Aims To assess the tolerability and pharmacokinetic profile of single and repeat doses of the oral matrix metalloproteinase inhibitor marimastat in healthy male volunteers. Methods A total of 31 subjects participated in two placebo-controlled, rising-dose studies. The first study assessed the pharmacokinetics and tolerability of single doses of marimastat of 25, 50, 100, 200, 400 and 800 mg. In the second study, continuous dosing over 6.5 days with three incremental dose levels of 50, 100 and 200 mg twice daily was assessed. Full pharmacokinetic profiles were obtained on days 0 and 6, and trough concentrations were measured on all days. For each pharmacokinetic profile in the studies, summary measures including C max , t max , elimination half-life and AUC were calculated. Urinary drug weights were also measured. All adverse events were documented, and haematological and biochemical variables, vital signs and ECGs were monitored throughout the study. Results Peak plasma concentrations were observed at 1.5-3 h for all subjects at all doses. Peak levels were approximately proportional to dose, as was drug exposure as calculated by AUC. Data from both studies indicate that the terminal elimination half-life is of the order of 8-10 h, and that there is no unexpected drug accumulation. Marimastat was well-tolerated, with adverse effects being mild and occurring with similar frequency to placebo. Small but reversible elevations in liver transaminases were noted with repeat dosing of marimastat, the most significant of these occurring at a dose of 200 mg twice daily. Conclusion Single and repeat oral doses of marimastat in healthy male subjects appear to be well-tolerated. The drug is rapidly absorbed with high peak levels achieved. It has a terminal elimination half-life of 8-10 h which would support twice daily dosing in further clinical trials.

In a placebo-controlled double-blind cross-over study, we gave 12 healthy male volunteers placebo or milnacipran orally, such that each volunteer received placebo and two doses of milnacipran. Blood samples taken before and at various times after dosing were analysed for plasma concentrations of unchanged milnacipran and the inhibitory effect of the plasma on the uptake of 3H-5-hydroxytryptamine (5HT) into normal human platelets or of 3H-noradrenaline into rat hypothalamus homogenate. The mean maximal inhibition of 5HT and noradrenaline uptake was correlated with drug dose. The inhibition of 5HT uptake was correlated with the inhibition of noradrenaline uptake and both were correlated with plasma concentration of unchanged drug at all times and doses tested. Thus, milnacipran, when given orally to man, circulates in a biologically active form with similar potency for the inhibition of 5HT and noradrenaline uptake.

The uptake of sulphamethoxazole, sulphadiazine, sulphamerazine, sulphanilamide, trimethoprim and brodimoprim by human peripheral blood leucocytes, has been investigated. High performance liquid chromatography (HPLC) was used to assay drug concentrations before and after incubation with leucocyte suspensions. Using radiolabelled material the intracellular localization of two of these compounds was also determined. The results indicated that all the investigated drugs were taken up by leucocytes. Differential studies demonstrated that mononuclear cells accumulated higher drug concentrations (0.13-0.55 microgram/10(7) cells), than resting neutrophils (0.02-0.26 microgram/10(7) cells) with the exception of sulphanilamide, which was taken up to a greater extent by neutrophils (0.75 microgram/10(7) cells). During neutrophil phagocytosis intracellular levels of all the drugs except brodimoprim increased from 3 to 130-fold as compared to resting neutrophils. The uptake of 14C-sulphanilamide and 14C-trimethoprim, in neutrophils and mononuclear blood cells, as assessed by measurement of the cell-associated radioactivity, correlated well with that determined by the HPLC procedure. In the intracellular localization studies 14C-sulphanilamide and 14C-trimethoprim exhibited similar distribution profiles. In neutrophils, 35-40% of radiolabelled drug was located in both the microsome and cytosol fractions whereas in peripheral blood mononuclear cells 40-60% was found in the cytosol and 10-20% in the microsome fraction. The results of this study suggest that, following activation, leucocytes may actively transport these drugs and release them locally at sites of infection. The ability of neutrophils to further concentrate the drugs during phagocytosis may result in reduced survival time of some ingested bacteria. These concepts may be important in designing treatment stratagems for intracellular pathogens.

A high performance liquid chromatographic (HPLC) method fot the determination of sulphadiazine and trimethoprim in medicated fish feedstock is described. It is based on the extraction of the drugs 2215 Copyright 0 1991 by Marcel Dekker. Inc. Downloaded by [McMaster University] at 16:22 15 June 2016 MC NALLY ET AL.into methanol followed by separation on a )I-Bondapak column using an aqueous acetonitrile mobile phase of pH 3.0. The method was validated by determining intra-and inter-assay precision and the coefficient of variation was found to be less than 8% for both drugs. Callbration curves were linear over the range 160-4000 pg drug per g of feedstock and the method was applied to the determination of a commercial feedstock formulation.

Ro 11-2465, a cyanide derivative of imipramine with serotonin uptake inhibitory properties, was investigated in six healthy volunteers for its effect on serotonin concentration in blood platelets. The initial dose was 1 mg daily, the maximum dose of 3 mg being reached on day 3 and maintained for 7 days. A significant decrease in the platelet serotonin concentration was not observed until 3 days after the start of drug administration, after which depletion was rapid. After 5 days of treatment, the reduction was about 80% compared to pre-drug level. Serotonin restoration after drug withdrawal was very slow, and 5 days after discontinuation, it was still 70% below its baseline level.