ng/mL. The bias and precision for intra- and-inter batch assays were <10 and 5%, respectively. The developed assay was used to evaluate pharmacokinetic properties of propafenone and its major metabolites in healthy human subjects., (Copyright © 2017 John Wiley & Sons, Ltd.)

Introduction: The β1 adrenergic receptor blocker metoprolol is often prescribed together with the antiarrhythmic drug propafenone. Both are metabolized by cytochrome P450 2D6 and propafenone is also an inhibitor of this enzyme. We present a pediatric case showing metoprolol and propafenone intoxication in combination., Case: A 14-year-old girl was admitted to a local emergency department after ingestion of metoprolol (probably 1g) and propafenone (probably 1.5-3g) in a suicide attempt. She developed cardiogenic shock with cardiac arrest and was fully resuscitated. Veno-arterial femorofemoral extracorporeal membrane oxygenation was started immediately. High serum levels of both drugs were detected approximately 10h after ingestion (2630ng/mL metoprolol and 2500ng/mL propafenone). Other serial samples for the monitoring of the levels of metoprolol and its metabolite alfa-hydroxymetoprolol were obtained between days 2 and 4 after admission. The metoprolol/alfa-hydroxymetoprolol ratio on the 2nd day was 36.1, indicative of a poor metabolizer phenotype. The elimination half-life of metoprolol was prolonged to 13.2h and the clearance decreased by about 70%. The patient condition gradually worsened, brain edema and intracerebral hemorrhage occurred, and on the 6th day, the patient died., Conclusion: We document a pediatric case report of death due to a mixed drug overdose of metoprolol and propafenone, along with data regarding serum metoprolol, alfa-hydroxymetoprolol, and propafenone levels., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Aim of the Study: Propafenone (PPF) is an antiarrhythmic drug, metabolized mainly by CYP2D6 to 5-hydroxypropafenone (5OH-PPF) and by CYP3A4 to norpropafenone (NOR-PPF). CYP2D6 shows a high degree of genetic polymorphism which is associated with diminished antiarrhythmic efficacy or cardiac seizures/cardiotoxicity. This study aimed to investigate the effect of the CYP2D6 polymorphism on the pharmacokinetics of PPF and its two main metabolites. The usefulness of PPF/5OH-PPF ratio for CYP2D6 phenotyping in healthy adults was also evaluated., Methods: Twelve healthy volunteers, 3 poor metabolizers (PM), 2 intermediate metabolizers (IM) and seven extensive metabolizers (EM) received an oral dose of PPF. Concentrations of PPF and its metabolites were analyzed in serum samples over 27h., Results: The PPF/5OH-PPF ratio distinguished EMs from PMs, but not from IMs. In PMs, the mean transit time (MTT) values were almost the same for PPF and NOR-PPF and much higher than those of EMs and IMs. 5OH-PPF was not detected in EMs. Mean MTT values of 5OH-PPF and NOR-PPF in IMs were 5.27- and 1.52-fold higher than those of EMs., Conclusion: A single time point serum PPF-MR approach is a useful tool to identify PMs. CYP2D6 polymorphism significantly affects the pharmacokinetics of PPF and its two metabolites., (Copyright © 2016 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.)

Aims: Propafenone is a well-known Class Ic antiarrhythmic agent. It has the typical chemical structure of a beta-blocker, but human studies on its beta-blocking effects revealed conflicting results., Methods and Results: Twelve healthy males received single oral doses of 600 mg propafenone and placebo according to a randomized, double-blind, placebo-controlled, cross-over protocol. Four hours following drug intake, heart rate and blood pressure were measured, and plasma concentrations of propafenone were determined at rest, during exercise and after recovery. At exercise, propafenone significantly decreased heart rate (-6%, P < 0.05), systolic blood pressure (-6%, P < 0.05), and the rate-pressure product (-11%, P < 0.05). Plasma concentrations of propafenone increased during exercise (+23%, P < 0.05) and decreased during recovery (-33%, P < 0.05)., Conclusion: Both effects on heart rate and blood pressure as well as the changes of plasma concentrations of propafenone during exercise represent two particular features of beta-blockers. Therefore, we conclude that propafenone is both a Class Ic and a Class II antiarrhythmic agent, and 600 mg propafenone, i.e. the dose recommended in current guidelines for cardioversion of paroxysmal atrial fibrillation, cause clinically significant beta-blockade. Thus, single oral doses of 600 mg propafenone appear also suitable for cardioversion of paroxysmal atrial fibrillation in patients with structural heart disease since beta-blockers are explicitly indicated in the treatment of both coronary artery disease and heart failure., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)

Flecainide, mexiletine, propafenone, and amiodarone are antiarrhythmic drugs that are used primarily in the treatment of cardiac arrhythmias. The monitoring of the use of these drugs has applications in therapeutic drug monitoring and overdose situations. LC-MS/MS is used to analyze plasma/serum extracts with loxapine as the internal standard to ensure accurate quantitation and control for any potential matrix effects. Positive ion electrospray is used to introduce the analytes into the mass spectrometer. Selected reaction monitoring of two product ions for each analyte allows for the calculation of ion ratios which ensures correct identification of each analyte, while a matrix matched calibration curve is used for quantitation.

A novel 96-well liquid-liquid microextraction system combined with modern HPLC was developed and used for the simultaneous analysis of 96 biological samples. The system made use of hollow fibers, a 96-well plate, and a plastic base with a center hole and a side hole. One end of the hollow fiber was sealed, while the other end was attached to one of the holes positioned at the center for the plastic base. The needle was inserted into the liquid from inside or outside of the hollow fiber through the center or the side holes, respectively. The system was tested with plasma samples containing three compounds, acidic indomethacin, neutral dexamethasone, and basic propafenone. Some parameters, such as the kind and dimension of hollow fiber, pH and salt concentration of the donor phase, the selection of organic solvent for the acceptor phase, and the extraction time were investigated. Under the optimization conditions, the Log D and drug concentration of indomethacin, dexamethasone, and propafenone in plasma and urine samples were analyzed. Then, the methodology was validated. The results demonstrated that ng/mL levels could be exactly and rapidly analyzed by our system, which was equipped with an auto-injection sampler, making sample analysis more convenient., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Purpose: The aim was to prepare and evaluate unitary doses of propafenone (UDP) used in children with supraventricular tachycardia., Methods: UDP were prepared from four brands of tablets at doses of propafenone, 11, 25 and 90 mg, used in the Cardiology Service of this Institute. The stability of doses was determined at 20±5°C and 40°C for up to day 30. Besides, a weight variation test was performed. Plasma levels of propafenone were determined at steady state in 3 children diagnosed with supraventricular tachycardia under treatment with UDP. Concentrations of drug in blood were measured using a high pressure liquid chromatography method, previously validated., Results: The stability of UDP, showed no significant statistical differences (p > 0.05) between doses or brands up to day 30, at both temperatures. The coefficient of variation from the weight variation was less than 6%. The plasma levels of propafenone at steady state were: patient 1, 31.57 ng/ml; patient 2, 226.46 ng/ml; and patient 3, 221.29 ng/ml., Conclusions: The actual administered dose for the patients could vary up to 6%, and doses prepared from different brands of tablets remain stables for up to day 30 at both temperatures. UDP is a temporal, safe and alternative option when pediatrics formulation of this drug is lacking.

A liquid chromatography-tandem mass spectrometry method, using pneumatically assisted electrospray ionization was developed for the determination of amiodarone, desethylamiodarone, propafenone, N-depropylpropafenone, 5-OH-propafenone, flecainide, and sotalol in human antemortem and postmortem whole blood. A mixture of methanol and acetonitrile was used to extract the samples, and the clear extracts obtained from the protein precipitation were injected directly onto an ethyl-linked phenyl LC column. The isotope dilution technique was applied for quantitative analysis. The relative intralaboratory reproducibility standard deviations were 5-9% at a concentration range of 1-5 mg/L and 9-12% at a concentration of 0.1 mg/L. The mean true recoveries were greater than 91% in the concentration range of 0.05-5 mg/L. The detection limits were in the range of 8-18 µg/L.

Propafenone and its 5-hydroxy metabolite exhibit different electrophysiological properties. Objectives of the CAQ-PAF study were (1) to develop a strategy favoring propafenone instead of 5-hydroxypropafenone in plasma following oral administration of propafenone and (2) to evaluate the potential of low-dose quinidine to chronically inhibit CYP2D6. Patients (n = 102) with atrial fibrillation received propafenone 150 mg 3 times daily with either quinidine 100 mg twice daily or placebo. Throughout the study (follow-up, 199 ± 155 days), quinidine successfully inhibited CYP2D6: propafenone concentrations were 3 times higher in patients receiving quinidine (1033 ± 611 ng/mL vs 328 ± 229 ng/mL; P < .001). Moreover, 80% (n = 10) of patients with propafenone levels greater than 1500 ng/mL were in sinus rhythm at 1 year. In contrast, recurrence of atrial fibrillation occurred in 22 of 23 patients with propafenone levels less than 1000 ng/mL (P < .0001). Thus, chronic inhibition of CYP2D6 is achievable with low-dose quinidine in humans. Increased plasma levels of propafenone may be highly beneficial to prevent recurrence of atrial fibrillation., (2012 American College of Clinical Pharmacology.)

A clinical study was conducted to assess the ability of a microdose (100 μg) to predict the human pharmacokinetics (PK) following a therapeutic dose of clarithromycin, sumatriptan, propafenone, paracetamol (acetaminophen) and phenobarbital, both within the study and by reference to the existing literature on these compounds and to explore the source of any nonlinearity if seen. For each drug, 6 healthy male volunteers were dosed with 100 μg (14)C-labelled compound. For clarithromycin, sumatriptan, and propafenone this labelled dose was administered alone, i.e. as a microdose, orally and intravenously (iv) and as an iv tracer dose concomitantly with an oral non-labelled therapeutic dose, in a 3-way cross over design. The oral therapeutic doses were 250, 50, and 150 mg, respectively. Paracetamol was given as the labelled microdose orally and iv using a 2-way cross over design, whereas phenobarbital was given only as the microdose orally. Plasma concentrations of total (14)C and parent drug were measured using accelerator mass spectrometry (AMS) or HPLC followed by AMS. Plasma concentrations following non-(14)C-labelled oral therapeutic doses were measured using either HPLC-electrochemical detection (clarithromycin) or HPLC-UV (sumatriptan, propafenone). For all five drugs an oral microdose predicted reasonably well the PK, including the shape of the plasma profile, following an oral therapeutic dose. For clarithromycin, sumatriptan, and propafenone, one parameter, oral bioavailability, was marginally outside of the normally acceptable 2-fold prediction interval around the mean therapeutic dose value. For clarithromycin, sumatriptan and propafenone, data obtained from an oral and iv microdose were compared within the same cohort of subjects used in the study, as well as those reported in the literature. For paracetamol (oral and iv) and phenobarbital (oral), microdose data were compared with those reported in the literature only. Where 100 μg iv (14)C-doses were given alone and with an oral non-labelled therapeutic dose, excellent accord between the PK parameters was observed indicating that the disposition kinetics of the drugs tested were unaffected by the presence of therapeutic concentrations. This observation implies that any deviation from linearity following the oral therapeutic doses occurs during the absorption process., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Propafenone is an anti-arrhythmic drug used in the management of supraventricular and ventricular arrhythmias. It is metabolised through cytochrome P450 2D6 pathways; the major metabolites possess anti-arrhythmic activity. The cytochrome P450 CYP2D6 is coded by more than 70 alleles resulting in great genetic polymorphism of CYP2D6 isoenzymes, and up to 7% of Caucasian population are poor metabolisers. This case report describes a patient with severe overdose of propafenone who presented with coma, seizures and cardiotoxicity. The patient was managed with intravenous glucagon, hypertonic sodium bicarbonate, hypertonic saline and inotropic support. The propafenone and its 5-hydroxypropafenone (5-OHP) metabolite were measured by high-performance liquid chromatography with ultraviolet detection (no assay was available at the time to measure N-despropyl propafenone concentrations). Toxicological screen showed propafenone concentrations at a maximum of 1.26 mg/L at 9-10 h post-presentation, falling to 0.25 mg/L at 27-28 h post-presentation. No propafenone metabolite 5-OHP was detected in any sample analysed. No antidepressant or analgesic drugs were detected in toxicological screen. Propafenone overdose has been reported to be associated with features of severe cardiovascular and CNS toxicity. Aggressive treatment, meticulous monitoring and supportive care was associated with a good outcome in this case.

Two HPLC methods are described for the enantioselective analysis of R- and S-propafenone in plasma. In a column switching approach, centrifuged plasma was injected onto a silica-based strong acid cation-exchanger and the fraction containing propafenone was switched on-line onto an enantioselective Chiralcel column for separation of the enantiomers. In another approach, propafenone was extracted from plasma by liquid-liquid extraction at pH 11.4. The extracted components were transferred into aqueous medium and separated on a Chiralcel ODR. Both methods were validated and showed comparable performance. Within-day and between-day precision was better than 5% for both methods. Linear calibration functions were obtained (r(2)>0.999), and the limit of detection for each enantiomer was 0.2 microg/mL for column switching and 0.55 microg/mL for liquid-liquid extraction. The analysis methods were applied for the determination of the effect of physical exercise on the enantiomeric ratio of R- and S-propafenone in plasma of healthy volunteers. During exercise, the concentration of both enantiomers reached a maximum, followed by a significant decrease during recovery.

A sensitive and selective LC-MS/MS method was developed and validated for the determination of aconitine in microdialysate and rat plasma. Extraction of plasma sample was conducted by use of 1% trichloracetic acid and acetonitrile solution with 10 ng/mL internal standard (propafenone) spiked. Microdialysates were analyzed without sample purification. After sample preparation, 2 microL were injected and separated with an isocratic mobile phase consisting of acetonitrile:0.1% formic acid (60:40, v/v) at a flow rate of 0.3 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple-reaction monitoring mode (MRM) using the electrospray ionization technique in positive mode. Overall, the assay exhibited good precision and accuracy. The diffusion properties of aconitine investigated in in vitro microdialysis experiments revealed unfavourable concentration dependence avertable by keeping a constant pH 5.77 using isotonic phosphate buffer solution as perfusate. The mean relative recoveries were 48.23% [coefficient of variation (CV 4.47%)] and 55.38% (CV 2.89%) for retrodialysis and recovery experiments, respectively. The in vivo recovery of aconitine was 34.48% (CV 3.05%) and was stable over the 6 h study period. Following characterization of aconitine both in vitro and in vivo microdialysis, the developed setting is suitable for application in pharmacokinetics and pharmacodynamics studies., ((c) 2009 John Wiley & Sons, Ltd.)

Objective: To investigate effects of IV administration of propafenone for naturally occurring and experimentally induced chronic atrial fibrillation in horses., Animals: 2 horses with naturally occurring atrial fibrillation and 4 horses with pacing-induced atrial fibrillation., Procedures: Horses received a bolus of propafenone (2 mg/kg, IV over 15 minutes). If atrial fibrillation persisted after 20 minutes, a continuous infusion of propafenone (7 microg/kg/min) was given for 120 minutes. Before, during, and after treatment, plasma propafenone concentrations, hematologic and serum biochemical values, and electolyte concentrations analyses were determined and clinical signs were monitored. Surface ECGs were recorded. If propafenone treatment failed, quinidine sulfate was administered., Results: Bolus and continuous infusion induced minimal adverse effects. During the 15-minute bolus administration, a slight increase in heart rate was observed and horses appeared more sensitive to external stimuli. Throughout treatment, no significant changes were observed in respiratory rate, QRS or corrected QT duration, or results of hematologic analyses. Although a significant increase in F-wave interval and atrial fibrillation cycle length was observed and plasma propafenone concentrations (569 to 1,268 ng/mL) reached the human therapeutic range (64 to 1,044 ng/mL), none of the horses cardioverted to sinus rhythm. Sinus rhythm could be restored in all horses via standard oral administration of quinidine., Conclusions and Clinical Relevance: A slow IV bolus of 2 mg of propafenone/kg followed by a continuous infusion of 7 microg/kg/min over 2 hours was not an effective treatment for chronic atrial fibrillation in horses.

We studied the efficacy of propafenone in preventing atrial tachyarrhythmias after cardiac surgery, and the possible relationships between CYP2D6 polymorphism and the efficacy, pharmacokinetics, and tolerability of propafenone. One hundred and sixty patients were randomized (double blind) to receive propafenone (n= 78) or placebo (n= 82) for 1 week after cardiac surgery. The patients who were assigned to the propafenone group received 1 mg/kg infused in 1 h, followed by a continuous infusion at a rate of 4 mg/kg/24 h until the following morning, and subsequently 450 mg/day orally until the sixth postoperative day. Thirty-seven patients completed the trial in the propafenone group and 45 in the placebo group. The frequency of occurrence of atrial tachyarrhythmia was lower in the propafenone group than in the placebo group (29.7% vs. 53.3%, P< 0.05; relative risk, 0.56). Plasma propafenone concentrations were markedly influenced by CYP2D6 genotype-derived phenotype.

We report here the successful treatment of a 16-year-old female who ingested 20 tablets of digoxin each containing 0.25 mg (total dose ingested equivalent to 0.1 mg/kg), 32 tablets of warfarin each containing 5mg (equivalent to 3.2 mg/kg), and approximately 15 tablets of propafenone each containing 300 mg (equivalent to 90 mg/kg). The patient developed hypotension and sinus bradycardia necessitating external cardiac pacing 17 hours after drug ingestion. In addition to gastric lavage, activated charcoal, blood alkalinisation, administration of vitamin K and temporary cardiac pacing, the authors performed plasma exchange for drug removal and administered rifampicin in order to increase the metabolism of digoxin, propafenone and warfarin. The patient was discharged without any sequelae. Plasma exchange may be lifesaving in drug ingestions where there is a low volume of distribution and high plasma protein binding. Rifampicin, an inducer of cytochrome p450, may be used in intoxications for elimination of drugs with inactive metabolites.

Propafenone is an effective antiarrhythmic agent used in children, while in Mexico no specific formulation for children is available, which causes errors in adequate dosage. The aim of this study was to determine the bioavailability of a suspension prepared extemporaneously using commercial tablets of propafenone. The bioavailability was determined in two groups of rabbits (n = 8): the first group received a single intravenous dose of 2 mg/kg of propafenone; the second was orally administered an extemporaneous suspension of propafenone prepared from commercial tablets. Blood samples were drawn at several times during the next 24 h and analysed by HPLC to determine drug levels. The extemporaneous suspension was tested previously with satisfactory results regarding physicochemical and microbiologic stability. The area under the curve (AUC) for the i.v. route was 5600.6 ng/ml.h and for oral administration the AUC was 3327.6 ng/ml.h. The bioavailability was calculated at 59.41%. These results are consistent with previous reports for solid dosage forms. The propafenone suspension prepared extemporaneously using commercial tablets is bioavailable using an animal model; nevertheless, it is necessary to carry out human studies either in volunteers or in patients to confirm these results.

A robust, inexpensive, and fully validated CE method for the simultaneous determination of the enantiomers of propafenone (PPF), 5-hydroxy-propafenone (5OH-PPF) and N-despropyl-propafenone (NOR-PPF) in serum and in in vitro media is described. It is based upon liquid-liquid extraction at alkaline pH followed by analysis of the reconstituted extract by CE in presence of a pH 2.0 running buffer composed of 100 mM sodium phosphate, 19% methanol, and 0.6% highly sulfated beta-CD. For each compound, the S-enantiomers are shown to migrate ahead of their antipodes, and the overall run time is about 30 min. Enantiomer levels between 25 and 1000 ng/mL provide linear calibration graphs, and the LOD for all enantiomers is between 10 and 12 ng/mL. The assay is shown to be suitable for the determination of the enantiomers of PPF and its metabolites in in vitro incubations comprising human liver microsomes or single CYP450 enzymes (SUPERSOMES). Incubations with CYP2D6 SUPERSOMES revealed, for the first time, the simultaneous formation of the enantiomers of 5OH-PPF and NOR-PPF with that enzyme. CE data can be used for the evaluation of the enzymatic N-dealkylation and hydroxylation rates.

A rapid and specific HPLC method has been developed and validated for the simultaneous determination of propafenone, an antiarrhythmic agent, and its major metabolites in human serum. The sample preparation was a simple deproteinization with a mixture of ZnSO4 and methanol, yielding almost 100% recoveries of three compounds. Separation was developed on a reverse-phase tracer excel C18 column (25 x 0.46 cm i.d., 5 microm), using an acetonitrile-phosphate buffer gradient at a flow rate of 1.7 ml min(-1), and UV detection of 210 nm. The calibration curves were linear (r2 > 0.999) in the concentration range of 10 - 750 ng ml(-1). The lower limit of quantification was 10 ng ml(-1) for all of the compounds studied. The within and between day precisions in the measurement of QC samples at four tested concentrations were in the range of 1.4 - 8.1% and 4.2 - 11.5% RSD, respectively. The developed procedure was applied to assess the pharmacokinetics of propafenone and its major metabolites following administration of a single 300 mg oral dose of propafenone hydrochloride to three healthy male volunteers.

First synthesized in 1970, propafenone is a frequently used 1C antiarrhythmic drug metabolized into two major metabolites, 5-hydroxypropafenone and norpropafenone. Paradoxically, fatal intoxication is rarely described, and only six cases have been reported in the literature. We report our experience with two patients found dead of self-inflicted poisoning where the propafenone blood concentration was very high (one concentration to our knowledge is one of the highest reported in the literature). At autopsy, no evidence of significant pathological disease were found. Propafenone was detected in blood by gas chromatography-mass spectrometry and by high-performance liquid chromatography using a diode-array detector, respectively, as propafenone artifact and propafenone. Blood propafenone concentrations were 4180 ng/mL and 9123 ng/mL. The literature regarding propafenone pharmacokinetic and intoxication is reviewed, and we discuss the low death rate attributed to this drug in contrast to its frequent use.

Aim: To determine the effect of CYP2D6*10 genotype on propafenone pharmacodynamics in Chinese patients with ventricular arrhythmia., Methods: Seventeen Chinese patients with ventricular premature contractions (VPC> or =1000/d) were recruited. They were normal in routine laboratory testing and administered propafenone hydrochloride 450-600 mg per day in three divided doses. Twelve lead cardiogram and 24 h Holter monitoring were performed before and after 7 d treatment of propafenone. Steady-state peak and trough concentrations of propafenone were measured by HPLC method. CYP2D6*10 genotypes of patients were assayed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP)., Results: Total inhibitory rate of VPC was 79.9 % in 17 patients with ventricular arrhythmia after propafenone treatment. PR interval prolongation was increased from 0.146 s+/-0.018 s to 0.161 s+/-0.022 s (P<0.05). CYP2D6 genotypes played an important role in plasma levels and effects of propafenone. In 450 mg/d group, patients with homozygous mutant of CYP2D6*10 not only had a Cmax of propafenone two times as high as those of wild-type genotype, but also showed a two fold higher inhibitory rate of VPC compared with those with homozygous CYP2D6*1 (P<0.05)., Conclusion: CYP2D6*10 genotype is relevant to decreased activity of CYP2D6 enzyme in Chinese patients. Elevated plasma concentration is consistent with better efficacy of propafenone in patients with ventricular arrhythmia.

Aim: To study the simultaneous modeling of pharmacokinetics and pharmacodynamics (PK-PD) of propafenone (Pro) in healthy subjects., Methods: Ten healthy Chinese volunteers, 5 extensive metabolizers (EM) and 5 intermediate metabolizers (IM) of CYP2D6, received a single dose (400 mg) of Pro hydrochloride. The blood samples and electrocardiogram (ECG) measurements were taken after administration over 15 h period. The concentrations of Pro in plasma were measured by a reverse-phase HPLC. PR interval was used as an average value of 10 PR interval measurements., Results: There was a delay between Pro level and percentage of PR interval prolongation. After PK-PD simulating, the relationship between effect concentration (Ce) and the effect met the sigmoid E(max) model. CYP2D6 (EM & IM) played an important role in both pharmacokinetics and pharmacodynamics which produced by Pro. The AUC (microg . h . L-1) of IM group was significantly higher than that of EM group (5126 +/- 1030 vs 2948 +/- 1230, P < 0.05). Whereas Ce50 (microg/L) was also greater in IM group than in EM group (747 +/- 281 vs 359 +/- 123, P < 0.05). On the other hand, gamma of EM group was about one fold larger than that of IM group (P < 0.05)., Conclusion: CYP2D6 phenotype of human may influence not only pharmacokinetic of Pro but also its pharmacological effects.

The objective of this study was to determine the percentage of patients with paroxysmal atrial fibrillation who were poor metabolizers of CYP2D6 in a Chinese population from Hong Kong and to assess the relationship between the dextromethorphan/dextrorphan ratio and the propafenone/5-hydroxypropafenone ratio or the steady-state propafenone concentration. Patients (n = 60) were recruited from the Arrhythmia Clinic at the University of Hong Kong and given dextromethorphan 30 mg. The dextromethorphan and dextrorphan concentrations in urine over the next 8 hours were used to determine metabolizer status. If the metabolic ratio was greater than 0.3, the patient was determined to be a poor metabolizer. In phase 2, patients (n = 38) were given propafenone 150 mg twice daily, and at steady state, the propafenone and 5-OH propafenone plasma concentrations were determined. It was found that 15% of the patients were poor metabolizers of dextromethorphan. There was a significant correlation between the metabolic ratios of dextromethorphan/dextrorphan and propafenone/5-OH propafenone (r = 0.49, p = 0.0019) and between the dextromethorphan/dextrorphan ratio and the concentration of propafenone (r = 0.32, p = 0.05). No correlations were found in the extensive or poor metabolizer subgroups. It was concluded that the percentage of poor metabolizers in atrial fibrillation patients from Hong Kong was much larger than in previous studies of Chinese patients who were not from Hong Kong. The ability to metabolize dextromethorphan to dextrorphan is related to the ability to metabolize propafenone to 5-hydroxypropafenone.

The frequent recurrence of paroxysmal atrial fibrillation (PAF) despite the use of standard antiarrhythmic agents prompted the use of new therapeutic approaches. There are few data on systematic assessment of PAF control with stepwise dose escalation and the use of a drug combination. Low-dose quinidine may promote the efficacy of propafenone by inhibiting its degradation through the cytochrome P450 pathway (CYP2D6). We prescribed propafenone 300 to 450 mg/day to 60 patients with PAF for 8 weeks, and 62% were symptomatically controlled. The 19 refractory patients were randomized in a double-blinded fashion to receive either a higher dose of propafenone (450 to 675 mg/day) or the standard dose of propafenone with low-dose quinidine 150 mg/day, each for an 8-week study period, and subsequently crossed over to the alternative treatment. The resulting serum propafenone concentrations were 259 +/- 208 and 336 +/- 237 mg/day (p >0.5), respectively. Both treatment arms prolonged the time to the first symptomatic atrial fibrillation (AF) recurrence and the interval between attacks, and AF was controlled in 37% of patients. However, the higher dose of propafenone was associated with gastrointestinal side effects not present with the low-dose quinidine combination. Of the 10 refractory patients, 7 were further controlled with a standard dose of propafenone plus quinidine (600 mg/day). Overall, control of PAF was achieved in 85% of patients at the end of 8 months; adverse effects necessitating withdrawal were observed in 6%, and uncontrolled AF in 5% of patients. There was no difference in the mean AF rate during recurrences in all phases, and ventricular proarrhythmia was not seen. This study documents the role of stepwise antiarrhythmic treatment of PAF. The use of a standard dose of propafenone, followed by low-dose quinidine combination to reduce propafenone degradation, and the combined standard dose of propafenone and quinidine may be used to maximize efficacy and tolerability.

A sensitive method was developed to determine propafenone, 5-hydroxypropafenone, N-despropylpropafenone and propafenone glucuronides in human plasma and urine by HPLC-electrospray ionization mass spectrometry with the respective deuterated analogues as internal standards. The analytes were extracted by a single solid-phase extraction, collecting two fractions, one containing the glucuronides and the other propafenone and the phase I metabolites 5-hydroxypropafenone and N-despropylpropafenone. The mobile phases used for HPLC were: (A) 5 mM ammonium acetate in water and (B) 5 mM ammonium acetate in methanol-tetrahydrofuran (50:50, v/v). Separation of the diastereoisomeric propafenone glucuronides was achieved on a Spherisorb ODS 2 column (150 x 2.0 mm I.D., particle size 5 microm) at a flow-rate of 0.3 ml/min using a linear gradient from 20% B to 50% B in 15 min. For separation of propafenone, 5-hydroxypropafenone and N-desalkylpropafenone a linear gradient from 50% B to 80% B in 10 min was employed. The mass spectrometer was operated in the selected ion monitoring mode using the respective MH+ ions for quantification. The limits of quantification achieved with this method were 10 pmol/ml for propafenone, 5-hydroxypropafenone, R- and S-propafenone glucuronide and 20 pmol/ml for N-desalkylpropafenone using 0.5 ml of plasma. Reproducibility and accuracy was below 12% for each analyte over the whole concentration range measured. The method was applied to a pharmacokinetic study assessing the influence of rifampicin on propafenone disposition.

Background and Objective: Mexiletine and propafenone are often used concomitantly and are metabolized by the same cytochrome P450 isozymes, namely CYP2D6, CYP1A2, and probably CYP3A4. Our objective was to study the potential pharmacokinetic and electrophysiological interactions between mexiletine and propafenone., Methods: Fifteen healthy volunteers, 8 extensive metabolizers and 7 poor metabolizers of CYP2D6, received oral doses of mexiletine 100 mg two times daily from day 1 to day 8 and oral doses of propafenone 150 mg two times daily from day 5 to day 12. Interdose studies were performed at steady-state on mexiletine alone (day 4), mexiletine plus propafenone (day 8), and propafenone alone (day 12)., Results: In subjects in the extensive metabolizer group, coadministration of propafenone decreased oral clearances of R-(-)-mexiletine (from 41+/-11 L/h to 28+/-7 L/h) and S-(+)-mexiletine (from 43+/-15 L/h to 29+/-11 L/h) to an extent such that these values were no longer different between the extensive and the poor metabolizer groups. Propafenone coadministration also decreased partial metabolic clearances of mexiletine to hydroxymethylmexiletine, p-hydroxymexiletine, and m-hydroxymexiletine in extensive metabolizers by 71%, 67%, and 73%, respectively. In contrast, propafenone did not alter the kinetics of mexiletine enantiomers in subjects in the poor metabolizer group except for a slight decrease in the formation of hydroxymethylmexiletine. Pharmacokinetic parameters of propafenone were not changed during concomitant administration of mexiletine in subjects of either phenotype. Finally, electrocardiographic parameters (QRS duration, QTc, RR, and PR intervals) were not modified during the combined administration of the drugs., Conclusion: Propafenone is a potent CYP2D6 inhibitor that may cause an increase in plasma concentrations of coadministered CYP2D6 substrates.

Gilbert's syndrome, a genetic deficiency in bilirubin UDP-glucuronosyltransferase (UGT1A1), may dispose to increased toxicity of propafenone in poor metabolizers (PMs) of cytochrome P4502D6 because glucuronidation of propafenone is the major metabolic pathway for drug elimination in PMs. A patient with Gilbert's syndrome who is also PM participated in an interaction study with propafenone and rifampicin along with five otherwise healthy PMs. Using stable isotope techniques, the pharmacokinetics of single doses of 140 mg propafenone i.v. (unlabelled) and 300 mg propafenone p.o. (labelled) were compared between the index patient and the five healthy controls. Propafenone did not accumulate in the plasma of the index patient either before or during induction: AUC(0-infinity) of propafenone in the index patient was within the 95% confidence interval of controls; AUC(0-infinity) of propafenone glucuronide and amount of urinary excretion of propafenone glucuronide in the patient were within or even greater than the 95% confidence intervals of controls. Therefore, individuals with Gilbert's syndrome who also have a PM phenotype appear to be at no higher risk for toxicity of propafenone than otherwise healthy PMs. An indirect conclusion from these in vivo data might be that propafenone is not a substrate of the UGT1A1 isoform.

HPLC on chiral stationary phases has been used for the enantioselective assay of propafenone (PPF), 5-hydroxypropafenone (PPF-50H) and N-despropylpropafenone (PPF-NOR) enantiomers. The results obtained on Chiralpak AD column showed that it is useful for the resolution of PPF and of its main metabolites, although the peaks obtained for PPF-NOR were not symmetrical under the conditions investigated. This column and circular dichroism-based detection system were used to determine the absolute configuration of the eluates. Furthermore, the influence of the mobile phase composition on the resolution of PPF and of its main metabolites was investigated on cellulose derivatives (Chiralcel OD-H and Chiralcel OD-R) and protein (Chiral AGP and Ultron ES-OVM)-based chiral stationary phases. The enantiomers of PPF were resolved on all the columns, except for the Ultron ES-OVM. This column, the Chiralpak AD and the Chiralcel OD-H columns were suitable for the resolution of the PPF-50H enantiomers. The PPF-NOR enantiomers were resolved on the Chiralpak AD, Chiral AGP and Chiralcel OD-R columns., (Copyright 2000 John Wiley & Sons, Ltd.)

Objective: A clinical study on enzyme induction in elderly subjects was performed by investigation of the effect of rifampin (INN, rifampicin) on propafenone disposition. Propafenone was chosen as a model drug because of its complex metabolism that permits the simultaneous in vivo assessment of induction of phase 1 and phase 2 pathways., Methods: Six extensive metabolizers of CYP2D6 (age, 70.5 +/- 3.5 years) ingested 600 mg rifampin once daily for 9 consecutive days. One day before the first rifampin dose and on the day of the last rifampin dose, each elderly individual received a single intravenous infusion of 70 mg unlabeled propafenone and received a single oral dose of 300 mg deuterated propafenone 2 hours later. Pharmacokinetics and pharmacodynamics of propafenone were compared before and during induction., Results: Maximum QRS prolongation after oral propafenone was decreased significantly by rifampin (18% +/- 5% versus 6% +/- 3%; P < .01). There were no substantial differences in pharmacokinetics and pharmacodynamics of intravenous propafenone during induction. However, bioavailability of propafenone dropped from 30% +/- 24% to 4% +/- 3% (P < .05). After oral propafenone was administered, clearances through N-dealkylation (6 +/- 3 mL/min versus 26 +/- 16 mL/min; P < .05) and glucuronidation (178 +/- 75 mL/min versus 739 +/- 533 mL/min; P < .05), but not 5-hydroxylation, were increased by rifampin, indicating substantial enzyme induction., Conclusions: Both phase 1 and phase 2 pathways of propafenone metabolism were induced by rifampin in elderly subjects, resulting in a clinically relevant drug interaction.

Objective: To determine the effect of 20 mg/day fluoxetine on the pharmacokinetics of propafenone enantiomers and CYP2D6 activity by phenotyping with dextromethorphan., Methods: Nine healthy Chinese volunteers (seven men and two women) were included in a two-phase study. Dextromethorphan (20 mg) was given before and after subjects took 20 mg/day fluoxetine for 10 days, and the dextromethorphan metabolic ratio was calculated to determine CYP2D6 phenotype. Pharmacokinetic studies of propafenone enantiomers after a single oral 400 mg dose before and after pretreatment with 20 mg/day fluoxetine for 10 days were also conducted in these subjects. Reversed-phase HPLC with precolumn derivatization was used to determine enantiomeric concentrations of propafenone in plasma., Results: Mean CYP2D6 dextromethorphan metabolic ratios before and after fluoxetine therapy were 0.028 +/- 0.031 and 0.080 +/- 0.058, respectively (P = .001), indicating that a strong inhibition of CYP2D6 by fluoxetine activity was observed in Chinese subjects. Propafenone metabolism was also impaired significantly after fluoxetine treatment. The elimination half-life, peak concentration, and area under the curve from 0 hours to infinity of two enantiomers after fluoxetine therapy were significantly increased compared with those at baseline (P < .01), whereas oral clearance decreased from 75.01 +/- 17.69 L/h to 49.36 +/- 8.62 L/h for S-propafenone (P = .005) and from 107.62 +/- 33.82 L/h to 70.60 +/- 12.42 L/h for R-propafenone (P = .027). In addition, fluoxetine increased the peak concentration of S-propafenone by 39% and that of R-propafenone by 71% (P < .05). A significant increase of the time to reach peak concentration was observed only in the R-enantiomer and not in the S-enantiomer of propafenone after fluoxetine therapy. There were no differences in the percentage changes of PR and QRS intervals before or after fluoxetine pretreatment at the time observed (P > .05)., Conclusion: We conclude that fluoxetine may cause significant inhibition of the CYP2D6 activity as determined by dextromethorphan phenotyping. This inhibition impairs the metabolism of propafenone enantiomers in Chinese subjects. Caution must be exercised when fluoxetine and propafenone are coadministered to avoid potential toxicity.

Objective: To determine the extent of removal of propafenone by continuous venovenous hemofiltration (CVVH) in a critically ill pediatric patient., Case Summary: A three-year-old white-Japanese girl was admitted to the critical care unit following cardiac surgery. Her postoperative course was complicated by the development of junctional ectopic tachycardia, requiring propafenone, and acute renal failure, which necessitated the use of CVVH. The serum and ultrafiltrate concentrations of propafenone and its 5-hydroxy metabolite were measured to determine both total and CVVH clearance., Conclusions: The data from this case report showed that propafenone was not significantly removed by CVVH. Furthermore, the total clearance of propafenone was not affected by the patient's renal or liver function impairment.

An enantioselective liquid chromatography method was developed for the simultaneous determination of propafenone (PPF) and 5-hydroxypropafenone (PPF-5OH) enantiomers in plasma. After liquid liquid extraction with dichloromethane, the enantiomers were resolved on a Chiralpak AD column using hexane-ethanol (88:12, v/v) plus 0.1% diethylamine as the mobile phase and monitored at 315 nm. Under these conditions the enantiomeric fractions of the drug and of its metabolite were analysed within 20 min. The extraction procedure resulted in absolute recoveries of 62.9 and 61.3% for (R)- and (S)-PPF, respectively, and of 57.6 and 56.5% for (R)- and (S)-PPF-5OH, respectively. This procedure was efficient in removing endogenous interferents as well the interference of an other PPF metabolite, N-despropylpropafenone (PPF-NOR). The calibration curves were linear over the concentration range 25-1250 ng/ml. Low values of the coefficients of variation were demonstrated for both within-day and between day assays. The method described in this paper allows the determination of PPF and PPF-5OH enantiomers at plasma levels as low as 25 ng/ml and can be used in clinical pharmacokinetic studies.

Column-switching chromatographic systems using conventional reversed-phase Separon SGX C18 and restricted access media LiChrospher ADS RP-18 precolumns were applied for the determination of propafenone and its main metabolite 5-hydroxypropafenone in human serum samples. The LiChrospher ADS RP-18 precolumn has been found to be more suitable for the sample clean-up. Serum samples were directly injected into the chromatographic system. Proteins and other endogenous compounds were removed by washing with 10% 2-propanol in water and the analytes separated on the Gromsil ODS AB analytical column. The chromatograms were detected at 246 nm. The method validation confirms the suitability of the column-switching system for the quantitation of propafenone and its metabolite. The presented assay shows good linearity with high correlation coefficients (0.992-0.999), high recoveries (96.6+/-6.1-103.5+/-5.8) and excellent values of the repeatabilities (1.23-4.5%). The limits of quantitation are 25-40 ng/ml for the injection volume of 50 microl. The complete analysis including the precolumn reconditioning and the sample clean-up requires 26 min, the sample throughput is approximately four samples in an hour.

A sensitive and stereospecific method was developed to determine propafenone (PPF), 5-hydroxypropafenone (5-OHP) as well as their glucuronide and sulfate conjugates in human plasma. Quantitative analyses and preparative isolations of PPF and 5-OHP were performed on a Nucleosil C18 column after liquid-liquid extraction. Afterwards the enantiomeric ratios of PPF and 5-OHP were determined on a Chiral-AGP column with ion trap mass spectrometric detection in the selected reaction monitoring (SRM) mode via electrospray ionization (ESI). The enantiomers of PPF and 5-OHP were separated with different mobile phases. For PPF enantiomers, the mobile phase consisted of 10 mM ammonium acetate buffer (pH 5.96)-1-propanol (100:9, v/v), at a flow-rate of 0.5 ml/min; And for 5-OHP enantiomers, the mobile phase was 10 mM ammonium acetate buffer (pH 4.1)-2-propanol (100:0.9, v/v), at a flow-rate of 0.6 ml/min. The SRM transitions m/z 342 to m/z 324 and m/z 358 to m/z 340 were monitored for detection of enantiomers of PPF and 5-OHP, respectively. Linear calibration curves were obtained in the concentration range of 20-1600 ng/ml for each enantiomer of PPF and 20-500 ng/ml for the 5-OHP enantiomer. The limits of quantification for each enantiomer of PPF and 5-OHP were found to be 20 ng/ml. Precision and accuracy were within 11% over the calibration range for each of the analytes. Incubation of the plasma samples with beta-glucuronidase/arylsulfatase and the use of the specific beta-glucuronidase inhibitor saccharo-1,4-lactone allows the quantitation of both the glucuronide and sulfate conjugates of the enantiomers. The method was applied to human plasma samples from ten Chinese male volunteers after oral administration of 300 mg racemic propafenone.

Buccal absorption has an advantage when compared with other administration routes because of its rapid onset of action. We examined the pharmacokinetics of buccal-absorbed propafenone in healthy humans. 1. After a single oral administration of 150 mg of propafenone, the average peak concentration of propafenone was 27.9+/-2.5 ng/ml, and that of 5-hydroxypropafenone was 61.7+/-6.6 ng/ml (n=5). The times to reach peak serum concentrations of propafenone and 5-hydroxypropafenone were 1.8+/-0.1 hr and 1.5+/-0.2 hr, respectively. 2. After a buccal absorption of 150 mg of propafenone, the time to reach peak serum concentration of propafenone was 16.9+/-2.3 min (n=8). The average peak concentration of propafenone was 30.4+/-1.4 ng/ml (n=8), and the concentrations of 5-hydroxypropafenone were below the detection limit in all subjects. The rapid upstroke of serum concentrations of propafenone by buccal administration may cause rapid onset of pharmacological conversion.

To elucidate contribution of an active metabolite to overall clinical responses to propafenone, steady-state disposition of propafenone and its active metabolite and the clinical responses to treatment were examined in pediatric patients receiving intravenous or oral propafenone. There were more than ten-fold interindividual differences in apparent clearance, resulting in a wide range of the steady-state trough plasma concentrations of propafenone. The active metabolite, 5-hydroxypropafenone, was detected in four of the six patients receiving oral propafenone; however, two neonates receiving oral propafenone and all eight receiving intravenous propafenone had no detectable levels of 5-hydroxypropafenone in plasma. In nine patients for whom electrocardiographic (ECG) data were available, the PQ interval was significantly increased, whereas the QRS duration and the QTc interval were not. There was no close relationship between plasma concentrations of propafenone or 5-hydroxypropafenone and ECG parameters. Lack of good correlation between serum concentrations and clinical response precludes using a serum-concentration targeting strategy with propafenone therapy.

We present a method for the enantioselective analysis of propafenone in human plasma for application in clinical pharmacokinetic studies. Propafenone enantiomers were resolved on a 10-microm Chiralcel OD-R column (250 x 4.6 mm I.D.) after solid-phase extraction using disposable solid-phase extraction tubes (RP-18). The mobile phase used for the resolution of propafenone enantiomers and the internal standard propranolol was 0.25 M sodium perchlorate (pH 4.0)-acetonitrile (60:40, v/v), at a flow-rate of 0.7 ml/min. The method showed a mean recovery of 99.9% for (S)-propafenone and 100.5% for (R)-propafenone, and the coefficients of variation obtained in the precision and accuracy study were below 10%. The proposed method presented quantitation limits of 25 ng/ml and was linear up to a concentration of 5000 ng/ml of each enantiomer.

Unlabelled: We prospectively evaluated reaching of steady state and clinical efficacy of propafenone (PPF), class Ic antiarrhythmic agent, in 16 patients (pts) (age 46-69, mean 57 years) with symptomatic ventricular arrhythmias (Low class II and IV). The majority (13 pts) had coronary artery disease. Drug was administered for 7 days (daily dose: 3 x 150 mg). Efficacy was defined as > 80% reduction of ventricular premature complexes (VPC) and class IV elimination in 24-hours Holter recording. Responders were continued on PPF for 3 weeks, in non-responders dose was titrated to 900 mg a day for the next 7 days. After second Holter evaluation the treatment was continued for 2 weeks in responders group. The non-responders were switched to other drug. After 4 weeks final Holter monitoring was performed. Serum concentration of PPF and its 2 metabolites: 5-hydroxy PPF and N-depropyl PPF were determined in 2, 3, 4, 5, 6, 7th day, just before the morning dose (3 x 150 mg/day) in 9 pts., Results: Trough serum concentrations of PPF differed in high degree: 0-226 ng/ml (2nd day), 22-438 ng/ml (4th day), 42-614 ng/ml (6-7 day). An increasing tendency of serum concentrations of PPF was observed, so steady-state was not reached. This great dispersion of concentration values is because of non-linear metabolism and individual differences. Defined efficacy critetion was achieved in 62% pts, 56% for lower dose. Mean frequency of VPC was reduced by 86% in 24-hour Holter recording and per hour (p = 0.0011). Reduction of couplets/24 h was 87% (p = 0.0175). Significant prolongation of PQ (14%, p = 0.009) and QRS (13%, p = 0.0052) were observed. Changes of QT interval were not significant. One case of proarrhythmia was the cause of stopping the treatment., Conclusions: Serum concentrations' values undermine common opinion, that steady state can be reached after 1-2 days of treatment. High dispersion of serum levels is the result of nonlinear metabolism of PPF and individual differences. In spite of this the study showed defined antiarrhythmic efficacy in 62.5% pts. In this group 90% success rate was achieved after lower dose 3 x 150 mg.

Case Report: Propafenone is a class IC antiarrhythmic agent metabolized into two major metabolites, 5-hydroxypropafenone and N-depropylpropafenone. The potency of 5-hydroxypropafenone to block fast sodium channels is comparable to that of its parent. We report the positive correlation between plasma concentrations and electrocardiographic changes in a patient with severe oral self-poisoning. Serial ECG changes were measured and plasma concentrations were determined by high-performance liquid chromatography. The initial plasma concentrations of propafenone were in the toxic range and correlated with the widening of the QRS-complex. The slow decline in concentration during this first phase might relate to saturation of the isoenzyme CYP2D6. The half-life of propafenone, calculated from the second phase, was approximately 3 hours, defining the patient as a fast metabolizer. The initial concentrations of the metabolite N-depropylpropafenone were surprisingly higher than those of 5-hydroxypropafenone which may also be due to saturation of CYP2D6.

A reversed phase HPLC method to stereoselectively determine enantiomers of propafenone in human plasma has been developed. After extraction of 1 ml plasma with 3 ml of n-C6H14:CH2Cl2:2-C3H7OH (100:50:5, v/v) and dried under N2, the enantiomers of propafenone were allowed to react with homochiral S(+)-1-(1-naphthyl) ethyl isocyanate (5.66 micrograms in 60 microliters CH2Cl2) at RT for 30 min, to give the diastereomeric derivatives. Their separation was achieved using HPLC with a C18-column and UV-detection (220 nm) and the enantiomeric ratios were measured. The concentration of each enantiomer were then calculated using the enantiomeric ratios and the racemic propafenone concentrations previously measured. This method after validation procedures has been applied to the multisample analyses of a human pharmacokinetic study with 10 healthy volunteers after an oral dose of 300 mg propafenone hydrochloride. The method was shown to be sensitive (7.5 ng.ml-1), convenient and reproducible.

Report of a suicidal mono-intoxication with the class IC antiarrythmic drug propafenone. A 20-year-old female physician's assistant secretly ingested the substance (presumably 20 tablets per 300 mg) about 4-6 h before her death, and in the interim remained under the supervision of her physician. An ECG taken about 1/2-2 h after ingestion showed widening of the QRS complex and signs of an acute load of the right ventricle; the clinical symptoms were nausea, vomiting and hypotonia. After about 4 h without serious symptoms acute loss of consciousness and cardiac failure occurred, resuscitation efforts remained unsuccessful. At autopsy propafenone was found in blood (12 micrograms ml-1), liver (60 micrograms g-1) and cardiac muscle (11 micrograms g-1).