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Indomethacin (I) pharmacokinetics was evaluated in 6 premature infants who received the drug for treatment of patent ductus arteriosus. Administered by oral or rectal route, I (0.2 mg/kg/24 h X 3) was promptly absorbed with peak plasma concentrations attained within 1 and 3 h. The elimination of I appeared to follow two compartment open model kinetics, with terminal plasma half-lives ranging from 30 to 90 h. Apparent plasma clearance values were between 0.076 and 0.335 ml/min/kg. Ductal closure was observed in 4 of the 6 infants. Data point to a possible relationship between therapeutic effects and I plasma concentrations.

To assess the relationships between the efficacy and blood levels of progabide (PGB) and its active acidic metabolite (PGA) in epileptics, observations were carried out on 89 adult patients with epilepsy of different types and severity in two groups at Paris and Genoa. The Paris group received progabide in addition to other antiepileptic drugs for 6 to 12 months, whereas the Genoa group received a polytherapy for the first two months then a monotherapy with progabide alone for up to 22 months. Blood levels from monthly or bimonthly samples were significantly higher in both surveys when there was a satisfactory therapeutic response and levels were also higher in those receiving monotherapy suggesting a synergism among antiepileptic drugs. It is concluded that therapeutic drug monitoring of PGB and PGA blood concentrations may be a useful technique in optimizing progabide treatment in epileptic patients.

Haloperidol plasma concentrations were determined in psychotic patients to whom the drug was given by three different routes of administration (i. v. perfusion, intramuscularly and orally). When measured 15 hours after the last administration, a significant difference (p < 0,001) was found in the steady state plasma concentration between the oral and the i.m. route. The values were higher after intramuscular administration and were subject to less interindividual fluctuation than after the oral. The reduction in plasma levels after oral administration in respect to i.m. were in accordance with the bioavailability of haloperidol. The opportunity of switching from oral to intramuscular treatment is discussed.

The pharmacokinetics of betaxolol was studied in 8 middle-aged (40-60 years) subjects after oral (20 mg) and intravenous (10 mg) administration. The principal parameters were almost identical to those observed in young healthy volunteers. The recommended therapeutic regimen, a single daily dose of 20 mg, appears well suited for middle aged, hypertensive patients.

Similar degree (65-66%) of binding of zolpidem (0.1 microgram/ml) was found with physiological concentrations of isolated human albumin (40 g/l) or alpha-1-acid glycoprotein (1 g/l). Zolpidem binding was studied in plasma from 6 healthy subjects, 12 patients with renal failure, 12 patients with liver cirrhosis and 12 chronic uremics maintained on hemodialysis as well as in 12 serum samples from the placental cord. The unbound fraction (mean +/- s.e.m.) was 8.1 +/- 0.2% (healthy volunteers), 10.8 +/- 0.4% (renal failure), 11.3 +/- 0.7% (liver cirrhosis); 14.9 +/- 1.0% (before hemodialysis); 9.8 +/- 0.4% (after hemodialysis) and 13.2 +/- 0.9% (placental cord). All values, except those after hemodialysis, were significantly different (Dunnett's test) from those of the volunteers. Hemodialysis significantly increased the binding of zolpidem in plasma. The kinetics of protein binding of zolpidem were investigated in plasma samples from 3 healthy subjects. The average number of binding sites was 1.83 x 10(-7) mol per gram protein and the average association constant was 4.49 x 10(5) M-1.

Low-molecular weight dialysable peptides, obtained by plasmin degradation of purified bovine fibrinogen preparations, have been shown to increase the chronotropic activity of isolated rat atria. This effect was dose dependent and was inhibited by inhibitors of glycolysis (NaF and 2-deoxy-D-glucose), but not by an inhibitor of oxidative phosphorylation (2, 4-dinitrophenol). Propranolol, a beta-blocking agent, was also ineffective. Fibrinogen-derived peptides increased both cAMP levels and phosphorylase alpha activity in stimulated atria. The increase of these parameters was transitory and appeared to precede the occurrence of the positive chronotropic effect. In the test situation used, the biochemical and functional modifications induced by fibrinogen-derived peptides were similar to those induced by glucagon.

1. In patients with mild or moderate essential hypertension, oral propranolol, given in incremental doses, produced a moderate but significant lowering of blood pressure which was correlated with the concentration of propranolol in plasma. 2. Propranolol also reduced plasma renin activity (PRA) in the supine posture, on standing and after intravenous frusemide. However, 'supine' and 'frusemide' PRA values were markedly reduced at a plasma concentration of propranolol that had little effect on blood pressure. 3. On administration of propranolol there was little correlation between blood pressure decrease and PRA suppression, and even less between pretreatment PRA values and hypotensive response. 4. It is concluded that in patients with mild and moderate hypertension and low or normal plasma renin activity, suppression of PRA is not an important determinant of the hypotensive response to propranolol.

(+/-)-1-(Isopropylamino)-3-[p-(2-cyclopropyl-methoxyethyl)-phenoxy]-2-propanol HCl (betaxolol, SL 75212) was given to groups of healthy volunteers, 10 mg daily for 7 days followed by 20 mg daily 7 days in one group, and increasing daily doses up to 60 mg/day for a total of 15 days in the other group. The pharmacokinetics were studied during dosing and in the washout period. The pharmacokinetic characteristics were unchanged after repeated doses, T/2 16-22 h, Vd 7.7-8.8 l/kg; clearance 0.28-0.33 l/h/kg.

Propranolol blood and plasma levels were measured after a single oral dose of 40 mg in patients with chronic renal failure, in patients undergoing regular dialysis treatment, and in healthy volunteers. Peak levels were observed in all cases within 1.5 to 3 hours. However, peak blood and plasma concentrations of propranolol in the chronic renal failure group were 2- to 3-fold higher (161 +/- 41 ng/ml) than those observed in the dialysis patients (47 +/- 9 ng/ml) and in the healthy volunteers (26 +/- 1 ng/ml). The apparent plasma clearance was also significantly reduced in the patients with chronic renal failure. The data suggest a reduced hepatic extraction in chronic renal failure patients. A significant increase in the fraction of the dose available to the systemic circulation was also found, together with a modification of apparent plasma half-life and volume of distribution in regular dialysis patients during the dialysis day as compared with the after-dialysis day. No extraction of propranolol by the dialyzer was noticed. Marked fluctuations in propranolol blood concentrations were also observed in patients on regular dialysis following continuous propranolol treatment. The suppressive effect of propranolol on plasma renin activity did not fully correlate with the hypotensive effect of the drug. On the basis of the reported data, propranolol should be used with great caution and at low doses in chronic renal failure.

Plasma levels of haloperidol were monitored in children and teenagers suffering from psychotic episodes and/or abnormal movements (tics and Gilles de la Tourette's syndrome). Steady-state concentrations of haloperidol ranged from 0.7 to 19 ng/ml without any apparent relationship with the administered dose (15--285 micrograms/kg/day) and a 15-fold variability was observed for the same daily dosage. On the contrary, a significant (p < 0.02) relationship was found between the age of the patients and the plasma concentrations to dose ratios, lower values being present in younger patients. Side effects too appeared to be related to plasma levels, with a significant increase (p < 0.01) in incidence for concentrations over 6 ng/ml. In most of the cases suffering from tics and Gilles de la Tourette's syndrome, a positive response was associated with plasma levels of 1--4 ng/ml, while no relationship could be established for the psychotic group. The relevance of monitoring plasma drug levels when prescribing haloperidol in pediatrics is discussed.

The kinetic and clinical profile of betaxolol--a beta 1-selective blocker with 80% to 90% bioavailability and a 16 to 20 hr t1/2--were studied in ten children aged 5 to 13 yr with chronic renal hypertension and mild to severe renal failure. An IV dose of 20 mg of betaxolol per 1.73 m2 body surface area (BSA) was followed by six daily oral doses. Six patients were maintained on combination therapy and four on betaxolol alone; two of these were newly treated. After the intravenous dose, t1/2 (mean +/- SE) was 19.9 +/- 1.7 hr, total clearance 0.30 +/- 0.03 l/kg/hr, and volume of distribution 8.2 +/- 0.7 l/kg. Clearance adjusted for BSA was 7.9 +/- 0.6 l/hr. The t1/2 correlated linearly to serum creatinine levels. After the last dose, peak concentration was 97.4 +/- 7.6 ng/ml, and t1/2 19.4 +/- 2.7 hr. Betaxolol 24-hr blood levels were twice as high as after the first dose. Blood pressure was reduced in two newly treated patients and two patients on combination therapy; previous responses were maintained in the others. The maximum effect was reached after the first dose and was maintained throughout the study week. Our results indicate that betaxolol disposition in children aged 5 to 13 yr with different degrees of renal failure is of the same order as that in young healthy adults, implying that there may be a higher rate of non-renal clearance. Renal failure-induced modification led to a doubling of the t1/2 in the most severe cases, again as in adult renal patients. There is an antihypertensive effect.

The available data on haloperidol pharmacokinetics and haloperidol plasma level monitoring in neuropsychiatric patients are reviewed and compared with authors' personal observations. It appears that although haloperidol disposition can be described by linear kinetics in volunteers, this is not the case in patients in whom a 7--10-fold variability in plasma levels is observed for the same dosage together with the possibility of saturation kinetics and/or first pass effect. Anticholinergics may interfere with haloperidol absorption, and significant differences in disposition rate and binding have been observed in children and cirrhotic patients. A clear correlation appears to exist between plasma concentrations and side effects or adverse reactions with threshold levels for extrapyramidal syndromes of 6--9 ng/ml. Threshold levels for therapeutic effects vary with syndromes and age. In Gilles de la Tourette syndrome, active levels are of the order of 1--3 ng/ml, whereas in psychotic syndromes levels of 10--15 ng/ml are requested. In mania, a good therapeutic effect has been observed with plasma levels of 2.5--4.5 ng/ml. In general, children require lower plasma levels for the same therapeutic effects. In chronic unresponsive schizophrenic patients, poor drug bioavailability is not the major factor for the lack of response, and the possibility that these patients constitute a nosological subgroup is suggested. Therapeutic drug monitoring of haloperidol appears justified because (a) no direct relationship exists between daily doses and haloperidol steady-state plasma levels; (b) there is a possibility of saturation kinetics at higher doses; (c) commonly associated drugs or diseases may alter the kinetic profile of the drug; (d) drug disposition is faster in children than in adults; (e) optimal plasma concentration appears to differ in various pathological syndromes and age groups; and (f) side-effects and adverse reactions are clearly related to haloperidol plasma levels.

The kinetics of distribution of di-propranolol (P) to various organs and tissues were studied in the rat after an i.v. dose of 2 mg/kg. The disposition of the drug can be adequately described by a two-compartment open model with a distribution half-life of 4.8 min, a terminal blood half-life of 63 min and an apparent volume of distribution beta of 8.5 liters/kg. Higher tissue concentrations were found to be present in heart, brain and kidney. Although the disappearance rate of P from abdominal aorta, muscles, adipose tissue and whole brain paralleled that of blood, the elimination rate constant for atria and kidney was significantly reduced suggesting a specific binding of P. After an i.v. dose of 5 mg/kg, P distributed rapidly to various brain areas following a vascularity pattern with higher concentrations in cortical areas of earlier times. An equilibrium between various brain areas was observed at 2 to 3 hr after dosing. There was a parallel decay of P concentrations in the blood and in cortical areas, whereas the elimination constants were significantly reduced for hypothealamic nuclei and the medulla (C1 and C2), suggesting again a specific binding. The data show that distribution, uptake and tissue binding of P in various peripheral organs and discrete brain areas is not a uniform process and they could give a partial explanation on the discrepancies observed clinically between the pharmacodynamics and pharmacokinetics. The data also suggest the possibility of specific P binding sites in heart, kidney and brain which could be of relevance for its mode of action.

Five, lactating, healthy white women were treated with a single 20 mg tablet of zolpidem 3-4 days after the delivery of a full term baby. The drug was administered at 20.00 h, 30 min after dinner, and milk samples were collected before and 3, 13 and 16 h. Venous blood 5 ml was taken before and 1.5, 3, 13, 16 h after zolpidem administration. The apparent elimination half life, estimated from plasma zolpidem concentrations was 2.6 h. The amount of zolpidem excreted in the milk at 3 h ranged between 0.76 and 3.88 micrograms, which represented 0.004 to 0.019% of the administered dose; no detectable (below 0.5 ng/ml) zolpidem was found in the milk at subsequent sampling times. The ratio of the zolpidem concentrations in breast milk and plasma at 3 h was 0.13. The apparent breast milk clearance of zolpidem, calculated from the ratio of the total amount of zolpidem excreted in milk to its AUC in plasma was 1.48 ml/h. The results show that the excretion of zolpidem in human milk is very low (below 0.02%) and that most of it takes place during the first 3 h following drug intake.

Eighteen newborns (gestational age 28 to 42 weeks and post-natal age 0.5 to 44 days) suffering from convulsions not controlled by phenobarbital were treated with clonazepam 0.1 mg/kg (8 cases) or 0.2 mg/kg (10 cases) administered by slow intravenous infusion. The plasma half-lives in these "phenobarbital pretreated neonates' were of the same order of magnitude as those reported in adults (20-43 h). Post-natal age did affect clearance, which was 50-70% less than in adults and older children. At the end of the infusion period, plasma clonazepam ranged from 28 to 117 ng/ml in the 0.1 mg/kg group and from 99 to 380 ng/ml in the 0.2 mg/kg group. In the former an immediate therapeutic response was observed in 7 out of 8 cases, and in the latter a significant and somehow delayed effect on convulsion was present only in 6 cases. The data suggest that optimal therapeutic response might already have been achieved with the 0.1 mg/kg dose. Higher doses and toxic concentrations of clonazepam may be detrimental to complete control of seizures and may expose the newborn to an unnecessary risk of adverse events.

The distribution and kinetics of D,L-propranolol in rat brain were examined after an intravenous injection of the drug. Measurements in brain areas and blood were performed by means of a sensitive and specific gas liquid chromatographic method. The disappearance rate in cortical areas paralleled that in blood. However D,L-propranolol decreased at a slower rate in hypothalamic and medullary nuclei. Since propranolol is believed to have central hypotensive effects, its retention by certain central nuclei involved in blood pressure regulation is of interest.

Over a 4-year period, 63 premature babies presenting with patent ductus arteriosus were treated with indomethacin at two different dosage levels (0.1 and 0.2 mg/kg). For all infants the permanent closure rate was 68% (56% with 0.1 mg/kg and 75% with 0.2 mg/kg - n.s.) and the positive response rate (i.e. permanent and transient closure) 84%. There was no difference between the two dosages in the incidence of side-effects, particularly on diuresis, and in mortality and morbidity rates; the overall mortality rate was 31%. Pharmacokinetic studies performed in 51 cases did not show any difference related to indomethacin dosage. The changes observed after 2 or 3 doses resulted from improvement in haemodynamics. This study confirms the effectiveness of indomethacin in the treatment of patent ductus arteriosus and suggests an advantage for the 0.2 mg/kg dose.

1 The effects of betaxolol (SL 75212), a new beta-adrenoceptor blocking agent, on the cardiovascular response to exercise have been studied in six normal subjects after placebo and single oral doses of 5, 10, 20 and 40 mg given double-blind in a randomized sequence. 2 All doses reduced exercise heart rate, with a significant reduction persisting to 23 h after doses of 20 mg and 40 mg. Systolic blood pressure on exercise was reduced after all doses, with a reduction continuing to 23 h after doses of 10 mg and above. 3 The mean elimination half-life of SL 75212 was 17.5 +/- 3.9 h. The plasma clearance ranged from 0.15--0.48 1 kg-1 h-1 and the volume of distribution from 5.8--13 1 kg-1. 4 There was a significant correlation between the peak blood levels and change in exercise heart rate (r = 0.53, P less than 0.05) and between the area under the blood concentration curve and the effect of the exercise heart rate (r = 0.55, P less than 0.01).

The efficacy and the safety of betaxolol (BTX), a cardio-selective adrenoceptor blocking agent with a long half life, was tested in 22 hypertensive pregnant women. BTX doses varied from 10 to 40 mg/day. BTX given as monotherapy (n = 19) or associated to dihydralazine (n = 3) led to a satisfactory control of arterial blood pressure (ABP). In the mother, the drug was very well tolerated. (table; see text) The fetal safety, evaluated by mean of cardiotocography and echography was also satisfactory. Fetal heart rythm was significantly slowed following first intake of BTX and remained stable until delivery; there was only one case of intra-uterine growth retardation pre-existing to the pharmacological treatment. Nine deliveries were ceasarian [fetal distress (n = 1); poor control ABPI (n = 1); obstetrical reasons (n = 7)]. Seventeen neonates were full-term and six were premature (twins included). The state of neonates at birth was very satisfactory (Apgar at 5 minutes greater than 9 in 21/23). Glycemia less than 1.66 mmoles/1 in two neonates, was normal within 24 to 48 hours. In conclusion, BTX was very efficacious in controlling increased blood pressure in pregnant women and its safety in the mother, the fetus and the newborn was very good.

Nomifensine pharmacokinetics were determined in healthy volunteers after the oral administration of 50 mg of the drug. Peak plasma levels of 95-177 ng/ml were attained within 1 to 4 hrs, and the apparent plasma half-lives ranged from 3.3 to 4.9 hrs. Assuming 100% bioavailability the drug has a relatively large apparent volume of distribution. From these findings it appears that the pharmacokinetics profile of nomifensine is considerably different from those of other known antidepressants. Implications for dosages schedules are discussed.

The concentrations of acebutolol and of its main active metabolite diacetolol in milk and plasma were studied in 7 hypertensive mothers treated with acebutolol, a cardioselective beta-adrenoceptor blocking agent. Clinical monitoring on their newborn babies was also done, as well as measurement of plasma level of the drug in them. The ratio between milk and plasma concentrations ranged from 1.9 to 9.2 for acebutolol and from 2.3 to 24.7 for diacetolol, and in any given milk sample, the diacetolol concentration was always higher than that of acebutolol. In a newborn infant, plasma concentrations of the two transplacentally acquired substances was raised when breast feeding started and remained high. Clinical signs of pharmacological beta-blockade were observed. Evaluation of the iatrogenic risk shows that pharmacologically active amounts of acebutolol might be received by a neonate if the daily maternal dosage exceeds 400 mg/day and/or renal function in the mother is impaired.