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- Mukonzo, Jackson K, et al.
(författare)
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HIV/AIDS Patients Display Lower Relative Bioavailability of Efavirenz than Healthy Subjects.
- 2011
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Ingår i: Clinical pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 50:8, s. 531-40
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pharmacokinetic studies of antiretroviral drugs are often conducted in adult healthy subjects, and the results are extrapolated to HIV/AIDS patients. HIV/AIDS, however, is known to cause morphological and physiological changes that may alter the pharmacokinetics of antiretroviral drugs. We examined the effect of HIV/AIDS on the pharmacokinetics of efavirenz in Ugandans. Methods: After a first oral dose of efavirenz 600 mg in treatment-naïve HIV-infected patients, blood samples were collected at nine time points up to 24 hours. The plasma-concentration time data from these patients were merged with previously reported data from adult healthy subjects. Population pharmacokinetic models were fitted to the data, using NONMEM VI software. Covariate analyses were performed to estimate the effects of HIV/AIDS disease, demographic characteristics (sex, bodyweight, age), biochemical variables (serum creatinine, urea, alanine aminotransferase) and pharmacogenetic variation in cytochrome P450 (CYP) 2B6, CYP3A5 and adenosine triphosphate-binding cassette, sub-family B, member 1 (ABCB1) on the population pharmacokinetic parameters. Results: Efavirenz plasma concentration-time data obtained from 29 HIV-1-infected, treatment-naïve patients were merged with previously reported data from 32 adult healthy subjects. The model identified sex and HIV/AIDS disease as statistically significant categorical predictors of efavirenz pharmacokinetics. Females were predicted to have a 2-fold higher volume of distribution of the peripheral compartment after oral administration (V(2)/F) than males (95% CI 1.53, 2.63), while HIV/AIDS patients were found to have 30% lower relative bioavailability (95% CI 18.7, 40.7) than healthy subjects. The increased V(2)/F in females resulted in a 2-fold longer elimination half-life than in males. Conclusion: On the basis of the findings of this analysis, we conclude that, apart from bodyweight-based differences, both HIV/AIDS disease and sex affect efavirenz pharmacokinetics in Ugandans. HIV/AIDS disease is associated with reduced relative bioavailability of efavirenz. We recommend that findings from healthy subject studies be confirmed in HIV/AIDS patients and that caution be applied in direct extrapolation of exposure data to the target patient population.
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| 2. |
- Siegmund, Werner, et al.
(författare)
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Pharmacokinetics and pharmacodynamics of propiverine in children aged between 5 and 10 years with symptoms of overactive bladder
- 2010
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Ingår i: Clinical Pharmacokinetics. - : Springer Science and Business Media LLC. - 0312-5963 .- 1179-1926. ; 49:5, s. 335-342
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND OBJECTIVES: Pharmacokinetic studies in children are particularly required for drugs with intensive hepatic and regioselective intestinal elimination and pharmacological effects that may be critical for absorption at therapeutic doses, such as a delay in intestinal transit. One example is the antimuscarinic drug propiverine, the pharmacokinetics of which were evaluated in the present study in children with symptoms of overactive bladder. METHODS: The pharmacokinetics of immediate-release propiverine were studied in a dose-escalating, parallel-group study (propiverine 5, 10 and 15 mg twice daily for 14 days) in 25 subjects (11 females and 14 males aged 5-10 years; bodyweight 17-44 kg; body mass index 14-21 kg/m2) with symptoms of overactive bladder during waking hours. Serum concentration-time curves of propiverine and its major metabolite propiverine N-oxide (M-5) were evaluated up to 3 hours and 8 hours after the first and last administration, respectively, using liquid chromatography with tandem mass spectrometry. The voiding frequency, number of incontinence and urgency episodes, single voided volume and urine flow variables were measured before and after treatment. RESULTS: Significant dose-related increases in the serum exposure (the area under the concentration-time curve, the maximum concentration and the minimum concentration) with propiverine and M-5 in the dose groups < or =0.3 mg/kg and 0.3 to < or =0.45 mg/kg after both single-dose and repeated-dose administration were found. The elimination half-lives of propiverine and M-5 at steady state were no different (mean +/- SD 12.2 +/- 11.2 and 14.5 +/- 9.94 hours, respectively). Higher doses did not result in additional dose-proportional increases in the respective pharmacokinetic parameters, particularly not after repeated-dose treatment. The voiding frequency, voided volume and urge symptoms were beneficially changed from baseline; significant dose-dependent changes were not observed. Most of the adverse events that were probably or possibly drug related were reported for patients in the high-dose group (>0.45 mg/kg). CONCLUSIONS: The disposition of propiverine is dose related after repeated administration of the recommended doses below 0.45 mg/kg (0.3-0.45 mg/kg) twice daily in children aged 5-10 years with symptoms of overactive bladder and urinary incontinence. (Trial registration numbers: [clinicaltrials.gov] NCT00795925; [EudraCT] 2004-001243-30).
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