Intermittent antimycobacterial dosage correction.
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Antibiotics, Antitubercular↗
Biomedical subjects
D Slain
Publications and source records attributed to D Slain.
Metabolic disposition and pharmacokinetics of [14C]-amprenavir, a human immunodeficiency virus type 1 (HIV-1) protease inhibitor, administered as a single oral dose to healthy male subjects.
The objective of this study was to determine the metabolic profile, routes of elimination, and total recovery of amprenavir and its metabolites after a single oral dose of [14C]-amprenavir. Six healthy male subjects each received a single oral 630 mg dose of amprenavir containing 95.76 microCi of [14C]-amprenavir in this Phase I mass balance study. The metabolic disposition of amprenavir was determined through analyses of radiocarbon in whole blood, plasma, urine, and stool samples, collected for a period of 10 to 17 days postdosing. Cerebral spinal fluid (CSF) sampling was conducted on day 1. The ratio of unchanged amprenavir AUC0-->infinity to plasma radiocarbon was 27%, suggesting that most of the radiocarbon was metabolites. The median total recovery of the administered dose of radiocarbon was 89% (range: 66%-93%), with 75% (range: 56%-80%) recovered in the feces and 14% (range: 10%-17%) in the urine. Most of the recovered radiocarbon in the feces and urine was excreted within 240 and 48 hours postdose, respectively. Of the 75% of the radiocarbon dose recovered in the feces, 62% was identified as a metabolite resulting from dioxidation of the tetrahydrofuran ring (GW549445X) and 32% as a metabolite resulting from subsequent oxidation of the p-aniline sulfonate group (GW549444X). Unchanged amprenavir was below the limit of quantitation in feces and urine. Therefore, approximately 94% of the dose excreted in the feces was accounted for by these two metabolites. Concentrations of radiocarbon in the CSF were below the limit of quantitation in 5 of 6 subjects sampled. In summary, oral amprenavir is extensively metabolized in humans, with concentrations of unchanged drug below the limits of quantitation in urine and feces. The majority (75%) of administered radiocarbon was excreted in feces.
Administration, Oral↗
Intravenous itraconazole.
OBJECTIVE: To review the pharmacology, mycology, chemistry, pharmacokinetics, efficacy, safety, tolerability, dosage, administration, and economic issues of intravenous itraconazole. DATA SOURCES: A MEDLINE search from 1978 to June 2000 of the English-language literature and an extensive review of meeting abstracts was conducted. Due to the paucity of published information concerning the pharmacokinetics, efficacy, and safety of the intravenous formulation of intravenous itraconazole, additional information was obtained from the manufacturer. DATA EXTRACTION: Data from in vitro and preclinical studies, as well as Phase II and III clinical trials, were included. DATA SYNTHESIS: The triazole antifungal agent itraconazole is available in a cyclodextrin-based intravenous formulation. Intravenous itraconazole is indicated for the treatment of pulmonary and extrapulmonary blastomycosis; histoplasmosis, including chronic cavitary pulmonary disease and disseminated, nonmeningeal histoplasmosis; and pulmonary and extrapulmonary aspergillosis in patients who are intolerant of or who are refractory to amphotericin B. This formulation provides quicker and more consistent therapeutic concentrations than the oral formulations. Clinical data comparing the efficacy of intravenous itraconazole with that of amphotericin B are lacking. CONCLUSIONS: Intravenous itraconazole offers a less toxic alternative for patients with pulmonary and extrapulmonary blastomycosis, histoplasmosis, and aspergillosis who cannot receive oral medications or who are intolerant of or refractory to amphotericin B.
Antifungal Agents↗
Variability in activity of hepatic CYP3A4 in patients infected with HIV.
STUDY OBJECTIVES: To evaluate hepatic cytochrome P450 (CYP) 3A4 activity in patients infected with the human immunodeficiency virus (HIV) using the erythromycin breath test (ERMBT), and to examine the relationship of the ERMBT to plasma concentrations of indinavir and nelfinavir. DESIGN: Prospective observational study. SETTING: University infectious diseases clinic. SUBJECTS: Thirty-nine HIV-positive patients and 47 healthy controls. INTERVENTION: After the ERMBT in patients and controls, 25 patients received indinavir or nelfinavir. MEASUREMENTS AND MAIN RESULTS: Compared with controls, ERMBT variability was significantly greater in HIV-positive patients, including a subset of 19 patients receiving no concurrent drugs reported to alter CYP3A4 activity. Correlation between the ERMBT and first-dose plasma indinavir concentrations nearly reached statistical significance (p=0.07). CONCLUSION: Variability in hepatic activity of CYP3A4 in HIV-positive patients may be greater than in controls and may explain some between-subject variability in plasma concentrations of indinavir. However, clearance mechanisms for protease inhibitors are complex, and if it is important to assess systemic exposure, the ERMBT is not a substitute for direct measurement of plasma concentrations.
Adolescent↗
Lipid-based amphotericin B for the treatment of fungal infections.
The frequency of life-threatening fungal infections has increased dramatically over the past few decades. For more than 30 years amphotericin B has been the standard treatment for systemic and deep-seated fungal infections, primarily because of its broad spectrum of activity. Its usefulness is limited by a relatively high frequency of significant adverse events including infusion-related reactions and nephrotoxicity. In an effort to overcome these side effects, a number of lipid-based formulations were developed, each with its own composition and pharmacokinetic behavior. The clinical significance of these differences is unknown. Available clinical data suggest the formulations have a reduced propensity for causing nephrotoxicity. However, considering limited efficacy data, they should be reserved as second-line therapy for patients who cannot tolerate or fail an adequate trial of conventional amphotericin B or cannot benefit from other antifungal agents.
Amphotericin B↗