Once-daily directly observed therapy lopinavir/ritonavir plus indinavir as a protease inhibitor-only salvage therapy in heavily pretreated HIV-1-infected patients: a pilot study

Lopinavir/ritonavir plus indinavir was administered once daily as directly observed protease inhibitor-only therapy in 12 heavily pretreated HIV-1-infected patients with multiple virological failures and advanced immunosuppression (CD4 cell count 95 x 10 cells/microl). The treatment was well tolerated. At weeks 12, 24 and 48, most patients on treatment achieved viral suppression of less than 400 copies/ml and a corresponding median CD4 T-cell count increase. Pharmacokinetic data indicated therapeutic concentrations for both protease inhibitors in most patients.

[Pneumocystis jirovecii pneumonia: an old disease with a new name]

Pneumocystis jirovecii pneumonia has historically been one of the most common opportunistic pneumonias and life-threatening infectious complications in HIV-infected patients. After the introduction of combination antiretroviral therapy, the incidence of Pneumocystis pneumonia and other opportunistic infections has decreased dramatically. Nowadays Pneumocystis pneumonia still occurs in patients unaware of their HIV status, in those not receiving combination antiretroviral therapy, or in those in whom it is ineffective due to resistance. Age factor is the diagnosis delaying one: patients aged more than 50 years are diagnosed with AIDS later than younger persons. Pneumocystis was thought to be a species of protozoa. Over the last 20 years, Pneumocystis has been shown to be a fungus, to be genetically diverse, host species specific, to colonize individuals with minor immunosuppression, and to cause clinical disease by "new" infection in addition to reactivation of latent childhood-acquired infection. Recently, the microorganism Pneumocystis carinii causing disease in humans has been renamed to Pneumocystis jirovecii. This article presents a clinical case of late diagnosis of Pneumocystis jirovecii pneumonia in a 62-year-old patient unaware of her HIV status and a review of literature reflecting epidemiological issues of Pneumocystis jirovecii and latest discoveries related to Pneumocystis as well as the rationale for renaming it.

Lamivudine and indinavir/ritonavir maintenance therapy in highly pretreated HIV-infected patients (Vista ANRS 109)

OBJECTIVE

In patients with extensive HIV resistance, one option is to delay salvage therapy until new drugs become available. We hypothesized that this delay period could be based on a simplified treatment, which would reduce drug toxicity, stabilize resistance, and prevent resurgence of wild-type virus.

METHODS

A prospective 24-week treatment simplification study in HIV-1-infected patients having failed several lines of antiretroviral therapy, with CD4+ T-cell counts > or = 100 cells/ml, plasma HIV RNA (viral load [VL]) > or = 4 log10 copies/ml and a resistance genotype predicting less than two active drugs. Treatment associated ritonavir-boosted low-dose indinavir (200 mg twice daily) and lamivudine (150 mg twice daily). The primary endpoint was a decrease in CD4+ T-cell counts > or = 25% or increase in VL > or = 0.7 log copies/ml relative to baseline.

RESULTS

Twenty-six patients were included. Baseline median VL was 4.5 log10 copies/ml and median CD4+ T-cell count was 290 cells/ml. During the study, 10/26 patients (38%, 95% confidence interval = 20.2-59.4) reached the primary endpoint. No patient had an AIDS-defining event. At week 24, the median change in plasma VL was +0.2 log10 copies/ml (interquartile range (IQR): 0-0.5; P = 0.003). The median change in CD4+ T-cell counts was -49 cells/ml (IQR: -14 to -93, P < 0.001), with a median decline slope of 10 cells/ml/month, which was not different from that measured under full highly active antiretroviral therapy during the 6 months preceding inclusion. There were no significant changes in HIV-1 protease and reverse transcriptase genotypes during the study.

CONCLUSIONS

In patients with advanced resistance, treatment simplification prevented resurgence of wild-type HIV, reduced drug burden, but failed to stabilize progression of the immune deficiency.

Incidence of and risk factors for insulin resistance in treatment-naive HIV-infected patients 48 weeks after starting highly active antiretroviral therapy

OBJECTIVES

to assess the incidence and risk factors for insulin resistance (IR) in a cohort of naive HIV-infected patients 48 weeks after starting highly active antiretroviral therapy (HAART).

DESIGN

prospective, two centre, observational, cohort study.

METHODS

One-hundred and thirty-seven patients who started HAART and maintained the same regimen for 48 weeks were included. IR was determined by the homeostasis model assessment (HOMA-IR) method. Individuals with a HOMA-IR value >3.8 were defined as insulin resistant. Independent associations with the development of IR at 48 weeks were evaluated.

RESULTS

Seventeen (12.4%) individuals showed a HOMA-IR value >3.8 at baseline and were excluded for incidence analyses. Fifteen patients developed IR at 48 weeks of HAART, giving an incidence of 13%. Independent predictors of the development or IR were indinavir exposure (beta-coefficient 5.45, 95% confidence interval [CI] 1.30-22.8; P=0.02), and hepatitis C virus (HCV) antibody positivity (beta-coefficient 5.22, 95% CI 1.34-20.33; P=0.01). The appearance of IR was associated with a higher BMI (beta-coefficient 1.72 for each 2 kg/m2 increase, 95% CI 1.54-1.94; P=0.02) and with the presence of lipodystrophy at 48 weeks (beta-coefficient 5.59, 95% CI 1.45-21.5; P=0.01).

CONCLUSIONS

HAART induces the development of IR in previously naive non-insulin-resistant HIV-infected individuals, with an incidence of 13% in the first year of therapy. Indinavir exposure, and HCV coinfection are associated with an increased risk of developing IR.

Tissue distribution of indinavir administered as solid lipid nanocapsule formulation in mdr1a (+/+) and mdr1a (-/-) CF-1 mice

PURPOSE

Due to protease inhibitor (PI) efflux transport by P-glycoprotein (P-gp), insufficient PI concentrations result in low ongoing HIV replication in the so-called virus sanctuaries (brain and testes). The aim of the present study was to evaluate indinavir-loaded nanocapsules (Ind-LNC) including Solutol HS15, an excipient reported to possess in vitro P-gp inhibiting properties, as a means to improve indinavir distribution into brain and testes of mice.

METHODS

Normal mdr1a (+/+) or P-gp-deficient mdr1a (-/-) CF-1 mice were dosed with Ind-LNC (10 mg indinavir/kg, i.v.). At 30 min post-administration, indinavir was determined in plasma, brain, testes, as well as in kidneys, liver, and heart by LC-MS/MS, and tissue/plasma concentration ratios were calculated. Results were compared with those of control groups that received an indinavir solution (Ind-Sol).

RESULTS

Using Ind-Sol, ratios were 21.3- and 3.3-fold higher in brains and testes of mdr1a (-/-) mice than of mdr1a (+/+) mice, respectively, whereas in the other organs ratios were not significantly different between the two substrains. When Ind-LNC was used, a similar [mdr1a(-/-) vs. mdr1a (+/+) mice] trend was observed. Moreover, ratios were found to be significantly increased (1.9-fold increase in average) in most organs (brain and testes in particular) with Ind-LNC compared to Ind-Sol, regardless of the substrain used.

CONCLUSIONS

In agreement with previous works, P-gp governs at least in part indinavir uptake into brain and testes. LNC formulation increased indinavir uptake in brain and testes by mechanisms other than, or additional to, P-gp inhibition.

Co-treatment with grapefruit juice inhibits while chronic administration activates intestinal P-glycoprotein-mediated drug efflux

P-Glycoprotein (P-gp) mediated efflux is recognized as a significant biochemical barrier affecting oral absorption for a number of drugs. Various conflicting reports have been published regarding the effects of grapefruit juice (GFJ) on P-gp-mediated drug efflux, in which GFJ has been shown both to inhibit and activate it. Hence, the present study adopted a two-way approach, involving both co-treatment and chronic administration. Bi-directional transport of paclitaxel (PCL) was carried out in the absence and presence of GFJ extract, in rat everted ileum sac. Further, the effect of chronic administration of GFJ to rats was characterized by permeability studies with indinavir (INDI). Co-treatment of GFJ extract at 100% concentration reduced the asymmetric transport of PCL (efflux ratio = 20.8) by increasing absorptive (A --> B) transport by 921% and reducing secretory (B --> A) transport by 41%. Further, GFJ showed a concentration dependent effect on PCL permeability. Imipramine, a passive permeability marker with absorptive permeability of 15.33 +/- 4.26 x 10(-6) cm/s showed no asymmetric transport and also no significant (P < 0.05) change in permeability in the presence of GFJ. Chronic administration of GFJ resulted in a significant decrease in absorptive transport of indinavir, which was even greater than that produced by rifampicin pretreatment. No change in permeability of propranolol, a passive permeability marker, was observed. Further, the decrease in absorptive transport of INDI was reversed by the P-gp inhibitor verapamil. In conclusion, GFJ extract inhibited P-gp-mediated efflux in co-treatment, whereas chronic administration led to increased levels of P-gp expression, thus having a profound effect on intestinal absorption and GFJ-drug interactions in vivo.

Comparison of two indinavir/ritonavir regimens in the treatment of HIV-infected individuals

BACKGROUND

Pharmacokinetic enhancement of protease inhibitors (PIs) with low-dose ritonavir (RTV) for salvage therapy is increasingly common. The purpose of this study was to compare the pharmacokinetics, safety, and tolerability of indinavir (IDV)/RTV at 800/200 mg (arm A) and 400/400 mg (arm B) administered twice daily in HIV-infected subjects failing their first PI-based regimen.

METHODS

A phase I/II, randomized, open-label, 24-week study was conducted. Formal 12-hour pharmacokinetic evaluations were performed, and study visits occurred at baseline; at weeks 1, 2, and 4; and every 4 week thereafter for 24 weeks. Clinical symptoms and laboratory assessments were collected. Subjects were allowed to switch arms because of toxicity.

RESULTS

Forty-four subjects were enrolled (22 per arm). IDV predose concentration, maximum plasma concentration and area under the curve were significantly higher in arm A. Fifty-five percent and 45% of subjects in arms A and B responded (<200 copies/mL at week 24; P = 0.76), respectively. CD4 cell responses were similar. All subjects had IDV-sensitive virus at baseline and at virologic failure. Tolerability was comparable, but all grade 3 or higher triglyceride increases occurred in arm B and more subjects in arm B switched because of toxicity (5 vs. 1 triglyceride increases).

CONCLUSIONS

This is the largest formal pharmacokinetic evaluation of 2 dosage combinations of IDV/RTV in HIV-infected individuals. Pharmacokinetic parameters were consistent with previous results in patients but lower than in seronegative controls. Both regimens exhibited similar tolerability and response rates. High toxicity with a low response suggests that the optimum IDV/RTV combination would include an RTV dose <400 mg and an IDV dose <800 mg in this population.

Effects on immunological and virological outcome of patients using one protease inhibitor or one non-nucleoside reverse transcriptase inhibitor in a triple antiretroviral therapy: normal clinical practice versus clinical trial findings

We compared the response of two standard 3-drug regimens containing two-nucleoside reverse transcriptase inhibitor (Zidovudine +Lamivudine) plus either a protease inhibitor (PIs) (Indinavir) or a non-nucleoside reverse transcriptase inhibitor (NNRTIs) (Efavirenz) among treatment-naïve or treatment-experienced HIV-infected persons. The obtained results will be compared to clinical trial findings. Through a retrospective study, we compared the virological and immunological response of 119 Tunisian HIV-1 infected patients (North Africa) who started for the first time/ in salvage use a triple antiretroviral treatment containing one NNRTI (group A1/group A2) or one PI (group B1/group B2). Viral load (VL) was analysed with Amplicor HIV-1 Monitor test and drug resistance mutations were examined by using two distinct line probe assays (LiPA). The analysis according to the received treatment showed an average of 0.45 log(10) drop in the mean VL among groups A2 and B2. For naïve patients, 62.5% of group A1 reached an undetectable VL versus 53.5% for group B1 (p < 0.001). With regard to the CD4 cell count change, we observed a mean increase of more than 65% versus baseline within group A1 in comparison with 42% for group B1 (p < 0.001). Genotypic resistance assays showed that patients of group A2 had significantly more resistance mutations than those of group B2 (2.66 vs. 0.75 (p = 0.0039)). Finally, 15 patients who were failing were switched to indinavir or efavirenz. When indinavir was replaced by efavirenz, we observed an increase in the plasma VL. With regard to the effects on immunological and virological outcome of patients using PIs or NNRTIs in a triple antiretroviral therapy, our observations in normal clinical practice supported the reported clinical trial findings but are not in favour of replacing indinavir by efavirenz in failing regimen.

Pharmacokinetic interactions between indinavir plus ritonavir and calcium channel blockers

BACKGROUND

Hypertension is an important modifiable cardiac risk factor in human immunodeficiency virus (HIV)-infected patients. Calcium channel blockers are substrates of cytochrome P450 3A and are commonly prescribed for hypertension. We evaluated potential bidirectional pharmacokinetic interactions between calcium channel blockers and coadministered indinavir and ritonavir.

METHODS

Healthy HIV- seronegative subjects received 120 mg diltiazem daily or 5 mg amlodipine daily for days 1 to 7 and 20 to 26. All subjects received 100 mg ritonavir and 800 mg indinavir every 12 hours on days 8 to 26. Twenty-four-hour pharmacokinetic collection was performed on days 7 and 26, with 12-hour collection on day 19.

RESULTS

Indinavir plus ritonavir increased the median amlodipine area under the curve from 0 to 24 hours (AUC) by 89.8%, from 122 to 230 ng.h/mL (n = 18, P < .0001), and increased the median diltiazem AUC by 26.5%, from 800 to 1060 ng.h/mL (n = 13, P = .06). Of 13 subjects, 2 (15%) had greater than 4-fold increases in diltiazem AUC. Desacetyldiltiazem AUC increased by 102.2% (P = .001), and desmethyldiltiazem AUC decreased by 27.4% (P = .01). Neither amlodipine nor diltiazem affected steady-state AUCs of the protease inhibitors. No serious cardiovascular adverse effects were observed.

CONCLUSIONS

Indinavir plus ritonavir increases the AUCs of both amlodipine and diltiazem, which may result in an increased response. If coadministration is indicated, amlodipine or diltiazem should be initiated at low doses with careful titration to response and side effects.

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.

Genotypic resistance analyses in nucleoside-pretreated patients failing an indinavir containing regimen: results from a randomized comparative trial: (Novavir ANRS 073)

BACKGROUND

Different studies have shown that most patients failing a first-line treatment containing a protease-inhibitor (PI) had low PI plasma levels and no PI-related resistance mutations. NOVAVIR was a randomized trial comparing stavudine/lamivudine/indinavir (d4T/3TC/IDV) and zidovudine/lamivudine/indinavir (AZT/3TC/IDV) in patients pretreated with AZT, didanosine (ddI) and/or zalcitabine (ddC) but naive for PIs.

OBJECTIVE

To study the mechanisms of virological failure in NOVAVIR trial through analyses of genotypic resistance profiles of reverse transcriptase (RT) and protease (PR), and plasma IDV concentrations at time to failure.

METHODS

Plasma HIV-RNA PR and RT sequences were determined in 27 failing patients (d4T/3TC/IDV n=11; AZT/3TC/IDV n=16) at baseline and at time to failure. IDV plasma measurements were performed in both samples.

RESULTS

At baseline, 20 out of the 27 patients had at least two thymidine analogs associated mutations. At time to failure, mutation M184V in the RT gene was present in 22 out of the 27 failing patients. Thirteen out of the 27 (48%) patients had acquisition of PI mutations compared to baseline sequence. Of the 26 patients with adherence data, 13 (50%) subjects were classified as having difficulty in adherence. The proportion of patients with low adherence was higher in the subgroup of patients failing without acquisition of new PI mutations.

CONCLUSIONS

In patients experienced with NRTIs, failure to PI-containing regimen may occur in spite of appropriate adherence to therapy and is associated with emergence of PI mutations in half of the cases. These results suggest that, although PIs have a high genetic barrier, sub-optimal activity of associated drugs may favor the selection of PI resistance mutations.

Low-doses of indinavir boosted with ritonavir in HIV-infected Thai patients: pharmacokinetics, efficacy and tolerability

OBJECTIVES

To assess the steady-state pharmacokinetics of two reduced doses of indinavir boosted with ritonavir (indinavir/ritonavir) in HIV-infected Thai patients.

PATIENTS AND METHODS

Thirteen immunocompromised antiretroviral-naive patients (6 males, 7 females) initiated 600/100 mg indinavir/ritonavir, zidovudine and lamivudine, every 12 h. After 1 month, blood samples were taken at pre-dose, and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 h after drug intake. Indinavir dosing was then reduced to 400 mg (twice daily) and 1 week later an identical series of samples were drawn. Patients then resumed 600 mg of indinavir. HIV-1 RNA viral load was determined at 8, 24 and 48 weeks. Indinavir plasma levels were determined by HPLC and pharmacokinetic parameters by non-compartmental analysis.

RESULTS

Median (range) weight was 58 kg (51-73) for men and 53 kg (46-59) for women. On 600 mg of indinavir, median indinavir AUC, C(max), and C(min) were 39.3 mg.h/L (20.6-50.5), 6.2 mg/L (3.7-9.0) and 0.41 mg/L (0.12-0.77), respectively, and on indinavir 400 mg, 18.3 mg.h/L (11.1-33.0), 3.8 mg/L (2.2-7.8) and 0.17 mg/L (0.10-0.39), respectively. No renal complications were observed. At 48 weeks, 6/13 (46%) patients had stopped 600 mg of indinavir due to intolerability (gastrointestinal and cutaneous), and 5/7 (71%) patients had a HIV-1 viral load <50 copies/mL.

CONCLUSIONS

Reduced doses of indinavir/ritonavir maintained adequate indinavir plasma levels compared to current guidelines suggesting that these doses are efficacious in this setting. Considering the poor tolerability of 600 mg of indinavir, the 400 mg of indinavir may be preferred due to its lower exposure indices but long-term efficacy data are needed.

Indinavir/ritonavir-based therapy in HIV-1-infected antiretroviral therapy-naive patients: comparison of 800/100 mg and 400/100 mg twice daily

Objectives To compare the efficacy and tolerability of indinavir (IDV)/ritonavir (RTV) at 800/100 and 400/100 mg twice daily (bid) in antiretroviral therapy (ART)-naive patients. Methods An open comparison of two groups of ART-naive patients treated with IDV/RTV 800/100 or 400/100 mg bid plus two nucleoside analogues was carried out. Viral load, CD4 cell count and tolerability were measured at baseline and at weeks 4, 12, 24 and 48. IDV plasma concentrations were measured retrospectively. Results A total of 107 patients were included in the study. Of these, 57 were treated with 800/100 and 50 with 400/100 mg IDV/RTV bid. At week 48, a viral load of <50 HIV-1 RNA copies/mL was achieved by 77 and 64% of the patients, respectively, and the median CD4 cell count increases were +171 and +164 cells/muL (intent-to-treat; P not significant), respectively. Side effects leading to protease inhibitor discontinuation occurred in 61% of subjects in the 800/100 mg group vs. 20% in the 400/100 mg group (P<0.0001). Switching from 800/100 to 400/100 mg dosage improved adverse events in 16 of 20 patients. IDV concentrations were above 0.15 mg/L in 89% of the 28 patients tested in the 400/100 mg group. Conclusions Indinavir/ritonavir 400/100 mg bid provided the same efficacy as 800/100 mg bid at 48 weeks in an ART-naive population, but safety and tolerance were significantly better for 400/100 mg, while convenience was also improved and cost was reduced.

Switch from Ritonavir to Indinavir in Combination Therapy for HIV‐1–Infected Children

BACKGROUND

Protease inhibitors are an effective component of combination antiretroviral treatment for children infected with human immunodeficiency virus 1 (HIV-1), but tolerance or toxicity issues sometimes require an alternative therapeutic strategy.

METHODS

HIV-1-infected children aged 2-17 years received combination therapy with either stavudine plus ritonavir or with zidovudine, lamivudine, and ritonavir as part of a randomized clinical trial. Twenty-one months after the start of the trial, ritonavir in capsule formulation became unavailable. The treatment regimen for 25 children was switched from ritonavir capsules to indinavir capsules (500 mg/m(2) every 8 h). The other study drugs remained unchanged. A matched-pairs analysis was performed to compare the results for these 25 children with the results for 25 matched children whose treatment regimen continued to include ritonavir (in liquid formulation).

RESULTS

There were no significant differences in the percentage of children with an HIV-1 RNA load of <or=200 copies/mL between the group receiving indinavir and the matched group receiving ritonavir (52% vs. 68%, at the start of indinavir treatment; 42% vs. 52%, at week 12; and 50% vs. 56%, at week 24). Similarly, there were no significant differences between the treatment groups with respect to median CD4 cell counts over time. Toxicities observed in the children treated with indinavir were most often flank pain or headache (16%), renal dysfunction (16%), hematuria (12%), and skin rash (12%) and were consistent with toxicities reported elsewhere. There was no evidence that the switch from ritonavir to indinavir therapy altered the pharmacokinetics of indinavir as a result of residual cytochrome P450 induction or inhibition caused by ritonavir.

CONCLUSIONS

The switch from one protease inhibitor (ritonavir) to another (indinavir) as a component of combination antiretroviral treatment in this patient population was a practical therapeutic strategy.

A pilot, double-blind, placebo-controlled trial of indinavir in patients with ALS

There is some evidence of retroviral infection in ALS. A randomized, double-blind, placebo-controlled trial of indinavir in ALS was performed to assess safety and efficacy trends. Nephrolithiasis and gastrointestinal side effects were frequent with indinavir treatment. Group differences in the rate of decline were not significant between the groups for the ALS Functional Rating Scale (p = 0.36) or for the secondary variables. The toxicity and negative efficacy trends discourage further indinavir trials in ALS.

Postexposure Prophylaxis After Sexual Assaults: A Prospective Cohort Study

OBJECTIVE

The objective of this study was to evaluate HIV postexposure prophylaxis (PEP) protocol in rape victims.

STUDY

The victims were assigned to 1 of 3 categories, according to the severity of exposure (I-low, II-moderate, III-high). HIV PEP was provided to victims in groups II (Zdv + 3TC) and III (Zdv + 3TC + PI) until 72 hours after exposure. The follow-up was 6 months.

RESULTS

From May 1997 to October 2001, 347 victims were attended. PEP was offered to 278 victims (141 in group II and 137 in group III). Side effects were more common in group III (P <0.01). No seroconversion was diagnosed in the 180 victims that completed the follow-up. Univariate analysis showed that the schooling level, knowledge of the aggressor's HIV status, and the use of PEP were associated with compliance.

CONCLUSIONS

Triple therapy was associated with side effects, which suggested that drug regimes should be reviewed. The variables related to a high risk of HIV transmission were also significant for compliance.

In vitro and in vivo prevention of HIV protease inhibitor-induced insulin resistance by a novel small molecule insulin receptor activator

Protease inhibitor (PI) therapy for the treatment of patients infected with human immunodeficiency virus is frequently associated with insulin resistance and diabetic complications. These adverse effects of PI treatment result to a large extent from their inhibition of insulin-stimulated glucose transport. Insulin receptor (IR) activators that enhance the insulin signaling pathway could be effective in treating this resistance. However, there are no agents reported that reverse inhibition of insulin action by PIs. Herein, we describe the effects of TLK19781. This compound is a non-peptide, small molecule, activator of the IR. We now report in cultured cells, made insulin resistant HIV by PI treatment, that TLK19781 both increased the content of insulin-stimulated GLUT4 at the plasma membrane, and enhanced insulin-stimulated glucose transport. In addition, oral administration of TLK19781 with the PI, indinavir improved glucose tolerance in rats made insulin resistant. These results suggest, therefore, that IR activators such as TLK19781 may be useful in treating the insulin resistance associated with PIs.

Dose reduction for the management of indinavir-related toxicity in human immunodeficiency virus type 1-infected patients in Taiwan: clinical and pharmacokinetic assessment

This study evaluated the feasibility of reducing the indinavir (IDV) dosage in Taiwanese patients receiving the standard IDV/ritonavir (RTV) dosage of 800/100 mg twice a day who had undetectable plasma human immunodeficiency virus type 1 (HIV-1) RNA but had developed IDV-related toxicities. After dosage reduction to IDV/RTV 600/100 mg twice a day, the dose-related toxicity decreased and plasma HIV RNA remained undetectable at 24 weeks post-switch in all patients. The maximal plasma concentration (Cmax) and area under the plasma concentration-time curve of IDV decreased significantly (median, 6.3 vs 4.3 microg/mL and 1892 vs 1292 microg.min/mL, p=0.01 and 0.001, respectively) but the minimal plasma concentration remained at a similar level (median, 1.0 vs 0.8 microg/mL, p=0.12). This study found that the reduction in the dosage of IDV in HIV-1 infected patients receiving the standard IDV/RTV regimen guided by therapeutic drug monitoring decreased the Cmax, dose-related toxicity and medical cost without compromising viral control.

Efficacy and safety of indinavir/ritonavir 400/100 mg twice daily plus two nucleoside analogues in treatment-naive HIV-1-infected patients with CD4+ T-cell counts <200 cells/mm3: 96-week outcomes

OBJECTIVE

To evaluate the efficacy and safety of indinavir/ritonavir 400/100 mg plus stavudine and lamivudine twice daily in antiretroviral-therapy-naive Thai HIV-1-infected patients.

METHODS

This was an open-label, non-randomized single arm study. Antiretroviral-naive patients (n=80) with CD4+ cell count < 200 x 10(6)/l were started on stavudine and lamivudine plus indinavir/ritonavir 400/100 mg twice daily. CD4+ cell count and HIV RNA were determined at week 0, 12, 24, 48 and 96. HIV RNA was measured to a level of 50 copies/ml by RT-PCR assay. Primary analysis was statistically performed as intent to treat. The primary endpoint was the percentage of patients with plasma HIV RNA below 50 copies/ml at week 96.

RESULT

Eighty antiretroviral-therapy-naive patients with median CD4+ cell count 19 x 10(6)/l (range: 2 - 197 x 10(6)/l) and median baseline plasma HIV RNA of 174,000 copies/ml (range 16,800-750,000 copies/ml) were enrolled. In the intent-to-treat analysis at week 96, the proportion of patients with HIV RNA of <50 copies/ml was 68.8% (95% confidence interval [CI]: 68.3-69.3), whereas it was 88.7% (95% CI: 88.1-89.3) in the on-treatment analysis at week 96. The regimen was well tolerated. Hyperglycaemia, hypercholesterolaemia and hypertriglyceridaemia were found in 8.3, 33.3 and 37.0% of the patients, respectively. Treatment was stopped in 18 patients; two from intolerance, two switched therapy, four as a result of serious adverse event-related death, and ten were lost to follow-up.

CONCLUSION

Our study demonstrates that indinavir/ritonavir 400/100 mg plus stavudine and lamivudine twice daily, the least expensive boosted protease inhibitor, appears to be effective and safe up to 96 weeks despite high baseline viraemia and low CD4+ cell count in antiretroviral-naive patients.

Pharmacokinetics of indinavir and ritonavir administered at 667 and 100 milligrams, respectively, every 12 hours compared with indinavir administered at 800 milligrams every 8 hours in human immunodeficiency virus-infected patients

Human immunodeficiency virus (HIV) patients on nucleoside or nucleotide reverse transcriptase inhibitors with HIV RNA at <1,000 copies/ml were randomized in an open-label study to administration of combined indinavir/ritonavir (IDV/RTV) at 667/100 mg every 12 h (q12h) or IDV alone at 800 mg q8h to determine the regimens' pharmacokinetics. On day 14, plasma IDV and RTV levels were determined over 24 h. Noncompartmental pharmacokinetics (minimum concentration of drug in serum [C(min)], area under the concentration-time curve from 0 to 24 h [AUC(0-24)], and maximum concentration of drug in serum [C(max)]) were expressed as geometric mean values with 90% confidence intervals (CI). The primary hypothesis was that the lower bound of the protocol-specified 90% CI for the geometric mean C(min) ratio of the combination compared to IDV alone regimen would be >/=2. Twenty-seven patients were enrolled, and 24 (15 male; average age, 42 years) completed the study. The C(min), AUC(0-24), and C(max) for IDV/RTV compared to IDV alone were 1,511 versus 250 nM, 119,557 versus 77,034 nM . h, and 10,428 versus 10,407 nM, respectively. Corresponding relationships for IDV/RTV compared to IDV alone were a 6.0-fold increase in C(min) (90% CI, 4.0, 9.3), an increase in AUC(0-24) (1.5-fold, 90% CI, 1.2, 2.0), and no increase in C(max). Adverse events were similar and generally mild, with no cases of nephrolithiasis. The geometric mean ratio of IDV C(min) for IDV/RTV compared to IDV was at least 2 by a lower bound of the 90% CI, satisfying the primary hypothesis. The C(max) was not increased, suggesting an IDV/RTV 667/100-mg toxicity profile may be similar to that of unboosted IDV.

Health-related quality of life in HIV patients switching to twice-daily indinavir/ritonavir regimen or continuing with three-times-daily indinavir-based therapy

OBJECTIVE

To evaluate health-related quality of life (HRQoL) changes in patients treated with indinavir three-times daily after switching to a twice-daily indinavir/ritonavir regimen or continuing with the same regimen.

METHODS

Patients on HAART including indinavir three-times-daily with undetectable viral load were randomly assigned to continue with this therapy or to change to a twice-daily indinavir/ritonavir (800/100 mg) regimen. The Medical Outcomes Study HIV Health Survey (MOS-HIV) questionnaire was used as the HRQoL measure.

RESULTS

A total of 118 patients participated in the study, of which 59 (50%) were randomly assigned to continue with the three-times-daily regimen. Patients had a mean age of 39 years and 80% of them were male. At baseline, subjects included in the three-times-daily group presented a significantly greater number of symptoms than subjects in the twice-daily group, but no statistically significant differences were observed in MOS-HIV scores between the groups. In the intention-to-treat (ITT) analysis, a reduction in HRQoL scores was observed in both groups, which was greater in the twice-daily group. In the per protocol analysis, reduction of HRQoL was minimal.

CONCLUSIONS

A HRQoL deterioration, greater in the twice-daily group, was observed in this study in the ITT analysis, while HRQoL remained stable in both groups in patients who continued with and tolerated the allocated regimen.

Population pharmacokinetics of indinavir in patients infected with human immunodeficiency virus

Indinavir is currently used at a fixed dose of 800 mg either three times a day or twice a day in combination with 100 mg of ritonavir. Dosage individualization based on plasma concentration monitoring might, however, be indicated. This study aimed to assess the pharmacokinetic profile of indinavir in patients infected with human immunodeficiency virus to characterize interpatient and intrapatient variability and to build up a Bayesian approach for dosage adaptation. A population analysis was performed with the NONMEM computer program with 569 plasma samples from a cohort of 239 unselected patients receiving indinavir. A one-compartment model with first-order absorption was adapted, and the influences of clinical characteristics on oral clearance (CL) and distribution volume (V) were examined. Predicted average drug exposure and trough and peak concentrations were derived for each patient and correlated with efficacy and toxicity markers. The population estimates of CL were 32.4 liters/h for female and 42.0 liters/h for male patients; oral V was 65.7 liters; and the rate constant of absorption (K(a)) was 1.0 h(-1). CL decreased by 63% with ritonavir intake and was moderately correlated to body weight. Both interpatient variability, best assigned to oral CL (coefficient of variation [CV], 39%) and K(a) (CV, 67%), and intrapatient variability were large (CV, 41%; standard deviation, 670 microg/liter). In conclusion, initial indinavir dosage should be decided according to ritonavir intake and sex, prior to plasma concentration measurements. The high interpatient pharmacokinetic variability represents an argument for therapeutic drug monitoring.

HIV-1 drug resistance in subjects with advanced HIV-1 infection in whom antiretroviral combination therapy is failing: a substudy of AIDS Clinical Trials Group Protocol 388

We evaluated phenotypic and genotypic markers of drug resistance in human immunodeficiency virus type 1 (HIV-1) at the time of virologic failure (VF) in subjects in the AIDS Clinical Trials Group Protocol 388 (ACTG 388) who received lamivudine-zidovudine (or lamivudine-stavudine) and either indinavir, efavirenz-indinavir, or nelfinavir-indinavir. At VF, phenotypically susceptible HIV-1 was found in 55% of subjects in the nelfinavir-indinavir arm, compared with 22% in the indinavir arm (P=.006). Phenotypic resistance to lamivudine was less common in the efavirenz-indinavir arm (33% of subjects; P=.002) and the nelfinavir-indinavir arm (43%; P=.003), compared with the indinavir arm (78%). Isolated phenotypic resistance to efavirenz at VF occurred in HIV-1 recovered from 33% of subjects in the efavirenz-indinavir arm; 24% of the subjects had HIV-1 with both efavirenz and lamivudine resistance. Results of genotypic tests were similar. The lower frequency of resistance in the nelfinavir-indinavir arm likely reflects decreased drug exposure that is due to intolerance, which is consistent with the lower potency and tolerability of this combination in ACTG 388. The lower frequency of lamivudine resistance in the efavirenz-indinavir arm is consistent with reports in other studies of potent regimens. Thus, although dual resistance to efavirenz and lamivudine occurred at VF in the efavirenz-indinavir arm, this risk was relatively low when evaluated in the context of the potency and tolerability of this regimen.

Impact of indinavir on the quality of life in patients with advanced HIV infection treated with zidovudine and lamivudine

OBJECTIVE

In AIDS Clinical Trial Group (ACTG) study 320, triple-combination antiretroviral therapy including indinavir significantly slowed progression to acquired immunodeficiency syndrome or death, compared with treatment with dual nucleoside reverse-transcriptase inhibitors (NRTIs) alone, in zidovudine-experienced patients with advanced human immunodeficiency virus (HIV) infection. We examined the impact of indinavir on quality of life in participants from this study.

METHODS

A total of 1156 protease inhibitor- and lamivudine-naive patients stratified by CD4 cell count (<or=50 and 51-200 cells/mm(3)) were randomized to receive zidovudine (or stavudine) and lamivudine, with or without indinavir. Health-related quality of life was measured using the ACTG QoL601-602 questionnaire, which assesses general health status measured on a visual analogue scale and 8 specific health-related domains. Quality-adjusted survival time was estimated using the visual analogue scale for general health.

RESULTS

Mean changes in general health scores after 24 weeks were +2.9 in the triple-therapy group versus -0.2 in the dual-therapy group (P=.018). By week 24, scores in all specific domains were higher with triple-drug therapy than dual-drug therapy, with statistically significant differences in role function, energy, and pain scores. Benefits of triple-drug therapy were largely confined to patients with CD4 cell counts of <or=50 cells/mm(3). Quality-adjusted survival time did not differ significantly between the 2 treatment groups.

CONCLUSIONS

Triple-drug therapy with indinavir and 2 NRTIs resulted in a significant improvement in general health status after 24 weeks, especially in patients with low CD4 cell counts. Patients receiving triple-drug therapy also had significantly better role function, energy, and pain scores than did patients treated with dual-drug therapy.

[Indinavir urolithiasis in HIV-positive patients. Treatment and prophylaxis]

TARGET

The approximate incidence of indinavir urolithiasis in HIV positive patients receiving the drug is 10%. The exact mechanism of lithogenesis is still unknown. Pure indinavir stones are radiolucent on plane abdominal X-ray or CT scan. Indinavir urolithiasis can be associated with acute unilateral renal colic or severe azotaemia.

MATERIAL AND METHODS

20 HIV patients were treated conservatively by increasing oral fluid intake (urine production of 2 l/day and more), discontinuation of indinavir therapy for 1 week and acidification of urine with l-methionin (urine pH 5,3-5,8). Some patients were additionally treated with endoscopic procedures.

RESULTS

In all patients renal function normalized. Increase of oral fluid intake, especially during the first 2 hours after intake of indinavir and during night prevented recurrence of indinavir urolithiasis.

CONCLUSION

HIV positive patients with renal colic or renal insufficiency and roentgenological absence of radio-opaque stone formations should make the urologist consider indinavir urolithiasis as a possible diagnosis.