RESUMEN
Sofosbuvir (SOVALDI(®)), a potent, once-daily, orally administered nucleotide analog prodrug inhibitor of the hepatitis C virus (HCV) NS5B polymerase is approved in the USA, EU, Canada, and other regions for the treatment of HCV infection as a component of an antiviral treatment regimen. Sofosbuvir undergoes intracellular activation to form GS-461203 (active triphosphate, not detected in plasma), and ultimately the inactive, renally eliminated metabolite GS-331007. GS-331007 was identified as the primary analyte of interest for clinical pharmacology studies as it accounted for >90 % of systemic drug-related material exposure, and provided comparable exposure-response relationships for viral kinetics as observed for sofosbuvir. GS-331007 and sofosbuvir exhibit linear pharmacokinetics with minimal accumulation upon multiple dosing. Compared to healthy subjects, HCV-infected patients had modestly lower (39 %) GS-331007 area under the plasma concentration-time curve (AUC) and higher sofosbuvir AUC (60 %). Sofosbuvir can be administered without dose modification in HCV-infected patients with any degree of hepatic impairment or mild to moderate renal impairment. Sofosbuvir has a low propensity for clinically significant drug interactions with common concomitant medications used by HCV-infected patients. Clinically significant alterations in GS-331007 or sofosbuvir exposures are limited to potent inducers of intestinal P-glycoprotein that may lower exposure. In HCV-infected patients, demographic variables do not significantly influence GS-331007 and sofosbuvir exposures and no consistent exposure-response relationships were observed for efficacy or safety. This review focuses on the clinical pharmacokinetics, pharmacodynamics, and pharmacokinetic-pharmacodynamic relationships of sofosbuvir, and summarizes a number of drug interaction studies with important concomitant medications commonly used by HCV-infected patients.
Asunto(s)
Antivirales/farmacología , Antivirales/farmacocinética , Sofosbuvir/farmacología , Sofosbuvir/farmacocinética , Proteínas no Estructurales Virales/antagonistas & inhibidores , Animales , Interacciones Farmacológicas , Hepatitis C Crónica/tratamiento farmacológico , Hepatitis C Crónica/metabolismo , Humanos , Profármacos/farmacocinética , Profármacos/farmacologíaRESUMEN
OBJECTIVE: To assess efficacy and safety of cobicistat versus ritonavir as pharmacoenhancers for atazanavir when administered with emtricitabine/tenofovir df as initial treatment for HIV-1 infection. DESIGN: Randomized, partially placebo-controlled, double-blind, multicenter study. PARTICIPANTS: Antiretroviral treatment-naive adults, screening HIV-1 RNA of at least 5000 copies/ml and CD4 cell count more than 50 cells/µl. INTERVENTION: Randomized 2 : 1 (stratified by HIV RNA ≤ or >100,000 copies/ml) to receive placebo-blinded once-daily cobicistat 150 mg or ritonavir 100 mg with open-label atazanavir and fixed-dose emtricitabine/tenofovir df. MAIN OUTCOME MEASURES: Efficacy and safety at weeks 24 and 48. RESULTS: Eighty-four percent of ATV/co participants and 86% of ATV/r participants suppressed HIV-1 RNA (<50 copies/ ml) at week 24, and 82 and 86% at week 48, respectively, and mean CD4 cell count increased 203 and 199 cells/µl at week 24 and 208 and 177 cells/µl at week 48, respectively. Study treatment discontinuation due to adverse events occurred in 4% ATV/co and in 3% ATV/r participants through 48 weeks. Treatment-related adverse events occurred in 36% ATV/co and 48% ATV/r participants; hyperbilirubinemia occurred in 96 and 100%, and ocular icterus or jaundice occurred in 14 and 17%, respectively. Mean estimated glomerular filtration rate (Cockcroft-Gault, ml/min) decrease occurred in both treatment groups and was evident at week 2 (ATV/co -9, ATV/r -4), reached a nadir by week 24 (-15, -14, respectively), and did not progress further through week 48 (-13, -14). CONCLUSION: Using cobicistat and ritonavir as pharmacoenhancers for atazanavir and administered with emtricitabine/tenofovir df achieved comparable rates of virologic suppression and CD4 cell count increase with satisfactory safety profiles.
Asunto(s)
Adenina/análogos & derivados , Terapia Antirretroviral Altamente Activa , Carbamatos/administración & dosificación , Desoxicitidina/análogos & derivados , Infecciones por VIH/tratamiento farmacológico , VIH-1 , Oligopéptidos/administración & dosificación , Organofosfonatos/administración & dosificación , Piridinas/administración & dosificación , Ritonavir/administración & dosificación , Tiazoles/administración & dosificación , Adenina/administración & dosificación , Sulfato de Atazanavir , Recuento de Linfocito CD4 , Cobicistat , Desoxicitidina/administración & dosificación , Método Doble Ciego , Esquema de Medicación , Emtricitabina , Femenino , Humanos , Masculino , ARN Viral , Tenofovir , Resultado del TratamientoRESUMEN
Elvitegravir is a potent, boosted, once-daily, HIV integrase inhibitor with antiviral activity against wild-type and drug-resistant strains of HIV. Because elvitegravir is metabolized primarily by cytochrome P450 (CYP) 3A enzymes, coadministration with a strong CYP3A inhibitor such as ritonavir or cobicistat (also known as GS-9350), an investigational pharmacoenhancer, substantially increases (boosts) elvitegravir plasma exposures and prolongs its elimination half-life to â¼9.5 hours, allowing once-daily administration of a low 150 mg dose. Boosting also results in low intra- and intersubject pharmacokinetic variability and high elvitegravir trough concentrations (â¼6- to 10-fold above the concentration producing 95% inhibition of wild-type HIV-1 virus [IC95] of 45 ng/mL [protein binding-adjusted]), which is the pharmacokinetic parameter best associated with its antiviral activity. Data from extensive evaluation of the potential for boosted elvitegravir to undergo drug-drug interactions with other antiretroviral agents or concomitant medications indicate the absence of clinically relevant interactions or the need for dose modification in several cases, except for dose reduction of elvitegravir from 150 to 85 mg when coadministered with atazanavir/ritonavir or lopinavir/ritonavir. Dose adjustments for maraviroc and rifabutin, when each is coadministered with boosted elvitegravir, are consistent with their observed interactions with other ritonavir-boosted agents. The presence of a strong CYP3A inhibitor such as ritonavir or cobicistat renders the potential for increase in systemic exposures of CYP3A substrates coadministered with boosted elvitegravir. This article reviews a comprehensive pharmacology programme, including drug-drug interaction studies, mechanistic and special population studies, that has allowed a thorough understanding of elvitegravir clinical pharmacokinetics and its impact on pharmacodynamics.
Asunto(s)
Inhibidores de Integrasa VIH/farmacocinética , Quinolonas/farmacocinética , Animales , Interacciones Farmacológicas , Quimioterapia Combinada , Infecciones por VIH/tratamiento farmacológico , Inhibidores de Integrasa VIH/efectos adversos , Inhibidores de Integrasa VIH/farmacología , Inhibidores de Integrasa VIH/uso terapéutico , Humanos , Quinolonas/efectos adversos , Quinolonas/farmacología , Quinolonas/uso terapéuticoRESUMEN
OBJECTIVE: Elvitegravir (EVG) is in phase 3 development in combination with ritonavir (RTV)-boosted protease inhibitors in treatment-experienced, HIV-infected patients. Two studies evaluated pharmacokinetic (PK) interactions among EVG and RTV-boosted tipranavir (TPV/r) or darunavir (DRV/r). METHODS: Healthy volunteers received EVG/r alone (study 1: 200/100 mg once daily; study 2: 125/100 mg once daily), TPV/r (500/200 mg twice daily) or DRV/r (600/100 mg twice daily) alone, and EVG (200 or 125 mg as applicable) added to TPV/r (500/200 mg twice daily) or DRV/r (600/100 mg twice daily) in a randomized crossover design, with assessment of steady-state PK for EVG, TPV, DRV, and RTV. Safety was assessed by clinical monitoring. Studies were powered to conclude lack of an interaction if the 90% confidence interval for the geometric mean ratios of the AUCtau and Cmax for EVG, TPV, and DRV were within predefined no-effect boundaries. Trough concentrations were also assessed. RESULTS: No subjects discontinued for adverse events during treatment with EVG/r alone. On coadministration, AUCtau and Cmax of EVG and TPV and EVG and DRV were within prespecified no-effect boundaries versus treatment alone; trough concentrations were also not substantially altered. CONCLUSIONS: The PK of EVG and TPV or DRV were not altered after coadministration of EVG with TPV/r or DRV/r. EVG PK was similar with varied RTV doses of 100 mg once daily, 100 mg twice daily, or 200 mg twice daily. EVG can be added to TPV/r or DRV/r regimens without dose adjustment.
Asunto(s)
Fármacos Anti-VIH/farmacocinética , Fármacos Anti-VIH/uso terapéutico , Piridinas/uso terapéutico , Pironas/uso terapéutico , Quinolonas/farmacocinética , Ritonavir/uso terapéutico , Sulfonamidas/uso terapéutico , Adolescente , Adulto , Fármacos Anti-VIH/efectos adversos , Darunavir , Interacciones Farmacológicas , Quimioterapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Quinolonas/efectos adversosRESUMEN
OBJECTIVE: Efavirenz (EFV; 600 mg), emtricitabine (FTC; 200 mg) and tenofovir disoproxil fumarate (TDF; 300 mg) are preferred agents for treatment of HIV-1 infection in adults. This study evaluated the pharmacokinetics (PK) and bioequivalence of an investigational coformulation of EFV/FTC/TDF (test) single-tablet regimen compared with the commercially available individual dosage forms (EFV+FTC+TDF; reference treatment) in healthy subjects. METHODS: Subjects were randomized to 1 of 2 treatment sequences (test-->reference or reference-->test) in an open-label crossover study design. Study drug was administered under fasted conditions, and serial blood samples were obtained over 504 hours after oral administration of each treatment. Formulation bioequivalence was assessed in accordance with the US Food and Drug Administration bioequivalence criteria. RESULTS: Forty-eight subjects were enrolled, and 45 completed the study, with all study treatments being generally well tolerated. For EFV (n = 44), the geometric mean ratios (90% confidence interval [CI]) for maximum concentration (C(max)), area under the plasma concentration-time curve from time 0 to the last quantifiable concentration (AUC(0-last)), and area under the plasma concentration-time curve from time 0 extrapolated to infinity (AUC(inf)) were 99.9 (93.4 to 107), 95.7 (90.5 to 101), and 95.2 (88.9 to 102), respectively. For FTC (n = 45), the geometric mean ratios (90% CI) for C(max), AUC(0-last), and AUC(inf) were 88.8 (84.0 to 93.9), 98.0 (94.9 to 101), and 98.0 (94.9 to 101), respectively. For tenofovir (n = 45), the geometric mean ratios (90% CI) for C(max), AUC(0-last), and AUC(inf) were 91.5 (84.6 to 98.8), 99.3 (91.0 to 108), and 100 (93.2 to 108), respectively. CONCLUSIONS: The coformulation of EFV/FTC/TDF is bioequivalent to administration of its individual components.
Asunto(s)
Adenina/análogos & derivados , Benzoxazinas/farmacocinética , Desoxicitidina/análogos & derivados , Organofosfonatos/farmacocinética , Adenina/administración & dosificación , Adenina/farmacocinética , Administración Oral , Adolescente , Adulto , Alquinos , Benzoxazinas/administración & dosificación , Estudios Cruzados , Ciclopropanos , Desoxicitidina/administración & dosificación , Desoxicitidina/farmacocinética , Emtricitabina , Ayuno , Femenino , Humanos , Masculino , Persona de Mediana Edad , Organofosfonatos/administración & dosificación , Comprimidos/administración & dosificación , Comprimidos/farmacocinética , Tenofovir , Equivalencia TerapéuticaRESUMEN
Human immunodeficiency virus-infected women (n=16) received indinavir (800 mg three times a day) plus zidovudine plus lamivudine from 14 to 28 weeks of gestation to 12 weeks postpartum. Two women and eight infants experienced grade 3 or 4 toxicities that were possibly treatment related. Indinavir area under the plasma concentration-time curve was 68% lower antepartum versus postpartum, suggesting increased intestinal and/or hepatic CYP3A activity during pregnancy.
Asunto(s)
Infecciones por VIH/tratamiento farmacológico , Inhibidores de la Proteasa del VIH , VIH-1 , Indinavir , Complicaciones Infecciosas del Embarazo/tratamiento farmacológico , Adulto , Citocromo P-450 CYP3A/metabolismo , Femenino , Inhibidores de la Proteasa del VIH/efectos adversos , Inhibidores de la Proteasa del VIH/farmacocinética , Humanos , Indinavir/efectos adversos , Indinavir/farmacocinética , Recién Nacido , Hígado/metabolismo , Masculino , Intercambio Materno-Fetal , EmbarazoRESUMEN
Human immunodeficiency virus (HIV)-infected women have reduced exposure [area under the curve (AUC)] to anti-HIV protease inhibitors [e.g., nelfinavir (NFV)] during pregnancy. To determine the mechanistic basis of this phenomenon, we administered NFV mesylate orally (2.5 mg) or intravenously (0.625 mg) to timed pregnant (gestational age: 18-19 days) and non-pregnant FVB mice. After oral but not after i.v. administration, the plasma clearance of NFV was higher (by 134%, p < 0.05) and bioavailability was lower (by 32%, p < 0.05) in pregnant (n = 3) versus nonpregnant mice (n = 3). These effects of pregnancy were not due to changes in plasma protein binding of NFV. The half-life of NFV depletion in hepatic S-9 fractions of pregnant mice (n = 8) was 2.2-fold faster (p < 0.05) than that in nonpregnant mice (n = 7). Hepatic CYP3A activity (testosterone 6beta-hydroxylation, n = 4) and expression (n = 8) were significantly higher (by 138 and 49%, p < 0.05) in pregnant mice than that in nonpregnant mice. In the intestine, no CYP3A activity was detected and CYP3A protein expression (n = 6, p > 0.05) was not significantly different between the two groups. P-glycoprotein expression (n = 6) in hepatic and intestinal tissue of pregnant mice was not significantly different from that in nonpregnant mice. These changes in disposition of NFV during pregnancy are predominately due to a change in its bioavailability. An increase in hepatic CYP3A can explain the reduced bioavailability of NFV during pregnancy. If such upregulation of hepatic CYP3A activity occurs in pregnant women, it has important implications for dose adjustment of a variety of drugs ingested by pregnant women and cleared predominately via CYP3A metabolism.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/fisiología , Citocromo P-450 CYP3A/fisiología , Inhibidores de la Proteasa del VIH/farmacocinética , Nelfinavir/farmacocinética , Preñez/metabolismo , Animales , Área Bajo la Curva , Femenino , Ratones , EmbarazoRESUMEN
Placental efflux transporters such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) protect the developing fetus from exposure to potentially toxic xenobiotics. However, little is known about the expression of these transporters in human placentae of different gestational ages. Therefore, we quantified the expression of P-gp and BCRP in human placentae of different gestational ages. We also measured the expression of various nuclear regulatory factors such as the pregnane xenobiotic factor to determine whether their expression also changes with gestational age. Syncitial microvillous plasma membranes were isolated from human placentae of various gestational ages (60-90 days, 90-120 days, and full-term C-section placentae). P-gp and BCRP expression (protein) in these preparations were measured by Western blot analysis followed by an ELISA. Expression (mRNA) of P-gp, BCRP, and nuclear regulatory factors in the placentae were quantified by quantitative real-time PCR. P-gp expression (relative to that of alkaline phosphatase) was significantly (P < 0.05) higher (44.8-fold as protein; 6.5-fold as mRNA) in early gestational age human placentae (60-90 days) vs. term placentae. In contrast, BCRP (protein and mRNA) and nuclear regulatory factors (mRNA) expression in placental tissue did not change significantly with gestational age. However, placental expression of P-gp and human chorionic gonadotropin-beta (hCG-beta) transcripts was highly correlated (r = 0.73; P < 0.0001; Spearman rank correlation). Expression of P-gp, but not BCRP, decreases dramatically with gestational age in human placentae. This decrease in P-gp expression is not caused by a change in expression of nuclear receptor transcripts but appears to be related to hCG-beta expression. The placental P-gp expression appears to be upregulated in early pregnancy to protect the fetus from xenobiotic toxicity at a time when it is most vulnerable to such toxicity.