Comparison of pharmacokinetics of saquinavir soft-gel capsule (SQV-SGC) combined with ritonavir (RTV), SQV hard-gel capsule with RTV,and SQV-SGC alone

Saquinavir (SQV) is a human immunodeficiency virus (HIV) specific protease inhibitor. When combined with ritonavir (RTV), plasma concentration of SQV is increased. In this study, we examined pharmacokinetics of SQV soft-gel capsule (SQV-SGC) 400 mg twice daily (BID) combined with RTV in HIV-1-infected patients (n = 4) and compared with those of SQV hard-gel capsule (SQV-HGC) 400 mg BID combined with RTV (n = 12). Pharmacokinetics of SQV-SGC 1,200 mg single dose in healthy subjects (n = 10) were also studied. Peak SQV concentration in plasma (Cmax) and area under the plasma concentration-time curve from 0 to 8 hour (AUC0-8 h) of SQV-SGC 400 mg BID combined with RTV group were higher than those of SQV-HGC 400 mg BID combined with RTV group; increase of 14.7% and 25.5%, respectively. Cmax and AUC0-8 h of SQV-SGC were higher than SQV-SGC 1,200 mg single dose group; increase of 3.9 fold and 8.5 fold, respectively. These results indicated that SQV-SGC combined with RTV therapy is the most potent antiviral effect among SQV-SGC with RTV, SQV-HGC with RTV, and SQV-SGC alone.     

The effect of ritonavir on saquinavir plasma concentration is independent of ritonavir dosage: combined analysis of pharmacokinetic data from 97 subjects

Objective

To determine the correlation between ritonavir (RTV) dose and the degree of enhancement of saquinavir (SQV) exposure.

Methods

Combined analysis of pharmacokinetic data at steady state obtained from two open‐label, randomized, parallel‐group, multiple‐dose, single‐centre studies involving healthy volunteers. Plasma samples for SQV assay were obtained from 97 healthy subjects following multiple dosing of a range of SQV (400–1800 mg) plus RTV (100–400 mg) dosages for 13–14 days. The pharmacokinetics of SQV were derived by model‐independent, noncompartmental methods. Data were analysed by multivariate regression of log transformed C_min and C_max (geometric means) of SQV dosage as the dependent variable and independent variables of SQV and RTV dosage. Ritonavir was fitted as both a continuous and a categorical variable.

Results

There is a strong effect of any dose of RTV on C_max and C_min of SQV (P < 0.0001 for both parameters), but no greater effect of higher vs. lower RTV dosages on either parameter (C_max: P=0.4373; C_min: P=0.3393). Higher SQV dosage correlates linearly with higher C_max (P=0.0093) and C_min (P=0.0010), but the effects of increasing SQV dosages are less than with the addition of any RTV dose.

Conclusions

RTV enhances SQV concentrations to increase C_max and C_min. This effect is similar for RTV dosages of 100–400 mg twice daily. Based on this concept of ‘mini‐dose’ RTV, once‐daily dosing of 1600 mg SQV/100 mg RTV and twice‐daily 1000 mg SQV/100 mg RTV are currently being evaluated in clinical trials.

     

Quality of life in asymptomatic- and symptomatic HIV infected patients in a trial of ritonavir/saquinavir therapy. The Prometheus Study Group

OBJECTIVE: To compare the impact on quality of life (QoL) of treatment with ritonavir (RTV)/saquinavir (SQV) versus RTV/SQV/stavudine (d4T) in asymptomatic [Centers for Disease Control (CDC) class A] and symptomatic HIV-infected patients (CDC B and C) who did or did not receive antiretroviral therapy (ARVT) before entry into the study. DESIGN: A multicenter randomized clinical trial. PATIENTS: Protease inhibitor- and d4T-naive patients were allocated to RTV/SQV (n = 84) versus RTV/SQV/d4T (n = 83). MAIN OUTCOME MEASURE: Changes from baseline in QoL assessed by the Medical Outcomes Study Health Survey for HIV (MOS-HIV) and a symptom checklist administered at baseline and after 12, 24, 36 and 48 weeks. RESULTS: Changes in QoL were comparable in both treatments, although more neuropathy was reported in the RTV/SQV/d4T group. QoL improved significantly in both groups regarding health distress, energy/fatigue, mental health, health perceptions, physical function and overall QoL, despite an increase in reported symptoms. More favourable changes in cognitive and social function were observed in symptomatic compared with asymptomatic patients, with symptomatic patients showing an improvement and asymptomatic patients showing a decline in function after baseline. ARVT-naive patients showed more favourable changes in mental health, health distress and social function compared with patients with previous ARVT. CONCLUSION: RTV/SQV and RTV/SQV/d4T were equally effective in improving the QoL of patients over 48 weeks, despite an increase in reported symptoms. Symptomatic patients reported more QoL benefit than asymptomatic patients, and ARVT-naive patients benefitted more than those with previous ARVT. The impact on patients' QoL should be considered in the search for the optimal management of HIV infection.     

Pharmacokinetic and tolerability profile of twice-daily saquinavir hard gelatin capsules and saquinavir soft gelatin capsules boosted with ritonavir in healthy volunteers

Objective

To evaluate the pharmacokinetics and safety of a boosted saquinavir (SQV)/ritonavir (RTV) combination, administered as either the hard gelatin capsule (HGC) or soft gelatin capsule (SGC) formulation of SQV, in 24 healthy volunteers.

Methods

This was a single‐centre, open‐label, randomized, 2 × 2 crossover study. Twelve subjects were randomized to receive SQV/RTV 1000 mg/100 mg twice daily (BID) orally for 10 days, as either the HGC or SGC formulation. The pharmacokinetic profile of SQV was determined on day 10. Subjects then crossed over to the opposite SQV formulation, and the pharmacokinetic profile was determined again on day 20. The primary analysis was the assessment of bioequivalence based on logarithmically transformed values for AUC_{(0?24 h)} and C_max for the two formulations.

Results

There was a statistically significant increase in the geometric means of all the pharmacokinetic variables evaluated for SQV‐HGC/RTV compared with SQV‐SGC/RTV. A mean AUC_{0?24 h}‐value of 15.798 µg/mL/h was reported for the HGC formulation compared with 11.655 µg/mL/h for the SGC formulation (P = 0.0043). The SQV‐HGC/RTV combination was better tolerated in terms of gastrointestinal system disorders. Furthermore, no elevations in triglycerides or total cholesterol were reported with SQV/RTV during the entire study period.

Conclusion

In healthy volunteers, RTV boosting of SQV‐HGC produces plasma exposures at least comparable to SQV‐SGC, which is accompanied by an improvement in gastrointestinal system disorders.

     

The rabbit study: ritonavir and saquinavir in combination in saquinavir-experienced and previously untreated patients.

Thirteen protease inhibitor-naive patients with HIV-1 infection, and 12 patients with a median of 58 months prior treatment with saquinavir (SQV) monotherapy, were treated with SQV (400 mg twice daily) and ritonavir (RIT, 500 mg twice daily) in a study designed to assess the effect of prior treatment with SQV monotherapy on the antiretroviral activity of RIT-SQV combination therapy. Median baseline viral load and CD4+ cell counts were 155,000 and 262,000 copies/ml and 333 and 225 cells/mm3 in the naive and experienced groups, respectively. Mean viral load changes at 24 weeks were -1.63 and -0.27 log copies/ml in the naive and SQV-experienced groups, respectively (intent-to-treat analysis). Baseline genotype by point mutation assay and sequencing in the SQV-experienced group was highly predictive of virological response. Eight of 11 SQV-experienced patients had evidence of phenotypic resistance to RIT at baseline, despite previous treatment with SQV only. There was strong correlation between phenotypic resistance to RIT and the presence of the L90M mutation. We conclude that prolonged prior treatment with saquinavir monotherapy may produce cross-resistance to ritonavir and reduce the subsequent response to ritonavir-saquinavir in combination. In this study, both phenotypic resistance to ritonavir and presence of the L90M mutation predicted the viral load response to ritonavir-saquinavir.     

Atazanavir and lopinavir/ritonavir: pharmacokinetics, safety and efficacy of a promising double-boosted protease inhibitor regimen

OBJECTIVE: To assess the pharmacokinetics and tolerability of lopinavir (LPV), ritonavir (RTV) and atazanavir (ATV) as a double-boosted protease inhibitor regimen in HIV-infected adults. METHODS: Sixteen patients who started LPV/RTV (400/100 mg b.i.d.) and ATV (300 mg q.d.) were enrolled in the study group (arm A). LPV pharmacokinetics were compared to those of two historical groups: arm B, 15 patients who received LPV/RTV (400/100 mg b.i.d.); and arm C, 25 patients who received LPV/RTV/saquinavir (SQV) (400/100/1000 mg b.i.d.). ATV pharmacokinetics were compared to those of 15 consecutive patients who received ATV and RTV (300/100 mg q.d.) (arm D). Drug concentrations were measured by HPLC. RESULTS: LPV concentrations were significantly higher in arm A than in arms B and C. Median (interquartile range) LPV area under the curve (AUC)0-12 values were 115.7 (99.8-136.5), 85.2 (68.3-109.2) and 85.1 (60.6-110.1) microg/h/ml, respectively. C(max) values were 12.2 (10.7-14.5), 9.5 (6.8-13.9) and 10.0 (6.9-13.6) microg/ml, respectively. C(min) values were 9.1 (7.1-10.4), 5.6 (4.7-8.2) and 5.5 (4.2-7.5) microg/ml, respectively. No difference was observed for ATV AUC0-24 or C(max) between arms A and D. ATV C(min) values were 1.07 (0.61-1.79) in arm A and 0.58 (0.32-0.83) in arm D (P = 0.001). Treatment was not discontinued in any patient because of adverse effects. At 24 weeks, viral load was < 50 copies/ml in 13 of 16 patients. CONCLUSIONS: The combination of ATV and LPV/RTV provided high plasma concentrations of both PI, which seemed to be appropriate for patients with multiple prior therapeutic failures, yielding good tolerability and substantial antiviral efficacy.     

Indinavir protein-free concentrations when used in indinavir/ritonavir combination therapy

OBJECTIVE: To describe the in vivo protein-binding characteristics of indinavir (IDV) in the presence of ritonavir (RTV) relative to total IDV plasma concentrations. DESIGN: The ACTG protocol 5055 was a multicenter study comparing the safety and pharmacokinetics of IDV/RTV at doses of 800/200 and 400/400 mg twice daily in HIV-infected adults. METHODS: Forty-four patients underwent a 12-h intensive pharmacokinetic assessment after 2 weeks of therapy. Three plasma samples from 35 patients at Cmax, 6 and 12 h post dose were used to determine the unbound IDV concentrations. Unbound IDV was separated in plasma samples using ultra-filtration and measured using high-performance liquid chromatography with UV detection. RESULTS: Mean IDV protein-bound fraction across all time points in the 800/200 and 400/400 arm were 53.4 and 51.8%, respectively. In the 800/200 arm, percentage binding at Cmax was 50% compared with 56% at 12 h (P = 0.008). In the 400/400 arm, percentage binding at Cmax was 49% compared with 54% at 12 h (P = 0.008). CONCLUSIONS: The extent of plasma protein binding of IDV in this study was less than in previously published data with IDV alone. Although IDV concentrations differed across the arms, the percentage of IDV protein binding at all time points was not different between the 800/200 and 400/400 arms. However, the percentage of IDV protein binding at Cmax was significantly lower compared with 12 h in each arm, possibly suggesting that IDV protein binding is concentration-dependent. These data suggest that RTV affects IDV protein-binding characteristics and IDV also exhibits concentration dependent binding when administered with RTV.     

Enhanced penetration of indinavir in cerebrospinal fluid and semen after the addition of low-dose ritonavir

OBJECTIVE: Penetration of antiretroviral drugs into anatomical HIV-1 reservoirs such as the male genital tract and the central nervous system is important. Data on indinavir (IDV) concentrations in seminal plasma are lacking and IDV concentrations in cerebrospinal fluid are at best borderline. DESIGN: Thirteen patients were treated with zidovudine (or stavudine), lamivudine, abacavir, nevirapine and IDV (1000 mg three times daily). When nevirapine led to low IDV concentrations, IDV was changed into the combination IDV/ritonavir (RTV) 800/100 mg twice daily to improve the pharmacokinetic profile of IDV. METHODS: A serum pharmacokinetic profile, a semen sample and a cerebrospinal fluid sample were collected at weeks 8, 24, 48 and 72. RESULTS: Addition of RTV increased the median IDV trough concentration in serum from 65 to 336 ng/ml (P = 0.005). Median IDV concentration in seminal plasma increased from 141 to 1634 ng/ml (P = 0.002) (n = 9) and in cerebrospinal fluid from 39 (n = 12) to 104 (n = 7) ng/ml (P < 0.001). In six patients with samples collected both before and after the addition of RTV, the IDV concentration in seminal plasma increased 8.2 times [95% confidence interval (CI) 5.2-11.6], and in cerebrospinal fluid 2.4 times (95% CI 1.8-3.9). CONCLUSIONS: IDV penetrates well into the male genital tract. The addition of low-dose RTV not only increases IDV concentrations in serum but also in seminal plasma and cerebrospinal fluid, thereby probably improving the potency of the regimen in these anatomical HIV reservoirs. Higher serum trough levels alone can not sufficiently explain the observed increases in seminal plasma and cerebrospinal fluid concentrations. Inhibition of P-glycoprotein-mediated transport by RTV might be an additional mechanism.     

Efficacy of nelfinavir-based treatment in the central nervous system of HIV-1 infected patients

We studied the HIV-1 load and nelfinavir (NFV) concentrations in cerebrospinal fluid (CSF) after long-term successful NFV-based therapy, using ultrasensitive methods of detection. 19 patients without virological failure in plasma, who had been treated with 2 nucleoside analogue reverse transcripaste inhibitors (NRTI) and NFV for a minimum of 18 months were included. HIV-RNA was determined in plasma and CSF using an ultrasensitive method (<2 copies/ml). Total and free concentrations of NFV were analysed using high liquid chromatography with UV-light detection. 12 out of 19 (63%) patients had <2 copies HIV-RNA/ml in CSF. Seven subjects ranged between 3 and 39 copies/ml, 2 of whom had a slightly higher viral load in CSF than in plasma. NFV was detected in CSF in 16 out of 18 patients analysed and was quantifiable in 8 patients, at concentrations ranging from 6 to 29 nM. There was no correlation between NFV concentration and HIV-RNA levels. Long-term therapy with NFV + 2 NRTI showed no increased rate of virological treatment failure within the central nervous system (CNS) in compliant patients, despite earlier reports of lack of NFV penetration to CNS. Using a highly sensitive method, NFV was detected and quantified in the CSF, although at low values, which could have contributed to the high anti-HIV-1 efficacy of the therapy seen in our subjects.     

TMC114/ritonavir substitution for protease inhibitor(s) in a non-suppressive antiretroviral regimen: a 14-day proof-of-principle trial

OBJECTIVE: To evaluate antiviral activity, tolerability, and safety of the protease inhibitor (PI) TMC114 boosted with low-dose ritonavir (RTV). DESIGN: A randomized, open-label, controlled, phase IIA clinical trial in 15 sites in Europe with 50 HIV-1-infected patients who had taken multiple PIs. METHODS: At entry, PIs in non-suppressive regimens were replaced with TMC114/RTV (300/100 or 600/100 mg twice daily, or 900/100 mg once daily) or left unchanged for 14 days. The time-averaged difference (DAVG) in HIV-1 RNA from baseline, change in HIV-1 RNA from baseline, proportions achieving plasma HIV-1 RNA < 400 copies/ml and > or = 0.5 and > or = 1.0 log10 copies/ml reductions in HIV-1 RNA, and safety were assessed. RESULTS: DAVG responses in all TMC114/RTV groups (range, -0.56 to -0.81 log10 copies/ml) were significantly greater (P < 0.001) than in the controls (-0.03 log10 copies/ml). Median change at day 14 was -1.38 and +0.02 log10 copies/ml for all TMC114/RTV groups and the control group, respectively. A reduction of > or = 0.5 and > or = 1.0 log10 copies/ml was attained by 97% and 76% of patients, respectively, in all TMC114/RTV groups and by 25% and 17%, respectively, in the control group. HIV-1 RNA < 400 copies/ml at any time during treatment was achieved by 40% in the TMC114/RTV groups and 8% in the control group. Most common reported adverse events were gastrointestinal and central nervous system disorders (mild to moderate severity). No dose relationship was observed. Biochemical, haematological and electrocardiographic parameters showed no significant changes. CONCLUSIONS: TMC114/RTV demonstrated a potent antiretroviral effect over 14 days in multiple-PI-experienced patients and was generally well tolerated.     

Efficacy of a twice-daily antiretroviral regimen containing 100 mg ritonavir/400 mg indinavir in HIV-infected patients

OBJECTIVE: To evaluate the pharmacokinetics, efficacy and tolerability of a low-dose boosted indinavir (IDV)/ritonavir (RTV) regimen [100 mg RTV/400 mg IDV twice daily (bid)] in patients previously receiving a standard IDV regimen [800 mg three times a day (tid)]. METHODS: In a prospective, open-label, cross-over trial, patients with plasma HIV RNA < 200 copies/ml receiving an IDV-containing regimen (800 mg tid) were switched to an RTV/IDV (100/400 mg bid)-containing regimen. Minimal and maximal IDV plasma concentrations ( Cmin and Cmax ) were determined before the switch (day 0), at week 2 and week 4 after the switch. The CD4 cell count and plasma HIV RNA were determined at day 0, week 2 and week 4, then every 8 weeks. The primary end-point was the percentage of patients with plasma HIV RNA below 200 copies ml at week 48. RESULTS: Twenty patients were enrolled. At baseline, on IDV 800 mg tid, median IDV Cmin was 194 ng/ml and median IDV Cmax was 8449 ng/ml. On RTV/IDV (100/400 mg), median IDV Cmin increased to 536 ng/ml at week 2 and 475 ng/ml at week 4, while Cmax decreased to 2983 ng/ml at week 2 and 2997 ng/ml at week 4 ( P < 0.001). The median area under the IDV plasma concentration-time curve measured in seven patients was 25 126 ng.h/ml, and the IDV half-life (t1/2 ) was 4.4 h. All patients had plasma HIV RNA remaining < 200 copies/ml at week 48. Tolerability of RTV/IDV was excellent. CONCLUSION: RTV/IDV (100/400 mg bid) yields significantly higher IDV plasma Cmin and lower IDV Cmax values relative to the standard IDV regimen, thereby improving both tolerability and efficacy.