The Effect of ABCB1 Polymorphism on the Pharmacokinetics of Saquinavir Alone and in Combination with Ritonavir

This genotype panel study investigated the effect of ABCB1 polymorphism in exon 26 (C3435T), exon 21 (G2677T/A), and exon 12 (C1236T) on saquinavir pharmacokinetics and on the expression and activity of P-glycoprotein (P-gp) in peripheral blood monocytic cells (PBMCs). One hundred and fifty healthy volunteers were genotyped to identify 15 TT3435 and 15 CC3435 individuals. In these individuals, saquinavir pharmacokinetics were assessed after administration of a single oral dose of saquinavir 1,000 mg and saquinavir/ritonavir 1,000/100 mg. PBMC P-gp expression and activity were assessed in 15 and 19 subjects. The co-administration of ritonavir on study day 2 caused a significant increase in saquinavir exposure, in both TT3435 and CC3435 individuals. No correlation was observed between the ABCB1 C3435T, G2677T/A, and C1236T polymorphisms, separately and in haplotypes, with saquinavir pharmacokinetics, administered with or without ritonavir and with PBMC P-gp expression and activity. In conclusion, ABCB1 polymorphism has no pronounced effect on saquinavir exposure.

Exploratory study comparing the metabolic toxicities of a lopinavir/ritonavir plus saquinavir dual protease inhibitor regimen versus a lopinavir/ritonavir plus zidovudine/lamivudine nucleoside regimen

OBJECTIVES

To assess the safety, efficacy and metabolic toxicity of lopinavir/ritonavir + saquinavir or zidovudine/lamivudine and evaluate the pharmacokinetics of lopinavir/ritonavir + saquinavir.

METHODS

HIV-1-infected, antiretroviral-naive subjects were randomized to lopinavir/ritonavir (400/100 mg) twice daily + saquinavir (800 mg) or zidovudine/lamivudine (150/300 mg) in a Phase II, 48 week study. Subjects receiving lopinavir/ritonavir + zidovudine/lamivudine initiated escalating doses of saquinavir (400, 600 and 800 mg) weekly for 3 weeks.

RESULTS

By intent-to-treat (non-completer = failure) analysis, 10/16 (63%) lopinavir/ritonavir + saquinavir-treated and 7/14 (50%) lopinavir/ritonavir + zidovudine/lamivudine-treated subjects achieved plasma HIV-1 RNA <50 copies/mL (P=0.713) at week 48. Safety, tolerability, metabolic changes and truncal fat increases were similar between groups. Small decreases in the lower extremity fat in the zidovudine/lamivudine group (-6%) and a statistically significant increase in the lower extremity fat in the saquinavir group (+19%) were observed. Lopinavir/ritonavir co-administered with saquinavir 600 or 800 mg twice daily produced saquinavir concentrations similar to those previously reported for saquinavir/ritonavir 1000/100 mg twice daily.

CONCLUSIONS

Treatment regimens had similar efficacy and tolerability. Metabolic parameters suggested lipoatrophy in the zidovudine/lamivudine treatment group. Saquinavir 600 and 800 mg twice daily produced concentrations similar to those previously reported for saquinavir/ritonavir 1000/100 mg twice daily.

Pharmacokinetics of saquinavir, atazanavir, and ritonavir in a twice-daily boosted double-protease inhibitor regimen

The objective of this study was to evaluate the pharmacokinetics of atazanavir (ATV), saquinavir (SQV), and ritonavir (RTV) in a boosted double-protease inhibitor (PI) therapy regimen without reverse transcriptase inhibitors (RTIs). The study design was as follows. Patients with limited RTI options received a PI combination of 300/100 mg ATV/RTV once daily and 1,000 mg SQV twice daily (group 1; n=49) without RTI comedication. The results were compared to the plasma concentrations of PIs of patients taking either 300 mg ATV/100 mg RTV once daily plus RTIs (group 2; n=72) or patients taking 1,000 mg SQV/100 mg RTV plus RTIs (group 3; n=90). The study methods were as follows. Patients were given a 12/24-h pharmacokinetic assessment at steady state. Drug concentrations were measured by liquid chromatography-tandem mass spectrometry. The minimum and maximum concentrations (Cmin and Cmax), area under the concentration-time curve under steady-state conditions (AUCss), elimination half-life, time of maximum concentration and lag time were subject to statistical analysis. The results show that patients treated with ATV/SQV/RTV exhibited significantly high SQV concentrations and moderate enhancement of the AUCss of ATV in comparison to those of patients of the control groups: for SQV in groups 1 and 3, the geometric mean (GM) of the AUCss was 22,794 versus 15,759 ng.h/ml (GM ratio [GMR]=1.45; P<0.05), the GM of the Cmax was 3,257 versus 2,331 ng/ml (GMR=1.40; P<0.05), and the GM of the Cmin was 438 versus 437 ng/ml (GMR=1.00); for ATV in groups 1 and 2, the GM of the AUCss was 39,154 versus 33,626 ng.h/ml (GMR=1.16), the GM of the Cmax was 3,488 versus 2,924 ng/ml (GMR=1.20), and the GM of the Cmin was 515 versus 428 ng/ml (GMR=1.21). RTV levels were comparable for all groups. A subgroup analysis detected only marginal differences in ATV plasma exposure if combined with tenofovir-disoproxilfumarate and without it. We conclude that our pharmacokinetic results support the use of a boosted double-PI regimen of ATV/SQV/RTV as a treatment option for patients who need antiretroviral therapy without RTIs.

Saquinavir, nelfinavir and M8 pharmacokinetics following combined saquinavir, ritonavir and nelfinavir administration

OBJECTIVES

This study evaluated the steady-state pharmacokinetic interaction between ritonavir-boosted saquinavir and nelfinavir.

METHODS

Open label, multiple-dose, two parallel-groups, single crossover study conducted in 24 HIV-infected patients (12 in each group). Patients in the nelfinavir group added saquinavir/ritonavir, 1000/100 mg twice daily to their ongoing stable treatment regimen consisting of nelfinavir, 1250 mg twice daily and two nucleoside reverse transcriptase inhibitors (NRTIs). Patients in the saquinavir group added nelfinavir, 1250 mg twice daily to their ongoing stable treatment regimen consisting of saquinavir/ritonavir, 1000/100 mg twice daily and two NRTIs. Pharmacokinetic assessments were performed before and 7 days after the start of combined treatment with nelfinavir/saquinavir/ritonavir. Blood samples were collected before and 1, 2, 3, 4, 6, 8, 10 and 12 h after dosing for measurement of nelfinavir, the nelfinavir metabolite M8 and saquinavir using liquid chromatography tandem mass spectrometry (LC-MS/MS).

RESULTS

The addition of saquinavir/ritonavir to the nelfinavir-containing regimen resulted in significant increases in the M8 pharmacokinetic parameters AUC(0-12), Cmax and C12; geometric mean ratios (90% confidence intervals) of 2.25 ng.h/mL (1.47-3.44), 1.74 ng/mL (1.25-2.40) and 4.21 ng/mL (2.10-8.47), respectively. The intra-individual changes in nelfinavir and saquinavir concentrations were highly variable. Statistical analysis could not discard a relevant interaction but includes the possibility that some parameters may be halved, others more than doubled. At the same time the analysis failed to show any directed change.

CONCLUSIONS

The co-administration of nelfinavir and saquinavir/ritonavir leads to unpredictable changes in concentrations of both drugs. It is unclear whether the increased concentrations of M8 are associated with a clinical benefit.

Estimation of population pharmacokinetic parameters of saquinavir in HIV patients with the MONOLIX software

In nonlinear mixed-effects models, estimation methods based on a linearization of the likelihood are widely used although they have several methodological drawbacks. Kuhn and Lavielle (Comput. Statist. Data Anal. 49:1020-1038 (2005)) developed an estimation method which combines the SAEM (Stochastic Approximation EM) algorithm, with a MCMC (Markov Chain Monte Carlo) procedure for maximum likelihood estimation in nonlinear mixed-effects models without linearization. This method is implemented in the Matlab software MONOLIX which is available at http://www.math.u-psud.fr/~lavielle/monolix/logiciels. In this paper we apply MONOLIX to the analysis of the pharmacokinetics of saquinavir, a protease inhibitor, from concentrations measured after single dose administration in 100 HIV patients, some with advance disease. We also illustrate how to use MONOLIX to build the covariate model using the Bayesian Information Criterion. Saquinavir oral clearance (CL/F) was estimated to be 1.26 L/h and to increase with body mass index, the inter-patient variability for CL/F being 120%. Several methodological developments are ongoing to extend SAEM which is a very promising estimation method for population pharmacockinetic/pharmacodynamic analyses.

Incidence and risk factors of bacterial pneumonia requiring hospitalization in HIV-infected patients started on a protease inhibitor-containing regimen

OBJECTIVE

To describe the incidence and risk factors of bacterial pneumonia occurring in patients treated with antiretrovirals.

METHODS

In the ongoing APROCO (Anti-proteases) cohort, 1281 patients at the initiation of a protease inhibitor (PI)-containing antiretroviral regimen were enrolled from 1997-1999. All events requiring hospitalization during follow up are recorded. Of these, bacterial pneumonia was defined as the occurrence of a new pulmonary infiltrate with fever and either evidence of a bacteriological cause (definite cases) or favourable outcome with antimicrobial therapy (presumptive cases). Risk factors of bacterial pneumonia were studied using survival analyses.

RESULTS

During a median follow up of 43 months, 29 patients had at least one episode of bacterial pneumonia, giving an incidence of 0.8/100 patient years. The 11 definite cases were attributable to Streptococcus pneumoniae (n=9), Legionella pneumophila (n=1) and Haemophilus influenzae (n=1). In multivariate analysis, bacterial pneumonia was significantly more frequent in older patients, injecting drug users, patients having a CD4 cell count>500 cells/microL at baseline and patients who initiated PI therapy with nonboosted saquinavir. It was significantly less frequent in nonsmokers. The occurrence of bacterial pneumonia was also associated with lower self-reported adherence to antiretroviral therapy and to higher plasma HIV-1 RNA levels during follow-up.

CONCLUSIONS

Bacterial pneumonia occurs rarely in patients treated with a PI-containing regimen and may be associated with virological failure.

Docosahexaenoic acid (DHA) inhibits saquinavir metabolism in-vitro and enhances its bioavailability in rats

This study investigated the effect of docosahexaenoic acid (DHA) on the metabolism of saquinavir by cytochrome P450 3A (CYP3A) in-vitro using rat liver microsomes and in-vivo using rats. DHA showed a concentration-dependent inhibition of in-vitro saquinavir metabolism with Km, Vmax and Ki values of 2.21 microM, 0.054 micromol h(-1) (mg protein)(-1) and 149.6 microM, respectively. After oral co-administration with 250 microg kg(-1) DHA, the bioavailability of saquinavir significantly increased approximately 4 fold (P < 0.01) without affecting the elimination half-life, as compared with the control. In contrast, oral administration of DHA did not affect the kinetic parameters of saquinavir administered intravenously. These results suggest that the inhibitory effect of DHA on saquinavir metabolism predominantly takes place in the gut and imply that DHA impairs the function of enteric, but not of hepatic, CYP3A. The pharmacokinetic interaction occurred only when DHA was taken simultaneously with oral administration of saquinavir. These results considered together with the lack of time-dependent saquinavir metabolism inactivation effects in-vitro, imply that the inhibitory effect of DHA is primarily reversible. It is concluded that DHA inhibited saquinavir metabolism in-vitro and enhanced the oral bioavailability of saquinavir in rats.

Viral decay dynamics in HIV-infected patients receiving ritonavir-boosted saquinavir and efavirenz with or without enfuvirtide: a randomized, controlled trial (HIV-NAT 012)

The availability of enfuvirtide enables assessment of whether human immunodeficiency virus (HIV) decay can be enhanced by targeting reverse transcriptase, protease, and fusion. We performed a 12-week study of 22 patients randomized to receive ritonavir-boosted saquinavir and efavirenz with (the 3-target arm) or without (the 2-target arm) enfuvirtide. We observed no difference in the mean+/-SD elimination-rate constant for overall decay (0.142+/-0.040 per day and 0.128 +/- 0.033 per day in the 2- and 3-target arms, respectively; P>.1) or for modeled first-phase decay rate (-0.62+/-0.34 per day and -0.51+/-0.16 per day; P>.1). Antiretroviral therapy that inhibits HIV reverse transcriptase and protease exerts potent antiviral effects that might not be augmented by the addition of an HIV fusion inhibitor.

Gender: a possible determinant in dosing of dermatologic drugs--an overview

The role of gender in pharmacokinetics could play a significant role in tailoring HIV and other drug regimens. Here we investigate sex as a factor in saquinavir pharmacokinetics. The HIV-positive women who use saquinavir in combination with other protease inhibitors frequently demonstrate higher saquinavir concentrations than their male counterparts. The majority of the data indicates that the root of women's higher saquinavir concentrations is not inherent to their gender. Rather, extenuating factors associated with HIV play a prominent role in the observed difference between men and women's pharmacokinetic parameters. The source of observed differences in saquinavir pharmacokinetics could not be definitively traced to CYP3A, the enzyme responsible for saquinavir's metabolism or drug transporters. Hormonal changes associated with HIV infection together with concurrent use of other protease inhibitors could help explain development of sex differences. These findings can be used to further investigate when and why gender-based differences in saquinavir pharmacokinetics exist and possible future dosage and therapy considerations. Our knowledge of gender-related pharmacokinetics should be extended for other systemic drugs in dermatology.

Intracellular delivery of saquinavir in biodegradable polymeric nanoparticles for HIV/AIDS

PURPOSE

This study aims at developing poly(ethylene oxide)-modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticulate system as an intracellular delivery vehicle for saquinavir, an anti-HIV protease inhibitor.

MATERIALS AND METHODS

Saquinavir-loaded PEO-PCL nanoparticles were prepared by a solvent displacement process. The formed nanoparticles were characterized for size, surface charge, and surface presence of PEO chains. Cellular uptake and distribution of the nanoparticle was examined in THP-1 human monocyte/macrophage (Mo/Mac) cell line. Intracellular saquinavir concentrations were measured as a function of dose and duration of incubation.

RESULTS

The PEO-PCL nanoparticles had a smooth surface and spherical shape and showed a relatively uniform size distribution with a mean particle diameter of approximately 200 nm. The surface presence of PEO chains was confirmed by an increase in the -C-O-(ether) signature of the C1s spectra in electron spectroscopy for chemical analysis. Rapid cellular uptake of rhodamine-123 encapsulated PEO-PCL nanoparticles was observed in THP-1 cells. Intracellular saquinavir concentrations when administered in the nanoparticle formulation were significantly higher than from aqueous solution.

CONCLUSIONS

This study shows that PEO-PCL nanoparticles provide a versatile platform for encapsulation of saquinavir and subsequent intracellular delivery in Mo/Mac cells.

Influence of atazanavir 200 mg on the intracellular and plasma pharmacokinetics of saquinavir and ritonavir 1600/100 mg administered once daily in HIV-infected patients

OBJECTIVES

To examine cellular and plasma concentrations of atazanavir when given in combination with saquinavir/ritonavir in HIV+ patients.

METHODS

Twelve HIV+ patients were receiving saquinavir/atazanavir/ritonavir 1600/200/100 mg once daily and venous blood samples were taken to determine cellular and plasma concentrations of each protease inhibitor at 2, 6, 12 and 24 h. Peripheral blood mononuclear cells were separated by density gradient centrifugation. The ratio of the cellular AUC0-24/plasma AUC0-24 was calculated to determine cellular drug accumulation. Lymphocyte P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and multidrug resistance-associated protein (MRP1) expression was determined by flow cytometry. Nine of the patients had previously received a regimen of saquinavir/ritonavir 1600/100 mg; therefore the effect of atazanavir on the cellular and plasma pharmacokinetics of saquinavir and ritonavir was examined.

RESULTS

In vivo cellular and plasma determinations of saquinavir, atazanavir and ritonavir gave accumulation ratios of 4.9, 1.2 and 1.7, respectively. There was no relationship between saquinavir, atazanavir or ritonavir accumulation and P-gp, MRP1 or BCRP expression. When comparing pharmacokinetic values in the nine patients receiving saquinavir/ritonavir with and without atazanavir, the median cellular saquinavir AUC0-24 was significantly increased (34.9-117.2 mg.h/L) on addition of atazanavir (P=0.004). The C24 of saquinavir in plasma and cells was significantly higher with atazanavir (plasma C24 0.05 versus 0.14 mg/L with atazanavir; cellular C24 0.61 versus 2.03 mg/L with atazanavir, P=0.02).

CONCLUSIONS

The mechanism of differential intracellular protease inhibitor accumulation is unclear. Co-administration of atazanavir caused an increase in both the plasma and cellular exposure (AUC0-24) and C24 of saquinavir but not ritonavir.

The LOPSAQ study: 48 week analysis of a boosted double protease inhibitor regimen containing lopinavir/ritonavir plus saquinavir without additional antiretroviral therapy

OBJECTIVES

To evaluate the virological, immunological and clinical responses to the boosted double protease inhibitor (PI) regimen combination of lopinavir/ritonavir and saquinavir ('LOPSAQ') without reverse transcriptase inhibitors (RTI) in HIV-positive patients who have few viable RTI treatment options.

METHODS

Cohort study of 128 heavily pre-treated patients who were experiencing therapy failure on their current regimen due to RTI resistance and/or systemic toxicities. Patients with PI-resistance mutations or RTI toxicity underwent a structured treatment interruption (STI) (n=76) until virus reverted to wild-type or until resolution of toxicity symptoms. Baseline was defined as the time point when lopinavir/ritonavir plus saquinavir therapy was initiated. Virological response was defined as viral load<400 copies/mL at week 48.

RESULTS

A total of 78 (61%) patients experienced a virological response to therapy (ITT). Median viral load at baseline was 5.06 log10 copies/mL; at week 48 median was 2.16 log10 copies. Median CD4 at week 48 was 280 cells/mm3 compared with 172 cells at baseline. At week 48, 78/128 patients were still on therapy. In univariable analyses, significant predictors of virological response included higher CD4 count (P<0.001), lower viral load (P=0.002), less PI-experience (P=0.006) at baseline and fewer PI-resistance mutations (P=0.043) at end of prior failing regimen; in the multivariable analysis only higher CD4 count at baseline (P=0.009) and fewer number of drugs previously taken (P=0.003) could be specified as independent predictors for response.

CONCLUSIONS

The combination of lopinavir/ritonavir and saquinavir without RTIs is a potential option as salvage therapy for patients experiencing therapy failure due to RTI resistance or toxicity. This regimen may not be suitable for patients with very low baseline CD4 cell counts, very broad antiretroviral therapy experience or extensive PI-resistance mutations.

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.

Efficacy, safety and pharmacokinetics of once-daily saquinavir soft-gelatin capsule/ritonavir in antiretroviral-naive, HIV-infected patients

CONTEXT

Once-daily HIV treatment regimens are being used in clinical practice with the objective of improving patient acceptance and adherence.

OBJECTIVE

To evaluate the efficacy and safety of saquinavir-soft-gelatin capsule (SGC)/ritonavir combination (1600 mg/100 mg) vs efavirenz (600 mg) both once daily and combined with 2 nucleoside analogs twice daily.

SETTING

Twenty-six centers in the United States, Canada, and Puerto Rico.

PATIENTS

A total of 171 antiretroviral naive HIV-infected individuals were enrolled in a 48-week, phase 3, open-label, randomized study.

MAIN OUTCOME MEASURE

Proportion of patients with HIV-RNA levels < 50 copies/mL. The pharmacokinetic profile of saquinavir-SGC was analyzed in a subset of randomly selected patients.

RESULTS

In the primary intent-to-treat population at week 48, 51% (38/75) and 71% (55/77) of patients in the saquinavir-SGC/ritonavir and efavirenz groups, respectively, achieved HIV-RNA suppression < 50 copies/mL (P = .5392, 95% 1-sided confidence interval [CI] = -33.5%). In the on-treatment (OT) population, 73% (38/52) and 93% (54/58) of patients in the saquinavir-SGC/ritonavir and efavirenz groups, respectively, had effective viral suppression < 50 copies/mL (P = .5015, 95% 1-sided CI = -33.4%). Mean CD4+ cell counts increased by 239 and 204 cells/microliters (mcL), in the saquinavir-SGC/ritonavir and efavirenz groups, respectively, in the OT analysis (P = .058). Both regimens were reasonably well tolerated, although more gastrointestinal adverse events were reported with saquinavir-SGC/ritonavir. Pharmacokinetic profiles in 6 patients showed an observed median Cmin at 24 hours of 429 ng/mL (range, 68-1750 ng/mL).

CONCLUSIONS

Once-daily efavirenz was statistically superior to once-daily saquinavir-SGC/ritonavir. Gastrointestinal adverse effects were commonly associated with treatment failure in the saquinavir-SGC/ritonavir arm of the study.

Variation in oral clearance of saquinavir is predicted by CYP3A5*1 genotype but not by enterocyte content of cytochrome P450 3A5

OBJECTIVE

Saquinavir, a widely prescribed human immunodeficiency virus 1 protease inhibitor, has a low and variable oral bioavailability that has been attributed to extensive first-pass extraction mediated by hepatic or intestinal cytochrome P450 (CYP) 3A4 and intestinal P-glycoprotein (P-gp). The polymorphic CYP3A5 has also been shown to influence the saquinavir metabolite/parent urinary ratio, suggesting a role for CYP3A5.

METHODS

Twenty healthy subjects received a single oral dose of saquinavir (600 mg) with water (control) and, on a separate occasion, with Seville orange juice (a selective intestinal CYP3A4/5 inhibitor). Hepatic CYP3A4 activity was evaluated by use of the erythromycin breath test. Duodenal biopsy specimens were used to assess relative intestinal CYP3A4 and CYP3A5 protein contents. Relative P-gp content was also assessed in the biopsy specimens and in lymphocytes. Genetic polymorphisms in MDR1 (in exon 21 and 26), CYP3A5 (*1 and *3), and CYP3A4*1B were identified by direct sequencing. Saquinavir plasma concentrations were measured by tandem liquid chromatography-mass spectrometry. Pharmacokinetic parameter estimates (maximum concentration, time to reach maximum concentration, area under the concentration-time curve, apparent oral clearance [CL/F]) were computed by standard noncompartmental methods. Stepwise multiple regression analysis was used to identify the hepatic or intestinal variables that predicted variation in saquinavir pharmacokinetic measures.

RESULTS

Baseline saquinavir CL/F was not correlated with liver CYP3A4 activity (the erythromycin breath test result), intestinal CYP3A4 content, or intestinal P-gp content (r(2) = 0.08, 0.08, and 0.007, respectively; P > .2). MDR1 genotype and lymphocyte P-gp content were also not predictive. Among the 6 subjects expressing intestinal CYP3A5, the mean saquinavir CL/F was almost twice as high as for the 14 nonexpressors (36.7 L/h [95% confidence interval (CI), 18.7-54.6 L/h] and 19.3 L/h [95% CI, 11.2-27.4 L/h], respectively; P = .03). However, among the 6 CYP3A5 expressors, there was an unexpected negative correlation between CL/F and intestinal CYP3A5 content (r(2) = 0.58, P = .05). Seville orange juice decreased the mean CL/F in all 20 subjects from 24.5 L/h (95% CI, 16.7-32.3 L/h) to 14.7 L/h (95% CI, 8.4-20.6 L/h) (P = .05). The effect size did not appear to be influenced by CYP3A5 expression.

CONCLUSIONS

The CYP3A5*1 genotype is associated with increased saquinavir CL/F. This does not appear to reflect intestinal CYP3A5 expression and presumably reflects the contribution of hepatic CYP3A5. The interaction with Seville orange juice in subjects not expressing CYP3A5 supports a role for intestinal CYP3A4. However, the modest nature of the interaction, combined with the inability to detect a correlation between CL/F and CYP3A4 enterocyte content, supports our recent in vitro work suggesting a smaller contribution of intestinal CYP3A4 than has been assumed.

Hypertriglyceridemia and hypercholesterolemia in human immunodeficiency virus-1-infected children treated with protease inhibitors

BACKGROUND

Adverse effects associated with highly active antiretroviral therapy (HAART), particularly protease inhibitors (PIs), have been identified in adult and pediatric patients. In this study, we monitored, for cholesterol and triglyceride levels, a cohort of HIV-1-infected children receiving a HAART regimen.

METHODS

HIV-infected patients <17 years old belonging to a cohort that has been followed since 1997 were enrolled in the study. Patients were receiving either a three- or four-drug antiretroviral regimen that included two nucleoside reverse transcriptase inhibitors (lamivudine and zidovudine) combined with one or two PIs (ritonavir and/or saquinavir). Cholesterol and triglyceride levels were measured on fasting serum samples drawn at the time of enrollment and every 3 months thereafter. Clinical evaluation was performed on a monthly basis.

RESULTS

Twenty four patients were included. Median age at HIV infection diagnosis was 15 months. Twenty one patients received a four-drug antiretroviral regimen, while three patients received ritonavir plus zidovudine and lamivudine. Median follow-up was 27 months; 62.5% of patients had hypercholesterolemia and 79.2% had hypertriglyceridemia, most typically after 15 months of treatment. None of the patients had physical changes in body fat distribution suggesting lipodystrophy.

CONCLUSIONS

Hyperlipidemia is a frequent complication in HIV-1-infected children undergoing antiretroviral treatment that includes PIs. Additional studies with larger cohorts and a longer follow-up are needed to propose a rationale and alternatives for patients who develop dyslipidemia while receiving PIs.

Quadruple-2 protease inhibitors (PI)-therapy does not accelerate viral decay and suppression in PI-naive HIV-1 infected patients with severe immunosuppression and high viral load as compared with standard triple therapy

To analyse if a four-drug combination including two protease inhibitors (PIs) accelerates viral decay and suppression as compared with standard triple therapy in heavily immunosuppressed HIV-1 infected patients, an open label clinical trial was designed. PIs naive patients receiving their first highly active antiretroviral therapy were included if their CD4 cell count was lower than 200/mm3 and their HIV viral load (VL) >100,000 RNA copies/mL. Every patient received two analogues and was randomized in two groups receiving either one PI (saquinavir soft gel capsule) or two PIs (saquinavir + nelfinavir). Viral efficacy (VL <50), time to reach VL <50, viral clearance rate constant and plasmatic elimination half-life were determined. In all, 30 patients were enrolled. No viral variable was significatively improved by the four-drug combination in the short term. No clinical benefit should be expected with a four-drug (two PIs) regimen in patients with low CD4+ cell count and high VL.

Lung cancer as an immune reconstitution disease in an HIV-1 positive man receiving HAART

A case of small-cell lung cancer with prompt worsening of the clinical course was observed in a patient with significant immune restoration after receiving effective highly active antiretroviral therapy (HAART) for seven months. Rapid and enormous enlargement of metastatic liver was the main symptom. Chest x-ray showed an enlargement of the left hilus. The patient died 22 days after the onset of the fulminant disease. We suggest that the occurrence and aggressive course of the lung cancer resulted from the development of immune reconstitution syndrome.

Four measures of antiretroviral medication adherence and virologic response in AIDS clinical trials group study 359

AIDS Clinical Trials Group (ACTG) 359 was a randomized, partially double-blinded factorial study of 6 antiretroviral regimens, all including saquinavir, among HIV-infected persons in whom prior therapy had failed (n = 258). Counts of remaining saquinavir capsules were determined between weeks 0 and 4; at weeks 4, 8, and 16, self-reported adherence was estimated from 2-day report of doses skipped, therapeutic coverage, and percent of doses taken were determined by electronic monitoring devices applied to saquinavir bottles, and the saquinavir 24-hour area under the curve (AUC) was estimated. Relationships were evaluated among these 4 adherence measures and the primary endpoint of week 16 HIV RNA change. Thirty percent of 254 subjects had HIV RNA < or =500 copies/mL at week 16. Only self-reported adherence and saquinavir AUC were significantly associated with week 16 HIV RNA change (P = 0.019 and 0.023, respectively), and these measures were higher in subjects with week 16 HIV RNA < or =500 copies/mL (P = 0.03 and 0.008, respectively). The ability to detect a correlation between electronically monitored adherence and virologic response was limited by the small sample size. Self-reported adherence and saquinavir AUC were significant predictors of virologic response, in this evaluation. These findings provide insight into methods of assessing and improving adherence to antiretroviral regimens.

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.

Virologic and immunologic response to a boosted double-protease inhibitor-based therapy in highly pretreated HIV-1-infected patients

PURPOSE

To assess the virologic and immunologic response to a boosted double-protease inhibitor (PI) regimen of highly pretreated patients infected with HIV-1 and to examine the role of PI resistance and concentration of serum saquinavir.

METHOD

In an open-label prospective study, lopinavir/ritonavir, saquinavir-sgc, lamivudine, and other nucleoside analogues were offered to highly pretreated patients who had advanced HIV-1 infection and who had failed at least 2 previous highly active antiretroviral therapy regimens including at least 1 nonnucleoside reverse transcriptase inhibitor. The relationship between baseline drug resistance and steady-state saquinavir serum levels and early (week 4) and sustained (week 48) virologic response was documented.

RESULTS

35 advanced HIV-1 patients were enrolled. The boosted double-PI regimen was well tolerated. Twenty-two (63%) of the 35 patients had a > 0.8 log(10) decrease in HIV viral load at week 4. After 48 weeks of follow-up, the 22 patients who remained on the study therapy had an average decrease in viral load of 1 log(10) and had a median increase in CD4 cells of 60 cell/microL. Multiple logistic regression analysis indicated that genotypic resistance to both PIs and the week-3 trough concentrations of saquinavir were associated with virologic outcome at week 4. The presence of > or = 6 lopinavir mutations [odds ratio (OR) 0.03; 95% CI 0.01 to 0.79] and the 48V mutation (OR 0.01; 95%CI <0.01 to 0.88) was independently associated with lower odds of achieving an early response, whereas a higher saquinavir concentration at week 3 (OR 8.36; 95% CI 1.28 to 54.70) was associated with greater odds of an early response.

CONCLUSION

These findings suggest that baseline PI resistance and saquinavir concentration were associated with virologic response and should be considered when planning salvage therapy.