Amisulpride binds selectively to dopamine D(2) and D(3) receptors in the limbic system. Low doses of amisulpride preferentially block presynaptic D(2)/D(3)-dopamine autoreceptors, thereby enhancing dopaminergic transmission, whereas higher doses block postsynaptic receptors, thus inhibiting dopaminergic hyperactivity. Amisulpride is clinically effective on the negative symptoms of acute schizophrenia exacerbations at low dosages (50-300 mg/day), and also on the positive symptoms of the disease at high dosages (400-800 mg/day). Nineteen clinical studies involving 358 volunteers have investigated the pharmacokinetics, pharmacodynamics and tolerability of amisulpride. Amisulpride shows linear pharmacokinetics, a bioavailability of 48%, low protein binding (17%) and an elimination half-life of approximately 12 h. It is predominantly eliminated in the urine as the parent compound. It exhibits no significant detrimental effects in psychometric or memory tests up to the dose of 400 mg/day, inducing only mild impairment at high doses, whereas EEG data suggest an alertness-enhancing effect at low doses (

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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.

Zolpidem is an imidazopyridine which binds specifically to the omega 1 receptor. Zolpidem demonstrated potent hypnotic activity at a dose of 10 mg. Pharmacodynamics and pharmacokinetics of zolpidem were studied after daytime administration in a randomised, double-blind, placebo-controlled, cross-over trial. Single doses of zolpidem (10 mg IV as a 3-min infusion and 20 mg orally) and placebo were firstly tested in 12 healthy young male volunteers. Two other doses (5 mg IV and orally) were then evaluated in 6 out of these 12 subjects. EEG (4 leads = Fp2-T4, Fp1-T3, T4-02 and T3-01), and Stanford Sleepiness Scale (SSS) were measured up to 5 h postdosing. Blood samples were also collected up to 24 h. The time course of the hypnotic activity of zolpidem, assessed by the score obtained on SSS, showed a similar profile whatever the route or the dose administered: slightly earlier onset after IV but sedative scores were reached at 30 min and the effect peaked between 1 and 1.5 h and lasted 4 h in both conditions. The EEG profile of zolpidem was characterised by a decrease of alpha activity and an increase in delta and in beta activity. The effect on beta activity was marked within the first hour and then disappeared. The time course of delta and alpha activities indicated a rapid onset (10 min after IV, 30 min after oral route) and a duration of 3-4 h. The amplitude of these relative EEG changes and their duration were independent of the route of administration and the dose administered. AUC and Cmax increased proportionally to the administered dose and elimination half life (2h), clearance and volume of distribution did not change according to the dose or the route of administration.(ABSTRACT TRUNCATED AT 250 WORDS)