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PubMed2005

HIV-1 intermittent viraemia in patients treated by non-nucleoside reverse transcriptase inhibitor-based regimen.

BACKGROUND: It has been demonstrated that, in patients treated by protease-inhibitor-based regimen, intermittent viraemia occurred frequently and was associated with higher concentrations of residual replication but not with virological failure. Risk factors associated with intermittent viraemia and its impact in patients treated by non-nucleoside-reverse-transcriptase-inhibitor-based (NNRTI) regimen need to be evaluated. METHODS: We analyzed the occurrence of blips (one HIV-1 RNA > 50 copies/ml with a subsequent value < 50 copies/ml), the level of these blips (between 3 and 50 copies/ml) and their effect on CD4 cell count and the occurrence of virological failure in 43 patients with stable suppression of HIV-1 plasma viraemia (< 50 copies/ml) under NNRTI-based therapy. RESULTS: Eight out of 43 patients had one episode of blips during the follow-up (median = 350 copies/ml). Comparing patients with and without blips, the median level of HIV-1 RNA at baseline was 7.5 versus 3 copies/ml (P = 0.008), respectively. Patients with blips had a significantly lower CD4 cell count after 12 and 18 months than the others. Plasma concentrations of NNRTI before, during, and after the blips were adequate. In addition, the occurrence of blips was not associated with virological failure. CONCLUSION: These results suggest that blips may reflect ongoing viraemia of below 50 copies/ml and can impair the CD4 cell count recovery under an NNRTI regimen. The impairment of CD4 cell count recovery seems to be affected more by the occurrence of blips than by the level of viraemia (< 50 copies/ml) itself. Nevertheless, despite a tight genetic barrier for resistance with NNRTI drugs, no virologic failure occurred during the follow-up.

Adult↗
PubMed2003

Cardiovascular and cerebrovascular events in patients treated for human immunodeficiency virus infection.

BACKGROUND: Metabolic abnormalities associated with human immunodeficiency virus (HIV) infection, including dysglycemia and hyperlipidemia, are increasingly prevalent, and there is concern about the possibility of an association with accelerated cardiovascular and cerebrovascular disease. METHODS: We conducted a retrospective study of the risk of cardiovascular and cerebrovascular disease among the 36,766 patients who received care for HIV infection at Veterans Affairs facilities between January 1993 and June 2001. RESULTS: For antiretroviral therapy, 70.2 percent of the patients received nucleoside analogues, 41.6 percent received protease inhibitors, and 25.6 percent received nonnucleoside reverse-transcriptase inhibitors for a median of 17 months, 16 months, and 9 months, respectively. Approximately 1000 patients received combination therapy with a protease inhibitor for at least 48 months, and approximately 1000 patients received combination therapy with a nonnucleoside reverse-transcriptase inhibitor for at least 24 months. Between 1995 and 2001, the rate of admissions for cardiovascular or cerebrovascular disease decreased from 1.7 to 0.9 per 100 patient-years, and the rate of death from any cause decreased from 21.3 to 5.0 deaths per 100 patient-years. Patient-level regression analyses indicated that there was no relation between the use of nucleoside analogues, protease inhibitors, or nonnucleoside reverse-transcriptase inhibitors and the hazard of cardiovascular or cerebrovascular events, but the use of antiretroviral drugs was associated with a decreased hazard of death from any cause. CONCLUSIONS: Use of newer therapies for HIV was associated with a large benefit in terms of mortality that was not diminished by any increase in the rate of cardiovascular or cerebrovascular events or related mortality. Fear of accelerated vascular disease need not compromise antiretroviral therapy over the short term. However, prolonged survival among HIV infected patients means that longer-term observation and analysis are required.

Adult↗
PubMed2001

Risk factors for severe hepatic injury after introduction of highly active antiretroviral therapy.

OBJECTIVES: Treatment of HIV infection with highly antiretroviral therapy (HAART) may be limited by liver toxicity. Its incidence and risk factors are not well known. PATIENTS AND METHODS: Retrospective chart review. Naive patients beginning HAART between January 1997 and January 2000. Severe transaminase elevation was defined as fivefold or higher rise over upper normal limits, or as > or =3.5-fold rise above abnormal baseline values. RESULTS: Of 222 study subjects, 38%, 5%, and 2% were coinfected with hepatitis C virus (HCV), hepatitis B virus, and hepatitis D virus, respectively. Besides two nucleoside reverse transcriptase inhibitors (NRTIs), 96 patients received protease inhibitors (PIs), 90 received nonnucleoside reverse transcriptase inhibitors (NNRTIs), and 35 received a PI + NNRTI combination. Severe hepatic injury developed in 21 (9%): 10% PI, 9%, and 9% PI + NNRTI. Both univariate and multivariate analyses identified alcohol abuse, HCV coinfection, and older age as independent risk factors. Predictor variables in the final multivariate model were: alcohol abuse (risk ratio [RR], 5.87; 95% confidence interval [CI], 1.49-23.15; p =.01], positive HCV serology (RR, 3.99; 95% CI, 1.32-12.10; p =.01], and older age (RR, 1.11; 95% CI, 1.04-1.18; p = 0.001). CONCLUSIONS: Nearly 10% of study subjects who start HAART experience severe transaminase elevation, irrespective of the treatment. Avoidance of alcohol abuse, especially in study subjects coinfected with HCV, will reduce the risk of hepatic injury after HAART. When possible, prior treatment for chronic HCV infection should be considered.

Adult↗
PubMed2006

A novel antiretroviral class (fusion inhibitors) in the management of HIV infection. Present features and future perspectives of enfuvirtide (T-20).

Enfuvirtide (Fuzeon, Roche), is the first member of a novel class of antiretroviral agents, the so-called fusion inhibitors, which act against HIV with a completely novel (extra cellular) mechanism of action, and can therefore be easily added to all anti-HIV association therapies including all other antiretroviral agents belonging to nucleoside/nucleotide reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors, and protease inhibitors, since no interactions of any type are expected with enfuvirtide. Despite the need of a twice-daily parenteral (subcutaneous) delivery due to the polypeptide structure of the drug, and its proportionally short elimination lifetime, two extensive multicentre randomized clinical trials and a huge amount of other clinical and laboratory experiences confirmed the elevated potency and the safety profile of enfuvirtide in appropriate samples of HIV-infected patients (both adults and children), who failed and/or became intolerant to all previously available anti-HIV regimens, and had a very restricted choice of antiviral compounds showing residual activity. As a consequence, enfuvirtide is recommended as an adjunct to an "optimized background" containing at least one or two antiretroviral drugs, which are still active against the isolated viral strain, as assessed by resistance testing. The extremely promising profile of this novel anti-HIV drug and the reduced potential for the development of viral resistance (with no possibility of cross-resistance with the other anti-HIV classes) however warrant further pharmacokinetic, pharmacodynamic, pharmacogenomic, and pharmacoeconomic investigation. Also more extensive and prolonged clinical and quality of life studies are strongly needed to establish the best positioning of enfuvirtide in the current therapeutic guidelines of HIV disease and its future role, besides its current approval for salvage therapy of adult and pediatric HIV-infected patients with limited therapeutic options.

Adult↗
PubMed2006

Overcoming HIV drug resistance through rational drug design based on molecular, biochemical, and structural profiles of HIV resistance.

There are 20 available drugs for the treatment of human immunodeficiency virus (HIV) infection. With a single exception, all of these drugs inhibit either HIV reverse transcriptase or protease. Reverse transcriptase inhibitors can be further categorized as nucleoside/nucleotide analogs or non-nucleoside reverse transcriptase inhibitors. Resistance that has emerged against all available antiretroviral drugs represents a major challenge in the therapy of HIV infection. Nevertheless, extensive analysis of the molecular and structural mechanisms by which such mutations confer resistance has accumulated over the years. This understanding has driven the development and refinement of novel compounds capable of maintaining antiviral activity against both wild-type and drug-resistant HIV strains. The molecular, biochemical, and structural profiles of reverse transcriptase inhibitor and protease inhibitor resistance are discussed. In addition, how this knowledge has been utilized to generate a new generation of antiviral drugs with activity against drug-resistant HIV is reviewed.

Anti-HIV Agents↗
PubMed2004

Antiviral drugs in current clinical use.

The current armamentarium for the chemotherapy of viral infections consists of 37 licensed antiviral drugs. For the treatment of human immunodeficiency virus (HIV) infections, 19 compounds have been formally approved: (i) the nucleoside reverse transcriptase inhibitors (NRTIs) zidovudine, didanosine, zalcitabine, stavudine, lamivudine, abacavir and emtricitabine; (ii) the nucleotide reverse transcriptase inhibitor (NtRTI) tenofovir disoproxil fumarate; (iii) the non-nucleoside reverse transcriptase inhibitors (NNRTIs) nevirapine, delavirdine and efavirenz; (iv) the protease inhibitors saquinavir, ritonavir, indinavir, nelfinavir, amprenavir, lopinavir (combined with ritonavir at a 4/1 ratio) and atazanavir; and the viral entry inhibitor enfuvirtide. For the treatment of chronic hepatitis B virus (HBV) infections, lamivudine as well as adefovir dipivoxil have been approved. Among the anti-herpesvirus agents, acyclovir, valaciclovir, penciclovir (when applied topically), famciclovir, idoxuridine and trifluridine (both applied topically) as well as brivudin are used in the treatment of herpes simplex virus (HSV) and/or varicella-zoster virus (VZV) infections; and ganciclovir, valganciclovir, foscarnet, cidofovir and fomivirsen (the latter upon intravitreal injection) have proven useful in the treatment of cytomegalovirus (CMV) infections in immunosuppressed patients (i.e. AIDS patients with CMV retinitis). Following amantadine and rimantadine, the neuraminidase inhibitors zanamivir and oseltamivir have recently become available for the therapy (and prophylaxis) of influenza virus infections. Ribavirin has been used (topically, as aerosol) in the treatment of respiratory syncytial virus (RSV) infections, and the combination of ribavirin with (pegylated) interferon-alpha has received increased acceptance for the treatment of hepatitis C virus (HCV) infections.

Anti-HIV Agents↗
PubMed2005

HIV-reverse transcriptase inhibition: inclusion of ligand-induced fit by cross-docking studies.

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) have, in addition to the nucleoside reverse transcriptase inhibitors (NRTIs) and protease inhibitors (PIs), a definitive role in the treatment of HIV-1 infections. Since the appearance of HEPT and TIBO, more than 30 structurally different classes of compounds have been reported as NNRTIs, which are specific inhibitors of HIV-1 replication, targeting the HIV-1 reverse transcriptase (RT). Nevirapine and delavirdine are the first formally licensed for clinical use, and others have been licensed afterward, while several are in preclinical or clinical development. The NNRTIs interact with a specific site of HIV-1 RT (nonnucleoside binding site, NNBS) that is close to, but distinct from, the NRTI binding site. In this work we report the application of the Autodock program assessing its usability through reproduction of 41 NNRTI experimental bound conformations. Moreover, cross-docking experiments on the wild-type and mutated RT forms were conducted to take into account the enzyme flexibility as a valuable tool for structure-based drug design (SBDD) studies and to gain insight on the mode of action of new anti-HIV agents active against both wild-type and resistant strains.

Binding Sites↗
PubMed2004

Safety and antiretroviral effectiveness of concomitant use of rifampicin and efavirenz for antiretroviral-naive patients in India who are coinfected with tuberculosis and HIV-1.

OBJECTIVE: To study the safety and antiretroviral effectiveness of concomitant use of rifampicin and efavirenz for antiretroviral-naïve patients in India who are coinfected with tuberculosis (TB) and HIV-1. DESIGN AND METHODS: The study was an observational longitudinal cohort investigation. HIV-1-infected patients with CD4 cell counts of < or = 200/microL who attended the Infectious Disease Clinic of Sterling Hospital (Ahmedabad, India) from June 2001 to December 2002 were recruited for the study. Patients were divided in 2 groups: group A, patients with active TB (n = 126); and group B, patients without TB (n = 129). Group A patients were given efavirenz with 2 nucleoside reverse transcriptase inhibitors along with rifampicin-containing anti-TB treatment. Group B patients were treated for presenting opportunistic infections and started therapy with efavirenz plus 2 nucleoside reverse transcriptase inhibitors. The nucleoside reverse transcriptase inhibitors were either zidovudine and lamivudine (n = 30) or stavudine and lamivudine (n = 225). Patients self-funded their investigations and medications (antiretroviral, anti-TB, and other opportunistic infection-related agents). Indian generic medications were used. RESULTS: Efavirenz-based highly active antiretroviral therapy with rifampicin for HIV/TB-coinfected patients resulted in an immunologic response that was comparable with that of the group not receiving rifampicin. Median CD4 cell counts at baseline, 3 months, 6 months, and 9 months in group A were 84/microL (range, 5-200/microL), 225/microL (range, 26-528/microL), 251/microL (range, 65-775/microL), and 275/microL (range, 61-611/microL), respectively, and in group B, these values were 118/microL (range, 2-200/microL), 244/microL (range, 38-881/microL), 294/microL (range, 23-1322/microL), and 295/microL (range, 26-991/microL), respectively. The overall increase in CD4 cell count was greater in group A than in group B at 9 months (190 vs. 176/microL, respectively). Patients in both groups tolerated the therapy well; the adverse effects profile was comparable except that group A patients had a higher incidence of hepatitis than group B patients (13.49% vs. 0, respectively; P < 0.0001). CONCLUSION: Clinical and immunologic benefits are comparable for patients receiving efavirenz-based antiretroviral therapy with or without rifampicin.

Adult↗
PubMed1984

Purification of a specific inhibitor of reverse transcriptase from human placenta.

Human placental extracts contain a factor which specifically and reversibly inhibits the reverse transcriptase of mammalian retroviruses. This placental inhibitor has been partially purified and characterized. It elutes at 0.1-0.2 M phosphate on hydroxyapatite chromatography and can be further purified by phosphocellulose chromatography where it elutes at 0.4 M KCl. By these purification procedures, specific activities of 40-70,000 units of inhibitor per mg of protein were obtained. The size of the inhibitor is about 60-65,000 daltons as estimated by velocity sedimentation. The inhibitor purified by these techniques selectively inhibits the activity of purified reverse transcriptase from Rauscher murine leukemia virus and baboon endogenous virus. It is substantially less active against the reverse transcriptase of avian myeloblastosis virus. The specificity of this inhibitor for mammalian enzymes and particularly for the human placental reverse transcriptase suggests that it plays a role in the regulation of DNA synthesis in human placental development.

Animals↗
PubMed2001

Tolerability of postexposure antiretroviral prophylaxis for occupational exposures to HIV.

A substantial body of evidence provides support (but not definitive proof of efficacy) for the use of antiretroviral agents as postexposure prophylaxis for occupational exposures to HIV in the healthcare workplace. Despite the lack of definitive evidence of the efficacy of these agents in this setting, over the past decade this intervention has become the standard of care for healthcare workers who sustain occupational exposures to HIV. Administration of these agents--even for a relatively short 28-day postexposure course--is often fraught with difficulty. All of the agents currently used for postexposure prophylaxis regimens have substantial adverse effects, and significant adverse effects occur in more than two-thirds of individuals electing prophylaxis. This manuscript reiterates current US Federal Government guidelines for the administration of postexposure prophylaxis, specifically noting that zidovudine plus lamivudine (with or without a protease inhibitor) remains the recommended regimen. The paper summarises the significant toxicities associated with nucleoside reverse transcriptase inhibitors (primarily nausea, vomiting, diarrhoea and bone marrow suppression), non-nucleoside reverse transcriptase inhibitors (rash, fever, gastrointestinal symptoms and hepatitis, including hepatic decompensation necessitating liver transplantation) and protease inhibitors (nausea, vomiting, diarrhoea, abdominal pain, hyperglycaemia, hyperlipidaemia, headache and anorexia). As a class, the antiretroviral agents have an extraordinary number of drug interactions. The non-nucleoside reverse transcriptase inhibitors and the protease inhibitors are metabolised through the cytochrome P450 pathway, and the effects of concomitant administration of protease inhibitors with other agents in the same class are discussed, as well as the effects of concomitant administration of protease inhibitors with non-nucleoside agents. The potential for numerous and medically risky drug interactions emphasises the importance of planning antiretroviral prophylaxis in consultation with practitioners or clinical pharmacists who are skilled in the use of these agents and knowledgeable about the potential for significant drug interactions that could either reduce the benefit of prophylaxis or increase the potential for toxicity. Another common problem encountered by individuals managing postexposure prophylaxis programmes relates to the administration of chemoprophylaxis to a pregnant healthcare worker who has sustained an occupational exposure to HIV. We address what is known about the potential for toxicity and emphasise the recently published warning concerning the deaths of pregnant women and their offspring from lactic acidosis while receiving regimens containing stavudine and didanosine.

Anti-HIV Agents↗
PubMed1992

In vitro selection and molecular characterization of human immunodeficiency virus-1 resistant to non-nucleoside inhibitors of reverse transcriptase.

Several newly discovered potent and selective non-nucleoside inhibitors of human immunodeficiency virus-1 reverse transcriptase (RT) are undergoing evaluation in clinical trials. We studied the potential for development of viral resistance to one of the prototype compounds, BI-RG-587, a dipyridodiazepinone derivative. Human immunodeficiency virus-1 resistant to BI-RG-587 emerged after only one cycle of in vitro infection in the presence of the drug. Resistant virus was cross-resistant to the non-nucleoside tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-thione derivative R82150 but remained susceptible to 2',3'-dideoxynucleosides and phosphonoformate. Both native (virion-associated) and recombinant RT derived from resistant virus were insensitive to BI-RG-587 and R82150. Nucleotide sequence analysis of multiple drug-resistant and -sensitive recombinant RT clones identified a single predicted amino acid change common to all resistant clones (tyrosine-181----cysteine). These studies suggest that the viral resistance to non-nucleoside RT inhibitors may develop in vivo. This possibility should be carefully monitored in clinical trials of these compounds.

Antiviral Agents↗
PubMedDate not supplied

Switching strategies to improve lipid profile and morphologic changes.

Metabolic alterations and body fat changes are well-recognized limitations of protease inhibitor-based regimens. Strategies of replacing protease inhibitors with nonnucleoside reverse transcriptase inhibitors or abacavir have been shown to improve metabolic abnormalities, particularly by decreasing cholesterol and triglyceride levels, and reducing cardiovascular risk. The various therapeutic options show differences in efficacy, tolerability, and metabolic outcomes. Abacavir seems to be better tolerated, at least in the only randomized trial in which the three options were compared face-to-face, but it is associated with higher virologic failure in patients with prior suboptimal nucleoside therapy. Nonnucleoside reverse transcriptase inhibitors, particularly nevirapine, result in a better lipid profile with a greater increase in HDL cholesterol and in the HDUtotal cholesterol ratio, one of the most important parameters associated with a reduction in cardiovascular risk. Efavirenz has been associated with increased triglyceride levels in some studies. Although protease inhibitor compounds as a family have been linked to metabolic and body fat alterations, new drugs such as atazanavir seem to be associated with a more favorable lipid profile. Lipoatrophy is a stigmatizing complication in HIV-infected patients receiving HAART. There is strong evidence suggesting a prominent role of thymidine analogs, mainly stavudine, in its development. Substitution of stavudine or zidovudine for abacavir or tenofovir partially improves peripheral fat loss. In addition, the lipid profile significantly improves. Finally, although the extended use of non-thymidine nucleoside analogs and the development of new families of antiretroviral drugs will probably result in a lower impact in lipids and morphologic changes, many patients are currently under treatment with these compounds. In this setting, switching strategies may be useful to minimize clinical and psychological consequences, improving the quality of life of HIV-infected patients treated with HAART.

Anti-HIV Agents↗
PubMed2004

New nucleoside/nucleotide backbone options: a review of recent studies.

The nucleoside/nucleotide reverse transcriptase inhibitor (NRTI/NtRTI) class continues to serve as an important component of the standard of care for HIV infection. Combinations of dual NRTIs/NtRTIs with protease inhibitors (PIs) or nonnucleoside reverse transcriptase inhibitors (NNRTIs) remain the most commonly used regimens in clinical practice. In recent years, clinical outcomes data on previously novel NRTI/NtRTI backbone combinations have provided clinicians with new options to address potency, tolerability, and convenience of antiretroviral therapy. However, the tolerability, drug-drug interactions, and resistance profiles of specific regimens using new NRTI/NtRTI combinations must be weighed against the needs and preferences of individual patients. This review summarizes recent efficacy and safety data on emerging NRTI/NtRTI combination backbones, including tenofovir DF (TDF) with lamivudine (3TC), abacavir with 3TC, didanosine (ddI) with 3TC, ddI with emtricitabine (FTC), and TDF with FTC.

Anti-HIV Agents↗
PubMed1998

Combination antiretroviral therapy for HIV infection.

The primary goal of antiretroviral therapy for human immunodeficiency virus (HIV) infection is suppression of viral replication. Evidence indicates that the optimal way to achieve this goal is by initiating combination therapy with two or more antiretroviral agents. The agents now licensed in the United States for use in combination therapy include five nucleoside analog reverse transcriptase inhibitors (zidovudine, didanosine, zalcitabine, stavudine and lamivudine), two nonnucleoside reverse transcriptase inhibitors (delavirdine and nevirapine) and four protease inhibitors (saquinavir, ritonavir, indinavir and nelfinavir). Current recommendations suggest that antiretroviral therapy be considered in any patient with a viral load higher than 5,000 to 20,000 copies per mL, regardless of the CD4+ count. Selection of the combination regimen must take into account the patient's prior history of antiretroviral use, the side effects of these agents and drug-drug interactions that occur among these agents and with other drugs as well. Because of the potential for viral resistance, nonnucleoside reverse transcriptase inhibitors and protease inhibitors should only be used in combination therapy. Antiretroviral agents are rapidly being developed and approved, so physicians must make increasingly complex treatment decisions about medications with which they may be unfamiliar.

Anti-HIV Agents↗
PubMed2004

The impact of the M184V substitution on drug resistance and viral fitness.

Treatment of HIV/AIDS with antiretroviral therapy can result in HIV-1 drug resistance, limiting its use. Resistance mutations arise prior to therapy due to errors in HIV-1 replication, and are also spread by sexual and other modes of transmission. However, it is also generally believed that resistance is due to multiple drug mutations to any single or combination of antiretroviral agents selected during viral replication in the presence of incompletely suppressive drug regimens. In the case of protease inhibitors and most nucleoside analog reverse transcriptase inhibitors, drug resistance is due to the accumulation of mutations in the HIV-1 protease and reverse transcriptase genes respectively. However, in the case of non-nucleoside reverse transcriptase inhibitors, a single primary drug mutation is usually sufficient to abrogate antiviral activity. This is also true of certain specific mutations, such as M184V in the reverse transcriptase enzyme, resulting in resistance to the nucleoside analog, lamivudine (Epivir, GlaxoSmithKline). However, it is thought that lamivudine may still contribute to the effectiveness of antiretroviral therapy, even after the appearance of the M184V mutation. M184V may affect sensitivity to other drugs, such as zidovudine (Retrovir, GlaxoSmithKline), in HIV-1 variants that already contain resistance mutations to zidovudine, during concomitant treatment with lamivudine. M184V also has a positive effect on HIV-1 RT fidelity, reducing spontaneous HIV mutagenesis. Processivity of the reverse transcriptase enzyme may be affected by mutations such as M184V, and this may be a major determinant of viral replication fitness.

Amino Acid Substitution↗
PubMed2001

Resistance profile and cross-resistance of HIV-1 among patients failing a non-nucleoside reverse transcriptase inhibitor-containing regimen.

The objectives were to determine the resistance profile and the rate of cross-resistance in HIV-1 infected patients failing an efavirenz or a nevirapine or a nevirapine then efavirenz containing regimens, and to investigate if zidovudine and more generally thymidine analog nucleosides lead to a particular genotypic pattern in nevirapine failing patients. A study was conducted in 104 patients with virological rebound to a non-nucleoside reverse transcriptase inhibitors (NNRTI) regimen (efavirenz n = 39, nevirapine n = 46 and nevirapine then efavirenz n = 19). Genotypic resistance testing was carried out of detectable plasma HIV-1 RNA (> 200 copies/ml). Among the 104 patients studied, only two patients failed to respond to the nevirapine regimen without selection of a NNRTI resistance mutation. All patients failing an efavirenz regimen harboured mutations conferring cross-resistance to nevirapine (K103N, Y188L, G190S). Among patients failing the nevirapine regimen and presenting with NNRTI mutations, 35 (80%) harboured mutations conferring cross-resistance to efavirenz (K101E, K103N, Y188L) and 9 (20%) harboured mutations conferring resistance to nevirapine alone (V106A and Y181C). In patients failing nevirapine then efavirenz therapy, all NNRTI resistance profile led to cross-resistance to all available NNRTIs. Among patients receiving nevirapine, the selection of mutations associated with a cross-resistance to efavirenz was more frequent statistically when a thymidine nucleoside analog (zidovudine or stavudine) was used in the regimen (P = 0.02). In conclusion, 100% of patients developed cross-resistance to nevirapine and efavirenz after treatment by efavirenz and 80% after treatment by nevirapine. The use of a thymidine analog concomitantly with nevirapine leads to the preferential selection of cross-resistance NNRTI mutations.

Alkynes↗
PubMed2005

Highly active antiretroviral therapy: current state of the art, new agents and their pharmacological interactions useful for improving therapeutic outcome.

Highly active antiretroviral therapy (HAART) dramatically changed the course of HIV infection. Currently, this therapy involves the use of agents from at least two distinct classes of antivirals: a protease inhibitor (PI) in combination with two nucleoside/nucleotide reverse transcriptase inhibitors (N(t)RTIs), or a non-nucleoside reverse transcriptase inhibitor (NNRTI) in combination with NRTIs. Recently, the third family of antivirals started to be used clinically, with the advent of enfuvirtide, the first fusion inhibitor (FI). Several pharmacological agents are available form these classes of antivirals, NRTIs, NNRTIs, PIs and FIs, which will be briefly reviewed here. Some more agents are in advanced clinical evaluation or have recently been approved (such as tenofovir, a NtRTI; atazanavir, a PI; tipranavir, another PI), mainly against drug-resistant viruses. Compounds inhibiting HIV integrase, the third enzyme of HIV, are also available ultimately, with several such derivatives in clinical trials (L-731, 988 and S-1360). Another approach to inhibit the growth of retroviruses, including HIV, targets the ejection of zinc ions from critical zinc finger viral proteins, which has as a consequence the inhibition of viral replication in the absence of mutations leading to drug resistance phenotypes. All steps in the process of HIV entry into the cell may be targeted by specific compounds that might be developed as novel types of antiretrovirals. Thus, inhibitors of the gp120-CD4 interaction have been detected (zintevir, FP-21399 and BMS-378806 in clinical trials). Small molecule chemokine antagonists acting as HIV entry inhibitors also were described in the last period, which interact both with the CXCR4 coreceptor (such as AMD3100; AMD3465; ALX40-4C; T22, T134 and T140), or which are antagonist of the CCR5 coreceptor (TAK-779, TAK-220, SCH-C, SCH-D, E913, AK-602 and NSC 651016 in clinical trials), together with new types of fusion inhibitors possessing the same mechanism of action as enfuvirtide (such as T1249). Compounds interacting with Tat/Tar have also been detected which inhibit HIV replication in low micromolar range (EM2487, tamacrazine, CGP 64222 or CGA 137053 among others). Unexploited viral and cellular targets (such as the maturation process-with a first potent compound available, PA-457; the cellular proteins Tsg101, APOBEC3G, or the viral ones Vif, Rev or RNase H) are also presented, together with recently emerged approaches for eradication of HIV reservoirs. A review on the pharmacology and interactions of these agents with other drugs is presented here, with emphasis on how these pharmacological interferences may improve the clinical use of antivirals, or how side effects due to these drugs may be managed better by taking them into account.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Clinical utility of current NNRTIs and perspectives of new agents in this class under development.

Highly active antiretroviral therapy (HAART) has significantly reduced the number of deaths caused by AIDS. However, the antiviral efficacy of HAART comprising protease inhibitors (PIs) and nucleoside reverse transcriptase inhibitors (NRTIs) is frequently accompanied by a decrease in patients' quality of life. PI-based therapies often fail due to poor adherence caused by heavy pill burden, complex dosing schedules and undesirable side effects. The current trend is to switch from PI-based to PI-sparing regimens consisting of non-nucleoside reverse transcriptase inhibitors (NNRTIs) and NRTIs. Despite some encouraging results from NNRTI-containing therapies, two major concerns in using the currently available NNRTIs remain: 1) low genetic barrier to the emergence of resistance and 2) cross-resistance due to single mutations that often render the whole class of NNRTIs ineffective. Clearly, new and improved NNRTIs are needed to address these concerns.

Alkynes↗