Differences in Durability of Treatment with Initial PI-Based Regimens

The durability of virologic response to antiretroviral therapy is dependent on the potency, tolerability, and adherence level of the regimen. In a prospective, nonrandomized cohort study, we compared the treatment outcome of a nelfinavir-based highly active antiretroviral therapy (HAART) regimen with that of an indinavir-based regimen, over 1 year of routine clinical practice. Information was derived from 134 treatment-naïve HIV-1-infected patients initiated on triple therapy with either nelfinavir (n = 44) or indinavir (n = 90). The proportions of patients achieving a virological response were similar between treatment groups (>1 log(10) reduction in HIV RNA at 3 months in 95% of patients taking nelfinavir and 88% taking indinavir; HIV RNA <50 copies/mL after 1 year in 79% and 69% of patients, respectively). Predicting factors for 1-year virological suppression were initial virological response (p =.02) and adherence >90% (p =.0001). Over 90% adherence was achieved in 70% of patients taking nelfinavir compared with 41% of those taking indinavir (p =.01). The probability of remaining on the initial protease inhibitor (PI) after 12 months was 77% in the nelfinavir group and 66% in the indinavir group, with the median time to changing treatment being 519 days and 462 days, respectively. Gastric intolerance and nephritic colic were the most common reasons for changing therapy in the indinavir group. In the clinical setting, HAART based on initial nelfinavir and indinavir therapy was associated with similarly good virological and immunological suppression at 1 year, however, nelfinavir-based treatment was associated with a longer durability, probably due to a better adherence and tolerance pattern.

Pharmacokinetic Interaction Study of Indinavir/Ritonavir and the Enteric-Coated Capsule Formulation of Didanosine in Healthy Volunteers

Didanosine enteric-coated should be taken on an empty stomach, but the once-daily combination of indinavir/ritonavir can be taken with food. Because these drugs are frequently included in 1 regimen, the food effects on the pharmacokinetics were evaluated. This was a randomized, 4-way crossover study of single doses of didanosine enteric-coated 400 mg and indinavir/ritonavir 1200/400 mg in 8 healthy subjects. The following regimens were given: didanosine enteric-coated 2 hours after breakfast (reference regimen A), indinavir/ritonavir with breakfast (reference regimen B), didanosine enteric-coated + indinavir/ritonavir 2 hours after breakfast (test regimen C), and didanosine enteric-coated + indinavir/ritonavir with breakfast (test regimen D). Breakfast was 550 kcal, 28% fat. Blood samples were drawn before and up to 24 hours after ingestion. Statistical comparisons of test regimens C and D with reference regimens A and B were made using the equivalence approach for indinavir and didanosine area under the curve and C(max) (0.80-1.25). Eight subjects (5 men, 3 women) were enrolled and completed the study. Indinavir area under the curves were bioequivalent in test regimens C and D compared to reference regimen B. A 14% increased C(max) was observed in test regimen C. Didanosine area under the curve in test regimen D was 4% lower and suggestive of bioequivalence compared to reference regimen A. However, test regimen C didanosine area under the curve was 23% lower and bioinequivalent compared to reference regimen A. Didanosine C(max) decreased 42% and 46% in test regimens C and D, respectively, in comparison to reference regimen A. In this study, dosing didanosine enteric-coated 400 mg once daily + indinavir/ritonavir 1200/400 mg once daily with breakfast indicated no decrease in the amount of absorption for either didanosine and indinavir and that this regimen could be administered with food.

Impact of short-term HAART initiated during the chronic stage or shortly post-exposure on SIV infection of male genital organs

Background

The male genital tract is suspected to constitute a viral sanctuary as persistent HIV shedding is found in the semen of a subset of HIV-infected men receiving effective antiretroviral therapy (HAART). The origin of this persistent shedding is currently unknown. Phylogenetic studies indicated that HIV in semen from untreated men arises from local sources and/or passive diffusion from the blood. We previously demonstrated in human and macaque low levels and localized infection of several semen-producing organs by HIV/SIV. Using a macaque model, this study investigates the impact of short term HAART (2–4 weeks) initiated either during the asymptomatic chronic stage or 4 h post-intravenous inoculation of SIVmac251 on the infection of male genital organs.

Methodology/Principal Findings

Short term HAART during the chronic stage decreased blood viral load. No major impact of HAART was observed on SIV DNA levels in male genital organs using a sensitive nested PCR assay. Using in situ hybridization, SIV RNA+ cells were detected in all male genital tract organs from untreated and treated animals with undetectable blood viral load following HAART. Infected CD68+ myeloid cells and CD3+ T lymphocytes were detected pre- and post-HAART. In contrast, short term HAART initiated 4 h post-SIV exposure led to a drastic decrease of the male genital tissues infection, although it failed to prevent systemic infection. In both cases, HAART tended to decrease the number of CD3+ T cells in the male organs.

Conclusions

Our results indicate that the established infection of male genital organs is not greatly impacted by short term HAART, whereas the same treatment during pre-acute phase of the infection efficiently impairs viral dissemination to the male genital tract. Further investigations are now needed to determine whether infection of male genital organs is responsible for long term persistent HIV shedding in semen despite HAART.

Impact of the herbal medicine Sophora flavescens on the oral pharmacokinetics of indinavir in rats: the involvement of CYP3A and P-glycoprotein

Sophora flavescens is a Chinese medicinal herb used for the treatment of gastrointestinal hemorrhage, skin diseases, pyretic stranguria and viral hepatitis. In this study the herb-drug interactions between S. flavescens and indinavir, a protease inhibitor for HIV treatment, were evaluated in rats. Concomitant oral administration of Sophora extract (0.158 g/kg or 0.63 g/kg, p.o.) and indinavir (40 mg/kg, p.o.) in rats twice a day for 7 days resulted in a dose-dependent decrease of plasma indinavir concentrations, with 55%-83% decrease in AUC(0-∞) and 38%-78% reduction in C(max). The CL (Clearance)/F (fraction of dose available in the systemic circulation) increased up to 7.4-fold in Sophora-treated rats. Oxymatrine treatment (45 mg/kg, p.o.) also decreased indinavir concentrations, while the ethyl acetate fraction of Sophora extract had no effect. Urinary indinavir (24-h) was reduced, while the fraction of indinavir in faeces was increased after Sophora treatment. Compared to the controls, multiple dosing of Sophora extract elevated both mRNA and protein levels of P-gp in the small intestine and liver. In addition, Sophora treatment increased intestinal and hepatic mRNA expression of CYP3A1, but had less effect on CYP3A2 expression. Although protein levels of CYP3A1 and CYP3A2 were not altered by Sophora treatment, hepatic CYP3A activity increased in the Sophora-treated rats. All available data demonstrated that Sophora flavescens reduced plasma indinavir concentration after multiple concomitant doses, possibly through hepatic CYP3A activity and induction of intestinal and hepatic P-gp. The animal study would be useful for predicting potential interactions between natural products and oral pharmaceutics and understanding the mechanisms prior to human studies. Results in the current study suggest that patients using indinavir might be cautioned in the use of S. flavescens extract or Sophora-derived products.

Pharmacokinetics of indinavir in Koreans and Caucasians

We evaluated whether the pharmacokinetic parameters of indinavir differ in Koreans and Caucasians. Indinavir was administered orally to 8 healthy Koreans and 4 healthy Caucasians, and plasma indinavir levels were quantified by high performance liquid chromatography. No significant differences were observed in terms of its pharmacokinetic parameters; however, the AUC difference between the 2 groups may be significant for larger sample sizes.

Improved pharmacokinetic and bioavailability support of drug discovery using serial blood sampling in mice

Pharmacokinetic studies in mice traditionally require one animal per time point, resulting in dosing and euthanizing a large number of animals and producing suboptimal quality of pharmacokinetic data due to inter-animal variability and dosing error. These studies are time-consuming and labor-intensive. To improve the throughput and quality of pharmacokinetic evaluation in mice, we have developed a serial blood sampling methodology using the lateral saphenous vein puncture technique. Two marketed drugs, indinavir and rosuvastatin, were selected for this validation study because of their distinctly different physicochemical and pharmacokinetic properties. Each compound was dosed orally and intravenously in mice using both discrete and serial blood sampling methods. The pharmacokinetic results from serial bleeding are in excellent agreement with those from discrete sampling for both compounds. Compared to the discrete sampling, the serial sampling procedure is a more humane method, allowing for rapid and repeated sampling from the same site without the need for anesthesia. The application of this new method has led to a remarkable reduction in animal and compound usage, a significant increase in throughput and speed, and a drastic improvement in pharmacokinetic data quality. This approach is especially useful for the first-tier in vivo pharmacokinetic screening of discovery compounds.

Indinavir-loaded pH-sensitive microparticles for taste masking: toward extemporaneous pediatric anti-HIV/AIDS liquid formulations with improved patient compliance

The aim of this work was to develop indinavir pediatric anti-HIV/AIDS formulations enabling convenient dose adjustment, ease of oral administration, and improved organoleptic properties by means of the generation of drug-loaded microparticles made of a polymer that is insoluble under intake conditions and dissolves fast in the stomach in order to completely release the active agent. Indinavir-loaded microparticles made of a pH-dependent polymeric excipient soluble at pH < 5, Eudragit E100, were prepared using a double emulsion solvent diffusion technique and the in vitro release profiles characterized. Finally, taste masking properties were evaluated in blind randomized sensory experiments by ten healthy human volunteers. The use of a w/o/o emulsion system resulted in indinavir loads around 90%. Thermal analysis of the microparticles by differential scanning calorimetry revealed that indinavir appeared mainly dispersed at the molecular level. Concentrations of residual organic solvents as determined by gas chromatography were below the upper limits specified by the European Pharmacopeia for pharmaceutical oral formulations. Then, the behavior of drug-containing microparticles in aqueous media at different pH values was assessed. While they selectively dissolved in gastric-like medium, in tap water (intake conditions), the matrix remained almost unchanged and efficiently prevented drug dissolution. Finally, sensoring taste tests performed by volunteers indicated that systems with indinavir loads approximately 15% displayed acceptable taste. This work explored the production of indinavir-containing microparticles based on a common pharmaceutical excipient as a means for the improvement of medicines of drugs involved in the treatment of HIV/AIDS. For systems containing about 15% drug, taste studies confirmed the acceptability of the formulation. In pediatric regimes, this composition would require an acceptable amount of formulation (0.7-1.5 g).

pH-dependent interactions of indinavir and lipids in nanoparticles and their ability to entrap a solute

We have investigated the ability of lipid-indinavir particles composed of 3-to-1 lipid-drug molar ratio to encapsulate an aqueous marker calcein and anti-HIV drug (3)H-phosphonylmethoxypropyl-adenine (PMPA). Even at a high density of indinavir associated to lipid-indinavir nanoparticles, they form an enclosed lipid membrane that allows encapsulation of calcein and PMPA in an aqueous compartment. At neutral pH, practically all indinavir was incorporated into lipid bilayer and lipid associated indinavir can be dissociated with half-maximum pH recorded between 5.2 and 5.5. pH-Dependent release of indinavir did not influence calcein release significantly. However, pH-dependent release of indinavir affected PMPA release. By lowering pH, PMPA release was enhanced in the presence of indinavir in the lipid bilayer. Collectively, these data indicate that indinavir incorporated in lipid particles provides (1) stable bilayers capable of encapsulating other hydrophilic drugs, (2) ability to dissociate indinavir (which is acid stable) from lipid membranes, by lowering the pH, and (3) enabling enhancement in pH-dependent release of aqueous contents. However, the degree of pH-dependent release could be related to the charge and size of an aqueous molecule.

Antiretroviral drug dosing errors in HIV-infected patients undergoing hemodialysis

BACKGROUND

Several studies have revealed the frequency of antiretroviral (ARV) drug prescription errors. We analyzed highly active antiretroviral therapy (HAART) prescribing practices for human immunodeficiency virus (HIV)-infected patients undergoing hemodialysis in France.

METHODS

Prescribed ARV drug doses in our cohort (consisting of all HIV-infected patients who underwent hemodialysis from 1 January 2002 and were prospectively followed up until 1 January 2004) were compared with the recommended doses for patients undergoing hemodialysis. The log-rank test was used to compare the outcomes among different groups of treated patients.

RESULTS

One hundred seven of the 129 patients in our cohort received a total of 317 ARV drugs, 59% of which were improperly prescribed. The dosing was too low for 18% of the patients and too high for 39% of the patients. Twenty-eight patients (26%) did not receive any of their ARV drugs at the recommended dose. The lowest prescribed dose (8% of the daily recommended dose) was observed with indinavir and zidovudine, and the highest prescribed dose (1000% of the recommended dose) was observed with stavudine. Among patients who received HAART, those who were prescribed an insufficient dose of a protease inhibitor had more-severe HIV disease and worse 2-year survival than did the other patients (mean rate of survival+/-standard deviation, 79.5%+/-7.5% vs. 95.4%+/-2.6%, respectively; P<.02). For dialyzable ARV drugs, the delay between ARV drug receipt by the patients and dialysis sessions was not respected in 9% of cases, and in 73% of cases, it was not known whether the patients took the ARV drugs before or after dialysis sessions.

CONCLUSION

This is, to our knowledge, the first study to show a significant association between ARV drug prescription errors and survival in patients undergoing dialysis.

Maintenance of indinavir by dose adjustment in HIV-1-infected patients with indinavir-related toxicity

OBJECTIVE

Treatment with indinavir/ritonavir (IDV/RTV) is very effective but hampered by frequent development of IDV-associated adverse events (mainly nephrotoxicity and skin changes). We tested whether dose reduction of IDV guided by therapeutic drug monitoring resulted in improved tolerability without compromising antiviral efficacy.

PATIENTS

HIV-infected patients with any IDV/RTV regimen who suffer from IDV-related adverse events were included. Viral load had to be adequately controlled for at least 2 months prior to inclusion. Dose reduction from 800 mg to 600 or 400 mg IDV b.i.d. followed a specified protocol. IDV-related toxicity and IDV plasma concentrations were monitored for 24 weeks. IDV concentrations were quantified with a validated high performance liquid chromatography method.

RESULTS

Twenty patients were included. Reasons for inclusion were: skin abnormalities 11, nephrotoxicity five, metabolic disturbances three, and hypertension one. IDV dose could be lowered to 400 mg b.i.d. in 13, to 600 mg b.i.d. in two patients. Five patients discontinued the treatment. Overall tolerability improved with respect to incidence and severity of adverse events. Median trough concentrations decreased from 1.02 mg/l (range 0.08-7.1) at baseline to 0.48 mg/l (0.11-1.4) after 24 weeks (p = 0.03) and remained above the critical threshold of 0.1 mg/l at any time after dose reduction. There was no change of CD4 cell counts or viral suppression. There were no significant changes in other laboratory parameters (creatinine, bilirubin, triglycerides, cholesterol, blood count, and urinalysis).

CONCLUSION

Dose reduction of IDV improved tolerability of IDV-containing highly active antiretroviral treatment (HAART). Sufficient IDV trough concentrations were maintained in all patients as was virologic control.

Less sensitive HIV-1 enzyme immunoassay as an adjuvant method for monitoring patients receiving antiretroviral therapy

Viral suppression after antiretroviral therapy is monitored by determining plasma HIV-1 through viral load assays. However, such assays only provide HIV-1 replication rates at the moment samples are drawn and do not reflect any trend in viremia fluctuation preceding sample collection. The objective of this study was to correlate the optical density (OD) of the less sensitive HIV-1 enzyme immunoassay (EIA), used in the serologic testing algorithm for recent HIV seroconversion, with viral loads in a group of HIV-infected patients on antiretroviral therapy. We studied samples from 20 previously antiretroviral-naive subjects treated with the zidovudine-lamivudine combination plus indinavir for a 20-week period. Viral loads were assessed using the less sensitive HIV-1 EIA at baseline and at 4-week intervals. There was a strong correlation between lower OD and viral load after introduction of antiretroviral drugs (p < 0.01). The ODs tended to decrease in parallel with drops in viral loads and remain steady when viral loads did not change significantly. These results suggest that the less sensitive HIV-1 EIA may be used as a complementary method for monitoring the efficacy of antiretroviral therapy, with special appeal in resource-poor areas where health professionals have limited laboratory expertise.

Efficacy and plasma concentrations of indinavir when boosted with ritonavir in human immunodeficiency virus-infected Thai children

We evaluated 19 children using 220-300 mg/m of indinavir (IDV) boosted with 100 mg ritonavir (RTV) (n = 12) or full-dose RTV (n = 7). Geometric mean (GM) (90% confidence interval, CI) of IDV Ctrough in children who took IDV with 100 mg RTV (n = 12) was 0.17 (0.06-0.50) mg/L. For children who took IDV with full-dosage RTV, GM (90% CI) was 0.40 (0.10-1.61) mg/L. C2hours were less than 10 mg/L in all subjects. Eighteen children had good virologic response. This report demonstrates that smaller IDV dosages given with RTV provide efficacious plasma concentrations and can be safely used.

Morphological and biochemical appraisal of the liver and renal effects of indinavir on rat pregnancy

Since indinavir is currently used in combination with other antiretroviral agents, there is a scarcity of studies in the literature on its single-drug perinatal safety. Thus, we decided to examine the gross maternal and fetal effects of indinavir administered alone during the entire period of rat pregnancy. Forty pregnant animals were assigned at random to four groups (C = control) treated with the drug vehicle (distilled water); the experimental groups were treated with indinavir as follows: E1 = 40 mg/kg; E2 = 120 mg/kg; E3 = 360 mg/kg from "zero" up to the 20th day of gestation. Drug or vehicle were administered daily by gavage. Each group consisted of ten animals. At term-pregnancy, the rats were deeply anesthetized and blood samples were collected for alanine aminotransferase (ALT) and aspartate aminotransferase (AST), creatinine and urea determinations. Fragments of maternal and fetal livers and kidneys were taken and routinely processed for histopathological study. Serum ALT activity in the E2 group was significantly higher (p < 0.01) than that of the other groups. The concentration of creatinine in blood was lower in the E2 and E3 groups than in group E1 (p < 0.01), whereas blood urea in group E3 was significantly lower than in the other groups (p < 0.01). Morphological (light microscopy) studies revealed that no significant effects of the drug could be detected regarding either maternal or fetal organs of the E1 and E2 groups. However, the maternal hepatocytes in the E3 group showed heterochromatic nuclei. In addition, there was some fatty infiltration, congested sinusoids and portal dilation. Maternal kidneys in the E2 and E3 groups revealed vascular dilation around the convoluted tubules. Regarding the biochemical determinations, the alterations observed were mild, without biological relevance, thus indicating that the treatment with indinavir during the entire gestation was essentially devoid of hepatic or renal effects which could result in altered metabolic parameters. It is concluded that indinavir was well tolerated in therapeutic and even in 9-fold higher doses. Notwithstanding, discrete morphological alterations occurred in the maternal compartment, but with no functional expression that could indicate deleterious effects on mothers and/or fetuses.

Improving data reliability using a non-compliance detection method versus using pharmacokinetic criteria

Data from clinical trials present numerous problems for the data analyst. These include non-compliance with the prescribed dosing regimen and inaccurate recollection of dosing history by patients as well as mistakes in recording data. Several methods have been proposed to address these issues. One such technique by Lu et al. (Selecting reliable pharmacokinetic data for explanatory analyses of clinical trials in the presence of possible noncompliance. J. Pharmacokinet. Pharmacodyn. 28:343-362 (2001)) identifies occasions in pharmacokinetic (PK) data where the preceding dosing history is likely to be unreliable. We used this method, implemented in the software program NONMEM (beta) VI, to clean a dataset containing indinavir (IDV) plasma concentrations from HIV-1 infected patients. The data was also cleaned by inspection in Microsoft Excel using clinical PK criteria. A one-compartment model with first order absorption and elimination was fit to both sets of cleaned data. IDV population PK parameters obtained from these analyses were similar to those reported previously. It is established that IDV nephrotoxicity is related to high IDV exposure. However, no relationships were found between any PK parameters and nephrotoxicity in the "compliance cleaned" dataset. In the "PK cleaned" dataset, the oral clearance and apparent volume were lower by 9.1% and 6.6%, respectively in patients with any type of nephrotoxicity and the maximum IDV concentration (C(max)) was 12.1% higher. In patients suffering from nephrolithiasis in particular, C(max) was 15.5% higher. Accordingly, the use of the non-compliance detection method did not improve the reliability of our dataset over the usual method of applying clinical criteria. In fact, analyses on the compliance-cleaned dataset missed some exposure-toxicity relationships. Thus, automated methods must be tested rigorously with 'real life' datasets, used with caution, and always in conjunction with clinical reasoning to avoid overlooking a signal in noisy data.

Pharmacogenetic characteristics of indinavir, zidovudine, and lamivudine therapy in HIV-infected adults: a pilot study

OBJECTIVE

The aim of the study was to investigate relationships among indinavir, lamivudine-triphosphate, and zidovudine-triphosphate pharmacokinetics and pharmacodynamics with polymorphisms in CYP3A5, MDR1, MRP2, MRP4, BCRP, and UGT1A1 genes.

STUDY DESIGN

Retrospective pilot investigation among 33 subjects who participated in a randomized pharmacological study of indinavir, lamivudine, and zidovudine. Subjects were defined as genetic variant carriers or not. Relationships were investigated with multivariable regression. Indinavir clearance was adjusted for African American race; triphosphates for sex; and HIV-response for study arm, drug exposure, and baseline HIV-RNA.

RESULTS

Genetically determined CYP3A5 expressors had 44% faster indinavir oral clearance versus nonexpressors (P = 0.002). MRP2-24C/T variant carriers had 24% faster indinavir oral clearance (P = 0.05). Lamivudine-triphosphate concentrations were elevated 20% in MRP4 T4131G variant carriers (P = 0.004). A trend for elevated zidovudine-triphosphates was observed in MRP4 G3724A variant carriers (P = 0.06). The log10 changes in HIV-RNA from baseline to week 52 were -3.7 for MDR1 2677 TT, -3.2 for GT, and -2.2 for GG (P < 0.05). Bilirubin increases were 2-fold higher in UGT1A1 [TA]7/[TA]7 genotypes. No relationships were identified with BCRP.

DISCUSSION

Novel relationships were identified among genetic variants in drug transporters and indinavir, lamivudine-triphosphate, and zidovudine-triphosphate concentrations. CYP3A5 expression was associated with faster indinavir oral clearance. These pilot data provide a scientific basis for more rational utilization of antiretroviral drugs.

Devenir à long terme d'un cas de périartérite noueuse cérébrale associée au VIH

INTRODUCTION

HIV-associated vasculitis is an infrequent entity, and only few data about its long-term evolution is available.

EXEGESIS

We report the long-term outcome of a patient with central nervous system HIV-associated periarteritis nodosa and then discuss the therapeutic options for this class of vasculitis.

CONCLUSION

This observation highlights the role of HAART in the treatment of HIV-associated vasculitis. Persistent remission can be obtained when viral replication is under control.

Feasibility of Weekly HIV Drug Delivery to Enhance Drug Localization in Lymphoid Tissues Based on Pharmacokinetic Models of Lipid-Associated Indinavir

PURPOSE

Compare the simulated pharmacokinetics of lipid-associated and soluble indinavir (IDV) to determine the potential for greater control of virus replication in the lymphoid tissues.

METHODS

Two-compartment mathematical models were developed to simulate the human pharmacokinetics of soluble and lipid-associated forms of IDV in the central compartment and the lymphoid tissue. The lipid-associated IDV model was then used to determine the minimum dosing schedule needed to attain central or lymph drug concentrations comparable to the soluble form.

RESULTS

Association of IDV to lipid nanoparticles has a favorable half-life and tissue distribution and allows comparable minimum drug concentration in the lymph (where the majority of viral replication occurs) to be achieved with a dosing schedule of every 95.5 h (approximately 4 days).

CONCLUSIONS

Presuming pharmacodynamics of lipid-associated IDV are similar to soluble IDV, estimations based on the proposed kinetic model suggest the novel delivery system could have a tremendous impact on the current standard of HIV treatment, particularly for therapy targeted to clear virus sanctuaries in lymphoid tissues. With less frequent and more effective dosing, lipid-associated indinavir delivery as an adjunct to conventional antiviral therapy could lead to better suppression of viral replication, increased immunological benefit, and fewer treatment failures.

Development of a macrophage-based nanoparticle platform for antiretroviral drug delivery

Complex dosing regimens, costs, side effects, biodistribution limitations, and variable drug pharmacokinetic patterns have affected the long-term efficacy of antiretroviral medicines. To address these problems, a nanoparticle indinavir (NP-IDV) formulation packaged into carrier bone marrow-derived macrophages (BMMs) was developed. Drug distribution and disease outcomes were assessed in immune-competent and human immunodeficiency virus type 1 (HIV-1)-infected humanized immune-deficient mice, respectively. In the former, NP-IDV formulation contained within BMMs was adoptively transferred. After a single administration, single-photon emission computed tomography, histology, and reverse-phase-high-performance liquid chromatography (RP-HPLC) demonstrated robust lung, liver, and spleen BMMs and drug distribution. Tissue and sera IDV levels were greater than or equal to 50 microM for 2 weeks. NP-IDV-BMMs administered to HIV-1-challenged humanized mice revealed reduced numbers of virus-infected cells in plasma, lymph nodes, spleen, liver, and lung, as well as, CD4(+) T-cell protection. We conclude that a single dose of NP-IDV, using BMMs as a carrier, is effective and warrants consideration for human testing.

Association of total bilirubin with indinavir and lopinavir plasma concentrations in HIV-infected patients receiving three different double-boosted dosing regimens

OBJECTIVES

The purpose of this study was to determine the pharmacokinetics and tolerability of three different indinavir and lopinavir/ritonavir dosing regimens.

METHODS

HIV-infected adults receiving lopinavir/ritonavir 400/100 mg twice daily with food had nine plasma samples taken over a 12 h dosing interval at baseline (BL), after adding indinavir 600 mg twice daily for 10 days (R1), indinavir 800 mg twice daily for 5 days (R2) and lopinavir/ritonavir 533/133 mg plus indinavir 600 mg twice daily for 10 days (R3). Plasma samples were assayed using HPLC.

RESULTS

A total of 12 patients completed the BL visit [10 male; mean (SD) age=43.9 (5.8) years] and 9, 7 and 7 completed R1, R2 and R3 visits, respectively. Two subjects discontinued treatment due to hypertriglyceridaemia. Compared with BL, the R3 lopinavir AUC (P<0.05) and Cmin (P=0.0025) were significantly higher and the R2 AUC trended higher (P=0.09). The indinavir AUC (P=0.030) and Cmax (P=0.035) were significantly higher for R2 compared with R1. There was a trend for increased total bilirubin (TB) after the addition of indinavir (P=0.09). Lopinavir and indinavir AUC, Cmax and Cmin were associated with TB during univariate analyses (P<0.01) while only lopinavir AUC (P=0.0004) and indinavir AUC (P=0.0028) were associated with TB during multivariate analysis. Only indinavir AUC was significant when both drugs were included in the model (P=0.0028).

CONCLUSIONS

Elevated lopinavir and indinavir concentrations are associated with elevated TB.

The use of pharmacokinetically guided indinavir dose reductions in the management of indinavir-associated renal toxicity

OBJECTIVES

Indinavir is associated with nephrotoxicity. Therapeutic drug monitoring of indinavir improves clinical outcome, but there is little data regarding therapeutic drug monitoring for patients with established indinavir-associated renal impairment. We prospectively studied the use of therapeutic drug monitoring in patients with virological success but established nephrotoxicity on an indinavir-containing regimen.

METHODS

We measured indinavir C(trough)/C(2h), serum creatinine, pyuria, blood pressure (BP), weight and HIV RNA. The major endpoint of interest was the number of patients achieving a normal creatinine level 20 weeks following final indinavir dose adjustment. Primary analysis was by intention to treat (ITT).

RESULTS

A total of 35 patients were enrolled; mean (SD) age 40.3 (5.8) years; mean (SD) BMI 21.5 (2.8) kg/m(2). At baseline 6/35 (17%) had a serum creatinine concentration within normal limits, but were offered enrolment because of previous nephrotoxicity (nephrolithiasis and/or abnormal serum creatinine), and a screening pharmacokinetic profile associated with increased nephrotoxicity risk. By ITT analysis 11/35 (31%) had normal creatinine at study end (P = 0.18). Of the 29 patients with abnormal creatinine at baseline, 7/29 (24.1%) had normal creatinine at study end (P = 0.016). Patients had a median (IQR) indinavir per dose adjustment over the study of 400 (400-800) mg. We observed improvements in estimated creatinine clearance, pyuria, resting BP and indinavir pharmacokinetic profile. HIV RNA control was maintained with continued immune recovery despite lower indinavir doses.

CONCLUSIONS

Patients experiencing nephrotoxicity on an indinavir-containing regimen were safely maintained on indinavir by means of therapeutic drug monitoring. Parameters of renal function improved but did not return to baseline values, at least in the short-term.

Pharmacodynamics of Antiretroviral Agents in HIV-1 Infected Patients: Using Viral Dynamic Models that Incorporate Drug Susceptibility and Adherence

We developed a novel HIV-1 dynamic model with consideration of pharmacokinetics, drug adherence and drug susceptibility to link plasma drug concentration to the long-term changes in HIV-1 RNA observation after initiation of therapy. A Bayesian approach is proposed to fit this model to clinical data from ACTG A5055, a study of two dosage regimens of indinavir (IDV) with ritonavir (RTV) in subjects failing their first protease inhibitor treatment. The HIV RNA testing was completed at days 0, 7, 14, 28, 56, 84, 112, 140, and 168. An intensive pharmacokinetic (PK) evaluation was performed on day 14 and multiple trough concentrations were subsequently collected. Pill counts were used to monitor adherence. IC(50) for IDV and RTV were determined at baseline and at virologic failure. Viral dynamic model fitting residuals were used to assess the significance of covariate effects on long-term virologic response. As univariate predictors, none of the four PK parameters C(trough), C(12 hour), C(max), and AUC was significantly related to virologic response (p > 0.05). By including drug susceptibility (IC(50)), or IC(50) and adherence measured by pill counts together, C(trough), C(12 hour), C(max) and AUC were each significantly correlated to long-term virologic response (p = 0.0055,0.0002,0.0136,0.0002 with IC(50) and adherence measured by pill counts considered). The IC(50) and adherence measured by pill counts alone were not related to the virologic response. In predicting virologic response adherence measured by pill counts did not provide any additional information to PK parameters (p = 0.064), to drug susceptibility IC(50) (p = 0.086), and to their combination (p = 0.22). Simple regression approaches did not detect any significant pharmacodynamic (PD) relationships. Any single factor of PK, adherence measured by pill counts and drug susceptibility did not contribute to long-term virologic response. But their combinations in viral dynamic modeling significantly predicted virologic response. The HIV dynamic modeling can appropriately capture complicated nonlinear relationships and interactions among multiple covariates.

Response to

In HIV-infected persons on highly active antiretroviral therapy, residual virus is found in lymphoid tissues. Indinavir concentrations in lymph node mononuclear cells of patients on highly active antiretroviral therapy were approximately 25% to 35% of those in blood mononuclear cells, suggesting that drug insufficiency contributes to residual virus in lymphoid tissues. Therefore, we developed novel lipid-indinavir nanoparticles targeted to lymphoid tissues. Given subcutaneously, these nanoparticles provided indinavir concentrations 250% to 2270% higher than plasma indinavir concentrations in both peripheral and visceral lymph nodes. Improved indinavir delivery was reflected in reduced viral RNA and CD4(+) T-cell rebound. This study optimized lipid nanoparticle formulation with respect to indinavir in lymphoid tissues of HIV-infected macaques. Regardless of lipid characteristic tested (charge, fluidity, and steric modification), indinavir binds completely to lipid at pH 7.4 but is reversed at pH 5.5 or lower. Compared with previous formulations, nanoparticles composed of disteroyl phosphatidylcholine and methyl polyethylene glycol-disteroyl phosphatidylethanolamine (DSPC:mPEG-DSPE) provided 6-fold higher indinavir levels in lymph nodes and enhanced drug exposure in blood. Enhanced anti-HIV activity paralleled improved intracellular drug accumulation. Collectively, these data suggest that indinavir nanoparticles composed of DSPC:mPEG-DSPE provided the most effective lymphoid delivery and could maximally suppress the virus in lymphoid tissues.

Population pharmacokinetics of indinavir alone and in combination with ritonavir in HIV-1-infected patients

AIMS

The aim of the study was to characterize the population pharmacokinetics of indinavir, define the relationship between the pharmacokinetics of indinavir and ritonavir, and to identify the factors influencing the pharmacokinetics of indinavir alone or when given with ritonavir.

METHODS

HIV-1-infected patients being treated with an indinavir-containing regimen were included. During regular visits, 102 blood samples were collected for the determination of plasma indinavir and ritonavir concentrations. Full pharmacokinetic curves were available from 45 patients. Concentrations of indinavir and ritonavir were determined by liquid chromatography coupled with electrospray tandem mass spectrometry. Pharmacokinetic analysis was performed using nonlinear mixed effect modelling (NONMEM).

RESULTS

The disposition of indinavir was best described by a single compartment model with first order absorption and elimination. Values for the clearance, volume of distribution and the absorption rate constant were 46.8 l h(-1) (24.2% IIV), 82.3 l (24.6% IIV) and 02.62 h(-1), respectively. An absorption lag-time of 0.485 h was detected in patients also taking ritonavir. Furthermore this drug, independent of dose (100-400 mg) or plasma concentration, decreased the clearance of indinavir by 64.6%. In contrast, co-administration of efavirenz or nevirapine increased the clearance of indinavir by 41%, irrespective of the presence or absence of ritonavir. Female patients had a 48% higher apparent bioavailability of indinavir than males.

CONCLUSIONS

The pharmacokinetic parameters of indinavir were adequately described by our population model. Female gender and concomitant use of ritonavir and non-nucleoside reverse transcriptase inhibitors strongly influenced the pharmacokinetics of this drug. The results support the concept of ritonavir boosting, maximum inhibition of indinavir metabolized being observed at 100 mg.

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.