Combination Of Saquinavir Research Articles

Antiretroviral drugs saquinavir and ritonavir reduce inhibitory concentration values of itraconazole against Histoplasma capsulatum strains in vitro

Recent studies have shown that some drugs that are not routinely used to treat fungal infections have antifungal activity, such as protease inhibitor antiretroviral drugs. This study investigated the in vitro susceptibility of Histoplasma capsulatum var. capsulatum to saquinavir and ritonavir, and its combination with the antifungal itraconazole. The susceptibility assay was performed according to Clinical and Laboratory Standards Institute guidelines. All strains were inhibited by the protease inhibitor antiretroviral drugs. Saquinavir showed minimum inhibitory concentrations ranging from 0.125 to 1μgmL−1 for both phases, and ritonavir presented minimum inhibitory concentrations ranging from 0.0312 to 4μgmL−1and from 0.0625 to 1μgmL−1 for filamentous and yeast phase, respectively. Concerning the antifungal itraconazole, the minimum inhibitory concentration values ranged from 0.0019 to 0.125μgmL−1 and from 0.0039 to 0.0312μgmL−1 for the filamentous and yeast phase, respectively. The combination of saquinavir or ritonavir with itraconazole was synergistic against H. capsulatum, with a significant reduction in the minimum inhibitory concentrations of both drugs against the strains (p<0.05). These data show an important in vitro synergy between protease inhibitors and itraconazole against the fungus H. capsulatum.

Abstract 4549: A comparative efficacy study of Saquinavir in combination with cisplatin or paclitaxel in platinum-resistant ovarian cancer cells

Abstract Background and Objective: Ovarian cancer is the 7th most common cancer affecting women Worldwide which has a 5-year survival rate of 45%. First line therapy, platinum and taxol compounds, produces 60% to 80% response rates in platinum sensitive ovarian cancer. However, incidence of resistance to this therapy is high resulting in poor prognosis. The present study evaluated the comparative efficacy of Saquinavir (SAQ) in combination with Cisplatin (CIS) or Paclitaxel (TAX) versus first line therapy, CIS+TAX, in platinum-resistant OVCAR-3 cells. Method: OVCAR-3cells were treated with varying concentrations of SAQ (20μM, 40μM, 60μM and 100μM). OVCAR-3 cells were treated with SAQ (100μM), SAQ+CIS(26μM), SAQ+TAX(1.5nM) and CIS+TAX. Cells were treated over a 24hr period in triplicate. Media only and DMSO only treated cells were used as controls. The cytotoxic effect of each treatment was determined using the automated Trypan Blue exclusion protocol and DNA fragmentation assay was performed to evaluate the mechanisms of induced cell death. Results: Dose dependent and statistically significant (p &amp;lt;0.05) cytotoxic effects were seen with SAQ in OVCAR-3 cells. An IC50 value of 84μM for SAQ was determined in OVCAR-3 cells. Significant cytotoxic effects (p&amp;lt;0.05) in OVCAR-3 treated cells were observed with SAQ, SAQ+TAX, SAQ+CIS AND CIS+TAX combinations when compared to controls. However, SAQ+CIS was the only combination that showed more significant cytotoxicity when compared to CIS+TAX (p = 0.041). SAQ+CIS combination produced an average percentage cell death of 73.25% in OVCAR-3 cells. Cell death by apoptosis was confirmed from observed fragmented DNA in OVCAR-3 cells treated with SAQ+TAX, SAQ+CIS and CIS+TAX. Conclusion: SAQ+CIS produced more significant cytotoxic effect than first line therapy, CIS+TAX, in platinum-resistant ovarian cancer cells. This data supports further evaluation of SAQ for its potential utilization in the treatment of platinum-resistant ovarian cancer. Note: This abstract was not presented at the meeting. Citation Format: Terry-Ann E. Waite, Monique Reboe, Arkene Levy, Sivanesan Dhandayuthapani, Appu Rathinavelu. A comparative efficacy study of Saquinavir in combination with cisplatin or paclitaxel in platinum-resistant ovarian cancer cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4549. doi:10.1158/1538-7445.AM2015-4549

Pharmacokinetic Interaction Study of Ritonavir-Boosted Saquinavir in Combination with Rifabutin in Healthy Subjects

The effect of multiple doses of rifabutin (150 mg) on the pharmacokinetics of saquinavir-ritonavir (1,000 mg of saquinavir and 100 mg of ritonavir [1,000/100 mg]) twice daily (BID) was assessed in 25 healthy subjects. Rifabutin reduced the area under the plasma drug concentration-time curve from 0 to 12 h postdose (AUC(0-12)), maximum observed concentration of drug in plasma (C(max)), and minimum observed concentration of drug in plasma at the end of the dosing interval (C(min)) for saquinavir by 13%, 15%, and 9%, respectively, for subjects receiving rifabutin (150 mg) every 3 days with saquinavir-ritonavir BID. No effects of rifabutin on ritonavir AUC(0-12), C(max), and C(min) were observed. No adjustment of the saquinavir-ritonavir dose (1,000/100 mg) BID is required when the drugs are administered in combination with rifabutin. The effect of multiple doses of saquinavir-ritonavir on rifabutin pharmacokinetics was evaluated in two groups of healthy subjects. In group 1 (n = 14), rifabutin (150 mg) was coadministered every 3 days with saquinavir-ritonavir BID. The AUC(0-72) and C(max) of the active moiety (rifabutin plus 25-O-desacetyl-rifabutin) increased by 134% and 130%, respectively, compared with administration of rifabutin (150 mg) once daily alone. Rifabutin exposure increased by 53% for AUC(0-72) and by 86% for C(max). In group 3 (n = 13), rifabutin was coadministered every 4 days with saquinavir-ritonavir BID. The AUC(0-96) and C(max) of the active moiety increased by 60% and 111%, respectively, compared to administration of 150 mg of rifabutin once daily alone. The AUC(0-96) of rifabutin was not affected, and C(max) increased by 68%. Monitoring of neutropenia and liver enzyme levels is recommended for patients receiving rifabutin with saquinavir-ritonavir BID.

British HIV Association guidelines for antiretroviral treatment of HIV‐2‐positive individuals 2010

British HIV Association guidelines for antiretroviral treatment of HIV‐2‐positive individuals 2010

Effect of Saquinavir‐Ritonavir on Cytochrome P450 3A4 Activity in Healthy Volunteers Using Midazolam as a Probe

To investigate the inhibitory potential of multiple doses of ritonavir-boosted saquinavir on the pharmacokinetics of oral midazolam, a cytochrome P450 (CYP) 3A4 model substrate. Prospective, open-label, one-sequence, two-period crossover study. Clinical pharmacology unit in the United Kingdom. Eighteen healthy adult male and female volunteers (median age 37.5 yrs). Intervention. A single oral dose of midazolam 7.5 mg was administered on day 1. A second dose was administered on day 16, after 14 days of oral saquinavir 1000 mg-ritonavir 100 mg twice/day. Serial blood samples were taken for measurement of plasma concentrations of midazolam and its metabolite, 1'-hydroxymidazolam. Pharmacokinetic parameters of midazolam and 1'-hydroxymidazolam were determined when midazolam was given alone (day 1) and after coadministration with saquinavir-ritonavir for 14 days (day 16). Two weeks of treatment with saquinavir-ritonavir resulted in a 4.3-fold increase in maximum plasma concentration (C(max)) and a 12.4-fold increase in the area under the plasma concentration-time curve from time zero extrapolated to infinity (AUC(0-infinity)) for midazolam. Midazolam's half-life increased from 4.7 to 14.9 hours. Concomitant reductions for 1'-hydroxymidazolam were approximately 7-fold for C(max) and 2-fold for AUC(0-infinity). The 1'-hydroxymidazolam AUC(0-infinity):midazolam AUC(0-infinity) ratio was only 1% during coadministration of midazolam with saquinavir-ritonavir compared with 33% for midazolam alone. Adverse-event reports indicated that the combination of saquinavir, ritonavir, and midazolam was well tolerated but resulted in prolonged sedation. Administration of ritonavir-boosted saquinavir markedly increased the exposure of midazolam by inhibiting its metabolism, confirming that the combination of saquinavir and ritonavir at steady state strongly inhibits CYP3A4 activity.

Pharmacokinetic Interaction Between Darunavir and Saquinavir in HIV-negative Volunteers

This was an open-label, crossover study to investigate the pharmacokinetic interaction between darunavir (TMC114), coadministered with low-dose ritonavir (darunavir/ritonavir), and the protease inhibitor saquinavir in HIV-negative healthy volunteers. Thirty-two volunteers were randomized into two cohorts (panel 1 and panel 2). In two separate sessions, panel 1 received 400/100 mg darunavir/ritonavir twice a day and 400/1000/100 mg darunavir/saquinavir/ritonavir twice a day; panel 2 received 1000/100 mg saquinavir/ritonavir twice a day and 400/1000/100 mg darunavir/saquinavir/ritonavir twice a day. All treatments were administered orally under fed conditions for 13 days with an additional single morning dose on day 14. Treatment sessions were separated by a washout period of at least 14 days. Twenty-six volunteers completed the study (n=14, panel 1; n=12, panel 2), whereas six discontinued as a result of adverse events. Coadministration of saquinavir with darunavir/ritonavir resulted in decreases of darunavir area under the curve and maximum and minimum plasma concentrations of 26%, 17%, and 42%, respectively, compared with administration of darunavir/ritonavir alone. Relative to treatment with saquinavir/ritonavir alone, saquinavir exposure was not significantly different with the addition of darunavir. Ritonavir area under the curve12h increased by 34% when saquinavir was added to treatment with darunavir/ritonavir. The coadministration of darunavir/saquinavir/ritonavir was generally well tolerated. Similar findings are expected with the approved 600/100 mg darunavir/ritonavir twice-a-day dose. The combination of saquinavir and darunavir/ritonavir is currently not recommended.

Synergistic Inhibition of Protease-Inhibitor-Resistant HIV type 1 by Saquinavir in Combination with Atazanavir or Lopinavir

Double-boosted protease inhibitors (PIs) are under investigation for the treatment of patients who are unable to take nucleoside reverse transcriptase inhibitors because of cross-resistance and/or intolerance. Evidence of synergistic inhibition of wild-type HIV has been reported for saquinavir with atazanavir or lopinavir. We investigated the activity of these two combinations against a panel of six site-directed mutant HIV-1 strains and 14 clinically derived recombinant HIV-1 strains presenting a range of PI-resistance profiles. No evidence of synergy was observed against wild-type virus for either combination. The combination of saquinavir and lopinavir showed evidence of synergy against four viruses displaying high-level resistance to lopinavir and low-level resistance to saquinavir. Similarly, evidence of synergy between saquinavir and atazanavir was only observed in two viruses which were more susceptible to saquinavir than to atazanavir. We hypothesize that differences between the PIs in intracellular protein-binding behaviour or inhibition of drug transporters (P glycoprotein, MDR1 and MDR2) could result in intracellular levels of saquinavir being increased by co-administration with lopinavir or atazanavir. The effect of this increase would be masked in cases involving viruses that were susceptible to atazanavir or lopinavir. In virus resistant to lopinavir or atazanavir but susceptible to saquinavir, the majority of the antiviral effect is due to saquinavir; thus even small increases in intracellular concentration could significantly increase virus inhibition. These results confirm that in vitro synergy can be observed between PIs and suggest that the degree of synergy observed might depend on the resistance profile of the virus.

Cerebrospinal fluid HIV-1 RNA, intrathecal immunoactivation, and drug concentrations after treatment with a combination of saquinavir, nelfinavir, and two nucleoside analogues: the M61022 study

BackgroundThe way various antiretroviral drugs and drug combinations affect HIV-1 infection in the central nervous system is still largely unknown. The aim of this study was to determine the cerebrospinal fluid (CSF) steady-state concentrations of saquinavir and nelfinavir in relation to plasma concentrations, and to study their effect in combination with two nucleoside reverse transcriptase inhibitors (NRTIs) on CSF viral loads, intrathecal immunoactivation, and blood-brain barrier integrity.MethodsPaired CSF and plasma samples from 8 antiretroviral-naïve HIV-1 infected patients starting combination therapy with saquinavir, nelfinavir, and two nucleoside analogues were collected prior to treatment, and again after approximately 12 and 48 weeks of antiretroviral therapy. Additional plasma samples were taken at weeks 2, 4, 8, 24, and 36. The concentrations of protease inhibitors were analysed, as were levels of HIV-1 RNA, CD4+ T-cell count, β2-microglobulin, neopterin, albumin ratio, IgG index, and monocytic cell count.ResultsNone of the patients in the study presented with HIV-1 RNA < 50 copies/mL in CSF or plasma prior to treatment, compared to 5/7 at the end of the study. Signs of cell-mediated intrathecal immunoactivation, measured by neopterin and β2-microglobulin, decreased significantly in both CSF and serum, although only 1/7 reached normal CSF neopterin levels after 48 weeks of treatment. There was no significant reduction of albumin ratio, IgG index or CSF monocytic cell count. Saquinavir median (range) concentrations were < 2.5 (< 2.5–96.0) nM unbound in plasma, and < 2.5 (< 2.5–9.0) nM total in CSF. Nelfinavir median (range) concentrations were 10.0 (< 2.0–31.0) nM unbound in plasma, and < 2.0 (< 2.0–23.0) nM total in CSF. Saquinavir and nelfinavir were detectable in 7/15 and 9/15 CSF samples, respectively.ConclusionSaquinavir and nelfinavir, in combination with two NRTIs, decrease the CSF viral load and, to a lesser extent, intrathecal immunoactivation. We found reasonably high CSF concentrations of nelfinavir, but suboptimal concentrations of saquinavir.

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.

Saquinavir drug exposure is not impaired by the boosted double protease inhibitor combination of lopinavir/ritonavir.

To assess the pharmacokinetic interaction of saquinavir and lopinavir/ritonavir. Patients from the Frankfurt HIV cohort with limited reverse transcriptase inhibitor (RTI) options received the protease inhibitor (PI) combination of saquinavir (soft-gel capsules, 1000 mg twice a day) plus lopinavir/ritonavir (400/100 mg twice a day), without RTI (LOPSAQ group). A control group received the same doses of saquinavir and ritonavir plus two to three RTI (RITSAQ group). A steady-state 12 h pharmacokinetic assessment was performed. Plasma levels of saquinavir, ritonavir and lopinavir were determined by liquid chromatography-tandem mass spectrophotometry. Minimum and maximum plasma concentrations (Cmin and Cmax), the clearance (Cltot) and the area under the concentration time curve (AUC) were calculated. Data were collected from 45 patients (LOPSAQ) and 32 patients (RITSAQ). There was no significant difference between the groups for median saquinavir Cmin, Cmax, Cltot and AUC (LOPSAQ: 543 ng/ml, 2300 ng/ml, 1020 ml/min and 16 977 ng*h/ml; RITSAQ: 427 ng/ml, 2410 ng/ml, 1105 ml/min and 15 130 ng*h/ml). Median ritonavir Cmin, Cmax and AUC were lower, the Cltot was higher in the LOPSAQ group (78 ng/ml, 428 ng/ml and 2972 ng*h/ml, 551 ml/min) compared with RITSAQ (194 ng/ml, 683 ng/ml and 6506 ng*h/ml, 266 ml/min; P < 0.001). Lopinavir levels were similar to historical data. Effective plasma levels of both saquinavir and lopinavir can be achieved by the co-administration of saquinavir soft-gel capsules and lopinavir/ritonavir. This boosted double PI combination could be an effective option for patients with limited RTI options.

Issues in the treatment of Mycobacterium tuberculosis in patients with human immunodeficiency virus infection.

The HIV/AIDS pandemic has led to a rise in the incidence of tuberculosis and an epidemic of co-infection in many developing countries. Treatment of Mycobacterium tuberculosis in persons with HIV infection presents several challenges to the clinician particularly in resource-poor countries. As will be discussed in this paper diagnosis of latent tuberculosis relies on tuberculin skin testing which has poor sensitivity and reproducibility in immunocompromised patients. The World Health Organization (WHO) recommends treatment of active tuberculosis as the primary means of global tuberculosis control. In practice treatment of active tuberculosis typically requires that a symptomatic patient self-report to a health service for evaluation and management. Even if this approach to tuberculosis control were sufficient many logistic and clinical problems remain involving tuberculosis diagnosis and therapy in the patient with HIV/AIDS. Recognizing the significant clinical and public health challenges surrounding the treatment of tuberculosis in patients with HIV infection this paper will address a number of issues relevant to the care of co-infected patients. These include current guidelines for the treatment of active tuberculosis as well as the diagnosis and treatment of latent tuberculosis in HIV-positive patients. The paper concludes with a discussion of promising new drugs for tuberculosis treatment. (excerpt)

Combination of Protease Inhibitors for the Treatment of HIV-1-Infected Patients: A Review of Pharmacokinetics and Clinical Experience

The use of highly active antiretroviral therapy, the combination of at least three different antiretroviral drugs for the treatment of HIV-1 infection, has greatly improved the prognosis for HIV-1-infected patients. The efficacy of a combination of a protease inhibitor (PI) plus two nucleoside analogue reverse transcriptase inhibitors has been well established over a period of up to 3 years. However, virological treatment failure has been reported in 40-60% of unselected patients within 1 year after initiation of a PI-containing regimen. This observation may, at least in part, be attributed to the poor pharmacokinetic characteristics of the PIs. Given as a single agent the PIs have several pharmacokinetic limitations; relatively short plasma-elimination half-lives and a modest and variable oral bioavailability, which is, for some of the PIs, influenced by food. To overcome these suboptimal pharmacokinetics, high doses (requiring large numbers of pills) must be ingested, often with food restrictions, which complicates patient adherence to the prescribed regimen. Positive drug-drug interactions increase the exposure to the PIs, allowing administration of lower doses at reduced dosing frequencies with less dietary restrictions. In addition to increasing the potency of an antiretroviral regimen, combinations of PIs may enhance patient adherence, both of which will contribute to a more durable suppression of viral replication. The favourable pharmacokinetics of PIs in combination are a result of interactions through cytochrome P450 3A4 (CYP3A4) isoenzymes and, possibly, the multi-drug transporting P-glycoprotein (P-gp). Antiretroviral synergy between PIs and non-overlapping primary resistance patterns in the HIV-1 protease genome may further enhance the antiretroviral potency and durability of combinations of PIs. Many combinations contain ritonavir because this PI has the most pronounced inhibiting effects on CYP3A4. The combination of saquinavir and ritonavir, both in a dose of 400 mg twice-a-day, is the most studied double PI combination, with clinical experience extending over 3 years. Combination of a PI with a low dose of ritonavir (< or = 400 mg/day), only to boost its pharmacokinetic properties, seems an attractive option for patients who cannot tolerate higher doses of ritonavir. A recently introduced PI, lopinavir, has been co-formulated with low-dose ritonavir, which allows for a convenient three-capsules, twice-a-day dosing regimen. In an attempt to prolong suppression of viral replication combinations of PIs are becoming increasingly popular. However, further clinical studies are needed to identify the optimal combinations for treatment of antiretroviral naive and experienced HIV-1-infected patients. This review covers combinations of saquinavir, indinavir, nelfinavir, amprenavir and lopinavir with different doses of ritonavir, as well as the combinations of saquinavir and indinavir with nelfinavir.

Dynamic correlation of apoptosis and immune activation during treatment of HIV infection.

T cells from HIV infected patients undergo spontaneous apoptosis at a faster rate than those from uninfected patients, are abnormally susceptible to activation induced cell death (AICD), and undergo increased apoptosis in response to Fas receptor ligation. These observations have led to the hypothesis CD4 T cell apoptosis may be a mechanism of CD4 T cell depletion and the pathogenesis of AIDS. Successful treatment of HIV infected patients is accompanied by quantitative and qualitative improvements in immune function reflecting at least partial reversibility of the underlying pathogenesis of HIV. In this report we correlate improvements in markers of immune function with a decrease in apoptosis, and changes in its regulation. Therapy with nelfinavir plus saquinavir in combination with two nucleoside analogue inhibitors of reverse transcriptase dramatically reduces plasma viremia and increases CD4 T cell counts. Coincident with these improvements, CD38 and HLA-DR coexpression on both CD4 and CD8 T cells decrease, and CD45RA and CD62L coexpression increase. Furthermore, spontaneous apoptosis decreases in both CD4 and CD8 T cells (CD4 apoptosis 17.4 vs 2.6%, P=0.005; CD8 apoptosis 15.0 vs 1.0%, P<0.001), as does both Fas mediated apoptosis (CD4 apoptosis 19.0 vs 3.5%, P=0.03; CD8 apoptosis 13.7 vs 1.5%, P=0.002) and CD3 induced AICD (CD4 apoptosis 13.7 vs 3.2%, P=0.001; CD8 apoptosis 29 vs 2.2%, P=0.08). Changes in apoptosis are not associated with changes in Fas receptor expression, but are significantly correlated with changes in activation marker profiles. Although this suggests a possible regulatory role for the apoptosis inhibitory protein FLIP, direct assessment did not reveal quantitative differences in FLIP expression between apoptosis resistant PBL's from HIV negative patients, and apoptosis sensitive PBL's from HIV positive patients. These findings support the hypothesis that apoptosis mediates HIV induced CD4 T cell depletion, but indicate the need for further studies into the molecular regulation of HIV induced apoptosis.

Correlation of response to treatment and HIV genotypic changes during Phase III trials with saquinavir and reverse transcriptase inhibitor combination therapy

Assessment of genotypic change in HIV protease during treatment with saquinavir (SQV) in combination with zidovudine (ZDV) and/or zalcitabine (ddC), to determine the influence of such changes on viral phenotype and response to treatment. Virologic substudies of Phase III clinical trials NV14256 and SV14604. Population sequencing of HIV protease genes amplified from pre- and post-treatment plasma. Phenotyping of peripheral blood mononuclear cell (PBMC)-derived virus isolates, and genotyping of proviral DNA clones amplified from PBMC used in the expansion of virus isolates. In both trials the incidence of Met90 remained at < or = 20% in subjects receiving SQV in combination with ddC (with or without ZDV) for 1 year. A Val48 substitution was observed in two out of 81 subjects after 24 weeks and in two out of 75 subjects after 48 weeks. In 12 out of 13 NV14256 subjects with viral load rebound during SQV monotherapy these substitutions were associated with the rebound. In subjects treated with SQV plus ddC, rebound was associated with SQV resistance in six out of 22 cases and ddC resistance in five out of 22 cases. The incidences of non-BRU residues at positions 10, 63 and 71 were increased significantly (P < 0.05, Fisher's exact test) after SQV treatment with or without ZDV. However, comparison of genotypic and phenotypic data showed that these changes were not associated with reduced sensitivity to SQV. Virological failure during combination therapy can be due to resistance to either treatment drug, emphasising the need to change both the reverse transcriptase inhibitor and the protease inhibitor. Only Val48 and Met90 correlated directly with the development of reduced drug sensitivity during treatment with SQV in vivo.

Safety profile of soft gelatin formulation of saquinavir in combination with nucleosides in a broad patient population

Safety profile of soft gelatin formulation of saquinavir in combination with nucleosides in a broad patient population

A syndrome of peripheral lipodystrophy, hyperlipidaemia and insulin resistance in patients receiving HIV protease inhibitors.

To describe a syndrome of peripheral lipodystrophy (fat wasting of the face, limbs and upper trunk), hyperlipidaemia and insulin resistance in patients receiving potent HIV protease inhibitor therapy. Cross-sectional study. Outpatient clinic of a university teaching hospital. HIV-infected patients either receiving at least one protease inhibitor (n=116) or protease inhibitor-naive (n=32), and healthy men (n=47). Lipodystrophy was assessed by physical examination and questionnaire and body composition by dual-energy X-ray absorptiometry. Fasting triglyceride, cholesterol, free fatty acid, glucose, insulin, C-peptide and fructosamine levels, other metabolic parameters, CD4 lymphocyte counts, and HIV RNA load were also assessed. HIV protease inhibitor-naive patients had similar body composition to healthy men. HIV protease inhibitor therapy was associated with substantially lower total body fat (13.2 versus 18.7 kg in protease inhibitor-naive patients; P=0.005), and significantly higher total cholesterol and triglyceride levels. Lipodystrophy was observed clinically in 74 (64%) protease inhibitor recipients after a mean 13.9 months and 1(3%) protease inhibitor-naive patient (P=0.0001). Fat loss occurred in all regions except the abdomen after a median 10 months. Patients with lipodystrophy experienced a relative weight loss of 0.5 kg per month and had significantly higher triglyceride, cholesterol, insulin and C-peptide levels and were more insulin-resistant than protease inhibitor recipients without lipodystrophy. Patients receiving ritonavir and saquinavir in combination had significantly lower body fat, higher lipids and shorter time to lipodystrophy than patients receiving indinavir. Three (2%) patients developed new or worsening diabetes mellitus. A syndrome of peripheral lipodystrophy, hyperlipidaemia and insulin resistance is a common complication of HIV protease inhibitors. Diabetes mellitus is relatively uncommon.

Antiretroviral Effect of Two Different Dose Regimens of Ritonavir and Saquinavir on HIV-Infected Adults in a Population-Based Setting

To characterize the antiviral effect and tolerability of higher dose (HD, 600 mg two times daily) and lower dose (LD, 400 mg two times daily) combination regimens of ritonavir and saquinavir in British Columbia (BC), Canada. Intent-to-treat analysis with suppression of plasma viral load to levels below 500 copies/ml as the main outcome measure. Adult human immunodeficiency virus (HIV)-positive individuals in the province of British Columbia prescribed ritonavir and saquinavir in combination between 1 September 1996 and 30 June 1997, with a minimum of two plasma viral loads, one at baseline and one after the initiation of therapy. A total of 84 participants [27 HD (32%) and 57 LD (68%)] were prescribed ritonavir and saquinavir. There was no difference at baseline in the two groups with respect to age (P=0.466), CD4 cell count (P=0.373) and baseline plasma viral load (P=0.656). However, LD were more likely to have had prior protease experience than HD participants (65 versus 40%, P=0.037). The median follow-up time was 9 months. A total of 44 (52%) subjects demonstrated a decrease in plasma viral load to levels <500 copies/ml. After adjusting for length of follow-up, baseline CD4 cell count and prior AIDS diagnosis, HD participants were as likely to be suppressed to <500 copies/ml as LD individuals (P=0.760). HD participants did report more adverse effects (P=0.042) than LD subjects. Our results provide confirmatory evidence that lower doses of ritonavir and saquinavir in combination are better tolerated and as effective as the standard doses of these drugs. This response, however, is seriously compromised by prior exposure to protease inhibitors.

Antagonism between human immunodeficiency virus type 1 protease inhibitors indinavir and saquinavir in vitro.

Human immunodeficiency virus type 1 (HIV-1) protease inhibitors are a promising class of antiretroviral agents that compromise enzymatic function through substrate mimicry. The in vitro susceptibility of a panel of HIV-1 clinical isolates demonstrating various drug resistance phenotypes to combinations of the HIV-1 protease inhibitors saquinavir and indinavir was determined. Antiviral effect was assessed by an HIV-1 p24 antigen reduction assay in phytohemagglutinin-stimulated peripheral blood mononuclear cells after harvesting of cell-free supernatant fluids at peak antigen production (days 4-7). Drug interactions were determined by median-dose-effect analysis, with the combination index (CI) calculated at several inhibitory concentrations (IC50, IC75, IC90, IC95, IC99). The interactive effects ranged from synergy at low efficacy doses to antagonism at higher doses against a pan-susceptible clinical isolate of HIV-1. Against a zidovudine-resistant isolate as well as a multidrug-resistant isolate, the combination of saquinavir and indinavir demonstrated antagonism at all doses.

Saquinavir. A review of its pharmacology and clinical potential in the management of HIV infection.

Saquinavir is a peptide derivative which inhibits the HIV protease enzyme, preventing post-translational processing of viral polyproteins. It was the first agent of its class to become available for the treatment of HIV infection. Well controlled studies have assessed the effects of saquinavir, when used alone or in combination with reverse transcriptase inhibitors, in patients with advanced HIV infection. Analysis of CD4+ cell counts and measures of viral load in the ACTG 229 study suggest that triple therapy with saquinavir, zidovudine and zalcitabine is more effective than double therapy with saquinavir plus zidovudine or zidovudine plus zalcitabine in patients who have previously received long term treatment with zidovudine. Similar assessments from a small study in previously untreated patients suggest that double therapy with saquinavir plus zidovudine is more effective than monotherapy with either agent. Combination therapy with saquinavir and zalcitabine significantly reduced the time to the first AIDS-defining event or death, and the time to death, compared with zalcitabine alone, according to data from a large, long term study (NV 14256) in patients with advanced HIV infection who had previously received zidovudine. Saquinavir is generally well tolerated, either as monotherapy or in combination with reverse transcriptase inhibitors; no change in tolerability profile was reported when saquinavir was added to treatment with nucleoside analogues. In vitro and clinical studies have documented the emergence of saquinavir-resistant HIV strains. Although the possible impact of resistance on the clinical efficacy of saquinavir has yet to be fully characterised, genotypic and phenotypic resistance appear to develop slowly during treatment with saquinavir, and the drug does not appear to have a significant effect on the incidence of mutations associated with cross-resistance to other protease inhibitors. Thus, laboratory and clinical results suggest that saquinavir in combination with reverse transcriptase inhibitors is effective in the treatment of advanced HIV infection. Initial data on the effects of saquinavir on disease progression and mortality are promising, and the apparent absence of mutations conferring cross-resistance to other protease inhibitors is a potentially valuable clinical feature. Additional data on disease progression, mortality and viral resistance, together with information on relative efficacy (in comparison with other protease inhibitors), will need to be assessed before the clinical value of saquinavir can be fully determined. Nevertheless, saquinavir represents a valuable new pharmacological option for the treatment of HIV infection and is likely to be a useful component of combined therapy with reverse transcriptase inhibitors and/or other protease inhibitors.

In Vivo Resistance to a Human Immunodeficiency Virus Type 1 Proteinase Inhibitor: Mutations, Kinetics, and Frequencies

Resistance to saquinavir (Ro 31-8959), an inhibitor of human immunodeficiency virus type I proteinase, was studied in peripheral blood mononuclear cell-derived proviral DNA from patients undergoing prolonged treatment. A Leu90-->Met exchange was the predominant resistance mutation in vivo; Gly48-->Val or doubly mutant virus was rarely observed. After 8-12 months of treatment with saquinavir alone (600 mg, 3 times/day) or in combination with zidovudine (200 mg, 3 times/day), approximately 45% of all patients carried provirus with mutant proteinase; the incidence was lower (22%) in patients treated with a combination of saquinavir, zidovudine, and dideoxycytidine. There was a good relationship between genotypic analysis of saquinavir resistance and data from virus assays, confirming that Leu90-->Met and Gly48-->Val are the essential exchanges in the proteinase that determine loss of sensitivity to this inhibitor. Absence of genotypic resistance correlated with a sustained decrease in plasma viral RNA. There was a positive correlation between a Met90 mutation and some residues at natural polymorphic sites (positions 10, 36, 63, and 71).