Multidrug-resistant tuberculosis and culture conversion with bedaquiline.

BACKGROUND: Bedaquiline (Sirturo, TMC207), a diarylquinoline that inhibits mycobacterial ATP synthase, has been associated with accelerated sputum-culture conversion in patients with multidrug-resistant tuberculosis, when added to a preferred background regimen for 8 weeks. METHODS: In this phase 2b trial, we randomly assigned 160 patients with newly diagnosed, smear-positive, multidrug-resistant tuberculosis to receive either 400 mg of bedaquiline once daily for 2 weeks, followed by 200 mg three times a week for 22 weeks, or placebo, both in combination with a preferred background regimen. The primary efficacy end point was the time to sputum-culture conversion in liquid broth. Patients were followed for 120 weeks from baseline. RESULTS: Bedaquiline reduced the median time to culture conversion, as compared with placebo, from 125 days to 83 days (hazard ratio in the bedaquiline group, 2.44; 95% confidence interval, 1.57 to 3.80; P<0.001 by Cox regression analysis) and increased the rate of culture conversion at 24 weeks (79% vs. 58%, P=0.008) and at 120 weeks (62% vs. 44%, P=0.04). On the basis of World Health Organization outcome definitions for multidrug-resistant tuberculosis, cure rates at 120 weeks were 58% in the bedaquiline group and 32% in the placebo group (P=0.003). The overall incidence of adverse events was similar in the two groups. There were 10 deaths in the bedaquiline group and 2 in the placebo group, with no causal pattern evident. CONCLUSIONS: The addition of bedaquiline to a preferred background regimen for 24 weeks resulted in faster culture conversion and significantly more culture conversions at 120 weeks, as compared with placebo. There were more deaths in the bedaquiline group than in the placebo group. (Funded by Janssen Pharmaceuticals; TMC207-C208 ClinicalTrials.gov number, NCT00449644.).

Bedaquiline in the treatment of multidrug- and extensively drug-resistant tuberculosis.

Bedaquiline, a diarylquinoline, improved cure rates when added to a multidrug-resistant tuberculosis (MDR-TB) treatment regimen in a previous placebo-controlled, phase 2 trial (TMC207-C208; NCT00449644). The current phase 2, multicenter, open-label, single-arm trial (TMC207-C209; NCT00910871) reported here was conducted to confirm the safety and efficacy of bedaquiline.Newly diagnosed or previously treated patients with MDR-TB (including pre-extensively drug-resistant (pre-XDR)-TB or extensively drug-resistant (XDR)-TB) received bedaquiline for 24 weeks with a background regimen of anti-TB drugs continued according to National TB Programme treatment guidelines. Patients were assessed during and up to 120 weeks after starting bedaquiline.Of 233 enrolled patients, 63.5% had MDR-TB, 18.9% had pre-XDR-TB and 16.3% had XDR-TB, with 87.1% having taken second-line drugs prior to enrolment. 16 patients (6.9%) died. 20 patients (8.6%) discontinued before week 24, most commonly due to adverse events or MDR-TB-related events. Adverse events were generally those commonly associated with MDR-TB treatment. In the efficacy population (n=205), culture conversion (missing outcome classified as failure) was 72.2% at 120 weeks, and 73.1%, 70.5% and 62.2% in MDR-TB, pre-XDR-TB and XDR-TB patients, respectively.Addition of bedaquiline to a background regimen was well tolerated and led to good outcomes in this clinically relevant patient cohort with MDR-TB.

Population pharmacokinetics of bedaquiline (TMC207), a novel antituberculosis drug.

Bedaquiline is a novel agent for the treatment of pulmonary multidrug-resistant Mycobacterium tuberculosis infections, in combination with other agents. The objective of this study was to develop a population pharmacokinetic (PK) model for bedaquiline to describe the concentration-time data from phase I and II studies in healthy subjects and patients with drug-susceptible or multidrug-resistant tuberculosis (TB). A total of 5,222 PK observations from 480 subjects were used in a nonlinear mixed-effects modeling approach. The PK was described with a 4-compartment disposition model with dual zero-order input (to capture dual peaks observed during absorption) and long terminal half-life (t1/2). The model included between-subject variability on apparent clearance (CL/F), apparent central volume of distribution (Vc/F), the fraction of dose via the first input, and bioavailability (F). Bedaquiline was widely distributed, with apparent volume at steady state of >10,000 liters and low clearance. The long terminal t1/2 was likely due to redistribution from the tissue compartments. The final covariate model adequately described the data and had good simulation characteristics. The CL/F was found to be 52.0% higher for subjects of black race than that for subjects of other races, and Vc/F was 15.7% lower for females than that for males, although their effects on bedaquiline exposure were not considered to be clinically relevant. Small differences in F and CL/F were observed between the studies. The residual unexplained variability was 20.6% and was higher (27.7%) for long-term phase II studies.

Lack of an effect of rilpivirine on the pharmacokinetics of ethinylestradiol and norethindrone in healthy volunteers.

UNLABELLED: Rilpivirine is a human immunodeficiency virus Type 1 (HIV-1) non-nucleoside reverse transcriptase inhibitor. OBJECTIVE: Rilpivirine metabolism involves cytochrome P450 3A4 (CYP3A4). This trial (ClinicalTrials. gov number: NCT00739622) evaluated the interaction between rilpivirine and ethinylestradiol/norethindrone (combination oral contraceptives), which are metabolized by multiple pathways, including CYP3A4. METHODS: During three consecutive 28-day cycles, 18 HIV-negative females received once-daily ethinylestradiol (35 µg)/norethindrone (1 mg) (Days 1 - 21); Days 22 - 28 were pill-free. Only in Cycle 3 was once-daily rilpivirine (25 mg) co-administered (Days 1 - 15). Minimum and maximum plasma concentrations (Cmin; Cmax) and area under the plasma concentration-time curve over 24 hours (AUC24h) of ethinylestradiol/norethindrone (Day 15, Cycles 2 and 3) and rilpivirine (Day 15, Cycle 3) were evaluated. RESULTS: Rilpivirine coadministration had no effect on (least square mean ratio, 90% confidence interval) ethinylestradiol Cmin (1.09, 1.03 - 1.16) or AUC24h (1.14, 1.10 - 1.19), but increased Cmax by 17% (1.17, 1.06 - 1.30), which is unlikely to affect ethinylestradiol pharmacodynamics. Norethindrone pharmacokinetics were unaffected by rilpivirine (AUC24h: 0.89, 0.84 - 0.94; Cmin: 0.99, 0.90 - 1.08; Cmax: 0.94, 0.83 - 1.06). Steady-state rilpivirine pharmacokinetics with ethinylestradiol/norethindrone was comparable with historical data for rilpivirine alone. Rilpivirine with ethinylestradiol/norethindrone was generally well tolerated. No new safety events were identified. CONCLUSIONS: Co-administration of rilpivirine, at the therapeutic dosing regimen, with ethinylestradiol/norethindrone does not affect hormone pharmacokinetics, and is, therefore, unlikely to affect the efficacy or safety of this oral hormonal contraceptive. Rilpivirine pharmacokinetics was not affected by ethinylestradiol/norethindrone. Rilpivirine (25 mg once daily) can be co-administered with ethinylestradiol/norethindrone-based contraceptives without dose modification.

Limited impact of IL28B genotype on response rates in telaprevir-treated patients with prior treatment failure.

BACKGROUND & AIMS: Nucleotide polymorphisms upstream of the interleukin 28B (IL28B) gene are strongly associated with hepatitis C virus (HCV) clearance in treatment-naïve patients treated with peginterferon/ribavirin (PegIFN/RBV). This subanalysis of the REALIZE study evaluated the impact of IL28B polymorphisms on sustained virologic response (SVR) in telaprevir-treated, HCV genotype 1-infected patients with prior PegIFN/RBV treatment failure. METHODS: Treatment-experienced patients were randomized to 12 weeks of telaprevir (750 mg every 8h) with/without a 4-week PegIFN/RBV lead-in, or placebo, each with PegIFN-α-2a (180 µg/week) and ribavirin (1000-1200 mg/day) for 48 weeks overall. Data from telaprevir arms were pooled. RESULTS: Eighty percent (527/662) of patients consented to genetic testing and were included. Similar proportions of patients had IL28B CC, CT and TT genotypes across treatment arms; baseline characteristics were generally well balanced. SVR rates were higher in the pooled telaprevir versus placebo group for all IL28B genotypes; CC: 79% versus 29%, respectively; CT: 60% versus 16%, respectively; TT: 61% versus 13%, respectively. Within each prior response category (relapse, partial or null response), SVR and viral breakthrough rates with telaprevir-based treatment were comparable across IL28B genotypes. IL28B genotype did not significantly affect SVR (2-step multivariate analyses; p >0.16 in pairwise comparison among CC, TT, and CT). Variations in rapid virologic response and relapse rates were noted in certain patient subgroups. CONCLUSIONS: Our findings suggest that IL28B genotype has a limited impact on SVR rates with telaprevir-based therapy in treatment-experienced patients. IL28B genotyping may have limited utility in the baseline evaluation of similar patients considered for telaprevir-based therapy.

The effect of CYP3A inhibitors and inducers on the pharmacokinetics of telaprevir in healthy volunteers.

AIM: To evaluate the effects of ketoconazole, rifampicin and efavirenz on the pharmacokinetics of telaprevir in healthy volunteers. METHOD: Results from three clinical studies are described. (1) Volunteers received a single 750 mg dose telaprevir with and without a single 400 mg dose ketoconazole. (2) Volunteers received (a) 1250 mg telaprevir followed by three 750 mg doses given every 8 h and (b) four 1250 mg telaprevir doses given every 8 h, with a single 400 mg dose ketoconazole given with the fourth dose of telaprevir. (3) Volunteers received either a single 750 mg dose telaprevir with or without 600 mg once daily rifampicin, or 750 mg every 8 h telaprevir with and without 600 mg once daily efavirenz. RESULTS: A single 400 mg dose of ketoconazole increased single dose telaprevir exposure: the geometric least-squares mean ratio (GLSMR, with 90% confidence limits) was 1.24 (1.10, 1.41) for C(max) and 1.62 (1.45, 1.81) for AUC(0,∞). However, after multiple doses of telaprevir, there was no discernible effect of ketoconazole on telaprevir exposure. Co-administration of rifampicin at steady-state markedly reduced single dose telaprevir exposure with GLSMRs of 0.14 (0.11, 0.18) for C(max) and 0.08 (0.07, 0.11) for AUC(0,∞), whereas efavirenz had a smaller effect on telaprevir exposure when both drugs were co-administered at steady-state, with GLSMRs of 0.91 (0.81, 1.02) for C(max) , 0.53 (0.44, 0.65) for C(min), and 0.74 (0.65, 0.84) for AUC(0,8 h). CONCLUSION: CYP3A inducers, rifampicin and efavirenz, can reduce telaprevir exposure to varying degrees based on their potency. The effect of ketoconazole as an inhibitor of telaprevir metabolism is more pronounced after a single dose of telaprevir than after repeated administration.

Effect of telaprevir on the pharmacokinetics of buprenorphine in volunteers on stable buprenorphine/naloxone maintenance therapy.

This was an open-label, single-sequence trial in hepatitis C virus-negative volunteers on stable, individualized, buprenorphine maintenance therapy. Telaprevir at 750 mg every 8 h was coadministered with buprenorphine/naloxone (4:1 ratio as sublingual tablets) for 7 days with food. Pharmacokinetic profiles of buprenorphine, norbuprenorphine, and naloxone were measured over the 24-hour dosing interval on day -1 (buprenorphine/naloxone alone, reference) and day 7 of telaprevir coadministration (test). Geometric least-squares mean ratios and associated 90% confidence intervals of treatment ratios (test/reference) were calculated using log-transformed pharmacokinetic parameters. Opioid withdrawal symptoms were evaluated throughout the study (via questionnaires and pupillometry). Pharmacokinetic data were available for 14 and 13 volunteers on day -1 and day 7, respectively. The area under the concentration-time curve (AUC) for buprenorphine was unchanged and the maximum concentration of drug in serum (C(max)) for buprenorphine, C(max) and AUC for norbuprenorphine, and C(max) naxolone were modestly decreased during coadministration with telaprevir. Geometric least-squares mean ratios (90% confidence intervals) for buprenorphine were 0.80 (0.69, 0.93) for the C(max) and 0.96 (0.84, 1.10) for the AUC from 0 to 24 h (AUC(0-24)); for norbuprenorphine, values were 0.85 (0.66, 1.09) for C(max) and 0.91 (0.71, 1.16) for AUC(0-24); for naloxone, the C(max) was 0.84 (0.62, 1.13). Coadministration of telaprevir did not increase withdrawal symptom frequency, and there were no serious adverse events reported during or after completion of telaprevir coadministration. Results suggest dose adjustment may not be necessary when telaprevir and buprenorphine/naloxone are coadministered.

The diarylquinoline TMC207 for multidrug-resistant tuberculosis.

BACKGROUND: The diarylquinoline TMC207 offers a new mechanism of antituberculosis action by inhibiting mycobacterial ATP synthase. TMC207 potently inhibits drug-sensitive and drug-resistant Mycobacterium tuberculosis in vitro and shows bactericidal activity in patients who have drug-susceptible pulmonary tuberculosis. METHODS: In the first stage of a two-stage, phase 2, randomized, controlled trial, we randomly assigned 47 patients who had newly diagnosed multidrug-resistant pulmonary tuberculosis to receive either TMC207 (400 mg daily for 2 weeks, followed by 200 mg three times a week for 6 weeks) (23 patients) or placebo (24 patients) in combination with a standard five-drug, second-line antituberculosis regimen. The primary efficacy end point was the conversion of sputum cultures, in liquid broth, from positive to negative. RESULTS: The addition of TMC207 to standard therapy for multidrug-resistant tuberculosis reduced the time to conversion to a negative sputum culture, as compared with placebo (hazard ratio, 11.8; 95% confidence interval, 2.3 to 61.3; P=0.003 by Cox regression analysis) and increased the proportion of patients with conversion of sputum culture (48% vs. 9%). The mean log(10) count of colony-forming units in the sputum declined more rapidly in the TMC207 group than in the placebo group. No significant differences in average plasma TMC207 concentrations were noted between patients with and those without culture conversion. Most adverse events were mild to moderate, and only nausea occurred significantly more frequently among patients in the TMC207 group than among patients in the placebo group (26% vs. 4%, P=0.04). CONCLUSIONS: The clinical activity of TMC207 validates ATP synthase as a viable target for the treatment of tuberculosis. (ClinicalTrials.gov number, NCT00449644.)

The effect of ß-carotene supplementation on the pharmacokinetics of nelfinavir and its active metabolite M8 in HIV-1-infected patients.

ß-Carotene supplements are often taken by individuals living with HIV-1. Contradictory results from in vitro studies suggest that ß-carotene may inhibit or induce cytochrome P450 enzymes and transporters. The study objective was to investigate the effect of ß-carotene on the steady-state pharmacokinetics of nelfinavir and its active metabolite M8 in HIV-1 infected individuals. Twelve hour nelfinavir pharmacokinetic analysis was conducted at baseline and after 28 days of ß-carotene supplementation (25,000 IU twice daily). Nelfinavir and M8 concentrations were measured with validated assays. Non-compartmental methods were used to calculate the pharmacokinetic parameters. Geometric mean ratios comparing day 28 to day 1 area under the plasma concentration-time curve (AUC(0-12 h)), maximum (C(max)) and minimum (C(min)) concentrations of nelfinavir and M8 are presented with 90% confidence intervals. Eleven subjects completed the study and were included in the analysis. There were no significant differences in nelfinavir AUC(0-12 h) and C(min) (-10%, +4%) after ß-carotene supplementation. The M8 C(min) was increased by 31% while the M8 AUC(0-12 h) and C(max) were unchanged. During the 28 day period, mean CD4+ % and CD4+:CD8+ ratio increased significantly (p < 0.01). ß-carotene supplementation increased serum carotene levels but did not cause any clinically significant difference in the nelfinavir and M8 exposure.

Inhibition of adenine nucleotide translocator pore function and protection against apoptosis in vivo by an HIV protease inhibitor.

Inhibitors of HIV protease have been shown to have antiapoptotic effects in vitro, yet whether these effects are seen in vivo remains controversial. In this study, we have evaluated the impact of the HIV protease inhibitor (PI) nelfinavir, boosted with ritonavir, in models of nonviral disease associated with excessive apoptosis. In mice with Fas-induced fatal hepatitis, Staphylococcal enterotoxin B-induced shock, and middle cerebral artery occlusion-induced stroke, we demonstrate that PIs significantly reduce apoptosis and improve histology, function, and/or behavioral recovery in each of these models. Further, we demonstrate that both in vitro and in vivo, PIs block apoptosis through the preservation of mitochondrial integrity and that in vitro PIs act to prevent pore function of the adenine nucleotide translocator (ANT) subunit of the mitochondrial permeability transition pore complex.

Time-dependent interaction between lopinavir/ritonavir and fexofenadine.

This study investigated the effect of single-dose and steady-state lopinavir/ritonavir on the exposure to fexofenadine, as a measure of P-glycoprotein activity. Sixteen volunteers (8 women) received single-dose oral fexofenadine 120 mg alone, in combination with single-dose ritonavir 100 mg or lopinavir/ritonavir 400/100 mg (randomized 1:1, stratified by sex), and in combination with steady-state lopinavir/ritonavir 400/100 mg twice daily. Single-dose ritonavir and lopinavir/ritonavir increased the area under the fexofenadine plasma concentration-time curve from 0 to infinity (AUC(infinity)) by 2.2- and 4.0-fold, respectively (P < .02). Steady-state lopinavir/ritonavir increased the fexofenadine AUC(infinity) by 2.9-fold. No changes were observed in the fexofenadine elimination half-life (P > .12). The fexofenadine AUC(infinity) was increased by lopinavir/ritonavir, likely due to increased bioavailability secondary to P-glycoprotein inhibition. After repeated administration of lopinavir/ritonavir, the interaction was attenuated compared to the single-dose effect, although a net inhibitory effect was maintained. Time-dependent inhibition of P-glycoprotein by lopinavir/ritonavir should be considered when P-glycoprotein substrates are coadministered.

Effect of high-dose vitamin C on hepatic cytochrome P450 3A4 activity.

STUDY OBJECTIVES: To investigate the effect of high-dose vitamin C on cytochrome P450 (CYP) 3A4 activity, and to evaluate possible sex-specific effects on CYP3A4 activity. DESIGN: Single-center longitudinal study. SETTING: Tertiary- and specialty-care teaching hospital. SUBJECTS: Fourteen healthy Caucasian adult volunteers (seven men, seven women). INTERVENTION: Subjects self-administered vitamin C 500 mg twice/day for 14 days. MEASUREMENTS AND MAIN RESULTS: Hepatic CYP3A4 activity was measured by using the erythromycin breath test on days 1 (baseline) and 15. Overall, no significant effect of vitamin C on CYP3A4 activity was observed. Sex and baseline results were significant predictors of changes in CYP3A4 activity. In men, mean activity increased by 21.9% (95% confidence interval -3.88-47.6%). The effect in women was not consistent. CONCLUSION: Sex and baseline CYP3A4 activity appeared to influence the effect of vitamin C on CYP3A4 activity.

The pharmacokinetics of nelfinavir and M8 during pregnancy and post partum.

OBJECTIVE: The objective of this study was to explore the pharmacokinetics of nelfinavir and its active metabolite hydroxy-t-butylamidenelfinavir (M8) during pregnancy and post partum. METHODS: Eleven human immunodeficiency virus type 1-infected pregnant women receiving 1250 mg nelfinavir twice daily were enrolled. Pharmacokinetics of nelfinavir and M8 were assessed over a 12-hour period during pregnancy (median, 32 weeks' gestation; range, 31-36 weeks) and post partum (median, 8 weeks post partum; range, 6-15 weeks). Drug concentrations were analyzed by HPLC coupled to tandem mass spectroscopy, and pharmacokinetic parameters were calculated by use of noncompartmental methods. RESULTS: The median area under the plasma concentration-time curve from 0 to 12 hours (AUC 0-12), the maximal plasma concentration (C max), and the concentration at the end of the dosing interval (C 12) for nelfinavir post partum were 33.5 h . microg/mL, 5.80 microg/mL, and 1.40 microg/mL, respectively. The values for the geometric mean ratio (GMR) (third trimester/post partum) for the nelfinavir AUC 0-12 , C max , and C 12 were 0.76 (90% confidence interval [CI], 0.54-1.06), 0.81 (90% CI, 0.57-1.15), and 0.43 (90% CI, 0.25-0.76), respectively. The GMR values for the M8 AUC 0-12 , C max , and C 12 were 0.32 (90% CI, 0.18-0.55), 0.31 (90% CI, 0.19-0.51), and 0.30 (90% CI, 0.14-0.64), respectively. The median ratio values of the AUC 0-12 of M8 and nelfinavir (M8/nelfinavir) during the third trimester and post partum were 11% and 27%, respectively (GMR, 0.42 [90% CI, 0.33-0.53]). CONCLUSIONS: Nelfinavir exposure was reduced during pregnancy, and the reduction was statistically significant for C 12 . M8 concentrations were about 70% lower during pregnancy compared with post partum, suggesting either induction of hepatic cytochrome P450 (CYP) 3A4 or inhibition of CYP2C19, or both, during pregnancy. Because 8 of 11 women had subtherapeutic nelfinavir trough concentrations during pregnancy, the safety and efficacy of therapeutic drug monitoring should be investigated.

Optimized antiretroviral therapy: the role of therapeutic drug monitoring and pharmacogenomics.

The identification of relationships between plasma concentrations of protease inhibitors and later, the non-nucleoside reverse transcriptase inhibitors and their efficacy and toxicity has caused a growing interest in the concept of therapeutic drug monitoring in the treatment of HIV infection. Some evidence suggests a beneficial effect of therapeutic drug monitoring of protease inhibitors. More recently, plasma protease inhibitor concentrations have been combined with viral susceptibility into one parameter, the inhibitory quotient, which may be a better predictor of the response to therapy, especially in pretreated patients. This paper reviews the current literature on therapeutic drug monitoring and the inhibitory quotient in the management of HIV infection and speculates on the future role of pharmacogenomics in this therapeutic area.

The effect of rilpivirine on the pharmacokinetics of methadone in HIV-negative volunteers.

Antiretrovirals may influence methadone exposure in HIV-1-infected patients receiving methadone for opiate addiction. Rilpivirine is a non-nucleoside reverse transcriptase inhibitor for treating HIV-1 infection. In this open-label trial (NCT00744770), 13 HIV-negative volunteers continued on their regular stable methadone therapy (60 to 100 mg once daily; Days -14 to 12), with rilpivirine coadministration (Days 1 to 11). Methadone and rilpivirine pharmacokinetics and opiate withdrawal symptoms (Short Opiate Withdrawal Scale, Desires for Drugs Questionnaire, pupillometry) were evaluated. Rilpivirine decreased methadone minimum and maximum plasma concentrations (Cmin ; Cmax ) and area under the plasma concentration-time curve versus methadone alone (least-square mean ratio; 90% confidence interval) by 22% (0.78; 0.67, 0.91), 14% (0.86; 0.78, 0.95), and 16% (0.84; 0.74, 0.95), respectively (R-methadone), and 21% (0.79; 0.67, 0.92), 13% (0.87; 0.78, 0.97), and 16% (0.84; 0.74, 0.96), respectively (S-methadone). Rilpivirine pharmacokinetics with methadone were consistent with historic data. No clinically relevant opiate withdrawal symptoms were reported. Methadone and rilpivirine coadministration was generally well tolerated. No grade 3/4 adverse events (AEs), serious AEs, or discontinuations due to AEs were seen. No methadone dose adjustment is prompted by rilpivirine coadministration. Clinical monitoring for opiate withdrawal is recommended, as some patients may require adjustment of methadone maintenance therapy.

Review of drug interactions with telaprevir and antiretrovirals.

HCV infection is a major cause of mortality worldwide. HCV-related deaths also represent a leading cause of mortality in HIV-coinfected individuals. Telaprevir is an NS3/4A protease inhibitor approved for the treatment of chronic HCV genotype 1 infection in adults in combination with pegylated interferon and ribavirin. Telaprevir-based treatment has been shown to increase rates of sustained viral response in HCV genotype-1-monoinfected patients, and studies in HCV-HIV-coinfected patients are ongoing. Drug-drug interactions of telaprevir with antiretroviral drugs were investigated in a series of studies in healthy subjects. This review summarizes the results of interaction studies with low-dose ritonavir, ritonavir-boosted HIV protease inhibitors (atazanavir, darunavir, fosamprenavir and lopinavir), efavirenz, etravirine, rilpivirine, tenofovir disoproxil fumarate and raltegravir.

Clinical perspective on drug-drug interactions with the non-nucleoside reverse transcriptase inhibitor rilpivirine.

Rilpivirine (TMC278) is a non-nucleoside reverse transcriptase inhibitor approved in combination with other antiretrovirals for the treatment of HIV-1 infection in treatment-naive adults (Edurant(®) 25 mg once daily; Complera(®) [USA]/Eviplera(®) [EU] once daily single-tablet regimen). Rilpivirine should be administered with a meal to optimize bioavailability. Its solubility is pH dependent. Rilpivirine is primarily excreted via the feces with negligible renal elimination. Rilpivirine is predominantly metabolized by cytochrome P450 3A4. There is no clinically relevant effect of age, gender, bodyweight, race, estimated glomerular filtration rate, or hepatitis B/C coinfection status on rilpivirine pharmacokinetics in adults. Drug-drug interactions were investigated with cytochrome P450 3A substrates, inducers and inhibitors, drugs altering intragastric pH, antiretrovirals, and other often coadministered drugs. Rilpivirine 25 mg once daily does not have a clinically relevant effect on exposure of coadministered drugs. Coadministration with cytochrome P450 3A inhibitors (ketoconazole, ritonavir-boosted protease inhibitors, telaprevir) results in increased rilpivirine plasma concentrations, but these are not considered clinically relevant; no dose adjustments are required. Coadministration of rilpivirine with cytochrome P450 3A inducers (e.g. rifampin, rifabutin) or compounds increasing gastric pH (e.g. omeprazole, famotidine) results in decreased rilpivirine plasma concentrations, which may increase the risk of virologic failure and resistance development. Therefore, strong cytochrome P450 3A inducers and proton-pump inhibitors are contraindicated. Histamine-2 receptor antagonists and antacids can be coadministered with rilpivirine, provided doses are temporally separated. No dose adjustments are required when rilpivirine is coadministered with: acetaminophen, phosphodiesterase type 5 inhibitors (sildenafil, etc.), atorvastatin (and other statins), oral contraceptives (ethinyl estradiol, norethindrone), chlorzoxazone (cytochrome P450 2E1 substrate), methadone, digoxin, tenofovir disoproxil fumarate, didanosine and other nuceos(t)ide reverse transcriptase inhibitors, and HIV integrase inhibitors (raltegravir, dolutegravir, GSK1265744).

Impact of food and different meal types on the pharmacokinetics of rilpivirine.

The objective of the study was to determine the impact of food and different meal types on the pharmacokinetics of rilpivirine, a nonnucleoside reverse transcriptase inhibitor. In this open-label, randomized, crossover study, healthy volunteers received a single, oral 75 mg dose of rilpivirine either with a normal-fat breakfast (reference), under fasting conditions, with a high-fat breakfast, or with a protein-rich nutritional drink. Pharmacokinetic parameters were determined by non-compartmental methods and analyzed using a linear mixed-effects model. Safety was assessed throughout. The least-squares mean ratio for area under the plasma concentration-time curve to last timepoint was 0.57 (90% confidence interval [CI]: 0.46-0.72) under fasting conditions compared to dosing with a normal-fat breakfast. With a high-fat breakfast or only a protein-rich nutritional drink, the corresponding values were 0.92 (90% CI: 0.80-1.07) and 0.50 (90% CI: 0.41-0.61), respectively, compared to dosing with a normal-fat breakfast. Under all conditions, rilpivirine was generally safe and well tolerated. Administration of rilpivirine under fasting conditions or with only a protein-rich nutritional drink substantially lowered the oral bioavailability when compared to administration with a normal-fat breakfast. Rilpivirine bioavailability was similar when administered with a high-fat or normal-fat breakfast. Rilpivirine should always be taken with a meal to ensure adequate bioavailability.

Telaprevir: pharmacokinetics and drug interactions.

Telaprevir is an inhibitor of the HCV NS3/4A protease. When used in combination with pegylated interferon and ribavirin, telaprevir has demonstrated a substantial increase in sustained virological response compared with pegylated interferon and ribavirin used alone. Telaprevir has good oral bioavailability, which is enhanced when administered with food. Telaprevir is extensively metabolized and primarily eliminated via faeces. No dose adjustment of telaprevir is needed in patients with mild to severe renal impairment or mild liver impairment. Telaprevir is a substrate and inhibitor of cytochrome P450 3A and P-glycoprotein and, thus, might interact with coadministered drugs that affect or are affected by these metabolic/transport pathways. This article reviews the pharmacokinetic and drug interaction profile of telaprevir.

Effect of telaprevir on the pharmacokinetics of midazolam and digoxin.

In this open-label study, 24 healthy volunteers received a single intravenous (IV) dose of 0.5 mg of midazolam on day 1 and a single oral dose each of 2 mg of midazolam and 0.5 mg of digoxin on day 3. Telaprevir 750 mg every 8 hours was administered from day 8 through day 23, along with a single IV dose of 0.5 mg of midazolam on day 17 and single oral doses of 2 mg of midazolam and 0.5 mg of digoxin on day 19. Midazolam, 1'-hydroxymidazolam, digoxin, and telaprevir concentrations in plasma and digoxin concentrations in urine were measured and pharmacokinetic parameters calculated. On comparing administration with versus without telaprevir, the geometric least squares mean ratios (with 90% confidence limits) for IV midazolam were 1.02 (0.80, 1.31) for maximum observed concentrations (C(max)) and 3.40 (3.04, 3.79) for area under the curve from 0 to 24 hours (AUC(0-24h)); for oral midazolam 2.86 (2.52, 3.25) for C(max) and 8.96 (7.75, 10.35) for AUC(0-24h); and for oral digoxin 1.50 (1.36, 1.65) for C(max) and 1.85 (1.70, 2.00) for area under the curve from 0 to infinity (AUC(0-∞)). Coadministration of telaprevir with oral midazolam resulted in approximately 3-fold decrease in the mean AUC(0-∞) of 1'-hydroxymidazolam. The renal clearance of digoxin was similar with or without telaprevir. Results show that telaprevir is an inhibitor of CYP3A and P-glycoprotein.