Measurements of SAA and iron may improve post operative monitoring. As sustained inflammation may indicate that the surgical wound has become infected, SAA and iron measurements may facilitate early recognition and hence early treatment of infection.
We investigated the pharmacokinetics of rifampicin and its major metabolites, 25-desacetylrifampicin and 3-formylrifampicin, in two groups of six patients with active pulmonary tuberculosis, who received either multiple oral or intravenous rifampicin therapy in combination with intravenous isoniazid and ethambutol. Serum concentrations of rifampicin were each determined after a single oral and intravenous test dose of 600 mg rifampicin at the beginning and after 1 and 3 weeks of tuberculostatic treatment. Analysis of rifampicin and its metabolites was performed by high-pressure liquid chromatography. It was found that, due to autoinduction of its metabolizing hepatic enzymes, the systemic clearance of rifampicin increased from 5.69 to 9.03 l/h after 3 weeks of multiple dosing. The volume of distribution of the drug was constant over the period of this study. The bioavailability of the active, orally administered rifampicin decreased from 93% after the first single oral dose to 68% after 3 weeks of oral and intravenous rifampicin therapy. Relating to the increase in systemic (hepatic) clearance, a bioavailability no lower than 90% can be predicted. The reduction to 68% indicates that, in addition to an increase of hepatic metabolism, an induction of a prehepatic "first-pass" effect resulted from multiple rifampicin doses. Our study of rifampicin metabolites confirm that prehepatic metabolism was induced, since a higher metabolic ratio resulted after the oral doses than after the intravenous rifampicin test doses. A preabsorptive process can therefore be excluded as a cause of reduced bioavailability.
Numerous studies have heen performed to describe the absorption, distribution, metabolism and excretion of terbinafine in healthy subjects and in special subpopulations. These studies have incorporated the use of both radiolabelled and non-radiolabelled drugs for the characterization, structural elucidation and quantification of terbinafine, and its metabolites, in biological fluids. In addition to studies in man, investigations in rats, dogs and rabbits have also been performed. Absorption of terbinafine following oral administrationTerbinafine was well-absorbed in all species tested. The absorption of terbinafine in animals following oral administration was as follows: > 60% in rats, >85"n in mice and >46% in dogs.' The absorption of terbinafine in man following a single oral 250 mg dose of '^C-labelled compound was >70'^o' In man, maximal plasma concentrations of terbinafine are reached within 2 h following oral administration.
Elimination kinetics of disulfiram were determined in 15 male alcoholics after 250 mg disulfiram taken by mouth as a single dose and again after 12 days of dosing. Apparent t 1/2s were calculated for disulfiram, diethyldithiocarbamate (DDTC), diethyldithiocarbamate-methyl ester (DDTC-Me), diethylamine (DEA), and carbon disulfide (CS2) and were found to be 7.3, 15.5, 22.1, 13.9, and 8.9 hr. Elimination t 1/2 for CS2 in breath was 13.3 hr. Average time to reach maximal plasma concentration after either single or repeated doses was 8 to 10 hr for disulfiram, DDTC, DDTC-Me, DEA, and CS2 in breath, while plasma CS2 concentration peaked 5 to 6 hr after disulfiram. In these studies, 22.4% and 31.3% of the disulfiram after single and repeated dosing was eliminated in the breath during one dosing interval. In urine, 1.7% and 8.3% of the disulfiram dose was eliminated as DDTC-glucuronide after single and repeated dosing, while DEA accounted for 1.6% and 5.7% of the dose. There was marked intersubject variability in plasma levels of disulfiram and its metabolites. This variability may be the result of the lipid solubility of disulfiram, differences in plasma protein binding, or the effect of enterohepatic cycling.
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