Single dose pharmacodynamics of thioridazine and remoxipride in healthy younger and older volunteers

Phenothiazines are widely used in older patients, but little experimental work has been carried out in this age group. Two groups of healthy volunteers, a younger group (Y: six males and six females, aged 20-42 years) and an older group (O: six males and eight females, aged 65-77 years) took part in a randomized double-blind three-period crossover study in which they received by mouth single doses of thioridazine (Y: 50 mg; O: 25 mg) remoxipride (Y: 100 mg; O: 50 mg) or placebo. Measures of central nervous system (CNS) and haemodynamic function were carried out before drug administration and at 1.5-h intervals up to 9 h post-dose, and blood samples were collected over a 24-h period. No significant differences in dose-corrected pharmacokinetic variables were found between the two groups. There was evidence of marked CNS depressant effects of thioridazine from both objective and subjective measures. The effects for remoxipride were similar, though generally less marked. After allowance was made for dose, there was little indication of any difference in degree of CNS depression between the two age groups. Haemodynamic measures showed orthostatic reductions in blood pressure with thioridazine which were particularly marked in the older group, who also showed lower compensatory increases in pulse rate. These results indicate potential problems with orthostatic hypotension with thioridazine in older patients. CNS depression may also be a problem, especially in patients with compromised cholinergic function.

The effects of remoxipride and chlorpromazine on eye movements and psychomotor performance in healthy volunteers

Fifteen healthy male volunteers received single doses of 100 mg immediate release remoxipride (IR), 150 mg controlled release remoxipride (CR), 50 mg chlorpromazine (CPZ), 2 mg lorazepam (LZ), and placebo in a randomised, five-period cross-over study. Both saccadic (SEM) and smooth pursuit eye movements (SPEM) as well as a battery of psychomotor performance tests were assessed at 1.5-h intervals over 9 h following drug administration. The areas under the response-time curves and the maximum effect during the study period were analysed by analysis of variance. The most consistent impairments were produced by LZ. The neuroleptics caused impairments to SEM, and tended to impair critical flicker fusion, continuous attention and both paced and unpaced versions of the digit-symbol substitution test as well as subjective measures of sedation. Only LZ impaired SPEM. Neither paced nor unpaced psychomotor tests distinguished between neuroleptics and benzodiazepines. The low therapeutic doses of IR and CR produced similar impairments to a sub-therapeutic dose of CPZ. Selectivity of pharmacological action does not appear to predict selectivity of effect on psychomotor function.

Interaction study between remoxipride and biperiden

Twelve healthy male volunteers took part in a double-blind randomised cross-over study composed of three treatment sessions: remoxipride 100 mg; remoxipride 100 mg plus biperiden 4 mg; and biperiden 4 mg. Plasma and urine concentrations of remoxipride and biperiden, plasma prolactin levels, salivary flow and adverse events were recorded to assess pharmacodynamic interactions. Remoxipride and biperiden had no effect on each other's plasma concentrations. Biperiden did not affect the urinary recovery or renal clearance of remoxipride. Prolactin levels were unaffected by biperiden but increased following remoxipride administration. Differences in prolactin Cmax and tmax following remoxipride versus concomitant (remoxipride + biperiden) treatment were not statistically significant. However, a slight but statistically significant (P = 0.04) increase in prolactin AUC was observed after concomitant treatment. No significant differences could be observed between the recorded salivary flow in all the treatment sessions. Single doses of remoxipride and biperiden showed no pharmacokinetic or pharmacodynamic interaction.

Disposition of oral [14C]cefcanel daloxate hydrochloride in healthy male subjects

The pharmacokinetics of the main metabolites of cefcanel daloxate hydrochloride, a new oral cephalosporin diester prodrug, was investigated. Cefcanel is antimicrobially active. After oral administration of a single dose of [14C]cefcanel daloxate hydrochloride to 7 healthy male volunteers (group A), plasma concentrations (t1/2 approximately 1 hr) and excretion of radioactivity, cefcanel (Aer = 38.2 +/- 3.8%, t1/2 approximately 1 hr), mandelic acid glycine conjugate (Aer = 3.7 +/- 0.5%, t1/2 approximately 15 hr) and N-mandelyl-2-aminoethanol (Aer = 7.5 +/- 3.0%) were evaluated. The absolute oral bioavailability of cefcanel was approximately 40% after administration of cefcanel daloxate hydrochloride and the extent of urinary excretion of cefcanel, mandelic acid glycine conjugate, and N-mandelyl-2-aminoethanol after an equimolar intravenous administration of cefcanel, were determined in a separate, similar group of volunteers (N = 12, group B). Total plasma clearance of cefcanel was 179.1 +/- 22.4 ml/min/1.73 m2 after intravenous administration. Renal clearances of cefcanel were 173.9 +/- 95.6 (po, group B), 166.6 +/- 31.9 (i.v., group B), and 136.3 +/- 16.1 ml/min/1.73 m2 (po, group A). Cefcanel was almost completely (92.6 +/- 7.3%) excreted in the urine as unmetabolized drug after intravenous administration (group B). However, when cefcanel daloxate hydrochloride was administered orally, more than 30% of the total urinary excretion was due to metabolites other than cefcanel. A large proportion of these metabolites were formed at a late stage, in the absence of systemic cefcanel. It is probable that biotransformed materials, distinct from cefcanel, were formed in the gastrointestinal tract and slowly absorbed rather than being systemic products of metabolic degradation of cefcanel.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of remoxipride in elderly psychotic patients

The pharmacokinetics of remoxipride when given as single doses of 50 mg and repeated doses of 50 mg, 100 mg, and 200 mg twice daily to 10 elderly psychotic patients (71-89 years) were compared with the findings of two other studies to reveal any age-related differences. The three studies comprised a total of 38 patients in three distinct age groups: elderly (71-89 years), middle-aged (46-69 years) and young (19-36 years). AUC, Cmax and Cmin of both total and unbound remoxipride increased with increasing age. The unbound fraction was similar in the three age groups. The half-life was prolonged in the elderly, most probably caused by a decrease in intrinsic clearance. A two-fold increase in AUC of both total and unbound concentrations was observed in the elderly group compared to the young, suggesting that patients over 70 years in general require half the dose needed by young adult patients. In general, the pharmacokinetics of remoxipride in the elderly are linear.

Tolerability and pharmacokinetics of remoxipride after intramuscular administration

A study was undertaken in seven schizophrenic patients to evaluate the tolerability and examine the pharmacokinetics of intramuscularly administered remoxipride after a single 200 mg dose and at steady state following repeated doses of 200 mg twice daily for one week. Comparisons of AUC, t1/2 and tmax using the Wilcoxon's signed rank test showed no significant difference between single dose and steady state indicating that the pharmacokinetics of intramuscular remoxipride were linear. The steady-state Cmax was found to be significantly larger than that after single dose and the increase was accounted for by the predicted accumulation factor, assuming linear kinetics. Although the inter-individual variability in plasma concentrations was large, the intra-individual variability was low as shown by the reproducibility of the single-dose and steady-state plasma curves. Remoxipride, administered intramuscularly, was well tolerated.