We assessed the pharmacokinetics of zidovudine (ZDV) in plasma and intracellular

We assessed the pharmacokinetics of zidovudine (ZDV) in plasma and intracellular ZDV phosphate anabolites in peripheral blood mononuclear cells in Thai human being immunodeficiency virus (HIV) type 1-infected patients and healthy volunteers. its active form, ZDV triphosphate (ZDVTP) (4). ZDVTP competes with endogenous dTTP for incorporation into viral DNA, thus inhibiting viral DNA synthesis. Following incorporation of ZDVTP, the azido (N3) group results in chain termination (9). As the effect of ZDV is dependent on the rate and extent of intracellular activation, concentrations in plasma are of limited value in predicting efficacy or toxicity (1, 10). Intracellular phosphorylation studies performed with human immunodeficiency virus (HIV)-infected patients and healthy volunteers have been performed mostly with Caucasian patients (1, 7, 10C12). ZDV has a major role in resource-poor countries in the prevention of vertical transmission of HIV. A recent report from Thailand showed that ZDV administered orally during late pregnancy and delivery reduced HIV transmission from infected mothers to infants by 50% compared with a placebo group (16). However, no studies to date have investigated the metabolism of ZDV in an Asian population. There are known ethnic differences in drug metabolism (6, 17), and thus any differences in manifestation of enzymes involved with ZDV rate of metabolism (glucuronyltransferase, CYP 3A, or, moreover, mobile kinases [14]) would alter plasma and intracellular pharmacokinetics. In this scholarly study, we have analyzed ZDV pharmacokinetics with ZDV-naive, HIV-infected Thai individuals and healthful volunteers. Twenty antiretroviral drug-naive HIV-positive individuals, 3 females and 17 men, aged 21 to 54 years (median age group, 26 years), and 7 male volunteers, aged 24 to 30 years (median age group, 28 years), participated with this scholarly research. The patients got a median bodyweight of 53 kg (range, 42.5 to 73.0 kg). HIV-positive individuals had been at different disease phases (A1, = 2; A2, = 4; B1, = 1; B2, = 4; B3, = 5; and C3, = 4) (Centers for Disease Control and Avoidance 1993 classification program), but all were steady at the proper time of sampling. Median Compact disc4 cell matters had been 246 cells/mm3 (range, 26 to 810 cells/mm3). All individuals and volunteers got regular renal function and a hemoglobin worth greater than 10 g/dl during the analysis. Two patients had been acquiring co-trimoxazole, one affected person was getting 600 mg of rifampin and 300 mg of isoniazid daily for tuberculosis, and another affected person was getting 300 mg of phenytoin (Dilantin) therapy daily for epilepsy. The serum aspartate and alanine transaminases had been within the standard limit except in a single affected person, whose values had been three times greater than regular. Written educated consent was from the topics, as well as the scholarly research was authorized by the ethics committee of Mahidol College or university, Thailand. After over night fasting from the scholarly research topics, bloodstream was sampled for baseline medication Compact disc4 and concentrations cell count number. Further examples (20 ml) had been gathered by order BAY 63-2521 venipuncture at 1, 2, 4, and 6 h after supervised ingestion of an individual 300-mg dosage of ZDV. After parting of plasma, peripheral bloodstream mononuclear cells (PBMCs) had been isolated order BAY 63-2521 by denseness cushion centrifugation, cleaned, and quantified utilizing a hemocytometer. PBMCs (5 106 cells) had been extracted with 60% methanol ahead of parting of ZDV and its own phosphate metabolites by high-performance water chromatography, as referred to previously (1). In short, samples had been eluted on the Partisil 10-SAX anion-exchange column (4.6 by 250 mm) MYO7A utilizing a mobile stage of ammonium dihydrogen phosphate buffer-methanol operate like a gradient over 40 min. Fractions eluted through the column related to ZDV, ZDV monophosphate (ZDVMP), ZDV diphosphate (ZDVDP), and ZDVTP had been collected. Collection intervals had been determined through the retention instances of genuine phosphorylated anabolites of ZDV (13, 15). Phosphorylated fractions had been hydrolyzed by over night incubation with acidity phosphatase (40 U/ml). Examples had been cleaned out using C18 Sep-Pak cartridges, and ZDV concentrations had been quantified with a commercially available order BAY 63-2521 radioimmunoassay kit (2). ZDV concentrations (nanograms per milliliter) obtained from the radioimmunoassay were converted to intracellular concentrations (picomoles per 106 cells) by correcting for sample volume and cell number. The lower limit of detection of this assay was 0.2 ng/ml, or 0.01 pmol/106 cells. Validation studies using this assay have been described previously (2, 11). Concentrations in plasma were determined directly from the data. The area under the ZDV concentration time curve from 0 to 6 h (AUC0C6) was determined by the log-linear trapezoidal rule using the TOPFIT computer program (Gustav Fischer Verlag, Stuttgart, Germany). Correlations between levels of total ZDV phosphates and plasma ZDV or.