Pharmacokinetic study of saquinavir hard gel caps/ritonavir in HIV-1-infected patients: 1600/100 mg once-daily compared with 2000/100 mg once-daily and 1000/100 mg twice-daily

Effect of a modified saquinavir/ritonavir dosing regimen with lower dose lead-in phase on QTc interval, pharmacokinetics, antiviral activity and safety in treatment-naïve HIV-1-infected patients

Background

Saquinavir/ritonavir (1000/100 mg twice daily [BID]) is associated with dose- and exposure-dependent prolongation of the QT interval. The QT risk is considered higher during the first week of therapy, when saquinavir peak exposure has been observed. A modified regimen with a lower dose lead-in phase may reduce potential saquinavir-/ritonavir-induced QT prolongations.

Objective

To explore the effect of the modified saquinavir/ritonavir regimen on QT interval, pharmacokinetics, antiviral activity, and safety in treatment-naïve HIV-1-infected patients.

Methods

Twenty-three HIV-1-infected treatment-naïve patients received saquinavir/ritonavir 500/100 mg BID on days 1–7 and 1000/100 mg BID on days 8–14 in combination with two nucleoside reverse transcriptase inhibitors. The primary endpoint was mean maximum change from dense predose baseline in QT values corrected using Fridericia’s formula (∆QTcF_dense) across study days. Secondary endpoints included maximum change from time-matched baseline in QTcF, antiviral activity, pharmacokinetics, and safety over the 14 days.

Results

The mean maximum ∆QTcF_dense was 3, 1, 7, 12, and 7 ms on days 3, 4, 7, 10, and 14, respectively. Across all study days, 2/21 patients had a maximum ∆QTcF_dense ≥30 ms (on day 10); the highest mean ∆QTcF_dense was <10 ms. During week 1, saquinavir exposure was highest on day 3 and lowest on day 7. All patients showed continuous declines in HIV-RNA; none experienced virologic breakthrough/rebound. The modified regimen was generally well tolerated.

Conclusion

Treatment initiation with the modified saquinavir/ritonavir regimen in treatment-naïve HIV-1-infected patients reduced saquinavir exposure during week 1, potentially mitigating/reducing QT liability while suppressing HIV-RNA during the course of treatment.

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)

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-to treat 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.

HIV and noncommunicable diseases: the Asian perspective

Asia is seeing a rise in noncommunicable diseases in their general population and among people living with HIV. Many Asians have low body weight, which can lead to higher plasma concentrations of antiretrovirals and, as a result, their toxicities. Examples are metabolic complications from protease inhibitors, chronic kidney disease from tenofovir, and hepatotoxicity from nevirapine. Asia has not only the highest burden of hepatitis B viral infection than any other continent but also a predominance of genotypes B and C, the latter associated with higher risk for hepatocellular carcinoma. HIV-associated neurocognitive disorders are equally common among Asians as other populations. Diastolic dysfunction and asymptomatic myocardial ischemia are not infrequent. Non-Hodgkin lymphoma is the most common AIDS-related cancer, whereas Kaposi sarcoma is relatively infrequent. Emerging data show high prevalence of human papillomavirus-associated anal dysplasia in men who have sex with men. Resource-limited countries in Asia suffer from lack of resources for national screening programs of noncommunicable diseases, which, in turn, limits the epidemiologic data that exist to guide the use of national health resources.

Thorough QT/QTc study of ritonavir-boosted saquinavir following multiple-dose administration of therapeutic and supratherapeutic doses in healthy participants

The effect of saquinavir-boosted ritonavir at therapeutic (1000/100 mg twice daily [bid]) and supratherapeutic (1500/100 mg bid) doses was evaluated in a double-blind, placebo- and positive-controlled (moxifloxacin 400 mg) 4-way crossover thorough QT/QTc study. Least squares mean estimated study-specific QTc (QTcS) change from dense predose baseline (ddQTcS(dense)) was the primary endpoint. Greatest mean increase in ddQTcS(dense) occurred 12 hours postdose for the 1000/100-mg group (18.9 ms) and 20 hours for the 1500/10-mg group (30.2 ms). The upper 1-sided 95% confidence interval was >20 ms from 2 to 20 hours postdose in both groups. ddQTcB(dense) and ddQTcF(dense) were similar to ddQTcS(dense). No QTcS, QTcF, or QTcB measurements were >500 ms. One participant receiving 1000/100 mg and 3 receiving 1500/100 mg had a maximum ddQTcS(dense) >60 ms. More participants with ≥1 adverse event received saquinavir/ritonavir. PubMed search and Roche postmarketing data did not reveal publications or reports directly presenting the effect of saquinavir on QT/QTc or causing torsade de pointes.

Generic and low dose antiretroviral therapy in adults and children: implication for scaling up treatment in resource limited settings

Although access to antiretroviral therapy (ART) for the treatment of HIV has increased during the last decade, many patients are still in need of treatment. With limited funds to provide ART to millions of patients worldwide, there is a need for alternative ways to scale up ART in resource limited settings. This review provides an overview of pharmacokinetic, safety and efficacy studies of generic and reduced dose ART. The production of generic ART has greatly influenced the decline in drug prices and the increased in ART access. Generic ART has good pharmacokinetic profile, safety and efficacy. Toxicity is however the main cause for ART discontinuation. Several dose reduction studies have shown adequate pharmacokinetic parameters and short term efficacy with reduced dose ART. Ethnicity may affect drug metabolism; several pharmacokinetic studies have confirmed higher plasma ART concentration in Asians. Randomized efficacy trial of reduced versus standard ART is warranted.

Efficacy, safety and pharmacokinetic of once-daily boosted saquinavir (1500/100 mg) together with 2 nucleos(t)ide reverse transcriptase inhibitors in real life: a multicentre prospective study

Background

Ritonavir-boosted saquinavir (SQVr) is nowadays regarded as an alternative antiretroviral drug probably due to several drawbacks, such as its high pill burden, twice daily dosing and the requirement of 200 mg ritonavir when given at the current standard 1000/100 mg bid dosing. Several once-daily SQVr dosing schemes have been studied with the 200 mg SQV old formulations, trying to overcome some of these disadvantages. SQV 500 mg strength tablets became available at the end of 2005, thus facilitating a once-daily regimen with fewer pills, although there is very limited experience with this formulation yet.

Methods

Prospective, multicentre study in which efficacy, safety and pharmacokinetics of a regimen of once-daily SQVr 1500/100 mg plus 2 NRTIs were evaluated under routine clinical care conditions in either antiretroviral-naïve patients or in those with no previous history of antiretroviral treatments and/or genotypic resistance tests suggesting SQV resistance. Plasma SQV trough levels were measured by HPLV-UV.

Results

Five hundred and fourteen caucasian patients were included (47.2% coinfected with hepatitis C and/or B virus; 7.8% with cirrhosis). Efficacy at 52 weeks (plasma RNA-HIV <50 copies/ml) was 67.7% (CI₉₅: 63.6 - 71.7%) by intention-to-treat, and 92.2% (CI₉₅: 89.8 - 94.6%) by on-treatment analysis. The reasons for failure were: dropout or loss to follow-up (18.4%), virological failure (7.8%), adverse events (3.1%), and other reasons (4.6%). The high rate of dropout may be explained by an enrollement and follow-up under routine clinical care condition, and a population with a significant number of drug users. The median SQV Cmin (n = 49) was 295 ng/ml (range, 53-2172). The only variable associated with virological failure in the multivariate analysis was adherence (OR: 3.36; CI95, 1.51-7.46, p = 0.003).

Conclusions

Our results suggests that SQVr (1500/100 mg) once-daily plus 2 NRTIs is an effective regimen, without severe clinical adverse events or hepatotoxicity, scarce lipid changes, and no interactions with methadone. All these factors and its once-daily administration suggest this regimen as an appropriate option in patients with no SQV resistance-associated mutations.

Once-daily treatment with saquinavir mesylate (2000 mg) and ritonavir (100 mg) together with a fixed-dose combination of abacavir/lamivudine (600/300 mg) or tenofovir/emtricitabine (245/200 mg) in HIV-1-infected patients

OBJECTIVES

To investigate the feasibility and pharmacokinetics of a once-daily regimen of 2000 mg saquinavir mesylate boosted with 100 mg ritonavir.

PATIENTS AND METHODS

Patients successfully treated with 1000 mg saquinavir boosted with 100 mg ritonavir twice daily together with two nucleoside or nucleotide reverse transcriptase inhibitors [N(t)RTIs] who were switched to 2000 mg saquinavir with 100 mg ritonavir once daily with unchanged N(t)RTI therapy were analysed. CD4 cells, HIV-RNA PCR and metabolic parameters were compared between baseline and 3, 6, 9 and 12 months after the switch. Saquinavir and ritonavir drug levels were measured before and a median of 3 weeks after switching from twice to once daily at 0, 1, 2, 4, 6, 9, 12 and 24 h after intake of the medication. The area under the serum concentration-time curve from 0 to 24 h (AUC(0-24)) was calculated using the trapezoidal rule.

RESULTS

Eighteen patients (16 males, median age of 41 years) with a median CD4 cell count of 464 cells/mm(3) were analysed. HIV-RNA PCR remained <500 copies/mL for all patients. After switching from 100 mg twice daily to 100 mg once daily, the AUC(0-24) for ritonavir decreased significantly [21 874 to 10 267 ng.h/mL, geometric mean ratio (GMR) = 0.47; P < 0.001], whereas the AUC(0-24) for saquinavir decreased only marginally from 35 000 to 34 490 ng.h/mL (GMR = 0.99; P = 0.426). The CD4 cell count and the fasting metabolic parameters remained unchanged.

CONCLUSIONS

Once-daily treatment with ritonavir-boosted saquinavir was well tolerated and resulted in similar saquinavir drug exposure despite much lower ritonavir concentrations when compared with a twice-daily dosing schedule.

Reducing the boosting dose of ritonavir does not affect saquinavir plasma concentrations in HIV-1-infected individuals

Currently, the optimal boosting dose for saquinavir is unknown. Therefore, we evaluated the pharmacokinetics profiles in a cross over setting comparing saquinavir/ritonavir 1500/50 mg (plus NRTI backbone) to saquinavir/ritonavir 1500/100 mg in the same HIV-infected, Thai individuals. The 50% reduction of ritonavir boosting did not result in a change in the pharmacokinetics of saquinavir, whereas the ritonavir exposure was significantly lower when a dose of 50 mg was administered.

Saquinavir exposure in HIV-infected patients with chronic viral hepatitis

OBJECTIVES

The aim of this study was to assess the influence of hepatitis B virus or hepatitis C virus co-infection and the extent of liver fibrosis on saquinavir and ritonavir pharmacokinetics in HIV-infected subjects without liver function impairment.

METHODS

A cross-sectional, comparative study enrolling HIV-infected adults receiving saquinavir/ritonavir 1000/100 mg twice daily or 1500/100 mg once daily was conducted. Patients with chronic viral hepatitis (HEP+) were grouped as having advanced liver fibrosis (HEP+/FIB+) or not (HEP+/FIB-) based on the FIB-4 index. Saquinavir and ritonavir trough concentrations (C(trough)) in plasma were determined by HPLC. The geometric mean ratio (GMR) was used to compare saquinavir and ritonavir C(trough) between HEP- and HEP+ patients, and the influence of the extent of liver fibrosis on saquinavir and ritonavir pharmacokinetics was explored using analysis of variance.

RESULTS

One hundred and thirty-eight patients on twice-daily saquinavir/ritonavir (67 HEP-, 71 HEP+) and 36 patients on once-daily saquinavir/ritonavir (12 HEP-, 24 HEP+) were included. Saquinavir C(trough) was comparable between HEP- and HEP+ patients receiving either saquinavir/ritonavir 1000/100 mg twice daily [GMR 0.91, 95% confidence interval (CI) 0.60-1.37; P = 0.655] or 1500/100 mg once daily (GMR 0.88, 95% CI 0.39-1.97; P = 0.752). Similarly, ritonavir C(trough) was also comparable between HEP- and HEP+ patients. The extent of liver fibrosis was not significantly related to saquinavir or ritonavir C(trough) in patients receiving either of the two studied doses.

CONCLUSIONS

Saquinavir C(trough) was not increased in HIV-infected patients with chronic viral hepatitis in the absence of liver function impairment. These results confirm that no specific dose modification of saquinavir/ritonavir should be recommended in this setting.

the HIV–NAT 017 Study Team, Bunupuradah T, van der Lugt J, Kosalaraksa P, Engchanil C, Boonrak P, Puthanakit T, Mengthaisong T, Mahanontharit A, Lumbiganon P, Tompkins E, Burger D, Ruxrungtham K, Ananworanich J. Safety and efficacy of a double-boosted protease inhibitor combination, saquinavir and lopinavir/ ritonavir, in pretreated children at 96 weeks

Background

This study aimed to assess the long-term efficacy, safety and use of therapeutic drug monitoring (TDM) of a double-boosted protease inhibitor (PI) combination, saquinavir (SQV) and lopinavir/ritonavir (LPV/r), in Thai HIV type-1 (HIV-1)-infected children who had failed on reverse transcriptase inhibitors.

Methods

In total, 50 children from two sites in Thailand were treated with standard dosing of SQV and LPV/r. CD4+ T-cell count and percentage, viral load (VL; HIV-1 RNA), minimum plasma drug concentrations (Cmin) and drug safety laboratory evaluations were monitored. Virological failure was defined as having two consecutive VL measures >400 copies/ml after week 12. An intention-to-treat analysis was performed.

Results

Baseline data were a median age of 9.3 years (interquartile range [IQR] 7.1–11.2), VL 4.8 log10 copies/ ml (IQR 4.5–5.1) and CD4+ T-cell percentage 7% (IQR 3.0– 9.5). CDC classifications were N=4%, A=14%, B=68% and C=14% of participants. Median CD4+ T-cell percentage and CD4+ T-cell count increase were 14% (IQR 7–19) and 558 cells/mm3 (IQR 308–782), respectively (both P<0.001). Overall, 37 (74%) children achieved VL<50 copies/ml with significant differences between sites (90% versus 63%). Over 96 weeks, 10 patients had virological failure. Total cholesterol and high-density lipoprotein increased significantly over time, whereas the triglycerides and low-density lipoprotein did not. Approximately 50% of participants reported no change in body shape, and 33%, 43% and 39% reported fatter arms, face and abdomen, respectively. LPV and SQV Cmin were high and stable over time.

Conclusions

Double-boosted SQV+LPV/r was an effective and safe alternative for a second-line regimen in children. Hypercholesterolaemia needs close follow-up. On the basis of the TDM results, PI dose reduction in this population should be considered.

Population pharmacokinetics of ritonavir-boosted saquinavir regimens in HIV-infected individuals

OBJECTIVES

The aim of this study was to develop and validate a population pharmacokinetic model in order to describe ritonavir-boosted saquinavir concentrations dosed twice and once daily in human immunodeficiency virus (HIV)-infected patients from the UK, Uganda and Thailand and to identify factors that may influence saquinavir pharmacokinetics.

METHODS

Pharmacokinetic data from 10 clinical studies were combined. Non-linear mixed effects modelling (NONMEM version V) was applied to determine the saquinavir pharmacokinetic parameters, interindividual/interoccasion variability (IIV/IOV) and residual error. Various covariates potentially related to saquinavir pharmacokinetics were explored, and the final model was validated by means of 95% prediction interval and testing the predictive performance of the model with data not included in the model-building process.

RESULTS

Ninety-seven patients were included from the UK (n = 52), Uganda (n = 18) and Thailand (n = 27), contributing 347 saquinavir profiles (1-14 profiles per patient). A one-compartment model with zero-order absorption and lag-time best described the data with IIV/IOV on apparent oral clearance (CL/F) and volume of distribution (V/F) and with IIV on duration and absorption lag-time. The ritonavir area under the curve over the dosing interval was significantly associated with saquinavir CL/F and V/F. A typical patient from the UK had approximately 1.5- and 3-fold higher saquinavir CL/F compared with patients from Uganda (89.0 versus 49.8 L/h) and Thailand (89.0 versus 26.7 L/h), respectively.

CONCLUSIONS

A model to characterize ritonavir-boosted saquinavir pharmacokinetics in HIV-infected adults has been developed and validated. The model could be used for dosage adaptation following therapeutic drug monitoring and to assess patients' suitability for once-daily boosted saquinavir therapy.

Pharmacokinetic analysis to assess forgiveness of boosted saquinavir regimens for missed or late dosing

OBJECTIVES

One potential concern of once-daily protease inhibitor administration is low trough concentrations and ultimately the 'forgiveness' or robustness in comparison with the originally licensed twice-daily dose. To give an estimation of 'forgiveness', we determined the length of time plasma drug concentrations were below target in HIV-infected patients receiving saquinavir/ritonavir regimens.

METHODS

Seventy-seven pharmacokinetic profiles (saquinavir/ritonavir 1000/100 mg twice daily, n = 34; 1600/100 mg once daily, n = 26; 2000/100 mg once daily, n = 17) from five studies were combined, presented as twice- and once-daily percentiles (P10-P90) and compared. At percentiles where trough concentrations fell below the alleged minimum effective concentration (MEC; 100 ng/mL), the length of time below MEC was determined.

RESULTS

Saquinavir concentrations were below MEC at P10 for 0.7 h for twice-daily saquinavir/ritonavir when compared with 8.6 and 6.6 h for 1600/100 and 2000/100 mg once daily, respectively. At P25, 1600/100 mg once daily produced suboptimal concentrations for 5.5 h in contrast to 0.5 h for 2000/100 mg once daily.

CONCLUSIONS

Here, we provide substantive data that indicate once-daily saquinavir, in particular 1600/100 mg, is not as robust as the twice-daily regimen based on a population of UK patients; this raises concern over late or missed doses. However, pharmacokinetic data can only ever be a guide to the impact on long-term efficacy.

Staccato Thailand Study Group, Ananworanich J, Gayet-Ageron A, Ruxrungtham K, Chetchotisakd P, Prasithsirikul W, Kiertiburanakul S, Munsakul W, Raksakulkarn P, Tansuphasawadikul S, LeBraz M, Jupimai T, Ubolyam S, Schutz M, Hirschel B. Long-Term Efficacy and Safety of First-Line Therapy with Once-Daily Saquinavir/Ritonavir

Background

The aim of this study was to assess the long-term efficacy and safety of first-line treatment with once-daily saquinavir/ritonavir plus two nucleoside reverse transcriptase inhibitors (NRTIs).

Methods

A total of 272 antiretroviral-naive patients with a CD4+ T-cell count of 200–350 cells/mm3 were treated with two NRTIs and saquinavir/ritonavir 1,600/100 mg per day for ≥24 weeks. Patients were followed up every 12 weeks for CD4+ T-cell counts, HIV RNA levels, clinical and laboratory toxicities. Intention-to-treat analyses were used for the first 24 weeks of treatment and as-treated analysis after week 24.

Results

The median baseline CD4+ T-cell count was 269 cells/mm3 and HIV RNA was 4.7 log10 copies/ml. At a median follow-up time of 56 (interquartile range [IQR] 25–113) weeks, 262/272 (96.3%) had HIV RNA <400 copies/ml, with a median HIV RNA decline of -2.89 (IQR 3.31–2.37) log10 copies/ml ( P<0.001) and a median rise in CD4+ T-cell count of 192 (IQR 117–317) cells ( P<0.001). At weeks 24, 48, 72 and 96, 249/272 (91.5%), 157/164 (95.7%), 113/126 (89.7%) and 84/90 (93.3%) had HIV RNA <400 copies/ml, respectively; at the same time points, 83.8%, 92.7%, 85.7% and 85.6% had HIV RNA <50 copies/ml. Drug-related adverse events were reported in 6.3%. Significant rises in total cholesterol, triglyceride, low-density lipoprotein and high-density lipoprotein were seen.

Conclusion

First-line highly active antiretroviral therapy with once-daily saquinavir/ritonavir plus two NRTIs showed strong antiviral efficacy.

Ketoconazole is inferior to ritonavir as an alternative booster for saquinavir in a once daily regimen in Thai HIV-1 infected patients

OBJECTIVE

To improve the pharmacokinetics of protease inhibitors, boosting with low-dose ritonavir is performed. However, toxicity, storage conditions and high costs of antiretroviral treatment may necessitate interruption of ritonavir. Ketoconazole was investigated as a potential booster of once-daily (o.d.) saquinavir.

METHODS

In a single-group, two-period design, 25 virologically and immunologically stable patients on saquinavir/ritonavir 2000/100 mg o.d. were switched to saquinavir/ketoconazole 2000/400 mg o.d. for 2 weeks. Two steady-state pharmacokinetic curves were recorded at both periods.

RESULTS

Fourteen females and 11 male patients were included. Median age was 34 years [interquartile range (IQR), 32-42 years], body weight 54 kg (IQR, 47-59 kg) and body mass index 21 kg/m (19-23 kg/m). The mean saquinavir area under the curve (AUC) during boosting with ritonavir was 57.93 +/- 27.96 mg/h/l, maximum observed concentration (Cmax) was 7.50 +/- 3.45 mg/l and concentration at 24 h (Cmin) was 0.35 +/- 0.30 mg/l. When ketoconazole was used, the saquinavir AUC, Cmax, and Cmin were 12.00 +/- 6.97 mg/h/l, 2.43 +/- 1.35 mg/l and 0.03 +/- 0.04 mg/l, respectively.

CONCLUSION

Boosting with ketoconazole resulted in 80% lower exposure to saquinavir. Although saquinavir AUC might still be adequate for treatment, concentrations at 24 h reached levels below the recommended trough concentrations of 0.1 mg/l, which may result in selection of resistant HIV-1 viral strains. Therefore, boosting of saquinavir by ketoconazole is not recommended.

Clinical and pharmacokinetic data support once-daily low-dose boosted saquinavir (1,200 milligrams saquinavir with 100 milligrams ritonavir) in treatment-naive or limited protease inhibitor-experienced human immunodeficiency virus-infected patients

We evaluated the plasma and intracellular pharmacokinetics, clinical efficacy, and safety of once-daily low-dose boosted saquinavir (SQVr; 1,200 of saquinavir [SQV] with 100 mg of ritonavir) plus two nucleotide reverse transcriptase inhibitors in treatment-naive or limited protease inhibitor (PI)-experienced human immunodeficiency virus (HIV)-infected patients. A prospective study without entry restrictions on the plasma HIV-RNA (VL) or CD4 cell count was carried out. Plasma and intracellular SQV levels were measured by high-performance liquid chromatography. Efficacy was evaluated by an intention-to-treat analysis; treatment failure was defined as virological failure (a VL of >50 copies/ml after 24 weeks or a confirmed rebound to >50 copies/ml) or interruption for any reason. A total of 151 patients were included in the study (106 of them either had never received PI or had no previous virological failure on PIs) and could be characterized as follows: previous C3 stage, 28.9%; injection-drug users, 69.1%; subjects with chronic viral hepatitis, 53%; and subjects with cirrhosis, 10%. The median baseline CD4 level was 184/mul, and the median VL was 4.8 log(10) copies/ml. Median C(max), area under the concentration-time curve from 0 to 24 h, and C(min) plasma and intracellular SQV levels were 3,672 and 10,105 ng/ml, 34,283 and 99,535 ng.h/ml, and 359 and 1,062 ng/ml, respectively. The efficacy as determined by intention to treat at 52 weeks was 69.7% (96% in the on-treatment analysis), with similar results regardless of the baseline VL and CD4 counts. Only five patients had virological failure despite adequate C(min) levels, but with a poor adherence (the only variable related to virological failure). Adverse events caused the withdrawal of the treatment in four patients (2.6%). In conclusion, given the pharmacokinetic profile, efficacy, and tolerability of this regimen, once-daily low-dose SQVr may be considered a treatment option in treatment-naive or limited PI-experienced HIV-infected patients, with the additional benefit of being currently the least-expensive PI-based regimen available.

Implementation of an Antiretroviral Access Program for HIV-1-Infected Individuals in Resource-Limited Settings

BACKGROUND

We assessed the effectiveness and safety of highly active antiretroviral therapy (HAART) in HIV-1-infected patients in resource-limited African countries. HIV-1 screening, therapy, counseling, monitoring, training, and education were provided free of charge.

METHODS

In an open-label cohort program, 206 antiretroviral-naive HIV-1-infected patients who could not afford HAART were recruited in 4 urban clinics in Senegal, Côte d'Ivoire, Uganda, and Kenya and were treated with saquinavir boosted with ritonavir (1600/100 mg once daily), lamivudine (150 mg twice daily), and zidovudine (300 mg twice daily). The primary outcome was a plasma viral load (pVL) of <400 copies/mL after 96 weeks of treatment. Secondary analyses included CD4 cell count changes and the occurrence of treatment-emergent adverse events.

RESULTS

The median age of the patient group was 36 years, 38% were male, 35% of the patients had AIDS, the median CD4 count was 119 cells/microL, and the median pVL was 304,210 copies/mL. Overall, 65%/52% (on treatment [OT]/intent to treat [ITT]) of the patients had a pVL <400 copies/mL after 96 weeks of follow-up. This proportion varied significantly between sites, however; although in Nairobi and Dakar, 51%/40% and 56%/46% (OT/ITT) were found, respectively, Abidjan and Kampala showed proportions of 69%/54% and 83%/69% (OT/ITT), respectively. The median increase in the CD4 count was 198 cells/microL (interquartile range: 86-319 cells/microL), ranging from 191 to 292 cells/microL between the sites. Fourteen patients (6.8%) died between 8 and 96 weeks of follow-up, whereas 18 (9%) developed an AIDS-defining event between 8 and 96 weeks of follow-up. Non-HIV-related serious adverse events occurred in 55 patients (26.7%), of whom 13 were diagnosed with severe anemia. Thirty-five patients (17%) changed treatment for toxicity reasons.

CONCLUSIONS

Although a statistically significant difference was observed between sites with respect to virologic success, overall virologic and immunologic responses to HAART in resource-limited African settings can be as good as in Western settings. There were some difficulties (eg, laboratory, logistics, proper training) during the early phase of the program. Therefore, provision of adequate medical care, counseling, proper instruction, and education of patients and medical staff during the entire study is warranted in such programs, with special care in the early phase.

Pharmacokinetic interaction between rifampicin and the once-daily combination of saquinavir and low-dose ritonavir in HIV-infected patients with tuberculosis

OBJECTIVES

To assess plasma steady-state pharmacokinetics (PK) of rifampicin, isoniazid, saquinavir and ritonavir in HIV and tuberculosis (TB) co-infected patients, and investigate potential interactions between TB drugs and protease inhibitors (PIs).

METHODS

Open-label, single-arm, sequential PK study including 22 patients with HIV infection and TB. During the first 2 months, patients received rifampicin, isoniazid and pyrazinamide, with or without ethambutol (first PK study, n = 22). Then patients stopped pyrazinamide and ethambutol and started once-daily antiretroviral therapy (ART) with didanosine, lamivudine, ritonavir (200 mg) and saquinavir (1600 mg) (second PK study, n = 18). Patients stopped all TB drugs after 9 months continuing the same ART (third PK study, n = 15). Differences between TB drug parameters in the first and second PK studies, and between PI parameters in the second and third PK studies were used to assess interactions.

RESULTS

Rifampicin and isoniazid pharmacokinetics did not change substantially with saquinavir and ritonavir. A significant 39.5%, 34.9% and 48.7% reduction in median saquinavir AUC(0-24), C(max) and C(trough), respectively, was seen with rifampicin and isoniazid. Ritonavir AUC(0-24), C(max) and C(trough) decreased 42.5%, 49.6% and 64.3%, respectively, with rifampicin and isoniazid.

CONCLUSIONS

There was a significant interaction between saquinavir, ritonavir and rifampicin, with reduction in median plasma concentrations of saquinavir and ritonavir. Saquinavir should be given with caution in patients receiving rifampicin. Twice-daily dosing or higher saquinavir doses in once-daily administration should be tested to obtain more appropriate plasma levels.

Clinical Validation of Saquinavir/Ritonavir Genotypic Resistance Score in Protease-Inhibitor-Experienced Patients

Objective

To identify a genotypic score for resistance to saquinavir boosted with ritonavir (SQV/r; 1,000/100 mg twice daily)-based regimens in protease inhibitor (PI)-experienced patients.

Methods

One-hundred and fifty-one PI-experienced patients receiving a SQV/r-containing regimen were enrolled retrospectively. The virological response (VR) was defined as the decrease in HIV RNA at months 3–5. The effect of each mutation in the protease gene on the VR to SQV/r regimen was assessed using non-parametric univariate analyses and then a step-by-step analysis was carried out using a Jonckheere-Tepstra (JT) non-parametric test to retain the group of mutations most strongly associated with VR.

Results

Among the 138 patients with detectable plasma SQV, the median VR was -1.48 [range: -4 to +1.2] log10 copies/ml. Changes at 12 codons were associated with a reduced VR to SQV/r: codons 10, 15, 20, 24, 46, 54, 62, 71, 73, 82, 84 and 90. The JT procedure led to selection of the following genotypic score, 10+15+20+ 24+62+73+82+84+90, as providing the strongest association with VR. In the 35 patients with none of the mutations in this score, the median decrease in HIV RNA was -2.24 log10 copies/ml and it was -1.88 ( n=29), -1.43 ( n=24), -0.52 ( n=30), -0.18 ( n=9), -0.11 ( n=6) and -0.30 ( n=5) log10 copies/ml in those with 1, 2, 3, 4, 5 and 6 mutations, respectively.

Conclusion

With this resistance score to SQV/r, the isolates were classified as having no evidence of resistance (0–2), possible resistance (3) or resistance (≥4) by grouping the number of mutations in samples for which the viral load reduction was similar.

Pharmacogenetics of HIV therapy

Drug treatment in HIV disease is characterized by variable responses, in terms of both efficacy and toxicity. Both genetic and environmental factors are important determinants of this variability, although the relative contributions are unclear and likely to vary with different drugs. Many of the antiretrovirals are metabolized by polymorphically expressed enzymes (cytochrome P450, CYP450; glucuronyl transferase, GT) and/or transported by drug transporters (ABC and SLC families). Initial studies of antiretroviral efficacy have therefore focused on these genes. For example, it has recently been shown that a CYP2B6 genetic variant predicts higher plasma efavirenz exposure and possibly increased central nervous system toxicity. A large number of studies on ABCB1 genetics with antiretrovirals have also been undertaken; however, as in other therapeutic areas, the data have been contradictory, and currently, no firm conclusions can be reached on the effect of ABCB1 variability as a determinant of efficacy. Indeed, this highlights the need for validation of initial association studies in pharmacogenetic research. By contrast, the clearest association between genetic variants and response relates to the hypersensitivity reaction that occurs with abacavir. The identification that the major histocompatibility complex haplotype 57.1 acts as a strong genetic predisposing factor can be regarded as a prime example of how fundamental research can be translated into a pharmacogenetic test. Nevirapine hypersensitivity has also been related to an HLA gene (HLA-DRB1*0101) but the predictive value does not appear to be sufficient to implement in clinical practice. Much more work needs to be done to define the genetic factors determining response to antiretroviral agents. These studies need to be sufficiently powered and utilize a modern genotyping strategy. Most importantly, the phenotype needs to be carefully characterized. We also need to disseminate this information: a pivotal resource for this can be found at www.HIV-pharmacogenomics.org.

Pharmacokinetic and safety evaluation of high-dose combinations of fosamprenavir and ritonavir

High-dose combinations of fosamprenavir (FPV) and ritonavir (RTV) were evaluated in healthy adult subjects in order to select doses for further study in multiple protease inhibitor (PI)-experienced patients infected with human immunodeficiency virus type 1. Two high-dose regimens, FPV 1,400 mg twice a day (BID) plus RTV 100 mg BID and FPV 1,400 mg BID plus RTV 200 mg BID, were planned to be compared to the approved regimen, FPV 700 mg BID plus RTV 100 mg BID, in a randomized three-period crossover study. Forty-two healthy adult subjects were enrolled, and 39 subjects completed period 1. Due to marked hepatic transaminase elevations, predominantly with FPV 1,400 mg BID plus RTV 200 mg BID, the study was terminated prematurely. For FPV 1,400 mg BID plus RTV 100 mg BID, the values for plasma amprenavir (APV) area under the concentration-time profile over the dosing interval (tau) at steady state [AUC(0-tau)], maximum concentration of drug in plasma (C(max)), and plasma concentration at the end of tau at steady state (C(tau)) were 54, 81, and 26% higher, respectively, and the values for plasma RTV AUC(0-tau), C(max), and C(tau) were 49% higher, 71% higher, and 11% lower, respectively, than those for FPV 700 mg BID plus RTV 100 mg BID. For FPV 1,400 mg BID plus RTV 200 mg BID, the values for plasma APV AUC(0-tau), C(max), and C(tau) were 26, 48, and 32% higher, respectively, and the values for plasma RTV AUC(0-tau), C(max), and C(tau) increased 4.15-fold, 4.17-fold, and 3.99-fold, respectively, compared to those for FPV 700 mg BID plus RTV 100 mg BID. FPV 1,400 mg BID plus RTV 200 mg BID is not recommended due to an increased rate of marked hepatic transaminase elevations and lack of pharmacokinetic advantage. FPV 1,400 mg BID plus RTV 100 mg BID is currently under clinical evaluation in multiple PI-experienced patients.

Once-Daily Regimen of Saquinavir, Ritonavir, Didanosine, and Lamivudine in HIV-Infected Patients With Standard Tuberculosis Therapy (TBQD Study)

OBJECTIVES

To assess the efficacy and safety of a once-daily regimen with didanosine, lamivudine, saquinavir, and low-dose ritonavir in antiretroviral (ARV)-naive patients with tuberculosis treated with rifampin and the influence of rifampin on plasma trough concentration (Ctrough) of saquinavir.

METHODS

Single-arm, prospective, multicenter, open-label pilot study, including 32 adult ARV-naive subjects with HIV infection and tuberculosis under standard treatment that included rifampin (600 mg q.d.) and isoniazid (300 mg q.d.). After 2 months of tuberculosis treatment, patients were started on once-daily ARV therapy, consisting of didanosine, lamivudine, ritonavir (200 mg), and saquinavir soft gel capsules (1600 mg). HIV RNA level, CD4 cell count, clinical and laboratory toxicity, and saquinavir Ctrough during and after antituberculosis therapy were analyzed.

RESULTS

After 48 weeks of follow-up, 20 of 32 patients (62.5%; 95% CI: 45.8% to 79.2%) in the intent-to-treat population and 20 of 28 (71.4%; 95% CI: 54.4% to 88.4%) in the on-treatment population had an HIV RNA level <50 copies/mL. Treatment tolerance was acceptable in all patients except for 2 with biologic hepatic toxicity leading to discontinuation. Seven patients had virologic failure. In 10 patients (36%), saquinavir Ctrough was <0.05 microg/mL during tuberculosis therapy and 5 of them had virologic failure. The median saquinavir Ctrough was 44% lower (interquartile range: 19% to 71%) with coadministration of rifampin than without.

CONCLUSION

The combination of didanosine, lamivudine, saquinavir, and ritonavir may be a useful treatment regimen for patients with tuberculosis in whom a once-daily protease inhibitor-containing regimen is considered indicated. Nevertheless, on the basis of pharmacokinetic profile the dose of 1600/200 mg of saquinavir/ritonavir cannot be recommended. Further studies with higher doses of saquinavir (2000 mg) boosted with ritonavir are warranted.

Interindividual variability of once-daily ritonavir boosted saquinavir pharmacokinetics in Thai and UK patients

OBJECTIVES

Differential exposure to saquinavir/ritonavir may lead to therapy failure. The objective was to identify factors that influence variability of saquinavir/ritonavir plasma concentrations.

METHODS

Saquinavir/ritonavir data, dosed as 1600/100 mg once daily, from three separate pharmacokinetic studies, in 45 patients from Thailand and the UK, were pooled. Pharmacokinetic parameters were based on non-compartmental analysis. Univariate analysis was performed with saquinavir as the dependent variable, and ritonavir area under the curve (AUC), gender, body weight, body mass index (BMI) and study site as independent variables. Variables with a P value <0.10 were included in a multivariate linear regression analysis.

RESULTS

Higher saquinavir AUCs, maximum concentrations (Cmax) and minimum concentrations (Cmin) were seen in Thai patients than in UK patients. Univariate analysis showed associations between body weight, gender, study site and ritonavir AUC and saquinavir AUC (P < 0.05), whereas BMI (P = 0.13) did not. In the multivariate analysis, ritonavir AUC (P = 0.0001) and study site (P = 0.0021) were significantly related to saquinavir AUC (R2 = 0.50).

CONCLUSIONS

The ritonavir AUC and study site appeared to be related to exposure of saquinavir. Study site should be viewed as the total of country- and study-specific differences--such as differences in lifestyle, environment, genetic background and dietary composition--between the analysed studies.

Pharmacokinetics and 24-week efficacy/safety of dual boosted saquinavir/lopinavir/ritonavir in nucleoside-pretreated children

OBJECTIVE

To assess the pharmacokinetics and 24-week efficacy and safety of dual boosted saquinavir/lopinavir/ritonavir combination in children.

DESIGN

Twenty reverse transcription inhibitor-pretreated children at 2 centers in Thailand were treated with saquinavir/lopinavir/ritonavir in an open label, single arm, 6-month prospective study. The dosage was 50 mg/kg twice daily (bid) for saquinavir and 230/57.5 mg/m bid for lopinavir/ritonavir. Ten children also received lamivudine.

METHODS

Samples were collected for a 12-hour pharmacokinetic profile in all children. Plasma concentrations of saquinavir, lopinavir and ritonavir were determined using a validated high performance liquid chromatography technique.

RESULTS

At baseline, the median age was 8.5 years, with human immunodeficiency virus (HIV) RNA 4.9 log10 copies/mL, CD4 count 129 cells/microL and CD4%, 6.5%. Median area under the concentration curve at 0-12 hours and Cmin were 39.4 mg/L.h and 1.4 mg/L for saquinavir and 118 mg/L.hr and 5.9 mg/L for lopinavir. After 24 weeks of treatment, HIV RNA was suppressed below 400 copies/mL for 16 of 20 (80%) children (intent-to-treat analysis) and below 50 copies/mL for 12 of 20 children (60%), and CD4% (count) rose by a median of 6% (216 cells/microL). Median changes of triglyceride and total cholesterol were 56 and 36.5 mg/dL, respectively (P = 0.01). Lopinavir Cmin <1 and saquinavir Cmin <0.28 mg/L correlated with HIV RNA >400 copies/mL, and lopinavir Cmax >15 mg/L correlated with rises in cholesterol (P < 0.05).

CONCLUSION

Plasma drug concentrations of saquinavir, lopinavir and ritonavir were at the higher limits of expected ranges for adult treatment at approved dosages (1000/100 mg bid for saquinavir, 400/100 mg bid for lopinavir/ritonavir). The regimen was well-tolerated and had good efficacy at 24 weeks. This dual boosted protease inhibitor combination should be assessed in larger trials of reverse transcription inhibitor-experienced children.

Phanuphak P, Ubolyam S, Sankote J, Pongprayoon P, Saenawat S, Wicharuk S, Nonenoy S, Wannachai N, Chautrakarn S, Chuenyam T, Jeanpan N, Nuchapong T, Jupimai T, le Braz M, Bunyaprawit P, Putthawong S, Penglimoon Y, Seekaow N, Karakate W, Khongsawad S, Kiatatchasai W, Ananworanich J, Hill A, Siangphoe U, Ruxrungtham K, Prasithsirikul W, Chetchotisakd P, Kiertiburanakul S, Munsakul W, Raksakulkarn P, Tansuphasawadikul S, Nuesch R, Cooper DA, Hirschel B. A Prospective Study of Efficacy and Safety of Once-Daily Saquinavir/Ritonavir plus Two Nucleoside Reverse Transcriptase Inhibitors in Treatment-Naive Thai Patients

Objective

To assess the efficacy and safety of first-line treatment with once-daily saquinavir/ritonavir with two nucleoside reverse transcriptase inhibitors (NRTIs), as induction therapy before enrollment in a randomized trial of structured treatment interruption strategies.

Design

Two-hundred antiretroviral-naive patients with CD4+ cell counts between 200–350 at screening were enrolled in this open-label 24week study.

Methods

Patients were followed up every 8 weeks for CD4+ cells, HIV RNA, and clinical and laboratory toxicities. Results: Two-hundred patients were enrolled with median baseline CD4+ cell count of 267 cells/μl and HIV RNA 50 118 (4.7 log10) copies/ml. After 24 weeks of treatment, 191 of 200 (96%) patients had below 400 copies/ml HIV RNA, with 177/200 (89%) below 50 copies/ml (intent to treat, missing equals failure method), with a median rise in CD4+ cell count of 122 cells/μl. There was no significant correlation between the minimum concentration of saquinavir and HIV RNA reductions at week 8 ( P=0.957) or absolute HIV RNA at week 24 ( P=0.77).

Conclusion

First-line highly active antiretroviral therapy (HAART) with once-daily saquinavir/ritonavir plus two NRTIs showed strong antiviral efficacy over 24 weeks, and should be evaluated in larger prospective randomized clinical trials.

Incidence and risk factors for rash in Thai patients randomized to regimens with nevirapine, efavirenz or both drugs

OBJECTIVE

To determine the incidence and risk factors for rash in Thai patients taking four different non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens.

METHODS

HIV-positive, antiretroviral-naive patients enrolled in the 2NN study in Thailand and followed for at least 1 week were included. Patients were randomized to efavirenz (EFV) 600 mg once daily (OD) versus nevirapine (NVP) 200 mg twice daily (BD) versus NVP 400 mg OD versus NVP 400 mg OD + EFV 800 mg OD with stavudine/lamivudine.

RESULTS

Of 202 patients, 95 (47%) and 69 (34.2%) developed a rash from all reasons and from NNRTI, respectively. For NNRTI-related rash the incidences were EFV (20%), NVP BD (21%), NVP OD (38%) and NVP + EFV (67%). The proportions of patients with grade I, II and III within the four treatment arms are as follows: EFV, 4.3, 13 and 2.9%; NVP BD, 2.3, 15.9 and 2.3%; NVP OD, 12.8, 19.1 and 6.4%; and NVP + EFV, 11.9, 47.6 and 7.1%. Multivariate analyses showed females with CD4 cell count > or =250 x 10 cells/l, high body mass index (>21.3 kg/m), and a rise in CD4 (> or =53 x 10 cells/l) and alanine aminotransferase (ALT) (> or =34 U/l) at week 4 to be risk factors for rash.

CONCLUSIONS

Thai patients had a high incidence of NNRTI-related rash when treated with NVP + EFV or NVP OD. NVP if used BD had the same rash incidence as EFV for rash of all grades. Females, and persons with earlier HIV disease or with a large rise in CD4+ cell count after starting therapy are at greater risk for NNRTI-related rash.

The 5th International Workshop on Clinical Pharmacology of HIV Therapy

The 5(th) International Workshop on Clinical Pharmacology of HIV Therapy was held at the Università Cattolica del Sacro Cuore, Rome, Italy on April 1 - 3, 2004. More than 180 participants registered for this workshop demonstrating the growing interest in antiretroviral pharmacology. The purpose of this meeting was to present and discuss antiretroviral pharmacokinetics, pharmacodynamics, drug interactions, therapeutic drug monitoring-related research and the assays necessary for measuring antiretroviral concentrations. A total of 31 oral and 48 poster presentations were accepted to this meeting, the largest number of accepted submissions in the 5-year history of this workshop. Herein, examples of the research that was presented are highlighted.