A semi-mechanistic pharmacokinetic model of saquinavir combined with itraconazole in HIV-1-positive patients

The mechanism of drug-drug interaction between saquinavir, a protease inhibitor used effectively for HIV/AIDS treatment, and itraconazole, an azole antifungal agent, is hypothesized to involve competitive inhibition at CYP3A4 enzyme, an important drug metabolizing enzyme in humans. The resulting interaction between these CYP3A4 substrates can be utilized clinically as a pharmacokinetic booster for prolonging saquinavir dosing regimen and/or decreasing saquinavir dose requirement in HIV/AIDS patients. To quantitatively describe this specific drug-drug interaction, based on the existing data, we aimed to develop a mathematical model incorporated with the competitive inhibition phenomena. PlotDigitizer was used to extract data from literature. Advance Continuous Simulating Language Extreme (ACSLX), a FORTRAN-based computer program, was employed as our developing tool. Our computer model simulations could successfully describe concentration-time course of saquinavir from selected pharmacokinetic studies in HIV-1-positive patients. To extend the model's utility as an aid in saquinavir dosage regimens, the developed model may be applied to other HIV/AIDS patients in genuine clinical settings.

Dose reduction effective in alleviating symptoms of saquinavir toxicity

Gastrointestinal intolerance is a limitation of boosted saquinavir antiretroviral treatment. We present three HIV-infected individuals whose severe toxicity symptoms started directly after initiation of a standard dose saquinavir hard-gel capsule-containing regimen (saquinavir/ritonavir 1000/100 mg). All patients underwent immediate 12 h pharmacokinetic (PK) assessment and showed extraordinarily high saquinavir plasma exposure. All three patients did not recover until the saquinavir exposure was decreased. This pilot case study anticipates a new concept of 'direct PK'-guided individual dose interventions under close viral load monitoring. Two major reasons for symptomatic saquinavir overexposure were defined: impaired liver function in a chronic hepatitis C virus co-infected individual at normal liver performance parameters and a delayed cytochrome p450 enzyme autoinduction. Overexposure seems to be an independent intolerance factor. Although delayed autoinduction is not well established as a reason for adverse events in saquinavir therapy, this observation may be confirmed in the near future by increased use.

Relation of cerebrospinal fluid/plasma HIV-RNA discordance with neurocognitive impairment

Neurological involvement is common in patients infected with HIV. The effectiveness of antiretroviral drugs in lowering the levels of HIV-RNA in cerebrospinal fluid (CSF) is limited by their inability to cross the blood-brain barrier. Discordance in CSF/plasma HIV-RNA levels may have a bearing on the progression of neurological disease in these patients. We report a woman with subacute neurocognitive impairment and abnormal findings on brain MRI, in whom there was a discordance between CSF/plasma HIV-RNA levels. The patient improved after a change in her highly active antiretroviral therapy (HAART) regimen. We also reviewed the available literature on the subject and found seven articles describing 27 patients.

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.

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.

Impact of pharmaceutical excipients on in vitro association of saquinavir to chylomicrons

This study was performed to investigate the impact of pharmaceutical excipients commonly used for lymphatic transport on in vitro drug association with chylomicrons (CM). A CM association study was conducted using saquinavir solubilized in four different pharmaceutical excipients. We observed a linear relationship between saquinavir solubility and drug association, suggesting that the solubility of saquinavir in excipients is a key determinant for successful lymphatic delivery. Broadly, these results suggest that excipients with good solubilization properties may be advantageous for enhancing lymphatic drug delivery.

Pharmacokinetics of a multipurpose pod-intravaginal ring simultaneously delivering five drugs in an ovine model

Multipurpose technologies that simultaneously protect from sexually transmitted infections and unintended pregnancy are urgently needed. Pod-intravaginal rings (IVRs) formulated with the antiretroviral agents (ARVs) tenofovir, nevirapine, and saquinavir and the contraceptives etonogestrel and estradiol were evaluated in sheep. Steady-state concentrations were maintained for 28 days with controlled, sustained delivery. This proof-of-principle study demonstrates that pod IVRs can deliver three ARVs from different mechanistic classes and a progestin-estrogen combination over the wide range needed for putative preventative efficacy.

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.

A comparison of intestinal lymphatic transport and systemic bioavailability of saquinavir from three lipid-based formulations in the anaesthetised rat model

Saquinavir is a lipophilic, poorly water-soluble HIV protease inhibitor that undergoes extensive first-pass metabolism and exhibits poor oral bioavailability. Redirection of the absorption pathway of anti-HIV compounds from the portal blood to the HIV-rich intestinal lymphatics may enhance therapeutic efficacy and reduce the extent of the first-pass effect. This study investigates the potential of targeted intestinal lymphatic transport of saquinavir via a lipid formulation approach. Three formulations containing oleic acid were examined: cremophor-oleic acid mixed micelles, d-alpha tocopheryl polyethylene glycol 1000 succinate (TPGS)-oleic acid mixed micelles and an oleic acid microemulsion. The mesenteric lymph duct cannulated anaesthetised rat model was employed. Plasma and lymph samples were analysed by HPLC. Lymph triglyceride was measured using an enzymatic colorimetric technique. The extent of lymphatic transport from the lipid vehicles was 0.025-0.05% of the dose administered. The microemulsion produced higher and more prolonged mesenteric lymph concentrations than the micellar formulations. A strong correlation existed between the concentration of saquinavir in intestinal lymph and lymph triglyceride levels. The systemic bioavailability was estimated to be 8.5% and 4.8% for the cremophor mixed micelle and the microemulsion, respectively. The cremophor mixed micelles produced higher bioavailability than TPGS mixed micelles, implying that the nature of the surfactant can influence the distribution of drug between lymph and plasma.

Effect of saquinavir/ritonavir (1000/100 mg bid) on the pharmacokinetics of methadone in opiate-dependent HIV-negative patients on stable methadone maintenance therapy

This study was performed to determine the effect of two protease inhibitors, saquinavir (SQV, oral 1000 mg bid) boosted by ritonavir (RTV, oral 100 mg bid), on pharmacokinetics (PK) of methadone in opiate-dependent HIV-negative patients on stable methadone maintenance therapy. This was a two-center, open-label, one-sequence cross-over, multiple-dose study in 13 HIV-negative patients who were on stable methadone therapy (oral, 60-120 mg qd). All patients continued methadone treatment on days 2-15. All patients received SQV/RTV in combination with methadone from days 2-15. PK of methadone was assessed on day 1 (alone) and on day 15 when methadone treatment was combined with SQV/RTV at steady state. Twelve patients completed the study. Median age, body weight and height were 50 years (range: 24-54 years), 80 kg (range: 57-97 kg) and 174 cm (range: 163-189 cm), respectively. All patients were Caucasian, and 11 were smokers. Median methadone dose was 85 mg qd. Geometric mean area under curve of the plasma concentration-time curve over 24 hour dosing interval (AUC(0-24 hour)) ratio of methadone with and without SQV/RTV was 0.81% (90% confidence interval: 71-91%). There was no significant plasma protein-binding displacement of methadone by SQV/RTV. The combination of SQV/RTV and methadone was well tolerated. There were no clinically significant adverse events or significant changes in laboratory parameters, electrocardiograms or vital signs. The 19% decrease in R-methadone AUC(0-24 hour) in the presence of SQV/RTV was not clinically relevant. There appears to be no need for methadone dose adjustment when methadone (60-120 mg qd) and SQV/RTV (1000/100 mg bid) are coadministered.

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 (C(min)) 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 log(10) 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/mm(3) (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 C(min) 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.

The pharmacokinetics, safety and efficacy of boosted saquinavir tablets in HIV type-1-infected pregnant women

BACKGROUND

Pregnancy affects the pharmacokinetics of most protease inhibitors. Saquinavir, when administered in a tablet formulation, has not been studied extensively in this setting.

METHODS

A pharmacokinetic, prospective, multicentre trial of HIV type-1-infected pregnant women treated with saquinavir (500 mg tablets) boosted with ritonavir at a dose of 1,000/100 mg twice daily plus a nucleoside backbone was conducted. Pharmacokinetic curves were recorded for 12 h in the second trimester (week 20 +/-2), the third trimester (week 33 +/-2) and post-partum (weeks 4-6). Blood was sampled pre-dosing and at 1, 2, 3, 4, 6, 8, 10 and 12 h post-dosing. Pharmacokinetic parameters were calculated using WinNonlin software version 4.1.

RESULTS

A total of 37 women were included in the analysis. Mean (+/-sd) values for saquinavir area under the curve (AUC(0-12h)) were 23.47 h*mg/l (11.92) at week 20 (n=16), 23.65 h*mg/l (9.07) at week 33 (n=31) and 25.00 h*mg/l (11.81) post-partum (n=9). There was no significant difference in the saquinavir AUC(0-12h) when comparing the data during pregnancy and post-partum. Subtherapeutic plasma concentrations of saquinavir (defined as <0.10 mg/l) were not observed throughout the study. No major safety concerns were noted.

CONCLUSIONS

Saquinavir exposure in the new tablet formulation generates adequate saquinavir concentrations throughout the course of pregnancy and is safe to use; therefore, no dose adjustment during pregnancy is needed.

Pharmacokinetics, safety and efficacy of saquinavir/ ritonavir 1,000/100 mg twice daily as HIV type-1 therapy and transmission prophylaxis in pregnancy

BACKGROUND

A saquinavir/ritonavir-containing regimen is one option for the prevention of mother-to-child transmission of HIV during pregnancy. We evaluated the pharmacokinetics, efficacy and safety of saquinavir/ritonavir 1,000/100 mg twice daily plus nucleos(t)ide reverse transcriptase inhibitors in 13 women during late pregnancy and compared the results to those of 15 non-pregnant women.

METHODS

Protease inhibitor plasma concentration profiles were assessed at 12 h using a standardized therapeutic drug monitoring procedure and measured by LC-MS/MS. Minimum and maximum concentrations (C(min) and C(max)), area under the plasma concentration-time curve (AUC(0-12 h)), and total clearance (CL(total)) were compared between the groups and correlated to demographic, physiological and clinical cofactors. Antiviral and immunological efficacy and safety were investigated.

RESULTS

The geometric means (90% confidence interval [CI]) for saquinavir C(min), C(max) and AUC(0-2 h) of pregnant versus non-pregnant women were 572 (437-717) versus 765 (485-1,052, P = 0.064) ng/ml, 2,168 (1,594-2,807) versus 3,344 (2,429-4,350; P = 0.045) ng/ml and 15,512 (11,657-19,943) versus 24,027 (17,454-31,548, P = 0.029) ng x h/ml. The geometric means (90% CI) for ritonavir C(min), C(max) and AUC(0+12 h) were 190 (148-234) versus 310 (240-381, P = 0.011) ng/ml, 781 (580-999) versus 1,552 (1,127-2,007, P = 0.004) ng/ml and 5,576 (4,303-7,006) versus 10,528 (8,131-13,177, P = 0.003) ng x h/ml. Age, weight, saquinavir dose per weight and body mass index differed significantly; saquinavir C(min) and AUC(0-12 h) were correlated with ritonavir C(min) and saquinavir dose per weight. After a mean of 11 weeks treatment, 12 of 13 pregnant women had a viral load < 400 copies/ml, which was similar to the results of non-pregnant women.

CONCLUSIONS

Although saquinavir plasma concentrations were significantly lower in pregnant women compared with non-pregnant women, all pregnant women displayed a saquinavir AUC(0-12 h) > 10,000 ng x h/ml, 92.3% had a viral load < 400 copies/ml at birth. Saquinavir was well tolerated by the mothers and all newborn children were HIV type-1 negative at 18 months of age.

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 6.30%. 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.

Limited-sampling strategy for the prediction of boosted hard-gel saquinavir exposure at a dosage of 1000/100 mg twice daily in human immunodeficiency virus-infected individuals

Area under the concentration time curve (AUC) over a dosing interval is considered to be the best estimate of drug exposure in a patient. However, determination of this parameter is costly and often impractical, requiring multiple samples and a great deal of time and resources. A limited-sampling strategy (LSS) may overcome some of these issues, making pharmacokinetic studies easier to perform, particularly in a limited-resource setting. The aim of this work was to develop and validate a pragmatic LSS for the accurate and precise prediction of boosted saquinavir AUC0-12 (AUC over the 12-hour dosing interval) at a dosage of 1000/100 mg twice daily. Pharmacokinetic data were obtained from 34 human immunodeficiency virus (HIV)-infected individuals stable on saquinavir/ritonavir-containing therapy, randomly split into two sets (n = 17 per set). One set was used to construct prediction models using univariate and multivariate analysis (development set), and the second was used to determine the predictive performance of the models (validation set). For single samples, 6- and 10-hour concentrations correlated best with saquinavir AUC0-12 (r2: 0.913 and 0.911, respectively), yet all single samples failed to produce precise and unbiased predictions. However, combinations at 2, 6; 0, 2, 6; 0, 4, 10; 0, 4, 12; and 2, 4, 6 hours achieved good predictive performances, and both precise [root mean squared relative prediction error (%RMSE): 6.4% to 11.9%] and unbiased [mean relative prediction error (%MPE), 95% CI: -2.7%, (-0.8)-2.7 to 1.6%, (-1.8)-4.7] estimations of saquinavir AUC0-12. Of these models, concentrations obtained at 0, 2, 6 and 2, 4, 6 hours are more practical in a clinical setting and are therefore the LSS with most potential. Provided that the technique is validated in specific patient populations, an LSS approach is a potentially useful tool to evaluate the AUC0-12 of saquinavir in resource-limited settings, reducing both costs and volumes of blood taken. It may also aid the choice of sampling times for population analysis.

Improved oral bioavailability and brain transport of Saquinavir upon administration in novel nanoemulsion formulations

The aim of this investigation was to develop novel oil-in-water (o/w) nanoemulsions containing Saquinavir (SQV), an anti-HIV protease inhibitor, for enhanced oral bioavailability and brain disposition. SQV was dissolved in different types of edible oils rich in essential polyunsaturated fatty acids (PUFA) to constitute the internal oil phase of the nanoemulsions. The external phase consisted of surfactants Lipoid-80 and deoxycholic acid dissolved in water. The nanoemulsions with an average oil droplet size of 100-200 nm, containing tritiated [(3)H]-SQV, were administered orally and intravenously to male Balb/c mice. The SQV bioavailability as well as distribution in different organ systems was examined. SQV concentrations in the systemic circulation administered in flax-seed oil nanoemulsions were threefold higher as compared to the control aqueous suspension. The oral bioavailability and distribution to the brain, a potential sanctuary site for HIV, were significantly enhanced with SQV delivered in nanoemulsion formulations. In comparing SQV in flax-seed oil nanoemulsion with aqueous suspension, the maximum concentration (C(max)) and the area-under-the-curve (AUC) values were found to be five- and threefold higher in the brain, respectively, suggesting enhanced rate and extent of SQV absorption following oral administration of nanoemulsions. The results of this study show that oil-in-water nanoemulsions made with PUFA-rich oils may be very promising for HIV/AIDS therapy, in particular, for reducing the viral load in important anatomical reservoir sites.

Clinical response and tolerability to and safety of saquinavir with low-dose ritonavir in human immunodeficiency virus type 1-infected mothers and their infants

Saquinavir boosted with low-dose ritonavir given with zidovudine and lamivudine was well tolerated by pregnant women and their infants. All mothers had <400 human immunodeficiency virus type 1 RNA copies/ml at delivery. Two had elevated liver transaminases and amylase. Seven infant adverse events were possibly treatment related (anemia, neutropenia, and hyperbilirubinemia).

Regimen-dependent variations in adherence to therapy and virological suppression in patients initiating protease inhibitor-based highly active antiretroviral therapy

OBJECTIVE

To examine differences among four protease inhibitor (PI)-based drug regimens in adherence to therapy and rate of achievement of virological suppression in a cohort of antiretroviral-naive patients initiating highly active antiretroviral therapy (HAART).

METHODS

Participants were antiretroviral-naive and were first dispensed combination therapy containing two nucleosides and a ritonavir (RTV)-boosted PI, or unboosted nelfinavir, between 1 January 2000 and 30 September 2003. Logistic regression analysis was used to examine associations between the prescribed PI and other baseline factors associated with being >90% adherent to therapy and then to determine the associations of prescribed drug regimen, adherence to therapy and baseline variables with the odds of achieving two consecutive viral loads of <500 HIV-1 RNA copies/mL. RESULTS A total of 385 subjects were available for analysis. Lopinavir (LPV)/RTV was prescribed for 168 patients (42% of total); 86 (22%) received indinavir (IDV)/RTV; 91 (24%) received nelfinavir (NFV) and 40 (10%) received saquinavir (SQV)/RTV. SQV/RTV-based HAART was associated with reduced adherence to therapy [odds ratio (OR)=0.40; 95% confidence interval (CI) 0.19-0.83]. In multivariate models, IDV/RTV (OR=0.45; 95% CI 0.22-0.92), SQV/RTV (OR=0.18; 95% CI 0.07-0.43) and NFV were associated with reduced odds of achieving virological suppression within 1 year in comparison to LPV/RTV-based therapy. For patients receiving NFV, adjusting for adherence (OR=0.73; 95% CI 0.36-1.47) rendered this association nonsignificant.

CONCLUSION

Patients prescribed IDV/RTV, NFV or SQV/RTV were less likely to achieve virological suppression on their first regimen compared with patients prescribed LPV/RTV. Reduced adherence to these therapies only partly explained these observed differences.

Inhibitory quotient as a prognostic factor of response to a salvage antiretroviral therapy containing ritonavir-boosted saquinavir. The CIVSA Study

BACKGROUND

The addition of a low dose of ritonavir to protease inhibitors (PIs) has become a widespread strategy to improve PI pharmacokinetics. As resistance is a major barrier to long-term suppression, in salvage therapy genotype and/or phenotype scoring is currently used to predict the response. We evaluated the relationship between the saquinavir (SQV) inhibitory quotient (IQ) (virtual and genotypic) and virological response.

METHODS

Eligible patients were on a PI-containing highly active antiretroviral therapy (HAART) regimen excluding SQV and had a viral load >5000 HIV-1 RNA copies/mL. The PI was switched to SQV/ritonavir (RTV) 1000/100 mg twice a day (bid) and the same two backbone nucleoside reverse transcriptase inhibitors (NRTIs) were maintained at least until week 4, when the resistance test results became available. Genotype and virtual phenotype were determined at baseline, while the SQV trough plasma concentration was determined at week 4.

RESULTS

Fifty-three patients were included in the study. Mean baseline viral load and CD4 count were 137,693 copies/mL and 263 cells/microL, respectively, the mean number of previous PIs was 2.3 and the mean number of protease gene mutations (PGMs) was 4.1. Using an on-treatment analysis, at week 16 the mean increase in CD4 count was 70.9 cells/microL, viral load was <200 copies/mL in 17 out of 37 patients (45.9%), and 30 out of 45 patients (66.7%) were considered virological responders (VRs) (viral load <200 copies/mL or viral load declined > or =1 log(10) at week 16). Median virtual phenotype was 1.3 (0.6-6.9). Baseline differences were detected between VR and non-VR populations: the mean numbers of PGMs were 3.2 and 5.8 (P<0.05), the mean numbers of SQV-associated mutations were 2 and 3.8 (P<0.05), and the mean CD4 counts were 365.9 and 184.3 cells/microL (P<0.05), respectively. Mean SQV trough concentrations at week 4 were 1.1 and 1.0 microg/mL (not significant), and mean virtual IQs were 0.7 and 0.1 (P<0.01), respectively. Multivariate analysis showed that baseline PGMs >5 or SQV-associated mutations>5, virtual phenotype, baseline viral load >50,000 copies/mL, and virtual IQ <0.5, but not genotypic IQ, were the variables independently associated with non-VR.

CONCLUSION

In heavily pretreated patients, the use of SQV virtual IQ or alternatively virtual phenotype, as well as PGMs, is a useful tool for the prediction of virological response.

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.

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.

Steady-state pharmacokinetics of atazanavir given alone or in combination with saquinavir hard-gel capsules or amprenavir in HIV-1-infected patients

OBJECTIVE

The aim of this pilot study was to examine the pharmacokinetics of atazanavir (ATV) when given in combination with amprenavir (APV) or saquinavir hard-gel capsules (SQV) to human immunodeficiency virus (HIV)-positive patients.

METHODS

Included in the study were 34 HIV-infected patients enrolled in the ATV Early Access Program, who were treated with unboosted ATV alone (group 1) or with the double protease inhibitor combinations, ATV plus APV (group 2) or ATV plus SQV (group 3). ATV was given at a daily dose of 400 mg q.d. with the morning meal with SQV 1200 mg per day or APV 1200 mg per day. Serial blood samples for steady-state ATV pharmacokinetics were collected before the morning dose and at 1, 2, 3, 6, 8 and 24 h post-dosing. ATV plasma concentrations were measured using a high-performance liquid chromatography method with ultraviolet detection.

RESULTS

Of the patients, 12 received ATV as a single protease inhibitor; 12 received ATV in combination with APV; and 10 in combination with SQV. Geometric mean (coefficient of variation) ATV C(trough) was 110 ng/ml (2.38), 86 ng/ml (0.84) and 149 ng/ml (2.01) in groups 1, 2 and 3, respectively. ATV C(trough) in both double protease inhibitor combination regimens was not significantly different from that as a single protease inhibitor [geometric mean ratio (GMR): 0.77; 95% confidence interval (CI): 0.38-1.58, P=not significant for group 2 versus group 1 and 1.34, 0.40-4.49, P=not significant, for group 3 versus group 1). Patients treated with ATV plus APV had a 40.2% lower ATV C(max) and a 30.8% smaller ATV AUC than the reference group treated with unboosted ATV alone: both these differences were statistically significant (GMR, 95% CI: 0.59, 0.41-0.85, P=0.005 and 0.69, 0.48-0.99, P=0.056, respectively). No difference was observed for either C(max) or AUC between the group treated with ATV plus SQV and the reference group (GMR, 95% CI: 0.78, 0.47-1.30, P=not significant and 1.24, 0.73-2.10, P=not significant, respectively).

CONCLUSION

ATV pharmacokinetics does not seem to be influenced by the concomitant administration of SQV, whereas APV significantly lowers plasma ATV levels.