Pharmacokinetics of once-daily saquinavir hard-gelatin capsules and saquinavir soft-gelatin capsules boosted with ritonavir in HIV-1-infected subjects

Pilot Study of Saquinavir and Lopinavir/Ritonavir Twice Daily in Protease Inhibitor-Naive HIV-Positive Patients

PURPOSE

Protease inhibitor (PI)-naive patients may have limited reverse transcriptase inhibitor (RTI) options due to resistance and/or toxicity. Effective, well-tolerated nucleoside reverse transcriptase inhibitor (NRTI)-sparing regimens are therefore needed.

METHOD

This prospective study evaluated the efficacy and safety of saquinavir/lopinavir/ritonavir (1000/400/100 mg bid) in PI-naive patients over 48 weeks. The regimen could be intensified with NRTIs if patients did not achieve virologic suppression by 12 weeks. The primary study endpoint was virologic suppression at 48 weeks. Additional study objectives included assessment of safety, CD4 cell counts, blood lipids, PI trough levels, and anthropometrics.

RESULTS

Of the 20 PI-naive study participants, 16 completed 48 weeks of study treatment, with no discontinuations attributed to virologic failure. Fourteen of 16 patients achieved virologic suppression with only the PIs; 2 patients required tenofovir intensification to achieve complete suppression. Median CD4 counts increased significantly over 48 weeks. Adverse events were generally mild and manageable. Extreme lipid elevations were uncommon, although moderate lipid elevations occurred in the majority of patients. Most patients reported some degree of central fat accumulation.

CONCLUSION

Our study demonstrates that saquinavir/lopinavir/ritonavir 1000/400/100 mg bid with tenofovir intensification is a potent nucleoside-sparing regimen for PI-naive patients, associated with durable HIV suppression and improved CD4 cell counts. Fat accumulation and metabolic changes observed in this study warrant confirmation from ongoing trials.

Sequence-specific alterations of epitope production by HIV protease inhibitors

Ag processing by intracellular proteases and peptidases and epitope presentation are critical for recognition of pathogen-infected cells by CD8+ T lymphocytes. First-generation HIV protease inhibitors (PIs) alter proteasome activity, but the effect of first- or second-generation PIs on other cellular peptidases, the underlying mechanism, and impact on Ag processing and epitope presentation to CTL are still unknown. In this article, we demonstrate that several HIV PIs altered not only proteasome but also aminopeptidase activities in PBMCs. Using an in vitro degradation assay involving PBMC cytosolic extracts, we showed that PIs altered the degradation patterns of oligopeptides and peptide production in a sequence-specific manner, enhancing the cleavage of certain residues and reducing others. PIs affected the sensitivity of peptides to intracellular degradation, and altered the kinetics and amount of HIV epitopes produced intracellularly. Accordingly, the endogenous degradation of incoming virions in the presence of PIs led to variations in CTL-mediated killing of HIV-infected cells. By altering host protease activities and the degradation patterns of proteins in a sequence-specific manner, HIV PIs may diversify peptides available for MHC class I presentation to CTL, alter the patterns of CTL responses, and provide a complementary approach to current therapies for the CTL-mediated clearance of abnormal cells in infection, cancer, or other immune disease.

Pharmacokinetics of Saquinavir With Atazanavir or Low-Dose Ritonavir Administered Once Daily (ASPIRE I) or Twice Daily (ASPIRE II) in Seronegative Volunteers

ASPIRE I and II were prospective, 3-way sequential crossover studies in healthy volunteers to compare the safety and pharmacokinetics of saquinavir/ritonavir (SQV/RTV) with saquinavir/atazanavir (SQV/ATV) administered either once daily (QD, ASPIRE I) or twice daily (BID, ASPIRE II). Treatments were separated by 10 days, and pharmacokinetic analyses were performed on days 11, 32, and 53. SQV pharmacokinetics were significantly higher when dosed with RTV compared to ATV (P < .05 for all comparisons). ATV pharmacokinetics were similar within treatment arms. ATV Cmin increased approximately 60%, and Cmax decreased approximately 35% with BID dosing compared with QD dosing. Women had higher exposure for all 3 protease inhibitors (PIs) compared with men after adjusting for weight. Adverse effects were primarily gastrointestinal-related with SQV/RTV and hyperbilirubinemia with SQV/ATV. Although SQV plasma concentrations were higher when coadministered with RTV, a combination of SQV/ATV administered BID may be a viable alternative in HIV-infected, PI-naive subjects intolerant to RTV.

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.

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.

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.

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.

Pharmacokinetics of saquinavir hard-gel/ritonavir and atazanavir when combined once daily in HIV Type 1-infected individuals administered different atazanavir doses

The pharmacokinetics and short-term safety of atazanavir 150 and 200 mg, when coadministered with saquinavir/ritonavir 1600/100 mg once daily, were evaluated. On day 1, atazanavir 150 mg once daily, was added to saquinavir/ritonavir regimens and sampling was performed to evaluate saquinavir, ritonavir, and atazanavir pharmacokinetics (day 11). Atazanavir was increased to 200 mg and pharmacokinetic assessment repeated (day 30). Geometric mean ratios (GMR) and 95% confidence intervals (CI) were used to compare saquinavir, ritonavir, and atazanavir pharmacokinetic parameters in the present study and for 14 of the subjects treated with saquinavir/ritonavir 1600/100 mg once daily without and with atazanavir 300 mg who participated in a previous trial. Geometric mean (GM) saquinavir AUC0-24, Ctrough, and Cmax were 30,589 and 32,312 ng . h/ml, 166 and 182 ng/ml, and 4267 and 4261 ng/ml when coadministered with atazanavir 150 and 200 mg (n = 18). On days 11 and 30, saquinavir and atazanavir Ctrough remained >100 ng/ml in 13/18, 14/18, 18/18, and 17/18 patients. Among the above mentioned 14 subjects, significant increases in saquinavir Ctrough (87%, 92%, 99%), Cmax (40%, 55%, 44%), and AUC0-24 (51%, 60%, 63%) were observed with atazanavir 300, 150, and 200 mg. Ritonavir AUC0-24 and Cmax were significantly increased with the addition of atazanavir 300 mg only. Atazanavir enhances saquinavir and ritonavir by a mechanism that requires elucidation. While saquinavir enhancement was apparently independent of atazanavir dose, atazanavir 300 mg produced an increase in ritonavir Cmax, which is not observed with lower atazanavir doses. Atazanavir-related hyperbilirubinemia was dose dependent. However, higher saquinavir and atazanavir exposure may be required to suppress HIV-resistant strain replication.

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.

Saquinavir 500 mg Film-Coated Tablets Demonstrate Bioequivalence to Saquinavir 200 mg Hard Capsules When Boosted with Twice-Daily Ritonavir in Healthy Volunteers

Objective

To establish the bioequivalence of a 500 mg film-coated tablet of saquinavir mesylate (FCT SQV) to the 200 mg hard-capsule saquinavir mesylate (HC SQV), both boosted with ritonavir and administered under fed conditions.

Methods

We carried out a multi-centre, open-label, randomized, two-sequence, four-period, two-treatment, replicated crossover study in 93 healthy men and 7 healthy women. Individuals were randomly assigned to receive sequential single doses of saquinavir in one of two treatment sequences: ABAB or BABA. Individuals received 100mg ritonavir twice daily for 24 days. On days 14, 17, 20 and 23, study participants took 1000mg of HC SQV (five 200 mg capsules, treatment A) or FCT SQV (two 500 mg tablets, treatment B) with a high-fat, high-calorie breakfast, and pharmacokinetic analyses were carried out over the next 24 hours. Area under the saquinavir concentration–time curve (AUC0–∞), maximum saquinavir plasma concentration (Cmax), time to Cmax and terminal half-life were calculated. The relative bioavailability of FCT SQV versus HC SQV was calculated as the ratio of the respective estimated mean saquinavir AUC0-∞ and Cmax. The calculation was based on an ANOVA including the factors site, sex, sequence, period, treatment and study participant to the log-transformed parameters log(AUC0-∞) and log(Cmax); the relative bioavailability and the 90% confidence intervals (CIs) were estimated using the treatment contrasts of the ANOVA. Bioequivalence was concluded as for both parameters, AUC0-∞ and Cmax, the 90% CIs for the relative bioavailability were entirely included in the reference region [0.80–1.25].

Results

Saquinavir plasma concentration–time profiles for the two formulations were similar. Geometric mean AUC0-∞ and Cmax values were clearly increased for FCT SQV (26 826 versus 24 430 h*ng/ml; and 3644 versus 3064 ng/ml, respectively); ratios of mean exposures were estimated to be 1.10 for AUC0-∞ and 1.19 for Cmax of saquinavir. However, the corresponding two-sided 90% CIs (1.04–1.16 and 1.14–1.25, respectively) all fell within the limits set for equivalence (0.80, 1.25). The adverse event profile for FCT SQV was similar to that for HC SQV.

Conclusion

The new 500 mg FCT SQV formulation is bioequivalent to the 200 mg HC SQV formulation, at the dose of 1000 mg, in combination with 100 mg ritonavir under fed conditions. The 500 mg FCT SQV formulation reduces pill count for boosted saquinavir (SQV/r) from six capsules to three tablets twice daily. This may increase patient acceptability of SQV/r, particularly in less treatment-experienced patients.

Once-daily antiretroviral therapy: Spanish Consensus Statement

BACKGROUND

Administration of antiretroviral therapy (ART) once daily is creating extraordinary interest among the members of the scientific community and also among those who receive the therapy. However, in clinical practice, some doubts remain about its use.

OBJECTIVES

This document examines the characteristics and possibilities of treatment administered once daily.

METHODS

Consensus of 248 Spanish experts in the field.

RESULTS

Once-daily dosing is considered an added value which could favour adherence and, therefore, efficacy, as well as the quality of life of certain patients, however, the objective of adequate adherence in the long term is often difficult to achieve regardless of the treatment used. In theory, any patient can receive once-daily therapy, although some patients could particularly benefit from it, e.g. those with unfavourable social or personal circumstances, including drug users, patients whose treatment must be supervised, patients receiving multiple medications, or those who need rescue therapy after multiple treatment failures. At present, it is possible to design once-daily ART using some of the combinations of drugs considered as first-choice in national and international recommendations for antiretroviral therapy, but the options are still limited. The marketing of new drugs with this characteristic could allow us to increase the number and types of patient who can benefit from once-daily regimens, including those patients who need rescue therapy.

CONCLUSIONS

Once-daily ART is a good alternative to regimens administered several times each day when a potent combination of active drugs is available.

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.

Clinical Pharmacokinetics and Summary of Efficacy and Tolerability of Atazanavir

The efficacy of HIV-1 protease inhibitors (PIs) as part of highly active antiretroviral therapy is now well established and has provided benefits to many patients with HIV infection. Atazanavir is a new azapeptide PI compound that was recently approved in the US and Europe. Atazanavir is recommended in combination with other antiretroviral agents for the treatment of HIV-1 infection. Atazanavir is rapidly absorbed and administration of a single dose of atazanavir with a light meal resulted in a 70% increase in area under the plasma concentration-time curve (AUC); therefore atazanavir should be taken with food. Atazanavir is 86% bound to human serum protein independently of concentration. Concentration in body fluids appeared to be lower than plasma concentration. Like other PIs, atazanavir is extensively metabolised by hepatic cytochrome P450 (CYP) 3A isoenzymes. The mean terminal elimination half-life in healthy volunteers was approximately 7 hours at steady state following administration of atazanavir 400 mg daily with a light meal. When atazanavir 300 mg was coadministered with ritonavir 100 mg on a once-daily dosage regimen, atazanavir AUC from 0 to 24 hours and minimum plasma concentration were increased by 3- to 4-fold and approximately 10-fold, respectively, compared with atazanavir 300 mg alone. Therefore, ritonavir boosted atazanavir regimen (ritonavir 100 mg and atazanavir 300 mg once daily) is increasingly favoured in some patients. Efavirenz, a potent CYP3A inducer, decreased atazanavir concentrations by 75% and, unexpectedly, tenofovir, a nucleotide reverse transcriptase inhibitor, decreased atazanavir concentrations by 25%. Average predose concentrations in HIV-infected patients who received atazanavir 400mg once daily were 273 ng/mL, which was believed to be several-fold higher than protein-binding corrected 50% inhibitory concentration of wild-type viruses. In HIV-infected patients who received once-daily ritonavir (100mg) boosted atazanavir (300 mg), mean (+/-SD) trough concentration was 862 (+/-838) ng/mL. Several clinical trials showed the efficacy of atazanavir 400 mg once daily with a nucleoside analogue backbone in antiretroviral-naive patients. The atazanavir 300/ritonavir 100 mg once-daily combination coadministered with other antiretrovirals showed the efficacy of this strategy in patients receiving efavirenz or in moderately antiretroviral-experienced HIV-infected patients. Recommended once-daily doses of atazanavir taken with food are either 400 mg or 300 mg in combination with low dose ritonavir (100 mg) in moderately antiretroviral-experienced patients. Major advantages of atazanavir to date are its simplicity of administration (once-daily administration) and its less undesirable effect on the lipid profiles in patients.

Hepatotoxicity associated with protease inhibitor-based antiretroviral regimens with or without concurrent ritonavir

OBJECTIVE

To determine the incidence of significant liver enzyme elevations following the initiation of protease inhibitor (PI)-based antiretroviral therapy (ART) with or without pharmacokinetic boosting with ritonavir (RTV), and to define the role of chronic viral hepatitis in its development.

DESIGN

Prospective, cohort analysis of 1161 PI-naive, HIV-infected patients receiving RTV-boosted (lopinavir, indinavir and saquinavir) and unboosted PI-based ART (indinavir, nelfinavir) that had at least one liver enzyme measurement before and during therapy.

METHODS

The incidence of grade 3 and 4 liver enzyme elevations among persons with and without hepatitis B and/or C co-infection treated with PI-based ART were compared. Severe hepatotoxicity was defined as an increase in serum liver enzyme >/= 5-times the upper limit of the normal range or 3.5-times an elevated baseline level.

RESULTS

The incidence of grade 3 or 4 elevations among PI-naive patients was: nelfinavir, 11%; lopinavir/RTV (200 mg/day), 9%; indinavir, 13%; indinavir/RTV (200-400 mg/day), 12.8%; and saquinavir/RTV (800 mg/day), 17.2%. The risk was significantly greater among persons with chronic viral hepatitis (63% of cases); however, the majority of hepatitis C virus (HCV)-infected patients treated with nelfinavir (84%), saquinavir/RTV (74%), indinavir, 86%, indinavir/RTV (90%) or lopinavir/RTV (87%) did not develop hepatotoxicity.

CONCLUSIONS

Our data suggest that the lopinavir/RTV is not associated with a significantly increased risk of hepatotoxity among HCV-infected and uninfected patients compared with an alternative PI-based regimen, nelfinavir. Accordingly, other medication-related factors (e.g, efficacy and non-hepatic toxicity) should guide individual treatment decisions.

Pharmacologic Perspectives for Once-Daily Antiretroviral Therapy

OBJECTIVE

To contrast available once-daily antiretroviral agents and combinations of these agents from a clinical pharmacologic viewpoint.

DATA SOURCES

Data were extracted from publications and major HIV conference proceedings cited in MEDLINE (1966–March 2004) using the search terms antiretroviral therapy, combination therapy, once-daily therapy, and pharmacokinetics. Additional references were obtained from the bibliographies of these sources.

STUDY SELECTION AND DATA EXTRACTION

Information pertaining to pharmacologic perspectives for once-daily antiretroviral agents was selected.

DATA SYNTHESIS

Maximal and durable suppression of plasma HIV RNA, the principal goal of therapy, depends on the intrinsic antiviral activity of the antiretroviral regimen. A favorable tolerability/toxicity profile is also fundamentally important. All once-daily agents exhibit some pharmacologic limitations or lack adequate long-term follow-up. Of available agents, efavirenz has a long and distinguished efficacy record, with reasonable safety and moderate tolerability. Lamivudine, and newer agents such as atazanavir (or atazanavir/ritonavir), emtricitabine, fosamprenavir/ritonavir, and tenofovir, may offer pharmacologic advantages in the current state of once-daily therapy. Important considerations exist for coadministering once-daily agents including drug–drug interactions, drug–food incompatibilities, and synergistic toxicities. Few controlled studies have compared once-daily regimens with conventional regimens.

CONCLUSIONS

Progress has been made toward once-daily therapy, but more clinical experience with available agents is needed, including comparative studies of entirely once-daily regimens versus conventional regimens. Limitations of currently available agents signify a need for improved antiretroviral utilization or new alternative agents.

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

OBJECTIVES

A pharmacokinetic comparison of three dosing regimens of saquinavir/ritonavir was carried out: 1600/100 mg once-daily with 1000/100 mg twice-daily, and 1600/100 mg once-daily with 2000/100 mg once-daily.

METHODS

Twenty patients on saquinavir hard gel caps/ritonavir 1600/100 mg once-daily in combination with two nucleoside reverse transcriptase inhibitors for at least 4 weeks were enrolled and randomized to either saquinavir hard gel caps/ritonavir 1000/100 mg twice-daily or 2000/100 mg once-daily. Two pharmacokinetic curves were plotted, at baseline (day 0) and 7 days after the switch. Plasma concentrations were measured at 0, 2, 4, 6, 8, 10, 12 (and 24 for once-daily dosing) hours after drug intake by validated high-performance liquid chromatographic assay (HPLC). The area under the plasma concentration-time curve (AUC0-24 or AUC0-12), maximum and minimum concentration (Cmax and Cmin) and elimination half-life were calculated using a non-compartmental model.

RESULTS

Compared with saquinavir/ritonavir 1600/100 mg once-daily dosing, the saquinavir AUC and Cmin improved significantly when dosed as 1000/100 mg twice-daily (53% and 299%, respectively), and as 2000/100 mg once-daily (71% and 65%, respectively). Low Cmin in three subjects at baseline was corrected after switch to the other dosages. Saquinavir/ritonavir 2000/100 mg once-daily was also associated with a significant increase in saquinavir Cmax (52%) compared with saquinavir/ritonavir 1600/100 mg once-daily.

CONCLUSIONS

Saquinavir/ritonavir when dosed as 2000/100 mg once-daily or 1000/100 mg twice-daily achieves higher saquinavir plasma levels compared with saquinavir/ritonavir 1600/100 mg once-daily. Taking the convenience of once-daily dosing into consideration, dosage of 2000/100 mg once-daily may be preferred.

Sex-Related Differences in the Pharmacokinetics of Once-Daily Saquinavir Soft-Gelatin Capsules Boosted with Low-Dose Ritonavir in Patients Infected with Human Immunodeficiency Virus Type 1

STUDY OBJECTIVES

To compare the steady-state pharmacokinetics and safety of saquinavir soft-gelatin capsules (SGC) plus low-dose ritonavir administered once/day in antiretroviral-naive adult patients infected with the human immunodeficiency virus type 1 (HIV-1) and to evaluate any sex-related differences.

DESIGN

Single-center, open-label, pharmacokinetic study.

SETTING

University-affiliated outpatient HIV clinic.

PATIENTS

Six men and seven women with HIV-1.

INTERVENTION

Each patient received saquinavir SGC 1600 mg and ritonavir 100 mg for a 14-day course of therapy. Nine serial blood samples during 24 hours were collected on day 14 of therapy

MEASUREMENTS AND MAIN RESULTS

Plasma saquinavir and ritonavir concentrations were measured by high-performance liquid chromatography. Standard noncompartmental methods were used to calculate the pharmacokinetic parameters. The unpaired Student t test was used for the statistical comparison of pharmacokinetic parameters between male and female patients. Once-daily saquinavir SGC plus ritonavir was generally well tolerated. Pharmacokinetic data from five men and five women were evaluable. The median saquinavir area under the concentration-time curve from 0-24 hours (AUC0-24) in the female patients (82,300 ng x hr/ml) was significantly (p=0.036) higher than that in the male patients (47,400 ng x hr/ml). This relationship remained significant for weight-adjusted saquinavir AUC0-24 values. Ritonavir's apparent oral clearance in the women was significantly (p=0.023) lower than that in the men.

CONCLUSION

Significantly higher plasma concentrations of saquinavir were achieved in female compared with male HIV-infected patients receiving once-daily saquinavir SGC 1600 mg plus ritonavir 100 mg.

Self-emulsifying drug delivery systems (SEDDS) for improved oral delivery of lipophilic drugs

The oral delivery of hydrophobic drugs presents a major challenge because of the low aqueous solubility of such compounds. Self-emulsifying drug delivery systems (SEDDS), which are isotropic mixtures of oils, surfactants, solvents and co-solvents/surfactants, can be used for the design of formulations in order to improve the oral absorption of highly lipophilic drug compounds. SEDDS can be orally administered in soft or hard gelatin capsules and form fine relatively stable oil-in-water (o/w) emulsions upon aqueous dilution owing to the gentle agitation of the gastrointestinal fluids. The efficiency of oral absorption of the drug compound from the SEDDS depends on many formulation-related parameters, such as surfactant concentration, oil/surfactant ratio, polarity of the emulsion, droplet size and charge, all of which in essence determine the self-emulsification ability. Thus, only very specific pharmaceutical excipient combinations will lead to efficient self-emulsifying systems. Although many studies have been carried out, there are few drug products on the pharmaceutical market formulated as SEDDS confirming the difficulty of formulating hydrophobic drug compounds into such formulations. At present, there are four drug products, Sandimmune and Sandimmun Neoral (cyclosporin A), Norvir (ritonavir), and Fortovase (saquinavir) on the pharmaceutical market, the active compounds of which have been formulated into specific SEDDS. Significant improvement in the oral bioavailability of these drug compounds has been demonstrated for each case. The fact that almost 40% of the new drug compounds are hydrophobic in nature implies that studies with SEDDS will continue, and more drug compounds formulated as SEDDS will reach the pharmaceutical market in the future.

Once-Daily Dosing of Saquinavir Soft-Gel Capsules and Ritonavir Combination in HIV-1-Infected Patients (Imea015 Study)

This was a prospective pilot study evaluating a saquinavir (SQV) soft-gel capsules (SGC)/ritonavir (RTV)-containing once-daily regimen over a follow-up of 3 months. The primary end-point was to determine the number of patients both remaining on treatment at month 3 and with trough SQV plasma concentration 24 h after the last intake (C24h) exceeding the inhibition of 95% of viral replication in vitro (IC95). The secondary end-points were to investigate the immuno-virological efficacy and safety of SQV-SGC/RTV once daily, and to explore SQV concentrations in peripheral blood mononuclear cells (PBMCs). Twenty-three antiretroviral-naive and 17 protease inhibitors (PIs) experienced HIV-1-infected patients with plasma HIV-1 RNA level below 200 copies/ml were enrolled. They were assigned to SQV-SGC/RTV (1600/100 mg once daily) combined with nucleoside and/or non-nucleoside reverse transcriptase inhibitors. In a subgroup of 13 patients, both plasma and intracellular SQV concentrations were determined. By intent to treat analysis the percentage of success at month 3 was 87.5% (confidence interval: 73.2–95.8%) with 78.3% in naive and 100% in PI-experienced patients. SQV C24h and intracellular concentrations [median (range, n)] were 241 ng/ml (40–1209, 35) and 323 ng/ml (168–475, 12), respectively. Intracellular concentrations showed an accumulation of SQV in PBMCs persisting during 24 h. Neither immunological nor virological failure was observed. Clinical and biological tolerance was acceptable in all patients but three with adverse effects leading to discontinuation. These data confirmed the short-term efficacy of SQV-SGC/RTV once-daily regimen based on SQV therapeutic drug monitoring.

This work was presented in part at the 2nd International Conference on Clinical Pharmacology of HIV Infection, Noordwijk, the Netherlands, 2-4 April 2001 (Abstract 3.16); and at the 1st International Conference on HIV Pathogenesis & Treatment, Buenos Aires, Argentina, 8–11 July 2001 (Abstract 344).

Twenty years of therapy for HIV-1 infection

Antiretroviral therapy, where available, has transformed HIV-1 disease into a treatable and somewhat chronic infection. This article summarizes the accomplishments thus far and what lies ahead in our struggle to improve the treatment of, and possibly eliminate, HIV-1 infection.