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Regional anesthesia is the preferred modality for obstetric patients undergoing cesarean section due to the risks associated with general anesthesia in pregnant women. Single-shot spinal anesthesia is usually administered, which may be associated with post-block maternal hypotension, despite adequate intravenous fluid therapy. This is deleterious for the uteroplacental circulation, leading to poor outcomes in both the mother and fetus. There are several vasopressors which are used for treatment of these hypotensive episodes. Mephentermine is a sympathomimetic, having both direct and indirect actions. It has many side effects, however, including increased risks of arrhythmias, hypertension, central nervous system stimulation and abuse potential. Yet, it is still used in many developing countries, due to low cost and easy availability. We hereby report a case of rhythm disturbance with missed beats following use of mephentermine to counter hypotension after spinal anesthesia for cesarean section. The rhythm disturbance had a spontaneous resolution, with the patient maintaining hemodynamic stability during and after the episode.

Mephentermine is structurally related to amphetamines and is banned for its use as a performance-enhancing drug in competitive sports. Limited literature is available on management of mephentermine dependence. Here, we describe a case of mephentermine dependence followed by review of literature and a discussion about its management. A 20-year-old professional wrestler presented with high-dose intravenous mephentermine use, and rapid development of dependence, in the absence of any comorbid substance use or psychiatric disorder. The client showed improvement with bupropion and individual counseling sessions. The present report highlights the need to explore effective treatment options for individuals who have been addicted to mephentermine.

A case report of 32 years old male presented to the drug addiction OPD and treatment center for the withdrawal symptoms of mephentermine. Mephentermine a synthetic derivative of amphetamines with cardiac stimulatory action is been misused for boast of endurance in bodybuilders. Abuse of mephentermine result in psychosis, cardiovascular disorder and development of tolerance and dependence over time. Given its potential of causing harm, the abuse and dependence liability of mephentermine needs to be highlighted to gym instructors and general public.

Introduction: Subarachnoid block, although being highly efficient with lesser drug doses, often has limitation such as hypotension, continues to be a matter of concern to the anesthetist. The present study was aimed to compare the use of phenylephrine, ephedrine, and mephentermine bolus for maintenance of blood pressure during spinal anesthesia in lower abdominal surgeries. Subjects and Methods: In a randomized, prospective study, 90 adult patients of either sex who developed hypotension during surgery under subarachnoid block were allocated into three groups to receive bolus phenylephrine, ephedrine, and mephentermine. The number of boluses and time taken to recover from hypotension was noted. Occurrence of adverse effects in the perioperative and postoperative period was also noted. Results: Results were analyzed by Student's paired t-test and Chi-square test. The ANOVA test was used to compare the group variances among the study groups. P < 0.05 was considered statistically significant. Thirty-four hypotensive events (average 1.03 events/patient) took place in mephentermine group. In phenylephrine group, a total of 53 hypotensive events took place. On an average, the group had a total of 1.61 hypotensive events per patient. No hypotensive event took place in ephedrine group after the first bolus of drug (average 1 event/patient). Mean heart rate in phenylephrine group was significantly lower as compared to the other two groups (P < 0.001). Conclusion: Mephentermine and ephedrine were similar in performance, offered a better hypotensive control, and had lower recurring events as compared to phenylephrine.

Background: Spinal blockade provides excellent anesthesia for patients undergoing cesarean section. However, hypotension after spinal anesthesia is a common adverse effect that is commonly experienced in patients undergoing cesarean section. The aim of our study was to analyze if a simple technique like leg wrapping with elastic crepe bandage would be effective in controlling postspinal hypotension. Materials and Methods: Sixty full-term pregnant patients who were posted for cesarean section belonging to American Society of Anesthesiologists I and II were divided into two groups. Patients in Group W had their legs wrapped with elastic crepe bandage and in the other Group N, leg wrapping was not done. All the patients were preloaded with Ringer lactate at 10 ml/kg before the spinal anesthesia. The hemodynamic parameters were monitored every 3 min until the delivery of the baby and every 5 min until the end of surgery. If hypotension occurred, then along with crystalloid loading a bolus dose of mephentermine 6 mg was given intravenously. Statistical Analysis: Statistical software “Numbers version 3.6.1 (2566)” was used for statistical calculations. Results: Frequency of hypotension in Group W (10%) was significantly less compared to Group N (60%). Vasopressor requirement was significantly less in Group W (P = 0.009), which was highly significant. Conclusion: Wrapping of lower extremities was a simple, easy, and an effective method of decreasing episodes of hypotension and vasopressor requirement after spinal anesthesia in cesarean patients and needs to be practiced routinely.

Purpose: Drug wastage is a major concern in anaesthesia. In addition to increasing the cost on the patient, it can increase the occupational hazard to the health care and sanitary workers and also cause environmental pollution. The principal objective of this study was to ascertain the extent of drug wastage in anaesthetics and ancillary drugs and calculate the financial costs of it at a tertiary care hospital. Methodology: This was a prospective study and was conducted to ascertain the quantity of drug wastage. This pilot study was conducted in the operation theatre between the months of March and April 2016. The prescription of the anaesthetic drugs, the recommended dose, the quantity used and remainder (waste) left were recorded. Costs of the drugs used and wasted were calculated. The financial loss incurred was thus calculated. Results: The results of this study indicated that maximum wastage of the anaesthetic drugs was for atropine sulphate (71.67%), fentanyl (40%), mephentermine sulphate (40%) and bupivacaine (33.62%). The cost analysis indicated that propofol contributed to the maximum as the financial loss was estimated to be 29.27% of the total loss, followed by bupivacaine 18.95%. Conclusion: The results indicate that the quantity and the financial impact of anaesthetic drug wastage were considerable and that efforts should be at minimising the expenditure without risking the patient's life or health.

BACKGROUND: Spinal anesthesia is the more commonly administered procedure for pelvic, lower abdominal and lower limb procedures. Hypotension is the most common complication of spinal anesthesia. It is a common practice to give intravenous fluids, usually crystalloids, prior to centro neuraxial block in order to prevent hypotension and this is usually referred as preloading. AIMS: Compare the efficacy of preloading with crystalloid to that of colloids in reducing the incidence and severity of hypotension in spinal anesthesia for lower abdominal surgery and also to find out if hydroxyl ethyl starch (HES) is a better colloid than polygelatin. STUDY DESIGN: The study population included 150 patients belonging to either sex undergoing elective lower abdominal surgeries under spinal anesthesia. METHODS AND MATERIAL: One hundred and fifty ASA I and II patients posted for lower abdominal surgeries under spinal anesthesia were randomly allocated to receive either 10mL/Kg of HES (Group A), 10mL/Kg of polygelatin (Group B) or 10mL/Kg of Ringer's lactate solution as preloading solution. Heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were recorded once in two minutes for the first ten minutes and once in five minutes for the next fifty minutes. The incidence of hypotension and the mean dose requirement of mephentermine were noted after spinal anesthesia. STATISTICAL METHODS: The analysis of variance to find the significance difference of pulse rate, SBP and MAP between the three groups of patients. The Post hoc test by Tukey to find the pair wise significance between the three groups. The Chi-square test to find the significance of proportions of mephentermine dose requirement between the three groups. RESULTS: The incidence of hypotension was 9 of 50 (18%) in Group A, 17 of 50 (34%) in Group B and 27 of 50 (54%) in group C. The mephentermine bolus requirements were also less in group A (9 times) when compared to group B (18times) and group C (32 times), which was statistically significant. INTERPRETATION AND CONCLUSION: HES reduced the incidence of hypotension after spinal anesthesia and required lesser mean dose requirements of mephentermine when compared to polygelatin and ringers lactate. It can be concluded from the present study that colloids offset hypotension and hypovolemia more effectively than crystalloids. Also it can be concluded that hydroxyethyl starch is a better

The goal of this study was to confirm the vasopressor and cardiac effects of POTENAY® INJETAVEL (POT), a mephentermine-based product, given to cattle with induced vascular/cardiac depression. Ten healthy Holstein cattle (206 ± 13 kg) followed a randomized-complete-block design (RCBD) utilizing crossover study design. Each animal randomly received (1 ml/25 kg, IM) of either POT (n = 10) or volume-matched placebo control (0.9%NaCl, CP, n = 10). A subset of animals (n = 5) received POT first (day 0) while the remaining (n = 5) received CP; after a six-day washout period, cattle received the opposite compound. Animals were anesthetized and catheterized for systemic/left ventricular hemodynamic monitoring. Myocardial dysfunction/hypotension was induced by increasing the end-tidal isoflurane concentration until arterial blood pressure was 20% lower than at baseline and remained stable. Once the animal was determined to be hypotensive and hemodynamically stable, steady-state hypotensive baseline data (BL2) were acquired, and treatment with either POT or CP was given. Data were acquired post-treatment at every 15 min for 90 min. POT improved cardiac output (+68 L/min, ±14%, p

Context: The purpose of adding an adjuvant to local anesthetic in a central neuraxial blockade is to augment the desirable pharmacological actions of the agent and/or to minimize its undesirable pharmacological effects. Clonidine is an alfa-2 receptor agonist which has gained popularity in recent times as an adjuvant in spinal anesthesia. Aims: To evaluate the influence of clonidine on the hemodynamic stability and the duration of anesthesia when added to intrathecal hyperbaric bupivacaine. Settings and Design: Prospective randomized double blind study. Subjects and Methods: Fifty patients scheduled for spinal anesthesia were randomized into two Groups A and B with 25 in each. Group A patients received 3 ml 0.5% heavy bupivacaine + 30 μg (0.2 ml) clonidine and Group B patients received 3 ml 0.5% heavy bupivacaine + 0.2 ml normal saline in the subarachnoid space. The blood pressure and heart rate were closely monitored. The time for attaining peak sensory block, time for two segment regression, decrease in the heart rate, total requirement of mephentermine to counter the hypotension, and the number of patients requiring mephentermine in each group was tabulated and analyzed. Statistical Analysis Used: Descriptive and inferential statistical methods were used to analyse the data. The power of the study was calculated using online power calculator for two independent sample study. Results: The time for attaining peak sensory block was similar in both the groups. The time for two segment regression in Group A was 62.6 min and in Group B was 38.08 min. Twelve percent of patients in Group A and 52% of patients in Group B required mephentermine with the mean consumption being 0.72 mg in Group A and 5.65 mg in Group B. Conclusions: Addition of low-dose clonidine to intrathecal bupivacaine not only prolonged the duration of spinal anesthesia but also provided a stable intraoperative hemodynamic profile.

Introduction: It is important to find an effective method to prevent and treat hypotension during subarachnoid block. Hence we compare the bolus doses of Phenylephrine and Mephentermine to treat hypotension post subarachnoid block. Methods: This randomized study was conducted in 100 patients of ASA I or II physical status undergoing infraumbilical surgeries under subarachnoid block. Patients were randomized into 2 groups of 50 each. Group P-Phenylephrine of 0.1 mg I.V bolus and Group M-Mephenteramine 6mg I.V bolus given when patient develops hypotension >20% basal respectively. Both the groups received 3ml of 0.5% hyperbaric bupivacaine for subarachnoid block. Vital parameters like blood pressure, heart rate and oxygen saturation were recorded. Any side effects observed were also recorded. Results: The demographic profile were comparable and statistically similar in both the groups. Both the vasopressors were able to maintain blood pressure above the hypotensive values in their respective groups successfully. The number of hypotension episodes was higher in Group P(34%) than Group M(32%) but statistically insignificant. The average number of drug doses required for recovery from hypotension was higher in the Group P(1.41) than Group M(1.25). The number of episodes of bradycardia was higher in the phenylephrine group(16%) than in the mephentermine group(4%). Conclusion: We conclude that intravenous bolus of phenylephrine and mephentermine are both effectve at maintaining intraoperative blood pressure during spinal anaesthesia in infraumbilical surgeries but mephenteramine is better than phenylephrine in maintaining BP persistently high and has lesser incidence of bradycardia.

An Evaluation of Vasopressor Therapy for Maternal Hypo - tension during Spinal Anesthesia. By James FM III, Griess FC, Kemp RA. Anesthesiology 1970; 33:25-34. Abstract reprinted with permission from Wolters Kluwer Health.† Abstract: During hypotension resulting from conduc - tion anesthesia in gravid ewes, uterine blood flow (UBF) decreased roughly in proportion to the decrease in maternal blood pressure. Ephedrine or mephentermine significantly increased UBF over that accomplished by metaraminol. Presumably, the preferential effects of these agents were the result of increased cardiac output owing to inotropic and chronotropic actions. However, UBF never exceeded 90% of prespinal levels with any vasoactive agent, and, for a given maternal system, the UBF response was variable, generally increasing but frequently remaining constant or decreasing. For these reasons, all other methods of com - bating hypotension should be used initially. If vasopressors are still required, agents of choice are those whose princi - pal mode of action lies in cardiac stimulation rather than peripheral vasoconstriction.

Summary This study compared the effects of intravenous infusions of phenylephrine and mephentermine on the prevention of maternal hypotension and neonatal outcome in patients receiving spinal anaesthesia for caesarean section. Sixty ASA 1-2 patients with term, uncomplicated singleton pregnancy undergoing caesarean section under spinal anaesthesia were randomly divided into two groups of 30 each, to receive a prophylactic intravenous infusion of either phenylephrine or mephentermine. The incidence of hypotension was statistically similar in the two groups. However, in patients receiving phenylephrine, 7 (23%) developed bradycardia and 6 (20%), reactive hypertension. Neonatal outcome, in terms of Apgar scores and umbilical artery pH, was similar in both the groups. To conclude, phenylephrine and mephentermine infusions are equally effective in preventing post spinal hypotension in patients undergoing caesarean section and are associated with a similar neonatal outcome.

Mephentermine and phentermine, substances prohibited in sports by the World Anti-Doping Agency, were found for the first time in urine specimens following the administration of a therapeutic medication, oxethazaine. In a recent sporting event, a urine specimen donor who tested positive for mephentermine and phentermine claimed consumption of Mucaine((R)) for treating stomach pain was the reason for testing positive. Five volunteers were administrated oxethazaine (a topical anesthetic found in the multi-ingredient medication Mucaine and its generic equivalent, Stoin, both of which are available in Taiwan), mephentermine, and phentermine. Excretion profiles of mephentermine and phentermine following the administration of these drugs were found to be similar. However, the mephentermine/phentermine ratios found in urine specimens collected at different time points following the administration of oxethazine and mephentermine were found to be characteristically different.

A GC method was developed for the identification and quantitation of eight sympathomimetic amines in urine, i.e., amphetamine, methamphetamine, mephentermine, ephedrine, pseudoephedrine, methylenedioxyamphetamine, methylenedioxymethamphetamine, and methylenedioxyethylamphetamine. Methoxyphenamine was used as the internal standard (IS). The assay is rapid, sensitive, and simple to perform. It involves a liquidliquid extraction procedure with simultaneous in-solution derivatization of the organic layer with pentafluorobenzoyl chloride (PFB-Cl), followed by GC/MS analysis. These derivatives and the IS were extracted from 1 mL alkaline urine into hexane before derivatization with PFB-Cl. The organic layer was then removed and evaporated to dryness before dissolution with hexane for GC/MS analysis. Calibration curves for each analyte showed linearity in the range of 255000 ng/mL (r2 ≥ 0.997). Recoveries ranged from 88 to 99, with the precision of recoveries typically ≤5%. The LOD values ranged from 7 to 28 ng/mL, and the LOQ values ranged from 23 to 94 ng/mL. At least four ions were available for each analyte for confirmation of identity by MS.

The urine specimens of numerous athletes were found to be positive for mephentermine both in-competition and out-of-competition in Taiwan. The donor of one specimen claimed she had only taken Mucaine® (contains oxethazaine) for relieving symptomatic peptic ulcer and gastritis. Oxethazaine is not included in the prohibited list of the World Anti-Doping Agency; however, its metabolized compounds, mephentermine and phentermine, are included in that list. This study applied LC–MS–MS to analyze the excretions of three volunteers who ingested oxethazaine and presented positive results for mephentermine and/or phentermine. Thus, oxethazaine is the source of mephentermine and phentermine. Moreover, the results showed that 48 brands of gastric medicines containing oxethazaine were legally imported or locally manufactured in Taiwan, information which could be useful for limiting the misuse of oxethazaine by athletes. The data suggested that the sports associations should warn athletes about the risks of taking oxethazaine.

Nonmedical use of prescription stimulants such as phentermine (PT) has been regulated by law enforcement authorities due to its euphorigenic and relaxing effects. Due to high potential for its abuse, reliable analytical methods were required to detect and identify PT and its metabolite in biological samples. Thus a dilute and shoot liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for simultaneous determination of PT, N-hydroxyphentermine (NHOPT) and mephentermine (MPT) in urine. A 5μL aliquot of diluted urine was injected into the LC-MS/MS system. Chromatographic separation was performed by reversed-phase C18 column with gradient elution for all analytes within 5min. Identification and quantification were based on multiple reaction monitoring (MRM) detection. Linear least-squares regression with a 1/x(2) weighting factor was used to generate a calibration curve and the assay was linear from 50 to 15000ng/mL (PT and MPT) and 5 to 750ng/mL (NHOPT). The intra- and inter-day precisions were within 8.9% while the intra- and inter-day accuracies ranged from -6.2% to 11.2%. The limits of quantification were 3.5ng/mL (PT), 1.5ng/mL (NHOPT) and 1.0ng/mL (MPT). Method validation requirements for selectivity, dilution integrity, matrix effect and stability were satisfied. The applicability of the developed method was examined by analyzing urine samples from drug abusers.

This study compared the effects of intravenous infusions of ephedrine and mephentermine for maintenance of maternal arterial pressure and neonatal outcome in pregnant women receiving subarachnoid block for lower segment Caesarean section. Sixty patients who developed hypotension following subarachnoid block for Caesarean section were randomly divided into two groups of 30 each to receive an intravenous infusion of ephedrine or mephentermine. Hypotension was defined as a decrease in systolic blood pressure of > or = 20% from the baseline value or an absolute value of

We previously showed that fresh synthesis of nitric oxide (NO) mediates transport of substrates across uptake -1, norepinephrine (NE), tyramine (T), mephentermine, ephedrine, imipramine and atomoxe...

This study was designed to determine the minimum effective dose (ED50) of mephentermine for prevention of post-spinal hypotension in women undergoing elective caesarean section. Dixon's up-down method of sequential allocation was used to determine the patient's dose of vasopressor drug. In our previous study, mephentermine appeared to be much more potent than ephedrine, so the present study was conducted using a lower initial dose and smaller dose interval for this vasopressor. Following administration of spinal anaesthesia, a prophylactic infusion of mephentermine was started with 5 mg infused over a period of 30 minutes as the initial dose and a dose interval of 1 mg. The ED50 of mephentermine of 3.7 mg (95% confidence interval 2.4 to 5.7 mg) was much less than that of ephedrine, as calculated in our previous study using the same methodology. Using these values gives a potency ratio of ephedrine to mephentermine of 1:6.8 (95% confidence interval 6.0 to 7.5).

Background: Hypotension following spinal anaesthesia (SA) is a common problem. Vasopressors play an important role in its management. The common approach in the routine clinical setting is immediate action after detection of hypotension rather than as a preventive measure. There are studies which compare bolus and intravenous (IV) infusion in the management of maternal hypotension, but literature about comparison of efficacy of intramuscular (IM) vasopressors is very limited. Hence, this study was planned in elective caesarean deliveries to compare the efficacy of IM phenylephrine, ephedrine, and mephentermine for the maintenance of arterial pressure during SA. Materials and Methods: A prospective, randomized, double-blind study was conducted where 120 parturients belonging to American Society of Anaesthesiologists II undergoing elective caesarean section under SA were evaluated after being randomized into four groups receiving either preemptive phenylephrine 4 mg IM, ephedrine 45 mg IM, mephentermine 30 mg IM, or normal saline 0.9% 2 ml IM as placebo, immediately following SA. The mean arterial blood pressure and heart rate were primarily evaluated and any other complications were also recorded. Results: It points toward significantly decreased incidence of hypotension in phenylephrine group compared to the other groups (P = 0.034). The incidence of rescue IV ephedrine requirement was maximum with the placebo group, least with mephentermine compared to ephedrine and placebo group. However, there was no statistical difference between the groups with respect to doses of IV ephedrine used (P = 0.08). Maternal nausea, vomiting, and newborn Apgar score were also comparable. Conclusion: All the vasopressors are effective in reducing the severity of hypotension, though phenylephrine was found to be better for the prevention of hypotension.

Background: Spinal anesthesia is often used for both elective and emergency cesarean section. One earlier study has shown that intrathecal levobupivacaine given in L 3-4 space did not provide satisfactory intraoperative analgesia in all parturients. We assume that the same dose may work if given in L 2-3 intrathecal space, especially in our population with shorter stature. Materials and Methods: After Institutional Ethical Committee approval, 100 parturients (American Society of Anesthesiologists I-II, aged 18-40 years) and after obtaining written informed consent to received spinal anesthesia for cesarean section were randomized into four groups: Group I (0.5% hyperbaric bupivacaine 7.5 mg in L 2-3 intrathecal space), Group II (0.5% hyperbaric levobupivacaine 7.5 mg in L 2-3 intrathecal space), Group III (0.5% hyperbaric bupivacaine 10 mg in L 3-4 intrathecal space), and Group IV (0.5% hyperbaric levobupivacaine 10 mg in L 3-4 intrathecal space), respectively. Hypotension (systolic blood pressure 20% from baseline) was treated with injection mephentermine 3 mg intravenous (iv) increment (s). For the ethical reason, inadequate analgesia was treated with 0.5 mg/kg iv ketamine. Statistical analysis was performed using the SPSS version 20 software windows. A P < 0.05 was considered significant. Results: Time to onset of sensory block was faster in 0.5% hyperbaric levobupivacaine 10 mg given in L 3-4 intrathecal space (Group IV P = 0.013). No significant difference was found in time to reach maximum block level (T 4 -T 6 ). Median peak sensory block level was significantly lower in Group II as compared with other group T 6 versus T 4 ; F = 106.159; P < 0.001). Time to regression by two dermatomes was significantly shorter with a lower dose of either bupivacaine or levobupivacaine given at L 2-3 intrathecal space (P = 0.028). The degree of motor block or motor block regression was similar in all the groups. Intraoperative rescue analgesia was required in 20% of patients in Group II (levobupivacaine 7.5 mg in L 2-3 ); it was 4% in each of the remaining groups (P = 0.082). Injection mephentermine used was 24%, 32%, 48%, and 28%, respectively, in Group I to IV though it did not reach statically significance. Conclusion: Levobupivacaine 7.5 mg can be used in lower segment cesarean section when given in L 2-3 space. Onset is faster, and hemodynamic stability is more with levobupivacaine. At the higher dose, the duration of action bupivacaine seems to be longer.

Oxethazaine, an over-the-counter (OTC) antacid, is a precursor of phentermine, which is the most abused anorectic by methamphetamine users in Korea. However, no studies have investigated the abuse potential of oxethazaine. Therefore, we examined and compared the consequences of oxethazaine and phentermine treatment on animal models of conditioned place preference (CPP) and self-administration. Furthermore, oxethazaine and its metabolites in rat plasma were monitored using liquid chromatography-tandem mass spectrometry (LC-MS/MS) after oxethazaine administration, and compared with phentermine itself after phentermine administration to clarify the relationship between phentermine production by oxethazaine ingestion and the possible oxethazaine dependence. Oxethazaine metabolites were also determined by LC-MS/MS in rat hair after oxethazaine administration to investigate the possibility of phentermine detection in hair from oxethazaine abusers. In the behavioral experiment, phentermine (3mg/kg) produced CPP in mice while oxethazaine (5, 10, and 15mg/kg) did not. Moreover, phentermine (0.25mg/kg/infusion) was self-administered by rats at 80% of free-feeding weight, whereas oxethazaine was not. In the analytical study, mephentermine and phentermine, both oxethazaine metabolites, were detected below the limit of quantitation or not detected in both plasma and hair from rats that had ingested oxethazaine (10mg/kg, single dose or for 2weeks). On the other hand, phentermine was detected in plasma and hair samples from rats that had ingested phentermine (10mg/kg, single dose or for 2weeks). Consequently, phentermine induced significant rewarding effects, but oxethazaine did not. Presumably, either oxethazaine does not have any abuse potential or oxethazaine metabolism to phentermine does not result in a pharmacologically active level of psychostimulant in the body. Furthermore, phentermine was not a major metabolite in hair obtained from oxethazaine abusers, which should make it possible to differentiate between chronic oxethazaine and phentermine users.

1. The N-demethylation of mephentermine (MP), p-hydroxymephentermine (p-hydroxy-MP) and N-hydroxymephentermine (N-hydroxy-MP), to produce phentermine (Ph), p-hydroxyphentermine (p-hydroxy-Ph) and N-hydroxyphentermine (N-hydroxy-Ph), and the p-hydroxylation of MP and Ph, to produce p-hydroxy-MP and p-hydroxy-Ph, were examined using rat liver microsomal preparations containing NADPH. Microsomal reduction of N-hydroxy-Ph to Ph was also examined using various cofactors. In addition, enzymic system for the N-demethylation and p-hydroxylation were examined using various inhibitors. 2. N-Hydroxy-MP demethylation to N-hydroxy-Ph proceeded at a rate almost 10-fold faster than other reactions. MP demethylation to Ph, MP oxidation to P-hydroxy-MP, Ph oxidation to p-hydroxy-Ph proceeded at similar rates, whilst p-hydroxy-MP demethylation to p-hydroxy-Ph was catalysed at the slowest rate. Microsomal reduction of N-hydroxy-Ph to Ph required NADH, and the activity was similar to that of MP oxidation to p-hydroxy-MP. 3. N-Demethylation of MP, p-hydroxy-MP and N-hydroxy-MP were inhibited not only by inhibitors of cytochrome P450, but also by methimazole, an inhibitor of the FAD-monooxygenase system. p-Hydroxylations of MP and Ph were inhibited only by inhibitors of cytochrome P450.

This study compared the effects of intravenous infusions of phenylephrine and mephentermine on the prevention of maternal hypotension and neonatal outcome in patients receiving spinal anaesthesia for caesarean section. Sixty ASA 1-2 patients with term, uncomplicated singleton pregnancy undergoing caesarean section under spinal anaesthesia were randomly divided into two groups of 30 each, to receive a prophylactic intravenous infusion of either phenylephrine or mephentermine. The incidence of hypotension was statistically similar in the two groups. However, in patients receiving phenylephrine, 7 (23%) developed bradycardia and 6 (20%), reactive hypertension. Neonatal outcome, in terms of Apgar scores and umbilical artery pH, was similar in both the groups. To conclude, phenylephrine and mephentermine infusions are equally effective in preventing post spinal hypotension in patients undergoing caesarean section and are associated with a similar neonatal outcome.

Hypotension is common following spinal anesthesia. Various vasopressors have been indicated to prevent it. The study compares three such agents namely phenylephrine, ephedrine and mephentermine.The study included 90 patients undergoing elective and emergency cesarean section who developed hypotension following subarachnoid blockade. Parturient were randomly divided into three groups each group had 30 patients. Group P received bolus of Phenylephrine 25 microgram, where as group E received Ephedrine 5mg and Group M received Mephentermine 6mg.It was found that rise of blood pressure was significantly higher in case of phenylephrine group in first six minutes, after the bolus, there was significant reduction in the heart rate in phenylephrine group, but there was tachycardia following administration of bolus ephedrine and mephenteramine. Neonatal APGAR score were similar in all three groups.All three drugs maintained hemodynamics within 20 percent of the baseline values on intravenous administration.

INTRODUCTION: Hypotension is common following spinal anesthesia. Various vasopressors have been indicated to prevent it. The study compares three such agents namely phenylephrine, ephedrine and mephentermine. METHODS: The study included 90 patients undergoing elective and emergency cesarean section who developed hypotension following subarachnoid blockade. Parturient were randomly divided into three groups each group had 30 patients. Group P received bolus of Phenylephrine 25 microgram, where as group E received Ephedrine 5mg and Group M received Mephentermine 6mg. RESULTS: It was found that rise of blood pressure was significantly higher in case of phenylephrine group in first six minutes, after the bolus, there was significant reduction in the heart rate in phenylephrine group, but there was tachycardia following administration of bolus ephedrine and mephenteramine. Neonatal APGAR score were similar in all three groups. CONCLUSIONS: All three drugs maintained hemodynamics within 20 percent of the baseline values on intravenous administration. Keywords: APGAR, ephedrine, hypotension, mephentermine, phenylephrine, spinal anesthesia.

A GC method was developed for the identification and quantitation of eight sympathomimetic amines in urine, i.e., amphetamine, methamphetamine, mephentermine, ephedrine, pseudoephedrine, methylenedioxyamphetamine, methylenedioxymethamphetamine, and methylenedioxyethylamphetamine. Methoxyphenamine was used as the internal standard (IS). The assay is rapid, sensitive, and simple to perform. It involves a liquid-liquid extraction procedure with simultaneous in-solution derivatization of the organic layer with pentafluorobenzoyl chloride (PFB-CI), followed by GC/MS analysis. These derivatives and the IS were extracted from 1 mL alkaline urine into hexane before derivatization with PFB-CI. The organic layer was then removed and evaporated to dryness before dissolution with hexane for GC/MS analysis. Calibration curves for each analyte showed linearity in the range of 25-5000 ng/mL (r2or = 0.997). Recoveries ranged from 88 to 99%, with the precision of recoveries typicallyor = 5%. The LOD values ranged from 7 to 28 ng/mL, and the LOQ values ranged from 23 to 94 ng/mL. At least four ions were available for each analyte for confirmation of identity by MS.

1. Intestinal metabolites produced in the incubation (0-24 h) of mephentermine (MP), phentermine (Ph), N-hydroxymephentermine (N-hydroxy-MP), N-hydroxyphentermine (N-hydroxy-Ph), p-hydroxymephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) with male Wistar rat intestinal contents under N2 were examined by g.l.c. and g.l.c.-electron impact (EI) mass spectrometry. Metabolites produced in the anaerobic incubation of bile from rats given MP, with the intestinal contents were also examined. In addition, urinary and biliary metabolites of p-hydroxy-MP and p-hydroxy-Ph dosed orally to rat were examined. 2. Metabolites in the anaerobic incubation of N-hydroxy-MP and N-hydroxy-Ph were MP and Ph, and Ph, respectively. No metabolites were detected in the incubation of MP, Ph, p-hydroxy-MP and p-hydroxy-Ph. 3. p-Hydroxy-MP and p-hydroxy-Ph (major), and MP and Ph (minor) were detected when bile from rats given MP was incubated with intestinal contents. 4. Unchanged p-hydroxy-MP, and conjugates of p-hydroxy-MP and p-hydroxy-Ph, were detected in the 24-h urine of rats dosed with p-hydroxy-MP, which accounted for about 3, 72 and 1% dose, respectively. Unchanged p-hydroxy-Ph and conjugated p-hydroxy-Ph were detected in the 24-h urine of rats dosed with p-hydroxy-Ph, which accounted for about 4 and 68% dose, respectively. 5. Conjugated p-hydroxy-MP and conjugated p-hydroxy-Ph, which accounted for about 3% doses, were detected in the 24-h bile of rats dosed with p-hydroxy-MP and p-hydroxy-Ph.(ABSTRACT TRUNCATED AT 250 WORDS)

The dosages and potency of intravenous mephentermine for prevention of post-spinal hypotension are not available in English literature. This study was designed to determine the minimum effective dose (ED50) of mephentermine and to compare its potency with that of ephedrine for prevention of post-spinal hypotension in parturients undergoing caesarean section. Dixon's up-down method of sequential allocation was used for vasopressor doses. Following administration of spinal anaesthesia, patients received a prophylactic infusion with 50 mg infused over a period of 30 minutes as the initial dose and dose intervals of 5 mg, of either ephedrine or mephentermine. The ED50of ephedrine was 25.0 mg (95% CI 15.5 to 40.4 mg). For mephentermine, the up-down method was abandoned due to the success of the minimum dose possible but the ED50appeared to be less than 5 mg. In conclusion, the minimum effective dose of mephentermine is much less than that of ephedrine for prevention of post-spinal hypotension. Another trial with a lower starting dose and smaller dose interval of mephentermine is required to determine the potency ratio of mephentermine and ephedrine.

Context Efforts to find a better adjuvant in regional anesthesia have been underway since long. Dexmedetomidine and sodium bicarbonate have been proven to be effective in providing the same pharmacological benefit through two different mechanisms of action. In this study, we sought to investigate which is superior between the two. Aims The aim of the study was to compare the efficacy of dexmedetomidine and sodium bicarbonate as adjuvants to lidocaine in epidural anesthesia. Settings and design This was a prospective, randomized, double-blind study. Materials and methods Sixty patients scheduled for lower-limb trauma orthopedic surgeries under epidural anesthesia were divided into two groups group D and group S, with 30 patients in each. Patients in group D received 12.5 ml of 2% lidocaine+dexmedetomidine 0.5 mg/kg in 1.5 ml solution, making a total volume of 14 ml. Patients in group S received 12.5 ml of 2% lidocaine+1.5 ml of 7.5% sodium bicarbonate, making a total volume of 14 ml. Onset, time for peak sensory level, time for two-segment regression, and the total mephentermine consumed to maintain the hemodynamics were recorded, tabulated, and statistically analyzed. Results The onset of sensory block was quicker in group D. The time for attaining peak sensory level and the mephentermine consumption was nearly the same in both groups. The time for two-segment regression was more in group D than in group S. Conclusion Dexmedetomidine is more effective than sodium bicarbonate in hastening the onset and prolonging the duration of blockade when used as an adjuvant to epidural lidocaine.

1. p-Hydroxymephentermine (p-hydroxy-MP) and p-hydroxyphentermine (p-hydroxy-Ph) were isolated as hydrochlorides from urine of male Wistar rats repeatedly dosed with mephentermine (MP). In addition, p-hydroxy-Ph was isolated as the hydrochloride from urine of the rats dosed with phentermine (Ph). 2. These results substantiate previous indications that p-hydroxylation of MP and Ph was a primary metabolic reaction in the rat.

Here is reported an unusual case of substance dependence with buprenorphine, mephentermine, & promethazine. This combination taken through intramuscular route produced a relatively mild & delayed abstinence syndrome with features viz. increased sleep and appetite in the patients. The neurophysiological basis for use of this rare form of additive (mephentermine) with buprenorphine is speculated.

BackgroundIntrathecal ketamine produces a short period of analgesia with stable haemodynamics. Midazolam with bupivacaine prolongs the duration of analgesia when administered intrathecally but does not prevent hypotension. The objective of this study was to assess the effect of a combination of intrathecal bupivacaine, ketamine and midazolam on the duration of analgesia and haemodynamic parameters.MethodsA prospective, randomized, double-blind study was carried out in 60 ASA I and II patients undergoing lower limb surgery under spinal anaesthesia. Patients were divided into three groups of 20 each. Patients in all the three groups received 3 mL of hyperbaric bupivacaine (0.5%) intrathecally. In addition, patients in Groups II and III received intrathecal ketamine (0.1 mg kg−1) and the same dose of ketamine along with midazolam (0.02 mg kg−1), respectively. All patients were evaluated for block characteristics, duration of pain-free period, total rescue analgesic requirement in the 24-h postoperative period, total dose of mephenteramine to treat hypotension and any central or neurological complication.ResultsNo patients in Group II required mephenteramine while 40% of patients in Group I and 10% in Group III required mephenteramine to maintain blood pressure after spinal anaesthesia. The mean ± standard deviation duration of pain-free period was 331.5 ± 89.9, 369.7 ± 124.2 and 730.5 ± 81.5 min in Group I, II and III, respectively. The pain-free interval was significantly greater in Group III compared to Groups I and II (P < 0.001). No patient had any complications.ConclusionA low dose of midazolam and ketamine with bupivacaine intrathecally results in prolonged analgesia and less haemodynamic fluctuations. However, the safety of this combination needs to be proved before its use in clinical practice.

A total of 200 cases were evaluated for post-spinal hypotension during caesarean section in TU teaching hospital Maharajgunj. Hypotension was reported in 76 (38%) cases. P value >0.05.The Maximum dose of mephentermin given was 30mg and minimum was 6mg. One patient had Spinal block as high as T1 sensory level. Another patient had severe drop of blood pressure followed by unrecorded blood pressure and pulse which was treated with endotracheal intubation, 100%oxygen and vasopressor (Mephentermine). Severe bradycardia (heart rate

Although mephentermine (Termin) and ephedrine are commonly used drugs for the treatment of hypotension during anesthesia but their abuse have markedly increased, especially in the young population due to its stimulant properties. Here, we report a case of 23-year-old man with a history of chronic mephentermine abuse, posted for Achilles tendon repair under spinal anesthesia. During intraoperative period, spinal induced hypotension showed unusual resistance to ephedrine boluses and was managed by using directly acting vasoconstrictor, that is, phenylephrine.

Dear Editor, Mephentermine is an amphetamine-derived phenethylamine which shares a strong chemical similarity with both methamphetamine and the resulting stimulant actions of the alpha and beta adrenoceptors. It has been proposed that phentermine, which is a main metabolite of mephentermine, acts by inhibiting

Background Substance abuse is a serious health concern. This report presents the case of a 22-year-old Brazilian man with a history of mephentermine use who fulfils all the criteria for chemical dependence listed by ICD-10. Mephentermine is a sympathomimetic agent derived from methamphetamine which, in Brazil, is restricted to veterinary use. Case description The subject used the substance at a high dose (120 mg) to improve his physical performance while working out at a gym. His symptoms included anorexia and insomnia. After days of intense activity, he felt fatigue and soreness. A physical examination revealed scars on both forearms from the injections and a psychological examination revealed moderate speech and motor agitation. Conclusions Cases such as this may be common among the general public. They should have some bearing upon medical practice and public health policies involving drugs.

A laboratory study interested in the analysis of human hair for drugs-of-abuse was conducted to determine if drugs could be detected and quantified from hair. Supercritical fluid extraction (SFE) techniques followed by GC-MS analysis were applied to extract amphetamines from hair. The group of amphetamines included methylenedioxyamphetamine (MDA), methylenedioxymetamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA) and internal standard mephentermine (MP). To validate information on amphetamine use in hair, powdered hair samples free from drugs were collected and soaked in a known amphetamine standard solution. Authentic fortified case hair samples taken from known drug users known to have consumed amphetamines were also analyzed for amphetamine. Results from this study show that amphetamine use can be detected in spiked and authentic fortified human hair using SFE techniques for qualitative and quantitative reproducible results.