Indinavir: a review of its use in the management of HIV infection

In Silico Drug Repurposing Studies for the Discovery of Novel Salicyl-AMP Ligase (MbtA)Inhibitors

Tuberculosis (TB) continues to pose a global health challenge, exacerbated by the rise of drug-resistant strains. The development of new TB therapies is an arduous and time-consuming process. To expedite the discovery of effective treatments, computational structure-based drug repurposing has emerged as a promising strategy. From this perspective, conditionally essential targets present a valuable opportunity, and the mycobactin biosynthesis pathway stands out as a prime example highlighting the intricate response of Mycobacterium tuberculosis (Mtb) to changes in iron availability. This study focuses on the repurposing and revival of FDA-approved drugs (library) as potential inhibitors of MbtA, a crucial enzyme in mycobactin biosynthesis in Mtb conserved among all species of mycobacteria. The literature suggests this pathway to be associated with drug efflux pumps, which potentially contribute to drug resistance. This makes it a potential target for antitubercular drug discovery. Herein, we utilized cheminformatics and structure-based drug repurposing approaches, viz., molecular docking, dynamics, and PCA analysis, to decode the intermolecular interactions and binding affinity of the FDA-reported molecules against MbtA. Virtual screening revealed ten molecules with significant binding affinities and interactions with MbtA. These drugs, originally designed for different therapeutic indications (four antiviral, three anticancer, one CYP450 inhibitor, one ACE inhibitor, and one leukotriene antagonist), were repurposed as potential MbtA inhibitors. Furthermore, our study explores the binding modes and interactions between these drugs and MbtA, shedding light on the structural basis of their inhibitory potential. Principal component analysis highlighted significant motions in MbtA-bound ligands, emphasizing the stability of the top protein-ligand complexes (PLCs). This computational approach provides a swift and cost-effective method for identifying new MbtA inhibitors, which can subsequently undergo validation through experimental assays. This streamlined process is facilitated by the fact that these compounds are already FDA-approved and have established safety and efficacy profiles. This study has the potential to lay the groundwork for addressing the urgent global health challenge at hand, specifically in the context of combating antimicrobial resistance (AMR) and tuberculosis (TB).

Site-Selective Amide Functionalization by Catalytic Azoline Engrafting

Direct peptide and protein activation is a challenging transformation because of the stabilizing effect of the amide group. While enzymes can be considered as prototypical systems that have evolved to achieve high selectivity and specificity, small-molecule catalysts that functionalize the amide group may accommodate a much larger selection of substrates but currently remain scarce. Here, by combining the desired features from both catalytic regimes we designed an artificial cyclodehydratase, a catalytic system for the site-selective modification of peptides and natural products by engrafting heterocycles into their scaffolds. The catalytic system features a molybdenum(VI) center that was decorated with a sterically congested tripod ligand. The optimized catalyst can introduce azolines into small molecules, natural products, and oligopeptides with high efficiency and minimal waste. We further demonstrate the utility of the new protocol in the direct functionalization of a single amide group in the presence of up to seven other chemically similar positions and in the direct conversion of these groups into amines and thioamides. This new mechanistic paradigm may address an unmet need for a general method for the selective and sustainable functionalization of peptides and natural products.

Identification of Hypericin as a Candidate Repurposed Therapeutic Agent for COVID-19 and Its Potential Anti-SARS-CoV-2 Activity

The COVID-19 pandemic has had an unprecedented impact on the global economy and public health. Its etiologic agent, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly transmissible, pathogenic and has a rapid global spread. Currently, the increase in the number of new confirmed cases has been slowed down due to the increase of vaccination in some regions of the world. Still, the rise of new variants has influenced the detection of additional waves of rising cases that some countries have experienced. Since the virus replication cycle is composed of many distinct stages, some viral proteins related to them, as the main-protease (Mpro) and RNA dependent RNA polymerase (RdRp), constitute individual potential antiviral targets. In this study, we challenged the mentioned enzymes against compounds pre-approved by health regulatory agencies in a virtual screening and later in Molecular Mechanics/Poisson–Bolzmann Surface Area (MM/PBSA) analysis. Our results showed that, among the identified potential drugs with anti-SARS-CoV-2 properties, Hypericin, an important component of the Hypericum perforatum that presents antiviral and antitumoral properties, binds with high affinity to viral Mpro and RdRp. Furthermore, we evaluated the activity of Hypericin anti-SARS-CoV-2 replication in an in vitro model of Vero-E6 infected cells. Therefore, we show that Hypericin inhibited viral replication in a dose dependent manner. Moreover, the cytotoxicity of the compound, in cultured cells, was evaluated, but no significant activity was found. Thus, the results observed in this study indicate that Hypericin is an excellent candidate for repurposing for the treatment of COVID-19, with possible inhibition of two important phases of virus maturation.

Reconstruction of the binding pathway of an anti-HIV drug, Indinavir, in complex with the HTLV-1 protease using unaggregated unbiased molecular dynamics simulation

Retroviruses are a growing concern for the health of human beings, and one of the dangerous members of this family is the Human T-cell Leukemia Virus 1 (HTLV-1) virus. It has affected more than 20 million people so far, and since there are no registered treatments against it yet, urgent treatment solutions are needed. One of the most promising drug targets to fight this virus is the protease enzyme of the virus's protein machinery. In this study, by utilizing a computational method called Unaggregated Unbiased Molecular Dynamics (UUMD), we reconstructed the binding pathway of a HTLV-1 protease inhibitor, Indinavir, to find the details of the binding pathway, the influential residues, and also the stable states of the binding pathway. We achieved the native conformation of the inhibitor in 6 rounds, 360 replicas by performing over 4 micro-seconds of UMD simulations. We found 3 Intermediate states between the solvated state and the native conformation state in the binding pathway. We also discovered that aromatic residues such as Trp98 and Trp98', catalytic residues Asp32 and Asp32', and the flap region's residues have the most influential roles in the binding pathway and also have the most contribution to the total interaction energies. We believe that the details found in this study would be a great guide for developing new treatment solutions against the HTLV-1 virus by inhibiting the HTLV-1 protease.

Shortening Synthetic Routes to Small Molecule Active Pharmaceutical Ingredients Employing Biocatalytic Methods

Biocatalysis, using enzymes for organic synthesis, has emerged as powerful tool for the synthesis of active pharmaceutical ingredients (APIs). The first industrial biocatalytic processes launched in the first half of the last century exploited whole-cell microorganisms where the specific enzyme at work was not known. In the meantime, novel molecular biology methods, such as efficient gene sequencing and synthesis, triggered breakthroughs in directed evolution for the rapid development of process-stable enzymes with broad substrate scope and good selectivities tailored for specific substrates. To date, enzymes are employed to enable shorter, more efficient, and more sustainable alternative routes toward (established) small molecule APIs, and are additionally used to perform standard reactions in API synthesis more efficiently. Herein, large-scale synthetic routes containing biocatalytic key steps toward >130 APIs of approved drugs and drug candidates are compared with the corresponding chemical protocols (if available) regarding the steps, reaction conditions, and scale. The review is structured according to the functional group formed in the reaction.

Repurposing of Antimicrobial Agents for Cancer Therapy: What Do We Know?

The substantial costs of clinical trials, the lengthy timelines of new drug discovery and development, along the high attrition rates underscore the need for alternative strategies for finding quickly suitable therapeutics agents. Given that most approved drugs possess more than one target tightly linked to other diseases, it encourages promptly testing these drugs in patients. Over the past decades, this has led to considerable attention for drug repurposing, which relies on identifying new uses for approved or investigational drugs outside the scope of the original medical indication. The known safety of approved drugs minimizes the possibility of failure for adverse toxicology, making them attractive de-risked compounds for new applications with potentially lower overall development costs and shorter development timelines. This latter case is an exciting opportunity, specifically in oncology, due to increased resistance towards the current therapies. Indeed, a large body of evidence shows that a wealth of non-cancer drugs has beneficial effects against cancer. Interestingly, 335 drugs are currently being evaluated in different clinical trials for their potential activities against various cancers (Redo database). This review aims to provide an extensive discussion about the anti-cancer activities exerted by antimicrobial agents and presents information about their mechanism(s) of action and stage of development/evaluation.

Piperazine based antimicrobial polymers: a review

Microbial infections are a life threatening concern in several areas, which include the biomedical sector, healthcare products, water purification systems, and food packaging. Polymers with low molecular weight bioactive agents or disinfectants help the scientific community to reduce the lethality rate caused by pathogenic microbes. Antimicrobial polymeric approach is one of the advanced approaches made by researchers in concern with the problems associated with small molecules that restrict their applications in broad spectrum. History reveals the synthesis of numerous antimicrobial polymers using various antimicrobial agents but lacks the use of piperazine molecule, which is of pharmaceutical importance. This review gives an insight into the current and future perspective for the development of piperazine-based antimicrobial polymers.

Identification of multipotent drugs for COVID-19 therapeutics with the evaluation of their SARS-CoV2 inhibitory activity

The SARS-CoV2 is a highly contagious pathogen that causes COVID-19 disease. It has affected millions of people globally with an average lethality of ~3%. There is an urgent need of drugs for the treatment of COVID-19. In the current studies, we have used bioinformatics techniques to screen the FDA approved drugs against nine SARS-CoV2 proteins to identify drugs for repurposing. Additionally, we analyzed if the identified molecules can also affect the human proteins whose expression in lung changed during SARS-CoV2 infection. Targeting such genes may also be a beneficial strategy to curb disease manifestation. We have identified 74 molecules that can bind to various SARS-CoV2 and human host proteins. We experimentally validated our in-silico predictions using vero E6 cells infected with SARS-CoV2 virus. Interestingly, many of our predicted molecules viz. capreomycin, celecoxib, mefloquine, montelukast, and nebivolol showed good activity (IC50) against SARS-CoV2. We hope that these studies may help in the development of new therapeutic options for the treatment of COVID-19.

Identification of potential antivirals against SARS-CoV-2 using virtual screening method

SARS-CoV-2 has triggered a major epidemic among people around the world, and it is the newest in the sequence to become prevalent among other infectious diseases. The drug repurposing concept has been utilized effectively for numerous viral infections. Considering the situation and the urgency, the idea of drug repurposing for coronavirus infection (COVID-19) is also being studied. The molecular docking method was used for the screening of 29 antiviral drugs against primary protease proteins (MPP) of SARS-CoV-2, spike ecto-domain, spike receptor binding domain, Nsp9 RNA binding protein, and HR2 domain. Among these drugs, in terms of least binding energy, Indinavir, Sorivudine, Cidofovir, and Darunavir showed minimum docking scores with all the key proteins. For ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) analysis, the ADMET properties of the top 4 drug candidates were retrieved through literature study. This analysis revealed that these drug candidates are well metabolized, distributed, and bioavailable, but have some undesirable effects. Furthermore, some approved structural analogues, such as Telbivudine, Tenofovir, Amprenavir, Fosamprenavir, etc., were predicted as similar drugs which may also be used for treating viral infections. We highly recommend these drug candidates as potential fighters against the deadly SARS-CoV-2 virus, and suggest in vivo trials for experimental validation of our findings.

Biocatalytic routes to anti-viral agents and their synthetic intermediates

An assessment of biocatalytic strategies for the synthesis of anti-viral agents, offering guidelines for the development of sustainable production methods for a future COVID-19 remedy.

Repurposing Known Drugs as Covalent and Non-covalent Inhibitors of the SARS-CoV-2 Papain-Like Protease

In the absence of an approved vaccine, developing effective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antivirals is essential to tackle the current pandemic health crisis due to the coronavirus disease 2019 (COVID-19) spread. As any traditional drug discovery program is a time-consuming and costly process requiring more than one decade to be completed, in silico repurposing of existing drugs is the preferred way for rapidly selecting promising clinical candidates. We present a virtual screening campaign to identify covalent and non-covalent inhibitors of the SARS-CoV-2 papain-like protease (PLpro) showing potential multitarget activities (i.e., a desirable polypharmacology profile) for the COVID-19 treatment. A dataset including 688 phase III and 1,702 phase IV clinical trial drugs was downloaded from ChEMBL (version 27.1) and docked to the recently released crystal structure of PLpro in complex with a covalently bound peptide inhibitor. The obtained results were analyzed by combining protein-ligand interaction fingerprint similarities, conventional docking scores, and MM-GBSA-binding free energies and allowed the identification of some interesting candidates for further in vitro testing. To the best of our knowledge, this study represents the first attempt to repurpose drugs for a covalent inhibition of PLpro and could pave the way for new therapeutic strategies against COVID-19.

Developing Insulin and BDNF Mimetics for Diabetes Therapy

Diabetes is a global public health concern nowadays. The majority of diabetes mellitus (DM) patients belong to type 2 diabetes mellitus (T2DM), which is highly associated with obesity. The general principle of current therapeutic strategies for patients with T2DM mainly focuses on restoring cellular insulin response by potentiating the insulin-induced signaling pathway. In late-stage T2DM, impaired insulin production requires the patients to receive insulin replacement therapy for maintaining their glucose homeostasis. T2DM patients also demonstrate a drop of brain-derived neurotrophic factor (BDNF) in their circulation, which suggests that replenishing BDNF or enhancing its downstream signaling pathway may be beneficial. Because of their protein nature, recombinant insulin or BDNF possess several limitations that hinder their clinical application in T2DM treatment. Thus, developing orally active "insulin pill" or "BDNF pill" is essential to provide a more convenient and effective therapy. This article reviews the current development of non-peptidyl chemicals that mimic insulin or BDNF and their potential as anti-diabetic agents.

Quantitative Structure Activity/Pharmacokinetics Relationship Studies of HIV-1 Protease Inhibitors Using Three Modelling Methods

BACKGROUND

HIV-1 protease inhibitor (PIs) is a good choice for AIDS patients. Nevertheless, for PIs, there are several bugs in clinical application, like drug resistance, the large dose, the high costs and so on, among which, the poor pharmacokinetics property is one of the important reasons that leads to the failure of its clinical application.

OBJECTIVE

We aimed to build computational models for studying the relationship between PIs structure and its pharmacological activities.

METHODS

We collected experimental values of k_off/K_i and structures of 50 PIs through a careful literature and database search. Quantitative structure activity/pharmacokinetics relationship (QSAR/QSPR) models were constructed by support vector machine (SVM), partial-least squares regression (PLSR) and back-propagation neural network (BPNN).

RESULTS

For QSAR models, SVM, PLSR and BPNN all generated reliable prediction models with the r² of 0.688, 0.768 and 0.787, respectively, and r²_pred of 0.748, 0.696 and 0.640, respectively. For QSPR models, the optimum models of SVM, PLSR and BPNN obtained the r² of 0.952, 0.869 and 0.960, respectively, and the r²_pred of 0.852, 0.628 and 0.814, respectively.

CONCLUSION

Among these three modelling methods, SVM showed superior ability than PLSR and BPNN both in QSAR/QSPR modelling of PIs, thus, we suspected that SVM was more suitable for predicting activities of PIs. In addition, 3D-MoRSE descriptors may have a tight relationship with the Ki values of PIs, and the GETAWAY descriptors have significant influence on both koff and Ki in PLSR equations.

A novel multi-parametric high content screening assay in ciPTEC-OAT1 to predict drug-induced nephrotoxicity during drug discovery

Drug-induced nephrotoxicity is a major concern in the clinic and hampers the use of available treatments as well as the development of innovative medicines. It is typically discovered late during drug development, which reflects a lack of in vitro nephrotoxicity assays available that can be employed readily in early drug discovery, to identify and hence steer away from the risk. Here, we report the development of a high content screening assay in ciPTEC-OAT1, a proximal tubular cell line that expresses several relevant renal transporters, using five fluorescent dyes to quantify cell health parameters. We used a validation set of 62 drugs, tested across a relevant concentration range compared to their exposure in humans, to develop a model that integrates multi-parametric data and drug exposure information, which identified most proximal tubular toxic drugs tested (sensitivity 75%) without any false positives (specificity 100%). Due to the relatively high throughput (straight-forward assay protocol, 96-well format, cost-effective) the assay is compatible with the needs in the early drug discovery setting to enable identification, quantification and subsequent mitigation of the risk for nephrotoxicity.

Determination of Phenotypic Resistance Cutoffs From Routine Clinical Data

Supplemental Digital Content is Available in the Text.

Background:

HIV-1 drug resistance can be measured with phenotypic drug-resistance tests. However, the output of these tests, the resistance factor (RF), requires interpretation with respect to the in vivo activity of the tested variant. Specifically, the dynamic range of the RF for each drug has to be divided into a suitable number of clinically meaningful intervals.

Methods:

We calculated a susceptible-to-intermediate and an intermediate-to-resistant cutoff per drug for RFs predicted by geno2pheno_[resistance]. Probability densities for therapeutic success and failure were estimated from 10,444 treatment episodes. The density estimation procedure corrects for the activity of the backbone drug compounds and for therapy failure without drug resistance. For estimating the probability of therapeutic success given an RF, we fit a sigmoid function. The cutoffs are given by the roots of the third derivative of the sigmoid function.

Results:

For performance assessment, we used geno2pheno_[resistance] RF predictions and the cutoffs for predicting therapeutic success in 2 independent sets of therapy episodes. HIVdb was used for performance comparison. On one test set (n = 807), our cutoffs and HIVdb performed equally well receiver operating characteristic curve [(ROC)–area under the curve (AUC): 0.68]. On the other test set (n = 917), our cutoffs (ROC–AUC: 0.63) and HIVdb (ROC–AUC: 0.65) performed comparatively well.

Conclusions:

Our method can be used for calculating clinically relevant cutoffs for (predicted) RFs. The method corrects for the activity of the backbone drug compounds and for therapy failure without drug resistance. Our method's performance is comparable with that of HIVdb. RF cutoffs for the latest version of geno2pheno_[resistance] have been estimated with this method.

A review of the toxicity of HIV medications

Antiretroviral therapy has changed human immunodeficiency virus (HIV) infection from a near-certainly fatal illness to one that can be managed chronically. More patients are taking antiretroviral drugs (ARVs) for longer periods of time, which naturally results in more observed toxicity. Overdose with ARVs is not commonly reported. The most serious overdose outcomes have been reported in neonates who were inadvertently administered supratherapeutic doses of HIV prophylaxis medications. Typical ARV regimens include a "backbone" of two nucleoside reverse transcriptase inhibitors (NRTI) and a "base" of either a protease inhibitor (PI) or nonnucleoside reverse transcriptase inhibitor. New classes of drugs called entry inhibitors and integrase inhibitors have also emerged. Older NRTIs were associated with mitochondrial toxicity, but this is less common in the newer drugs, emtricitabine, lamivudine, and tenofovir. Mitochondrial toxicity results from NRTI inhibition of a mitochondrial DNA polymerase. Mitochondrial toxicity manifests as myopathy, neuropathy, hepatic failure, and lactic acidosis. Routine lactate assessment in asymptomatic patients is not indicated. Lactate concentration should be obtained in patients taking NRTIs who have fatigue, nausea, vomiting, or vague abdominal pain. Mitochondrial toxicity can be fatal and is treated by supportive care and discontinuing NRTIs. Metabolic cofactors like thiamine, carnitine, and riboflavin may be helpful in managing mitochondrial toxicity. Lipodystrophy describes changes in fat distribution and lipid metabolism that have been attributed to both PIs and NRTIs. Lipodystrophy consists of loss of fat around the face (lipoatrophy), increase in truncal fat, and hypertriglyceridemia. There is no specific treatment of lipodystrophy. Clinicians should be able to recognize effects of chronic toxicity of ARVs, especially mitochondrial toxicity.

Effect of safety issues with HIV drugs on the approval process of other drugs in the same class: an analysis of European Public Assessment Reports

BACKGROUND

Knowledge on the safety of new medicines is limited at the time of market entry. Nearly half of all drugs used to treat HIV registered in the EU required ≥1 Direct Healthcare Professional Communication (DHPC) in the past 10 years for safety issues identified post-approval.

OBJECTIVE

The aim was to evaluate the extent to which regulators and industry have addressed the risk of safety issues for HIV drugs based on prior experience with other drugs in the same class and whether doing so impacts development time of these drugs.

METHODS

HIV drugs receiving ≥1 DHPC in the Netherlands between January 1999 and December 2008 were identified. Each drug with a DHPC ('index' drug) was paired with subsequently approved HIV drug(s) in the same class (Anatomical Therapeutic Chemical [ATC] 4th level) ['follow-on' drugs]. Characteristics of safety issues were extracted from the DHPCs of the 'index' drugs. European Public Assessment Reports (EPARs) were reviewed regarding whether the safety issues had been considered during development and approval. Consideration of previously identified safety issues in 'follow-on' drug applications was assessed regarding attention paid to adverse drug reaction (ADR) symptoms in pre-marketing studies, Summary of Product Characteristics (SmPC) and postmarketing commitments, and whether size of the safety population was in accordance with Regulatory guidelines. 'Index' drugs were also paired with drugs in the same class already on the market ('older' drugs). For 'older' drugs, we identified whether the safety issue led to appropriate changes in the current SmPC (January 2011) compared with the SmPC at the time of marketing authorization. Clinical development time was assessed using time from first patent application to market authorization as proxy, and comparison was made between 'index' and 'follow-on' drugs.

RESULTS

For 9 (43%) of the 21 centrally authorized HIV drugs, 11 serious safety issues that required a DHPC were identified. Two drugs were excluded from our analysis (DHPCs related to contamination/medication error). Six 'index' drugs were paired, each with one to six 'follow-on' drugs. Three concerned drug-drug interactions (DDIs); the other three were intracranial haemorrhage, neuromuscular weakness and severe skin/hepatic reactions. All but one 'follow-on' drug had information in the EPAR on that specific ADR (i.e. attention was paid to the ADR). The DDIs were addressed in pre-marketing studies and/or the SmPC. Two of the other ADRs were addressed by postmarketing surveillance commitments; intracranial haemorrhage was not addressed. Three safety issues for two 'index' drugs could not be paired with a 'follow-on' drug as no drug in the same class was approved after the corresponding DHPCs were issued. Five of the nine safety issues were added to at least one of the current SmPCs for the 'older' drugs already on the market at the time of DHPC issue. Two safety issues were already in the SmPC of the 'older' drugs at time of market approval and two were not introduced into the SmPC of 'older' drugs. Population size to assess short-term safety complied with the guidelines for four 'index', seven 'follow-on' and three 'older' drugs; population size to assess long-term safety complied for one, three and two drugs, respectively. For five drugs, EPARs did not provide adequate information on population size. No statistically significant difference in development time between 'index' and 'follow-on' drugs was found.

CONCLUSION

Generally, safety issues were taken into account in the approval process of other drugs in the class. The approaches were different and determined by the nature of the ADR. Taking safety issues into account in the approval process did not seem to impact on the time taken to perform the pre-approval clinical programme.

Potential of polymeric nanoparticles in AIDS treatment and prevention

IMPORTANCE OF THE FIELD

Acquired immunodeficiency syndrome (AIDS) remains one of the greatest challenges in public health. The AIDS virus is now responsible for > 2.5 million new infections worldwide each year. Despite significant advances in understanding the mechanism of viral infection and identifying effective treatment approaches, the search for optimum treatment strategies for AIDS remains a major challenge. Recent advances in the field of drug delivery have provided evidence that engineered nanosystems may contribute to the enhancement of current antiretroviral therapy.

AREAS COVERED IN THIS REVIEW

This review describes the potential of polymeric nanoparticle-based drug delivery systems in the future treatment of AIDS. Polymeric nanoparticles have been developed to improve physicochemical drug characteristics (by increasing drug solubility and stability), to achieve sustained drug release profile, to provide targeting to the cellular and anatomic human immunodeficiency virus (HIV) latent reservoirs and to be applied as an adjuvant in anti-HIV vaccine formulations.

WHAT THE READER WILL GAIN

The insight that will be gained is knowledge about the progress in the development of polymeric nanoparticle-based drug delivery systems for antiretroviral drugs as alternative for AIDS treatment and prevention.

TAKE HOME MESSAGE

The advances in the field of targeted drug delivery can result in more efficient strategies for AIDS treatment and prevention.

Metabolic and hepatobiliary side effects of antiretroviral therapy (ART)

Although antiretroviral therapy (ART) for human immunodeficiency virus (HIV) has been in use since 1987, the initiation of highly active ART has produced an increase in adverse drug reactions. This is a new challenge as many of the adverse drug reactions attributable to ART may be indistinguishable from non-drug-related illnesses. The emergency physician must be aware of the potential complications of ART as affected patients may present with nonspecific symptoms. The focus of this article is the metabolic and hepatobiliary adverse effects of ART.

[Toxicogenetics of antiretroviral treatment (II): neurotoxicity, hepatotoxicity, lactic acidosis, kidney damage, and other adverse effects of antiretroviral drugs]

Several pharmacogenetics studies have analyzed the influence of specific genetic polymorphisms on the toxicity of antiretroviral treatment. The present review describes some of the adverse effects of antiretroviral drugs in which a genetic predisposition may be involved: efavirenz-induced neurological toxicity, generally associated with the 516G>T polymorphism of liver enzyme cytochrome P450 2B6 (CYP2B6); hypersensitivity reactions to nevirapine, associated with specific alleles of major histocompatibility complex, mainly the HLA-DRB1*0101 allele, which, in combination with a high CD4 lymphocyte count, has been associated with systemic reactions and hepatitis in Caucasians, and the HLA-Cw8 allele, which is associated with hypersensitivity reactions in persons from the Italian island of Sardinia and from Japan; nevirapine-induced hepatotoxicity associated with the C>T polymorphism in position 3435T of the ABCB1 (MDR-1) gene codifying for glycoprotein P (lower risk); hyperbilirubinemia in patients exposed to atazanavir or indinavir carrying the UGT1A1*28 polymorphism; peripheral neuropathy with nucleoside analogues associated with haplogroup T of the mitochondrial genome (higher risk) and with the HFE C282Y genotype of the hemochromatosis gene (lower risk); the mutation in codon 964 (R964C) of the POLG gene that codifies the mitochondrial polymerase DNA gamma described in a Thai patient with lactic acidosis; the ABCC2 gene haplotypes associated with tenofovir-induced proximal tubulopathy, and the risk of pancreatitis in persons with mutations in the CFTR and SPINK-1 genes.

Indinavir Trough Concentration as a Determinant of Early Nephrolithiasis in HIV-1-Infected Adults

Indinavir plasma levels are associated with antiretroviral efficacy; however, little data are available regarding toxicity. We assessed the relationship between indinavir pharmacokinetic (PK) characteristics and severe nephrolithiasis as well as other severe or serious adverse reactions. Patients included in the ANRS CO8 APROCO-COPILOTE cohort and receiving 800 mg indinavir three times daily as a first-line protease inhibitor were eligible for this study. To be included in the analysis, their plasma sample at month 1 (M1) had to be available (n = 282) to estimate using population PK modeling, indinavir PK characteristics, ie, maximum (Cmax) and trough plasma (Cres) concentrations, area under the curve (AUC), and observed/predicted concentration ratio (CR). A Cox model was used to estimate the independent effect of Cmax, Cres, AUC, and CR on the hazard of severe nephrolithiasis and serious adverse reactions. At M1, median Cmax was 6205 ng/mL, Cres 631 ng/mL, AUC 24,242 ng . h/mL, and CR 0.6. After a median follow up of 12 months, 11% of patients (30 of 282) had experienced at least one serious adverse reaction among which 12 were nephrolithiasis. In the multivariate analyses, early high indinavir Cres (ie, >/=1000 ng/mL at M1) was associated with a higher rate of severe nephrolithiasis (hazard ratio = 6.7; 95% confidence interval = 1.8-25.2; P < 0.01) and was also associated with a higher rate of all serious adverse reactions but only when nephrolithiasis were included among those cases. Prospective and early indinavir Cres determination should be recommended in the patient's care management and dosage adjustments.

Efficacy and safety of three doses of tipranavir boosted with ritonavir in treatment-experienced HIV type-1 infected patients

The efficacy, safety, and pharmacokinetics of three doses of tipranavir/ritonavir (TPV/r) in highly treatment-experienced human immunodeficiency virus (HIV)-1-infected patients with protease inhibitor (PI)-resistant isolates were evaluated. A 24-week multicenter, double-blind, randomized, dose-finding trial was conducted. All patients were three-drug class experienced and had taken at least two PI-based regimens. All had at least one primary PI mutation and had plasma HIV-RNA > 1000 copies/ml. Patients remained on their background non-PI antiretroviral medications for the first 14 days. After this 14-day period of functional TPV/r monotherapy, the background antiretroviral medications were optimized based on treatment history and the screening genotype. A total of 216 patients were randomized. All groups [TPV/r 500 mg/100 mg (n = 73), 500 mg/200 mg (n = 72), and 750 mg/200 mg (n = 71) twice daily] achieved an approximate 1 log10 reduction in the median HIV-RNA at week 2. A significant reduction was sustained through 24 weeks in the TPV/r 500 mg/200 mg and 750 mg/200 mg groups. The 500 mg/200 mg dose achieved optimal median TPV trough concentrations and lower interpatient variability. The most frequently reported adverse events (AEs) were diarrhea, nausea, vomiting, fatigue, and headache. The TPV/r 750 mg/200 mg group had the highest rate of grade 3 or 4 laboratory abnormalities and study discontinuations due to AEs. All doses of TPV/r tested in this study were associated with HIV-1 viral load reductions through 24 weeks. The 500 mg/200 mg dose achieved the best efficacy, safety, and pharmacokinetic profile in this highly treatment-experienced population and was selected for the pivotal phase 3 studies.

Hyperbilirubinemia in the setting of antiviral therapy

Hyperbilirubinemia is a common side effect of antiviral medications. The mechanisms underlying its development are multiple and unique to each therapy. During administration of antiviral medications, the hyperbilirubinemia observed in the absence of liver injury is most frequently manifested by isolated increases in the indirect-reacting fraction. Relevant mechanisms leading to indirect hyperbilirubinemia in this setting include hemolysis, decreased hepatic bilirubin clearance as a result of impairment of bilirubin conjugation, or circumstances in which both processes occur simultaneously. Underlying genetic susceptibilities may potentiate these side effects of antiviral therapy. Conjugated (direct-reacting) hyperbilirubinemia can be a consequence of generalized hepatocellular injury, selective cholestatic defects, biliary obstruction, or, rarely, genetic disorders of bilirubin transport. In the specific setting of antiviral therapy, preexisting liver disease or antiviral hepatotoxicity, such as is encountered with the use of the nucleoside and non-nucleoside human immunodeficiency virus reverse transcriptase inhibitors, are the most frequent causes of direct-reacting or mixed direct- and indirect-reacting hyperbilirubinemia. Modification in antiviral drug choice or dose may be required in cases of liver injury or of brisk hemolysis leading to significant anemia. The mild indirect hyperbilirubinemia associated with impairment in conjugation tends to be well tolerated and of little consequence. The decision to continue or discontinue antiviral therapy in the face of hyperbilirubinemia should be made after an assessment of the cause of the elevated bilirubin level and a thorough assessment of the risks and benefits of antiviral therapy.

Development of a capillary electrophoretic method for the separation of diastereoisomers of a new human immunodeficiency virus protease inhibitor

A capillary electrophoretic (CE) method was developed for the separation of diastereoisomers of a new human immunodeficiency virus (HIV) protease inhibitor TMC114. In total 16 isomers of this drug have been synthesized (eight pairs of enantiomers). We succeeded in the separation of the eight diastereoisomers, but no enantiomers could be separated. Because of the high similarity and water-insolubility of these isomers, the separation is a real challenge. Different CE modes were tried out: capillary zone electrophoresis (CZE), nonaqueous capillary electrophoresis (NACE), micellar electrokinetic capillary chromatography (MEKC), and microemulsion electrokinetic capillary chromatography (MEEKC). Only MEEKC offered resolution of these compounds.

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.

Triple nucleoside treatment with abacavir plus the lamivudine/zidovudine combination tablet (COM) compared to indinavir/COM in antiretroviral therapy-naïve adults: results of a 48-week open-label, equivalence trial (CNA3014)

OBJECTIVE

An equivalence (non-inferiority) trial comparing antiviral response, tolerability, and adherence with a triple nucleoside regimen containing abacavir 300 mg (ABC) plus a lamivudine 150-mg/zidovudine 300-mg combination tablet (COM) twice daily vs. a regimen containing the protease inhibitor indinavir (IDV) 800 mg three times daily plus COM twice daily (IDV/COM) in antiretroviral-naïve, HIV-infected patients.

METHODS

Adult patients with plasma HIV-1 RNA levels > or = 5000 copies/mL and CD4+ cell counts > or = 100 cells/mm(3) were randomized to receive open-label ABC/COM (n = 169) or IDV/COM (n = 173) for 48 weeks. The intent-to-treat (ITT) population was the primary population evaluated. ITT: switch/missing equals failure (ITT: S/M = F) and as-treated (AT) analyses were used for assessing the proportion of patients achieving plasma HIV-1 RNA level < 400 and < 50 copies/mL at each clinic visit. In the ITT: S/M = F analysis, patients who switched treatment or had missing values were considered treatment failures; the AT analysis examined virologic data only while patients received study treatment. ABC/COM was considered equivalent (non-inferior) to IDV/COM if the lower limit of the 95% confidence intervals (CIs) about the difference in proportions of ABC/COM- vs. IDV/COM-treated patients attaining plasma HIV-1 RNA < 400 copies/mL exceeded -15% at week 48.

RESULTS

The study population was diverse with respect to ethnicity (38% Asian, 27% Hispanic, 28% white, 3% black, 4% other) and gender (39% women, 61% men). Baseline median HIV-1 RNA was 4.80 log(10) copies/mL and CD4+ cell count was 315 cells/mm(3). ABC/COM met the criterion of equivalence to IDV/COM. In the ITT: S/M = F analysis at Week 48, a greater proportion of ABC/COM-treated patients achieved HIV-1 RNA < 400 copies/mL (66% [109/164] vs. 50% [82/165]; treatment difference 16.6%, 95% CI (6.0, 27.2), p = 0.002) and HIV-1 RNA < 50 copies/mL (60% [99/164] vs. 50% [83/165]; treatment difference 9.6%, 95% CI [-1.1, 20.2]), whereas the AT analysis showed similar proportions achieving these endpoints (< 400 copies/mL: 85 vs. 83%; < 50 copies/mL: 79 vs 81%). Comparable proportions of patients with screening HIV-1 RNA values > 100 000 copies/mL achieved HIV-1 RNA < 400 copies/mL (ABC/COM: 60% [35/58]; IDV/COM: 51% [33/65]; treatment difference 9.6%, 95% CI [-7.9, 27.1]; ITT: S/M = F analysis). A significantly greater proportion taking ABC/COM were > or = 95% adherent (72% [109/151] vs. 45% [70/154] with IDV/COM, p < 0.001). Median increases from baseline in CD4+ cell counts were similar in the two treatment groups (+148 vs. +152 cells/mm(3)). Significantly more patients on IDV/COM reported drug-related adverse events (87% [142/165] vs. 65% [108/164] with ABC/COM, p < 0.001), similar proportions discontinued treatment due to adverse events (13 vs. 10%), and a slightly greater proportion in the ABC/COM group reported serious adverse events (13 vs. 8%). About half of the latter comprised suspected ABC-related hypersensitivity reactions (overall rate, 6%). Most adverse events were gastrointestinal in nature in both treatment groups.

CONCLUSION

ABC/COM was at least equivalent to IDV/COM over 48 weeks in the treatment of antiretroviral-naïve patients. ABC/COM was associated with a significantly higher adherence rate and lower incidence of drug-related adverse events than IDV/COM. The study was limited in that it was not powered to determine equivalence of treatments within high vs. low viral load strata, adherence was not monitored electronically, and bias could not be ruled out due to the open-label study design.

Decline in HIV infectivity following the introduction of highly active antiretroviral therapy

OBJECTIVE

Little is known about the degree to which widespread use of antiretroviral therapy in a community reduces uninfected individuals' risk of acquiring HIV. We estimated the degree to which the probability of HIV infection from an infected partner (the infectivity) declined following the introduction of highly active antiretroviral therapy (HAART) in San Francisco.

DESIGN

Homosexual men from the San Francisco Young Men's Health Study, who were initially uninfected with HIV, were asked about sexual practices, and tested for HIV antibodies at each of four follow-up visits during a 6-year period spanning the advent of widespread use of HAART (1994-1999).

METHODS

We estimated the infectivity of HIV (per-partnership probability of transmission from an infected partner) using a probabilistic risk model based on observed incident infections and self-reported sexual risk behavior, and tested the hypothesis that infectivity was the same before and after HAART was introduced.

RESULTS

A total of 534 homosexual men were evaluated. Decreasing trends in HIV seroincidence were observed despite increases in reported number of unprotected receptive anal intercourse partners. Conservatively assuming a constant prevalence of HIV infection between 1994 and 1999, HIV infectivity decreased from 0.120 prior to widespread use of HAART, to 0.048 after the widespread use of HAART- a decline of 60% (P=0.028).

CONCLUSIONS

Use of HAART by infected persons in a community appears to reduce their infectiousness and therefore may provide an important HIV prevention tool.

Comparison of Two Reduced-Dose Regimens of Indinavir (600 Mg Vs 400 Mg Twice Daily) and Ritonavir (100 Mg Twice Daily) in Healthy Volunteers (Coredir)

Objective

To assess the pharmacokinetics and tolerability of reduced dosages of twice daily indinavir (IDV) boosted by low-dose ritonavir (RTV) in healthy volunteers.

Methods

Pharmacokinetics and tolerability of IDV/RTV twice daily (600/100 mg and 400/100 mg) were assessed in a randomized crossover design in 16 healthy volunteers. Each dosage was taken twice daily for 2 weeks before 12 h pharmacokinetics were obtained.

Results

Sixteen subjects were included, with a mean age ±SD of 30 ±4 years; seven female, nine male. Fifteen subjects completed the study. After dose reduction of IDV AUC, Cmax and Cmin decreased significantly. In the 400 mg group three out of 15 subjects had IDV levels below 0.10 mg/l vs none in the 600 mg group. All subjects reported mild to moderate side effects throughout the study period, which were more severe in the 600 mg group (mostly renal, dry skin/lips, paresthesias/oral discomfort). In the 600 mg group four subjects reported dysuria and one subject discontinued because of flank pain, whereas two subjects reported dysuria and no subject discontinued in the 400 mg group, respectively. Eight subjects developed crystalluria without a significant difference between both groups. No significant change in serum creatinine was observed.

Conclusions

IDV/RTV 400/100 mg twice daily resulted in significant lower IDV exposure, with three out of 15 subjects revealing Cmin values below the recommended threshold for wild-type virus of 0.10 mg/l. Tolerability, however, was lower in the 600 mg IDV group. Therapeutic drug monitoring in the individual patient appears to be necessary to guarantee appropriate drug levels and simultaneously minimize toxicity. Presented in part at the 6th International Congress on Drug Therapy in HIV Infection. Glasgow, Scotland, UK, November 2002. Abstract P182.

Decline in HIV infectivity following the introduction of highly active antiretroviral therapy

OBJECTIVE

Little is known about the degree to which widespread use of antiretroviral therapy in a community reduces uninfected individuals' risk of acquiring HIV. We estimated the degree to which the probability of HIV infection from an infected partner (the infectivity) declined following the introduction of highly active antiretroviral therapy (HAART) in San Francisco.

DESIGN

Homosexual men from the San Francisco Young Men's Health Study, who were initially uninfected with HIV, were asked about sexual practices, and tested for HIV antibodies at each of four follow-up visits during a 6-year period spanning the advent of widespread use of HAART (1994-1999).

METHODS

We estimated the infectivity of HIV (per-partnership probability of transmission from an infected partner) using a probabilistic risk model based on observed incident infections and self-reported sexual risk behavior, and tested the hypothesis that infectivity was the same before and after HAART was introduced.

RESULTS

A total of 534 homosexual men were evaluated. Decreasing trends in HIV seroincidence were observed despite increases in reported number of unprotected receptive anal intercourse partners. Conservatively assuming a constant prevalence of HIV infection between 1994 and 1999, HIV infectivity decreased from 0.120 prior to widespread use of HAART, to 0.048 after the widespread use of HAART- a decline of 60% (P=0.028).

CONCLUSIONS

Use of HAART by infected persons in a community appears to reduce their infectiousness and therefore may provide an important HIV prevention tool.

Lamivudine/zidovudine/abacavir: triple combination tablet

The triple combination tablet containing lamivudine (150 mg), zidovudine (300 mg) and abacavir (300 mg, as abacavir sulfate) is a new formulation of three nucleoside analogue reverse transcriptase inhibitors. Two studies in treatment-naive patients (one double-blind, one nonblind) have reported that lamivudine/zidovudine (dual combination tablet) plus abacavir showed efficacy similar to that of lamivudine/zidovudine plus indinavir. In both studies, similar numbers of patients in each treatment group had plasma HIV RNA levels </=400 copies/mL at week 48 (51% vs 51% and 64% vs 50%). In treatment-experienced patients with baseline plasma HIV RNA levels <50 copies/mL, switching to lamivudine/zidovudine/abacavir (triple combination tablet) was as effective as remaining on highly active antiretroviral treatment (mainly protease inhibitor [PI]-based). Virological failure, the primary endpoint, defined as two consecutive plasma HIV RNA values >400 copies/mL, was reported in 22% of patients in both treatment groups at week 48. Treatment-naive patients receiving lamivudine/zidovudine/abacavir combination therapy experienced several adverse events, including nausea, malaise/fatigue and vomiting.

Drug interactions between antiretroviral drugs and comedicated agents

HIV-infected individuals usually receive a wide variety of drugs in addition to their antiretroviral drug regimen. Since both non-nucleoside reverse transcriptase inhibitors and protease inhibitors are extensively metabolised by the cytochrome P450 system, there is a considerable potential for pharmacokinetic drug interactions when they are administered concomitantly with other drugs metabolised via the same pathway. In addition, protease inhibitors are substrates as well as inhibitors of the drug transporter P-glycoprotein, which also can result in pharmacokinetic drug interactions. The nucleoside reverse transcriptase inhibitors are predominantly excreted by the renal system and may also give rise to interactions. This review will discuss the pharmacokinetics of the different classes of antiretroviral drugs and the mechanisms by which drug interactions can occur. Furthermore, a literature overview of drug interactions is given, including the following items when available: coadministered agent and dosage, type of study that is performed to study the drug interaction, the subjects involved and, if specified, the type of subjects (healthy volunteers, HIV-infected individuals, sex), antiretroviral drug(s) and dosage, interaction mechanism, the effect and if possible the magnitude of interaction, comments, advice on what to do when the interaction occurs or how to avoid it, and references. This discussion of the different mechanisms of drug interactions, and the accompanying overview of data, will assist in providing optimal care to HIV-infected patients.

Continued indinavir versus switching to indinavir/ritonavir in HIV-infected patients with suppressed viral load

OBJECTIVE

To compare continued indinavir (IDV) 8-hourly (q8h) with switching to indinavir/ritonavir (IDV/RTV) 12-hourly (q12h) in HIV-positive patients having suppressed viral load with IDV q8h plus two nucleoside reverse transcriptase inhibitors (NRTI).

DESIGN

Multicentre, international, randomized, open-label study enrolling HIV-1 infected patients on IDV 800 mg q8h plus two NRTI with CD4 cell counts > or = 100 x 106/l and plasma HIV RNA < 500 copies/ml for > or = 3 months.

METHODS

Patients were randomized to continue on the same regimen or to switch to IDV plus liquid RTV (IDV/RTV 800 mg/100 mg q12h). Primary endpoint was the proportion of patients remaining < 500 copies/ml at 48 weeks.

RESULTS

A total of 323 patients (IDV/RTV, 162; IDV, 161) were evaluable. At 48 weeks, the proportions of patients with plasma HIV RNA < 500 copies/ml were 93%, 88% and 58% in the IDV/RTV arm versus 92% (P = 1), 86% (P = 0.87) and 74% (P = 0.003) in the IDV arm using on-treatment (OT) and intent-to-treat (ITT) [switches included (ITT, S = I) and switches = failure (ITT, S = F)] analyses respectively. Mean increase in CD4 cell count was 88 x 106/cells/l (IDV/RTV arm) and 60 x 106 cells/l (IDV arm) (P = 0.08). More patients discontinued study medication due to adverse events in the IDV/RTV arm than in the IDV arm (P < 0.001).

CONCLUSIONS

Equivalence of continuing IDV q8h versus switching to IDV/RTV (liquid) q12h in suppressed stable patients was demonstrated by OT and ITT S = I analyses. However, the IDV q8h arm performed better when discontinuations were classified as failures. IDV/RTV q12h can be convenient and equally effective for patients able to tolerate it.

Virologic rebound on HAART in the context of low treatment adherence is associated with a low prevalence of antiretroviral drug resistance

The contributions of viral drug resistance, drug pharmacokinetics, and treatment adherence to failure of protease inhibitor (PI)-based highly active antiretroviral therapy (HAART) have been explored in isolation. We examined the interactions between these factors. Patients on their first PI-based HAART combination for >6 months with plasma HIV viral load (VL) >1000 copies/mL ("viremic" group) were compared with patients with a stable VL <50 copies/mL ("nonviremic" group). Data were collected on adherence (measured electronically), PI plasma levels (sampled randomly, at trough and twice after an observed dose), viral genotype, and phenotype. Mean adherence was significantly lower in the viremic group (84.3% versus 100.1%; p =.005). In the viremic group, substitutions in HIV protease were detected most frequently in the following positions in subjects on indinavir (IDV): L10I/V (35.7%), M46I/L (35.7%), A71T/V (35.7%), V82A (42.9%); and for subjects on nelfinavir (NFV): D30N (50.0%), V77I (56.3%), N88D (37.5%). Phenotypic resistance was detected in 20% of isolates from patients on IDV and 42% on NFV. Lower adherence was associated with detection of fewer resistance substitutions (r = 0.52; p =.005) and less phenotypic resistance (rho = 0.56, p =.005). There were no differences between the groups in pharmacokinetics. However, in viremic subjects, lower postdose NFV levels were associated with higher resistance (rho = -0.61, p =.02).

Administration of Indinavir and Low-Dose Ritonavir (800/100 Mg Twice Daily) with Food Reduces Nephrotoxic Peak Plasma Levels of Indinavir

Background

The objective of this study was to compare indinavir peak plasma (Cmax) values after administration of indinavir/ritonavir 800/100 mg on an empty stomach or with food. High indinavir Cmax values have been associated with indinavir-related nephrotoxicity.

Methods

This was an open-label, randomized, two-treatment, two-period, cross-over pharmacokinetic study performed at steady state. HIV-infected patients who had been using indinavir/ritonavir 800/100 mg twice daily for at least 4 weeks were randomized to take this combination with a light breakfast (two filled rolls and 130 ml of fluid) on a first study day, and without food on a second day, or in the reverse order. The pharmacokinetics of indinavir and ritonavir were assessed after plasma and urine sampling during 12 h.

Results

Data for nine patients were evaluated. Administration of indinavir/ritonavir 800/100 mg on an empty stomach resulted in a higher indinavir Cmax [geometric mean (GM) ratio – fasting/fed and 95% confidence interval (CI): 1.28 (1.08–1.52), P=0.01] and a trend to a shorter indinavir tmax ( P=0.07) compared to administration with food. The mode of administration of indinavir/ritonavir did not affect plasma indinavir Cmin and AUC values, parameters that have been associated with the antiviral efficacy of indinavir, nor the urinary excretion of indinavir.

Conclusions

Administration of indinavir/ritonavir 800/100 mg on an empty stomach results in a higher indinavir Cmax compared to ingestion with a light meal. Stated the other way round, intake with a light meal reduces indinavir Cmax, which probably reflects a food-induced delay in the absorption of indinavir. It is recommended to administer indinavir/ritonavir 800/100 mg with food, as a possible means to prevent indinavir-related nephrotoxicity in patients who start or continue with this regimen.

Ritonavir/Saquinavir plus One Nucleoside Reverse Transcriptase Inhibitor (NRTI) versus Indinavir plus Two Nrtis in Protease Inhibitor-Naive HIV-1-Infected Adults (Iris Study)

Objectives

To compare the efficacy, tolerability and safety of a ritonavir 400 mg/saquinavir hard gel fomulation 400 mg twice daily versus an indinavir 800 mg once every 8 h containing first-line protease inhibitor (PI) treatment regimen.

Methods

Open, randomized, multicentre clinical trial. PI-naive patients received either ritonavir/saquinavir and one nucleoside reverse transcriptase inhibitor (NRTI) or indinavir and two NRTIs. Intention-to-treat (ITT) and on-treatment (OT) analyses were performed.

Results

The baseline characteristics of the study participants were similar in both arms, 67 patients (37%) were naive to antiretroviral treatment. The proportion of patients who achieved a plasma viral load below the level of detection of 400 copies/ml at week 48 was 43% (39/90) in the ritonavir/saquinavir arm and 63% (57/90) in the indinavir arm ( P=0.005, ITT analysis). Using an OT analysis, these percentages were 84% and 88%, respectively ( P=0.6). There were more drop-outs in the ritonavir/saquinavir arm than in the indinavir arm (35.6% (32/90) versus 15.6% (14/90), P=0.002), mainly due to gastro-intestinal side-effects. Abnormal liver tests and increased lipids levels were more frequently reported in the ritonavir/saquinavir arm than in the indinavir arm.

Conclusion

In PI-naive patients, indinavir in combination with two NRTIs was more effective and better tolerated than ritonavir/saquinavir plus one NRTI. Both treatments were very effective for patients who were able to tolerate them.

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

The use of highly active antiretroviral therapy, the combination of at least three different antiretroviral drugs for the treatment of HIV-1 infection, has greatly improved the prognosis for HIV-1-infected patients. The efficacy of a combination of a protease inhibitor (PI) plus two nucleoside analogue reverse transcriptase inhibitors has been well established over a period of up to 3 years. However, virological treatment failure has been reported in 40–60% of unselected patients within 1 year after initiation of a PI-containing regimen. This observation may, at least in part, be attributed to the poor pharmacokinetic characteristics of the PIs. Given as a single agent the PIs have several pharmacokinetic limitations; relatively short plasma-elimination half-lives and a modest and variable oral bioavailability, which is, for some of the PIs, influenced by food. To overcome these suboptimal pharmacokinetics, high doses (requiring large numbers of pills) must be ingested, often with food restrictions, which complicates patient adherence to the prescribed regimen.

Positive drug–drug interactions increase the exposure to the PIs, allowing administration of lower doses at reduced dosing frequencies with less dietary restrictions. In addition to increasing the potency of an antiretroviral regimen, combinations of PIs may enhance patient adherence, both of which will contribute to a more durable suppression of viral replication. The favourable pharmacokinetics of PIs in combination are a result of interactions through cytochrome P450 3A4 (CYP3A4) isoenzymes and, possibly, the multi-drug transporting P-glycoprotein (P-gp). Antiretroviral synergy between PIs and non-overlapping primary resistance patterns in the HIV-1 protease genome may further enhance the anti-retroviral potency and durability of combinations of PIs. Many combinations contain ritonavir because this PI has the most pronounced inhibiting effects on CYP3A4. The combination of saquinavir and ritonavir, both in a dose of 400 mg twice-a-day, is the most studied double PI combination, with clinical experience extending over 3 years. Combination of a PI with a low dose of ritonavir (≤400 mg/day), only to boost its pharmacokinetic properties, seems an attractive option for patients who cannot tolerate higher doses of ritonavir. A recently introduced PI, lopinavir, has been co-formulated with low-dose ritonavir, which allows for a convenient three-capsules, twice-a-day dosing regimen. In an attempt to prolong suppression of viral replication combinations of PIs are becoming increasingly popular. However, further clinical studies are needed to identify the optimal combinations for treatment of antiretroviral naive and experienced HIV-1-infected patients. This review covers combinations of saquinavir, indinavir, nelfinavir, amprenavir and lopinavir with different doses of ritonavir, as well as the combinations of saquinavir and indinavir with nelfinavir.

HIV-1 Vif-derived peptide inhibits drug-resistant HIV proteases

Vif, one of the six accessory genes expressed by HIV-1, is essential for the productive infection of natural target cells. Previously we suggested that Vif acts as a regulator of the viral protease (PR): It prevents the autoprocessing of Gag and Gag-Pol precursors until virus assembly, and it may control the PR activity in the preintegration complex at the early stage of infection. It was demonstrated before that Vif, and specifically the 98 amino acid stretch residing at the N'-terminal part of Vif (N'-Vif), inhibits both the autoprocessing of truncated Gag-Pol polyproteins in bacterial cells and the hydrolysis of synthetic peptides by PR in cell-free systems. Linear synthetic peptides derived from N'-Vif specifically inhibit and bind HIV-1 PR in vitro, and arrest virus production in tissue culture. Peptide mapping of N'-Vif revealed that Vif88-98 is the most potent PR inhibitor. Here we report that this peptide inhibits both HIV-1 and HIV-2, but not ASLV proteases in vitro. Vif88-98 retains its inhibitory effect against drug-resistant HIV-1 PR variants, isolated from patients undergoing long-term treatment with anti-PR drugs. Variants of HIV protease bearing the mutation G48V are resistant to inhibition by this Vif-derived peptide, as shown by in vitro assays. In agreement with the in vitro experiments, Vif88-98 has no effect on the production of infectious particles in cells infected with a G48V mutated virus.

Characteristics of nausea reported by HIV-infected patients initiating combination antiretroviral regimens

Reliable data on the incidence and severity of nausea accompanying combination antiretroviral therapies is lacking. A prospective time series design was used to assess the rate, severity, and distress of nausea in a cohort of 75 HIV-positive patients who were beginning or changing a combination of two or more antiretroviral medications. Data were collected via telephone at weekly intervals for 12 weeks. The rate of nausea across regimens was greatest at Week 1 (39%) and declined progressively over time. By Week 12, the rate of nausea was only 5%. Severity of nausea was ranked as moderate or severe by a substantial proportion of patients through Week 10; however, nausea severity and distress were also found to diminish over time. The nausea associated with combination antiretroviral therapy is quite common and may adversely affect medication adherence. Findings indicate that clinicians should consider initiating interventions for management of antiretroviral-related nausea at baseline.