Steady-State Pharmacokinetics of Lamivudine Once-Daily Versus Twice-Daily Dosing in Chinese HIV-Infected Patients

Abstract

Objective: The present study aimed to compare the pharmacokinetics of lamivudine in 300 mg once-daily and 150 mg twice-daily dosing regimens in HIV-infected Chinese patients. Methods: HIV-infected patients received lamivudine 300 mg once daily or 150 mg twice daily as part of a highly active antiretroviral therapy regimen. After the patients received lamivudine for at least 3 months, serial blood samples were collected for 24 hours. The samples were measured by a validated high-performance liquid chromatography (HPLC) assay. The pharmacokinetics of once-daily versus twice-daily dosing was evaluated by noncompartment models. Results: Ten patients received lamivudine 300 mg once daily and 5 patients received 150 mg twice daily. The C_max was significantly higher in the once-daily arm than the twice-daily arm (2.23 vs 1.61 μg/mL, P <.05), whereas the C_min was markedly lower (0.05 vs 0.12 μg/mL, P <.05). The half-lives were 3.32 hours and 2.62 hours, and AUC₂₄ values were 11.8 μg/mL·h and 13.0 μg/mL·h in the 300 mg once-daily and 150 mg twice-daily regimens, respectively (P ≯.05). Conclusion: The shorter half-life was observed first in Chinese HIV patients with once- and twice-daily regimens. The 300 mg once-daily regimen was associated with lower trough concentrations and remarkable interpatient variability. Further studies in large groups of HIV patients are needed to confirm the influence of shorter half-lives in Chinese patients on efficacy and toxicity.     

Comparison of Two Once-Daily Regimens with a Regimen Consisting of Nelfinavir,Didanosine, and Stavudine in Antiretroviral Therapy-Naïve Adults: 48-Week Results from the Antiretroviral Regimen Evaluation Study (ARES)

Abstract

Background: To improve the dosing frequency and pill burden of antiretroviral therapy, we compared two once-daily dosed regimens to a twice-daily dosed regimen. Method: HIV-1-infected, antiretroviral drug-naïve adults were randomized to either twice-daily nelfinavir and stavudine and once-daily didanosine (regimen A) or simplified once-daily dosed antiretroviral regimens consisting of nevirapine, didanosine, and lamivudine (regimen B) or saquinavir, ritonavir, didanosine, and lamivudine (regimen C). Results: At 48 weeks of therapy, the proportion of patients with a blood plasma HIV-1 RNA concentration (pVL) <50 copies/mL by intention-totreat analysis was 42.3%, 50.0%, and 56.5% for regimens A (n = 26), B (n = 22), and C (n = 23), respectively. The time to a pVL <50 copies/mL for the first time was significantly shorter in regimen C, and there was significantly more progression to CDC events in regimen B. These differences are possibly due to differences in baseline characteristics. Adverse events were lowest for regimen C; more signs associated with mitochondrial toxicity occurred in regimen A. Increase in CD4 count was comparable between arms. Conclusion: No statistically significant difference in efficacy was found between the two investigated once-daily dosed treatment regimens (B and C) and the reference (A). Regimen C possibly had a better virological response and less toxicity than regimens A and B.     

Study of Once-Daily Versus Twice-Daily Fosamprenavir plus Ritonavir Administered with Abacavir/Lamivudine Once Daily in Antiretroviral-Naïve HIV-1–Infected Adult Subjects

Abstract

Purpose: Fosamprenavir/ritonavir 1400 mg/100 mg once-daily regimen may have a more favourable tolerability and lipid profile than the fosamprenavir/ritonavir twice-daily regimen, while maintaining comparable antiviral efficacy. Methods: This open-label study had a group-sequential design with a stage 1 Week 24 futility analysis, with both efficacy and safety go-criteria for progression to stage 2. There were 214 antiretroviral-naive, HIV-1–infected subjects who were randomised to receive either fosamprenavir/ritonavir 1400 mg/100 mg once daily or fosamprenavir/ ritonavir 700 mg/100 mg twice daily, both with abacavir/lamivudine fixed-dose combination tablet. Primary endpoints were the proportion of subjects achieving HIV-1 RNA <400 copies/mL at Week 48 and the mean change from baseline in fasting non-HDL cholesterol. Results: Though stage 1 futility analysis did not meet criteria for progression to stage 2, subjects enrolled in stage 1 were followed to Week 48 per protocol. At Week 48, noninferior efficacy of once daily to twice daily (95% CI around the treatment difference, –11.4 to 9.5) was achieved, with 86/106 (81%) subjects in the once-daily and 87/106 (82%) in the twice-daily arm achieving HIV-1 RNA <400 copies/mL. Mean change from baseline at Week 48 in non-HDL cholesterol was 1.10 mmol/L and 1.26 mmol/L (p = .478) for the once-daily and twice-daily arms, respectively. Conclusion: Though the study did not continue to stage 2, fosamprenavir/ritonavir once daily demonstrated noninferior antiviral efficacy to fosamprenavir/ritonavir twice daily.     

Switch From Etravirine Twice Daily to Once Daily in Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI)-Resistant HIV-Infected Patients With Suppressed Viremia: The Monetra Study

Abstract

Background: Etravirine (ETR) is recommended as twice-daily dosing in pretreated patients. There are no data regarding the use of ETR once daily in HIV-experienced patients with prior resistance to first-generation non-nucleoside reverse transcripase inhibitors (NNRTIs).Objectives: To evaluate the capacity of once-daily ETR to maintain suppressed viremia over 48 weeks after switching from ETR twice daily in NNRTI-experienced patients.Methods: In this pilot open-label study, patients with plasma viral load (pVL) <50 copies/mL on a stable ETR 200 mg bid regimen were enrolled to switch to ETR 400 mg qd and followed up over 48 weeks. The primary endpoint was the proportion of patients with pVL <50 copies/mL at week 24. Secondary endpoints included the rate of pVL< 50 copies/mL at week 48, ETR pharmacokinetic parameters, and tolerability and resistance profile.Results: Twenty-four patients were included. They had extensive antiretroviral treatment for a median of 14 years (range, 1-19). All except for 2 had prior resistance to NNRTIs. Seven patients discontinued ETR once daily prior to week 48 for virological failure (3), protocol deviation (3), and side effects (1). At week 24, 95% of patients maintained pVL< 50 copies/mL (95% CI, 78.4-99.7) and 85% at week 48 (95%CI, 65.6-95.8). Two of the 3 patients with virological failure had ETR resistance mutations prior to initiation. The median ETR C_trough level remained stable after switching from twice daily 515 ng/mL (340-758) to once daily 422 ng/mL (264-655).Conclusion: These results suggest that ETR is effective as a once-daily regimen in patients with prior NNRTI experience when HIV is sensitive to ETR. The stability of C_trough concentrations on a once-daily regimen confirms the once-daily profile of the drug in experienced patients.     

Pharmacokinetic analysis of nevirapine extended release 400 mg once daily vs nevirapine immediate release 200 mg twice daily formulation in treatment-naïve patients with HIV-1 infection

Background: VERxVE data showed non-inferior virologic efficacy with extended release nevirapine (NVP-XR) dosed 400 mg once daily (QD) versus immediate release nevirapine (NVP-IR) 200 mg twice daily in a double-blind, non-inferiority study in treatment-naïve HIV-1-positive patients.

Objective: To study the pharmacokinetics (PK) of the NVP formulations and identify possible associations with demographic factors.

Methods: Patients with viral load ≥1000 copies/mL and CD4+ count > 50– <400 cells/mm³ (males) and >50– <250 cells/mm³ (females) at screening received NVP-IR 200 mg QD during a 14-day lead-in and were then stratified by baseline viral load and randomized to NVP-XR or -IR. NVP trough concentrations at steady state (SS) (C_pre,ss,N) were measured up to week 48 for all participating patients. In a PK sub-study, SS parameters – AUC_0–24, C_max, C_min, and peak-to-trough fluctuation were obtained and analyzed with relative bioavailability assessed at week 4 by plasma collection over 24 h.

Results: Trough concentrations were stable from week 4 to week 48 for all patients (n = 1011) with both formulations, with NVP-XR/IR ratios of 0.77–0.82. Overall, 49 patients completed the PK sub-study: 24 XR and 25 IR. NVP-XR showed less peak-to-trough fluctuation (34.5%) than IR (55.2%), and lower AUC_0–24, C_min, C_max, and trough concentrations than IR. However, no effect of SS trough concentrations was found on the virologic response proportion at least up to 1000 ng/mL. No significant association was found between NVP PK and gender, race, and viral load.

Conclusion: These data suggest NVP-XR achieves lower but effective NVP exposure compared with NVP-IR.     

Atazanavir Plasma Concentrations Vary Significantly Between Patients and Correlate with Increased Serum Bilirubin Concentrations

Abstract

Background: Atazanavir (ATV) is recommended to be dosed at 400 mg once daily or 300 mg daily coadministered with 100 mg ritonavir (RTV). Method: 31 male patients receiving ATV either alone or boosted with RTV for more than 2 weeks had ATV concentration measured by high performance liquid chromatography (HPLC). ATV concentrations were adjusted to obtain a 24-hour trough level using a standard pharmacokinetic formula. Results: 25 samples were taken from patients who received 300 mg ATV, 6 with 200 mg, 3 with 400 mg, and 2 with 150 mg, all boosted with 100 mg RTV. In the unboosted group, patients received 400 mg (7) or 600 mg (2). The median adjusted 24-hour trough ATV concentration was 630 ng/mL (interquartile range [IQR] 355-1034) in the boosted and 113 ng/mL (IQR 50-225) in the unboosted group (p = .001). Median serum bilirubin concentration was 34 IU/L (IQR 27.5-49) and 41 IU/L (IQR 31-45) in the boosted and unboosted groups, respectively. In the boosted group, high ATV concentrations were significantly correlated with increased serum bilirubin concentrations (p = .003). Conclusion: ATV concentrations showed considerable interpatient variability. Bilirubin concentrations are an indicator of high ATV concentrations and may prove to be useful in selecting patients for therapeutic drug monitoring (TDM).     

Didanosine dosed once daily is equivalent to twice daily dosing for patients on double or triple combination antiretroviral therapy. The AI454-147 Team

OBJECTIVE: To compare the antiviral activity, effect on CD4 cell count, and tolerability of didanosine (ddI) administered once daily and twice daily in HIV-1-infected patients receiving ddI with stavudine or zidovudine, with or without a protease inhibitor. The study was designed to demonstrate that once-daily dosing of ddI was not inferior to twice-daily dosing. DESIGN: Randomized, open-label, multicenter, two-arm study. PATIENTS AND METHODS: 121 HIV-1-infected adults on a stable regimen including ddI (twice daily) during the previous 3 months with a stable viral load <10,000 copies/ml started therapy. Of these, 62 were randomized to switch to a combination that included ddI once daily and 59 to continue with ddI twice daily. The ddI dose was 400 mg/day (250 mg/day if body weight was <60 kg). The primary efficacy analysis compared the time-averaged difference (TAD) between the two treatment regimens in change from baseline log10 plasma HIV-1 RNA levels over 24 weeks of therapy, with an equivalence margin between the two treatment groups of <0.5 log10 copies/ml. RESULTS: At week 24, the mean plasma HIV-1 RNA level had increased by 0.31 and 0.17 log10 copies/ml in the ddI once-daily and ddI twice-daily groups, respectively. The time-averaged difference between the two groups in change from baseline plasma HIV-1 RNA levels over 24 weeks was (0.05 log10 copies/ml (95% confidence interval, -0.21 to +0.12 log10 copies/ml), indicating that the antiviral activity of ddI once daily is similar to that of ddI twice daily. After 24 weeks of treatment, changes from baseline in CD4 cell counts were similar in the two groups. Both regimens were generally well-tolerated. CONCLUSIONS: Once-daily and twice-daily ddI are equally effective at reducing plasma HIV-1 RNA levels when used in a combination regimen with stavudine or zidovudine, with or without a protease inhibitor.     

Comparison of once-daily to twice-daily treatment with mometasone furoate dry powder inhaler.

BACKGROUND: Once-daily dosing with an effective inhaled corticosteroid (ICS) would likely enhance compliance and, therefore, aid in the management of asthma. OBJECTIVE: Several once-daily dosing regimens of mometasone furoate (MF) administered by dry powder inhaler (DPI) were compared with a twice-daily dosing regimen in 286 patients with mild to moderate persistent asthma who were previously being treated with ICS. METHODS: During a 2-week open-label phase, patients received MF-DPI, 200 microg twice daily. They were then randomized to continue MF-DPI, 200 microg twice-daily treatment or to receive MF-DPI, 200 microg once daily in the morning (AM), 200 microg once daily in the evening (PM), 400 microg once daily AM, or placebo as part of the 12-week, double-blind phase. The primary efficacy variable was the mean change from the baseline to endpoint (last evaluable observation) for FEV1. RESULTS: Once-daily MF-DPI, 400 microg, AM maintained FEV1, and morning peak expiratory flow rate, FVC, FEF25%-75%, and asthma symptom scores, at levels similar to those for MF-DPI, 200 microg twice daily and significantly better than placebo. Once-daily MF-DPI, 200 microg, PM was effective in maintaining pulmonary function, but was less effective on other efficacy measures. In comparison to the other MF-DPI groups, once-daily MF-DPI, 200 microg, AM was not as effective overall. The incidence of local adverse events, including oral candidiasis, was low with all dosages. CONCLUSIONS: Once-daily MF-DPI, 400 microg, AM was as effective as MF-DPI, 200 microg twice daily, whereas once-daily MF-DPI, 200 microg, was more effective when administered in the evening compared with morning, for patients receiving ICS therapy. Once-daily dosing offers an effective and convenient treatment that could aid compliance in the treatment of asthma.     

Pharmacokinetics,Efficacy, and Safety of Darunavir/Ritonavir 800/100 mg Once-Daily in Treatment-Naïve and -Experienced Patients

Abstract

Darunavir is a new protease inhibitor (PI) with in vitro activity against wild-type and PI-resistant HIV; it is used with the pharmacokinetic booster ritonavir. The currently approved dose of darunavir/ritonavir is 600/100 mg twice-daily, licensed for treatment-experienced patients. However, during the clinical development of darunavir, a range of once-daily and twice-daily doses of darunavir/ritonavir were evaluated. The relatively long terminal elimination plasma half-life of darunavir (15 hours) supports once-daily dosing. In treatment-naïve patients, the ARTEMIS trial has shown high rates of HIV RNA suppression for darunavir-ritonavir at the 800/100 mg once-daily dose (84% with HIV RNA <50 copies/mL at Week 48) versus a control arm of lopinavir/ritonavir (78% with HIV RNA <50 copies/mL). In a population pharmacokinetic substudy, darunavir 24-hour minimum plasma concentration levels remained above the predefined EC₅₀ of 55 ng/mL for all 335 patients evaluated in the ARTEMIS trial. Once-daily darunavir/ritonavir has also been evaluated in treatment-experienced patients in the TMC114-C207 proof-of-principle trial and the POWER 1 and 2 trials. For the overall POWER trial population, with significant baseline resistance to PIs, the rates of HIV RNA suppression <50 copies/mL at Week 24 for darunavir/ritonavir 800/100 mg once-daily were lower than for the 600/100 mg twice-daily dosage (31% vs. 47%, respectively). However, for patients with no genotypic darunavir resistance-associated mutations at baseline, rates of HIV RNA suppression were 62% and 67% for the 800/100 mg once-daily and 600/100 mg twice-daily doses. The current evidence from clinical trials of darunavir/ritonavir supports the efficacy of the 800/100 mg once-daily dose for treatment-naïve patients and further evaluation for treatment-experienced patients with no genotypic resistance to darunavir.     

Steady-State Amprenavir,Tenofovir, and Emtricitabine Pharmacokinetics Before and After Reducing Ritonavir Boosting of a Fosamprenavir/Tenofovir/Emtricitabine Regimen from 200 mg to 100 mg Once Daily (TELEX II)

Abstract

Purpose: Evaluate how reducing ritonavir (RTV) boosting from 200 mg to 100 mg once daily (QD) affects steady-state pharmacokinetics of components of a fosamprenavir (FPV)-based regimen. Methods: Prospective, open-label, pharmacokinetic study in 12 HIV-infected patients stabilized on FPV/RTV 1400 mg/200 mg + tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) 300 mg/200 mg QD (TELEX II). Pharmacokinetics were assessed by noncompartmental analysis at baseline and 4 weeks after RTV reduction to 100 mg QD. Results: Baseline median minimum plasma concentration (C_min) and area under the plasma concentration-time curve over 24 hours post dose (AUC_24h) were as follows: APV: 1,708 ng/mL, 84,260 h ? ng/mL; tenofovir: 53 ng/mL, 2,420 h ? ng/mL; FTC: 58 ng/mL, 9,190 h ? ng/mL; RTV: 80 ng/mL, 10,230 h ? ng/mL. Four weeks after reducing RTV, changes in C_min and AUC_24h were: APV: +26%, +0.6%; tenofovir: +77%, +30%; FTC: +188%, +13%; RTV –64%, –79%. Component plasma concentration ranges were consistent with historical values. Median APV C_min was 14.7-fold above the protein-binding-adjusted 50% inhibitory concentration of wild-type HIV. Four weeks after RTV reduction, HIV-1 RNA levels remained <50 copies/mL in all patients, median CD4+ count increased from 465 to 495 cells/mm³, and favorable lipid changes and no adverse events were observed. Conclusion: Reducing RTV boosting from 200 to 100 mg QD of FPV/TDF/FTC QD conferred no detrimental effect on APV, tenofovir, FTC, or RTV pharmacokinetics and maintained virologic suppression.     

Abacavir once or twice daily combined with once-daily lamivudine and efavirenz for the treatment of antiretroviral-naive HIV-infected adults: results of the Ziagen Once Daily in Antiretroviral Combination Study

The long intracellular half-life of abacavir (ABC) supports its once-daily use, and this would be expected to simplify treatment if ABC could be given as part of a complete once-daily regimen. A randomized double-blind clinical trial compared the efficacy and safety of 600 mg of ABC administered once daily (n = 384) versus 300 mg of ABC administered twice daily (n = 386) in combination with 300 mg of lamivudine (3TC) and 600 mg of efavirenz (EFV) administered once daily in antiretroviral-naive patients over 48 weeks. The baseline median plasma HIV-1 RNA level was 4.89 log10 copies/mL (44% with viral load >100,000 copies/mL), and the median CD4 cell count was 262 cells/mm. ABC administered once daily was non-inferior to the twice-daily regimen, with 66% and 68% of patients in these respective treatment arms achieving a confirmed plasma HIV-1 RNA level <50 copies/mL (95% confidence interval: -8.4%, 4.9%). The ABC once-daily and twice-daily regimens were similar with respect to infrequency of virologic failure (10% vs. 8%), emergence of resistance mutations, CD4 cell increases from baseline (median, 188 vs. 200 cells/mm), safety profile, and incidence of ABC-related hypersensitivity reactions (9% vs. 7%). ABC administered once daily in combination with 3TC and EFV administered once daily was non-inferior to the ABC twice-daily dosing schedule when combined with 3TC and EFV over 48 weeks.     

A once-daily lopinavir/ritonavir-based regimen provides noninferior antiviral activity compared with a twice-daily regimen

OBJECTIVE: To evaluate the safety and noninferiority and to explore the efficacy of administration of once-daily versus twice-daily lopinavir/ritonavir (LPV/r) in antiretroviral-naive HIV-1-infected subjects. DESIGN: Randomized, open-label, multicenter, comparative study. METHODS: One hundred ninety antiretroviral-naive subjects with plasma HIV-1 RNA level >1000 copies/mL and any CD4 cell count were randomized to lopinavir/ritonavir at a dose of 800/200 mg administered once daily (n = 115) or lopinavir/ritonavir at a dose of 400/100 mg administered twice daily (n = 75). Subjects also received tenofovir disoproxil fumarate (TDF) at a dose of 300 mg and emtricitabine (FTC) at a dose of 200 mg administered once daily. RESULTS: The median baseline plasma HIV-1 RNA level and CD4 count were 4.8 log10 copies/mL and 216 cells/mm, respectively. Before week 48, 20% (once daily) and 29% (twice daily) subjects discontinued. Virologic responses of the subjects through 48 weeks were comparable; 70% (once daily) and 64% (twice daily) achieved an HIV-1 RNA level <50 copies/mL by intent-to-treat, noncompleter = failure analysis. No subject demonstrated LPV or TDF resistance, but 3 subjects (2 in the once-daily group, 1 in the twice-daily group) demonstrated FTC resistance. Mean increases in CD4 count were similar. Diarrhea (16% in the once-daily group, 5% in the twice-daily group; P = 0.036) was the most common moderate or severe study drug-related adverse event. CONCLUSIONS: Through 48 weeks, a once-daily regimen of lopinavir/ritonavir + TDF + FTC appears to have similar virologic and immunologic responses in antiretroviral-naive subjects as the same regimen with lopinavir/ritonavir administered twice daily. Both regimens were relatively well tolerated, and no LPV or TDF resistance was observed.     

A retrospective, cohort-based survey of patients using twice-daily indinavir + ritonavir combinations: pharmacokinetics, safety, and efficacy

OBJECTIVE: To describe the pharmacokinetics, safety, and efficacy of twice-daily indinavir + ritonavir regimens DESIGN: A cohort-based survey of HIV-infected patients who either used indinavir 800 mg + ritonavir 100 mg twice daily or indinavir 400 mg + ritonavir 400 mg twice daily. METHODS: Data were extracted from a database of samples sent to our laboratory for measurement of indinavir + ritonavir plasma concentrations. Patient characteristics, safety, and efficacy measurements were collected by retrospective chart review. RESULTS: 100 Patients using 800-mg indinavir + 100-mg ritonavir twice daily and 32 patients using 400-mg indinavir + 400-mg ritonavir twice daily were eligible. Median peak and trough concentrations of indinavir were 6.8 and 0.77 mg/L in the 800/100 group and 2.6 and 0.45 mg/L in the 400/400 group. The most frequently found side effects were nausea and vomiting, which occurred in 22.1% and 34.9% of the patients in the 800/100 and the 400/400 groups, respectively. Viral load data were analyzed for patients who switched from 800-mg indinavir three times daily to one of the indinavir + ritonavir twice daily regimens. At the time of switch 63% (800/100 group) and 60% (400/400 group) had an undetectable viral load and this increased to 77% and 70%, respectively, during follow-up. Patients who switched to the 400/400 group discontinued treatment more frequently than patients who switched to the 800/100 group (70% vs. 26%, p =.008). CONCLUSIONS: Indinavir + ritonavir regimens show improved pharmacokinetic properties, allowing twice-daily dosing with food. Clinical data suggest that safety and efficacy is at least as good as with indinavir three-times-daily regimens without ritonavir. Prospective, comparative trials are needed to properly assess the role in HIV therapy of these twice-daily indinavir + ritonavir regimens.     

Ketoconazole pharmacokinetics during chronic dosing in adults with haematological malignancy

Ketoconazole pharmacokinetics were determined in nine adults with haematological malignancy after one week on a 200 mg daily dose and later after one week on a 400 mg daily dose. The area under the serum concentration time curve (AUC) reached 12.3 ± 7.7 mg/l.h (mean ± S.D.) on the 200 mg dose and increased to 23.0 ± 18.2 mg/l.h on the 400 mg dose (p < 0.05). The half-life of ketoconazole was 3.1 + 1.9 h on the 200 mg dose and 3.5 ± 1.7 h on the 400 mg dose. Peak concentrations were 3.2 ±1.8 mg/l and 4.6 ± 3.2 mg/l on the 200 mg and 400 mg doses, respectively. Trough ketoconazole concentrations were undetectable 24 h after either dose. There was no correlation between the leucocyte count and any pharmacokinetic parameter for ketoconazole. Variation in AUC was 20-fold on the 200 mg daily dose and 8-fold on the 400 mg per day regimen. Measurement of serum levels during ketoconazole treatment appears necessary in view of the unpredictable concentrations achieved. Once-a-day dosage regimens of ketoconazole in immunocompromised patients may be inappropriate. Future clinical trials should adopt a two or three times a day dosing regimen, as this may confer a pharmacokinetic and therapeutic advantage.     

Similar Virologic and Immunologic Efficacy With Fosamprenavir Boosted With 100 mg or 200 mg of Ritonavir in HIV-Infected Patients: Results of the LESS Trial

Abstract

Purpose: Ritonavir (RTV) effectively boosts most protease inhibitors but is associated with significant dose-dependent adverse events (AEs). In an effort to better manage toxicities through a reduced dose of RTV, this study compared fosamprenavir (FPV) boosted with RTV 100 mg (FPV/r100) or with RTV 200 mg (FPV/r200) daily. Methods: This 24-week, open-label study enrolled patients taking a FPV/r200-containing regimen who had HIV RNA <400 copies/mL and randomized them 1:2 to continue that regimen or simplify to FPV/r100 once daily. Other medications were not altered. The primary endpoint was the percentage of patients without suspected or confirmed virologic failure (HIV RNA ≥400 copies/mL) through week 24 by a missing/discontinuation equals failure (M/D=F) analysis. Noninferiority criteria were demonstrated if the lower bound of the 95% confidence interval (CI) for the difference in the primary endpoint rates between groups was greater than ?12. Results: The 2 regimens met prespecified noninferiority criteria (FPV/r100, 92%; FPV/r200, 94%; 95% CI, ?9.36 to 5.12). At week 24, the percentage of patients with HIV RNA <50 copies/mL by M/ D=F was 83% in the FPV/r100 group and 85% in the FPV/r200 group. Drug-related grade 2?4 AEs were uncommon (FPV/r100, 4%; FPV/r200, 7%). Median changes in lipids were similar in both groups, with the exception of triglycerides (FPV/r100, ?21 mg/dL; FPV/r200, ?2 mg/dL). Conclusions: This 24-week study demonstrated that among previously suppressed patients, once-daily FPV/r100 was similar to FPV/r200 in virologic and immunologic effects but was associated with greater decreases from baseline in triglyceride levels.     

Further studies on the chronotherapy of asthma with inhaled steroids: The effect of dosage timing on drug efficacy

Background: Chronotherapy studies with inhaled corticosteroids have shown optimal therapeutic benefit when steroids are administered four times per day (QID) or once daily at 3 PM.Objective: This study evaluated whether more convenient once-daily dosage times (8 AM and 5:30 PM) produce improvement in asthma equivalent to QID.Methods: Efficacy outcome measures included FEV₁, peak expiratory flow rates, bronchial responsiveness, use of β₂-agonists, nocturnal awakenings, and responses to a quality of life questionnaire. Systemic effects were blood eosinophil count, cortisol level, 24-hour urinary cortisol, and evaluation for oral candidiasis and dysphonia.Results: Baseline measurements for all three treatment groups were similar. For morning peak expiratory flow rate, significant improvement was seen for the QID group (p = 0.001) and the 5:30 PM group (p = 0.003), but not the 8 AM group (p = 0.75). For evening peak expiratory flow rate, significant improvement was seen for the QID group (p = 0.005) and the 5:30 PM group (p = 0.01), but not for the 8 AM group (p = 0.47). There were significant improvements in all other outcome variables for each group except PC₂₀. There was a significant improvement in PC₂₀ only in the QID group. The systemic effects of the three regimens were comparable.Conclusion: Dosing of inhaled steroid at 5:30 PM had no increased systemic effects and produced efficacy similar to QID dosing. Dosing at 8 AM did not produce results consistently comparable to QID dosing. Optimal once-daily dosing of inhaled steroid is between 3 PM and 5:30 PM.     

Pharmacokinetics of Clarithromycin Extended-Release (ER) Tablets in Patients with AIDS

Abstract

Background: Clarithromycin is a key agent in effective antimycobacterial therapy and prophylaxis for AIDS-related disseminated Mycobacterium avium complex (dMAC) infection. Immediate-release (IR) clarithromycin tablets are dosed at 500 mg bid for these indications. A new extended-release (ER) tablet of clarithromycin has been developed and approved at a dosing interval of once every 24 hours for treatment of respiratory tract bacterial infections. However, the pharmacokinetics of clarithromycin ER in AIDS patients with or at risk for dMAC has not been previously investigated. Method: We conducted a randomized, crossover trial in which 14 AIDS patients received clarithromycin ER, 1000 mg once daily, and clarithromycin IR, 500 mg bid, each for 1 week, with pharmacokinetic sampling at the end of each week. Results: The mean of the individual AUC ratios for clarithromycin ER vs. IR was 1.09 (90% CI, 0.94-1.24). Adverse events were no more severe or frequent with clarithromycin ER than IR. Conclusion: Clarithromycin ER is a once-daily regimen that is as well tolerated as standard bid IR clarithromycin dosing and has average bioequivalence to the IR formulation in patients with AIDS.     

Pharmacokinetics of Saquinavir-SGC in HIV-Infected Pregnant Women

Abstract

Purpose: To evaluate saquinavir (SQV) pharmacokinetics, tolerance, and safety in 10 HIV-infected pregnant women between 14-32 weeks gestation. Method: This was a phase I, prospective, area-under-the-curve (AUC) targeted study. Antepartum treatment consisted of SQV 1200 mg tid, lamivudine 150 mg bid, and zidovudine 200 mg tid. The SQV targeted exposure was an 8-hour AUC (AUC₈) of 3000 ng · h/mL; the study was to be halted if the first 4 participants did not achieve this AUC₈. Cord blood and plasma samples were collected in neonates at birth. Results: Four women completed the SQV pharmacokinetic assessments. Exposure in all 4 patients was below the target AUC₈. Median (range) AUC₈ and trough (C8H) were 1672 (738-2614) ng · h/mL and 60 (<15-332) ng/mL, respectively. Oral clearance (CL/F) was 9.3 (5.1-16.6) L/h/kg and C_max was 599 (177–953) ng/mL. Cord and neonate plasma concentrations were mostly undetectable; 1 of 5 infants was HIV-infected at 24 weeks. Conclusion: These data suggest highly variable SQV pharmacokinetics in pregnant women, and exposure at 1200 mg tid may not be adequate for longer term therapy; both the AUC₈ and C8H were considerably below average. Because ritonavir has been shown to significantly increase SQV concentrations, this combination should be further explored in this population.