No abstract

The pharmacokinetics of phenytoin was studied in 66 epileptic Chinese children and adults. The data were analysed by the population approach, using the non-linear mixed effect model, in the MULTI (ELS) program. There was no age or gender-related effect on either the apparent maximum elimination rate (kmax) or Michaelis-Menten constant (KM). Kmax was related to body weight 0.656. The population pharmacokinetics was similar in children and adults. Kmax and KM were estimated to be 30.72 mg.kg-0.656 day-1 and 2.307 mg.l-1, respectively. Kmax was higher than reported values, and KM was comparable to that reported in a study in Japanese, but was much lower than that reported in studies of European patients. The inter-individual variability of KM (CV 65.58%) was substantially higher than that of kmax (CV 28.49%), and the residual (intra-individual) variability was found 21.33% (CV).

The tnatcrn;tl R: s pLtsnLt COIICL'lltration Lttio or salbuumol was recently reported to be signific:tntly ltighn than the cord r:ttio after :tdministration of ;t 'iinglc ltttLtVL'nou> dose ofLtlTtllate to women prior to Caesarian section IKI. This fi11ding was ;tttributcd to etLttttioselcctive pbccntal-t(rral tneubolisttt resulting in !own concentrations of the (R)-enantiontL'I" (cutomn) in the fre urnury excretloll 1:11.

Serum chloramphenicol and chloramphenicol succinate concentrations in patients given equivalent doses of chloramphenicol base either intravenously or orally for typhoid fever were measured by high-performance liquid chromatography. The mean serum chloramphenicol concentrations were significantly lower in the 11 patients treated with intravenous chloramphenicol succinate than in the 15 patients treated with oral chloramphenicol capsules.

The effects of mefloquine and quinine on acetylcholine-induced contractures of the toad rectus abdominis muscle have been investigated. Both drugs depressed acetylcholine-induced contractures in a dose-related and non-competitive manner. A partial reversal of the block was observed in the presence of 4-aminopyridine (10, 50 microM) and increased Ca2+ content (1.25x) of the Ringer solution. In both cases, the mefloquine-induced blockade was more readily reversed than that induced by quinine. Mefloquine and quinine at concentrations greater than 100 and 500 microM, respectively, also elicited a direct contractile response on the muscle. Quantitative differences in their contractile activity have been attributed to the greater lipid solubility and tissue binding affinity of mefloquine.