Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Saquinavir is an HIV protease inhibitor with no, or limited, effect on the activity of other structurally related human aspartic proteinases. As with other HIV protease inhibitors, saquinavir inhibits the cleavage of the gag-pol protein substrate leading to the release of structurally defective and functionally inactive viral particles. It is active on both HIV-1 and HIV-2, and also has activity on chronically infected cells and HIV strains resistant to reverse transcriptase inhibitors. Synergy of action has been observed with other antiretroviral drugs. Saquinavir is characterised by a low bioavailability which is further reduced in the fasting state. Metabolism is mainly hepatic through cytochrome P450 (CYP) 3A4, but intestinal metabolism through the same system has also been reported. To achieve higher drug plasma concentrations and increase the antiviral effect, a new formulation of saquinavir with a higher bioavailability has recently been introduced. Higher plasma drug concentrations may also be obtained by combining the drug with CYP blockers, such as ritonavir or ketoconazole. Because of its metabolic interference with the CYP system, saquinavir cannot be coadministered with astemizole, terfenadine or cisapride. Rifampicin (rifampin) is also contraindicated because coadministration can lead to decreases in saquinavir concentrations. Interactions have also been reported with other drugs metabolised through the same system, including non-nucleoside reverse transcriptase inhibitors and HIV protease inhibitors. Resistance has been observed after both in vitro and in vivo drug exposure, with a relatively specific mutation profile compared with other protease inhibitors. Saquinavir is generally well tolerated, with mild gastrointestinal symptoms representing the most commonly observed adverse effects. Although characterized by low bioavailability, in phase III trials saquinavir has been shown to have clinical efficacy in terms of survival and progression rate. As with the other protease inhibitors, saquinavir should be used in combination with other antiretroviral drugs. Current therapeutic guidelines, however, recommend the selection of an initial treatment regimen with other protease inhibitors with higher in vivo activity in terms of RNA and CD4 response. The results of ongoing studies will clarify to what extent a new saquinavir formulation, recently introduced, is superior to the previous one in terms of antiviral activity and to provide comparisons with other protease inhibitors. Further studies are also needed to define the best place of saquinavir within treatment strategies based on protease inhibitors, particularly in respect to the optimal sequence for its use with other protease inhibitors, and the dynamics of cross-resistance and its role within regimens based on the combination of protease inhibitors.
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PMID:Saquinavir. Clinical pharmacology and efficacy. 953 81

RANTES has been found to suppress human immunodeficiency virus type 1 (HIV-1) replication. To further elucidate the role of this chemokine in HIV-1 infection, RANTES levels were analyzed in serum and platelet-free plasma (PFP) in 53 HIV-1-infected patients and 20 controls. RANTES levels were significantly elevated in both serum and PFP in all clinical stages of HIV-1 infection, with the highest levels in CDC groups A and B. In longitudinal testing, the progressors were characterized by a pronounced decline in serum levels over time; the nonprogressors, however, had only a slight reduction or an increase in RANTES levels. During 16 weeks of indinavir therapy, there was an increase in circulating RANTES levels and enhanced release of RANTES from stimulated CD8+ lymphocytes. The decline in RANTES levels along with disease progression is compatible with RANTES having a beneficial role in HIV-1-infected patients. The increase in RANTES levels during protease inhibitor-containing regimens may represent a previously unrecognized immunologic effect of such therapy.
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PMID:Circulating levels of RANTES in human immunodeficiency virus type 1 infection: effect of potent antiretroviral therapy. 953 90

The virologic and immunologic efficacy of ritonavir, an HIV protease inhibitor, was examined in 14 HIV-infected patients with a mean CD4+ cell count of 183 x 10(6)/l at baseline. All had been exposed to nucleoside analogs for longer than 6 months; and ritonavir was added to previous ongoing antiretroviral drugs. A mean reduction of 1.5 logs was seen in plasma viral load 4 weeks after began ritonavir, and 9 (64.3%) of 14 patients achieved undetectable levels (< 4,000 HIV-RNA copies/ml). A mean increase of 222 x 10(6) cells was observed in the CD4+ count. Nine (64.3%) individuals reported side effects, although they did not force to stop the medication. In conclusion, the addition of ritonavir seem to be a reasonable alternative strategy in patients with advanced HIV disease and heavy previous exposure to nucleoside analogs.
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PMID:[Efficacy of ritonavir in HIV positive patients pretreated with nucleoside analogues]. 954 3

A 33-year-old HIV-infected man was given antiretroviral therapy with zidovudine and lamivudine. After ten months' treatment the patient had elevated hepatic transaminase levels. Severe hepatic steatosis was found in the biopsy. Clinical history, laboratory, microbiologic and X-ray examination revealed no other abnormalities. The transaminase levels remained high after withdrawal of zidovudine alone, but a decrease was observed when both zidovudine and lamivudine were stopped. Rechallenge of lamivudine therapy caused the levels to increase again. The hepatic steatosis was considered to be caused by the antiretroviral therapy, lamivudine having a synergistic influence on this side effect of zidovudine. Ten months after the therapy was changed to the protease inhibitor indinavir combined with zalcitabine and stavudine, two other nucleoside analogues, hepatic steatosis recurred.
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PMID:[Hepatic steatosis during treatment with zidovudine and lamivudine in an HIV-positive patient]. 956 77

With the development and FDA approval of an increasing number of antiretroviral agents, decisions regarding the treatment of HIV-infected persons have become complex; and the field continues to evolve rapidly. In 1996, the Department of Health and Human Services and the Henry J. Kaiser Family Foundation convened the Panel on Clinical Practices for the Treatment of HIV to develop guidelines for the clinical management of HIV-infected persons. This report includes the guidelines developed by the Panel regarding the use of laboratory testing in initiating and managing antiretroviral therapy, considerations for initiating therapy, whom to treat, what regimen of antiretroviral agents to use, when to change the antiretroviral regimen, treatment of the acutely HIV-infected person, special considerations in adolescents, and special considerations in pregnant women. Viral load and CD4+ T cell testing should ideally be performed twice before initiating or changing an antiretroviral treatment regimen. All patients who have advanced or symptomatic HIV disease should receive aggressive antiretroviral therapy. Initiation of therapy in the asymptomatic person is more complex and involves consideration of multiple virologic, immunologic, and psychosocial factors. In general, persons who have <500 CD4+ T cells per mm3 should be offered therapy; however, the strength of the recommendation to treat should be based on the patient's willingness to accept therapy as well as the prognosis for AIDS-free survival as determined by the HIV RNA copy per mL of plasma and the CD4+ T cell count. Persons who have >500 CD4+ T cells per mm3 can be observed or can be offered therapy; again, risk of progression to AIDS, as determined by HIV RNA viremia and CD4+ T cell count, should guide the decision to treat. Once the decision to initiate antiretroviral therapy has been made, treatment should be aggressive with the goal of maximal viral suppression. In general, a protease inhibitor and two nucleoside [corrected] reverse transcriptase inhibitors should be used initially. Other regimens may be utilized but are considered less than optimal Many factors, including reappearance of previously undetectable HIV RNA, may indicate treatment failure. Decisions to change therapy and decisions regarding new regimens must be carefully considered; there are minimal clinical data to guide these decisions. Patients with acute HIV infection should probably be administered aggressive antiretroviral therapy; once initiated, duration of treatment is unknown and will likely need to continue for several years, if not for life. Special considerations apply to adolescents and pregnant women and are discussed in detail.
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PMID:Guidelines for the use of antiretroviral agents in HIV-infected adults and adolescents. Department of Health and Human Services and Henry J. Kaiser Family Foundation. 957 21

Ten subjects received 600 to 1,200 mg of the human immunodeficiency virus type 1 (HIV-1) protease inhibitor ritonavir per day. Following 2 weeks of therapy, plasma HIV RNA levels decreased by a mean of 1. 57 (range, 0.89 to 1.96) log units. With continued therapy, HIV RNA levels began to rise in eight subjects. The initial rise in plasma RNA levels was temporally associated with the development and quantitative increase in the V82 resistance mutation. Doubling times of the V82A mutant virus were estimated to be 2.4 to 4.8 days. An L63P/A mutation was commonly present at baseline even in subjects with a durable virologic response. The concomitant acquisition of an L63P/A mutation with the V82A/F mutation at the time when plasma RNA levels rebounded suggests a role for the L63P/A mutation in improving the fitness of the V82A/F mutation. Subsequent additional genotypic changes at codons 54 and 84 were often associated with further increases in plasma RNA levels. Ongoing viral replication in the presence of drugs resulted in the appearance of additional genotypic changes, including the L90M saquinavir resistance mutation, and decreased phenotypic susceptibility. The relative fitness of the protease V82A ritonavir resistance mutation and reverse transcriptase T215Y/F zidovudine resistance mutation following drug withdrawal were estimated to be 96 to 98% that of the wild type. Durability of the virologic response was associated with plasma RNA levels at the nadir. A virologic response beyond 60 days was not observed unless plasma HIV RNA levels were suppressed below 2,000 copies/ml, consistent with estimates from V82A doubling times for selection of a single resistance mutation to dominate the replicating population.
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PMID:Genotypic changes in human immunodeficiency virus type 1 associated with loss of suppression of plasma viral RNA levels in subjects treated with ritonavir (Norvir) monotherapy. 957 87

Some HIV-protease inhibitor derivatives having an N-carbomethoxycarbonyl-prolyl-phenylalanine benzyl ester (CPF) moiety as a binding site to gp120 were designed and synthesized. Almost all the compounds bearing CPF on the phenoxyacetyl group showed protease-inhibitory activity. Compounds 25a and 25b, which have the CPF moiety at the ortho- and meta-positions of the phenoxyacetyl group, respectively, had anti-HIV activity, although the others showed only protease-inhibitory activity. These results suggest that 25b binds to gp120 and inhibits HIV protease.
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PMID:Syntheses of HIV-protease inhibitors having a peptide moiety which binds to GP120. 957 45

This study explores whether previous failures on antiretroviral drug regimens preclude the possibility of immune restoration. This was assessed by evaluating T cell subset changes in individuals who received a salvage regimen of highly active antiretroviral therapy (HAART) after initially failing protease inhibitor monotherapy. Ten HIV-1-infected asymptomatic patients received a regimen of indinavir, zidovudine, and 3TC after failing saquinavir monotherapy. Changes in absolute numbers of naive, memory, and activated CD4+ and CD8+ T cells expressing a selection of CD45RA, CD62L, CD45RO, HLA-DR, and CD38 markers were monitored prospectively over 6 months. These measurements were correlated with plasma viral load along with alterations in a selected CD8+ V alpha/Vbeta T cell receptor (TCR) repertoire. Over 6 months there was a progressive increase in numbers of CD4+ memory (CD45RA-CD62L+) and naive (CD45RA+CD62L+) T cells, which displayed a modest inverse correlation with viral load. Two phases of CD8+ memory cell changes were identified, consisting of a transient increase in CD45RA+CD62L- numbers after 2 months and thereafter a progressive rise in CD45RA-CD62L+ cells until 6 months. A strong correlation existed between reduced viral load and loss of activated CD8+CD38+HLA-DR+ cell numbers. There was also a temporary broadening of the CD8+ V alpha/Vbeta TCR repertoire at 8 weeks, which became skewed after 6 months in parallel with reduced viral suppression. Closer analysis of naive and memory cell subset proportions in individual patients revealed that enlarged pools of naive subsets were evident in those patients with rebounds in viral load. Overall, drug-experienced patients responding to HAART displayed increased numbers of naive and memory CD4+ subsets, and reduced CD8+ cell activation with a loss of TCR skewing.
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PMID:Changes in CD4+ and CD8+ T cell subsets in response to highly active antiretroviral therapy in HIV type 1-infected patients with prior protease inhibitor experience. 959 10

Weight loss and wasting are significant complications of HIV disease. HIV protease inhibitor therapy promotes clinical, immunologic and virologic improvement in HIV-infected patients. In this study, we sought to determine the specific effect of HIV protease inhibitors on patient weight. Ten consecutive HIV patients were treated with protease inhibitor-containing regimens over six months. CD4 T-cell counts, plasma viral load levels and bariatric changes were monitored during the study. Patients experienced a mean weight gain of 19 Pounds (P = 0.006). There was a significant increase in mean CD4 T-cell count (P = 0.008) and a significant decrease in mean viral load level (P = 0.004). The increase in CD4 T cells did not correlate with weight gain, whereas the decrease in viral load did show a significant correlation with the weight increase (P = 0.003). The mechanism of protease inhibitor-induced weight gain is discussed. The medications may also be useful for wasting diseases unrelated to HIV.
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PMID:Weight gain associated with protease inhibitor therapy in HIV-infected patients. 960 7

Amprenavir is a viral protease inhibitor with specificity for the HIV protease enzyme. The resistance profile of amprenavir appears to differ from that of other protease inhibitors such as saquinavir and indinavir. Twelve hours after single-dose administration of amprenavir 1200mg to HIV-infected individuals, the mean plasma concentration of the drug was more than 10-fold greater than the 50% inhibitory concentration for HIV-1IIIB in peripheral blood lymphocytes. In a small nonblind study, amprenavir monotherapy increased CD4+ cell count and decreased viral load in 37 patients with HIV infection and no previous exposure to protease inhibitor therapy. Combination therapy comprising amprenavir and other antiretroviral agents (abacavir, zidovudine, lamivudine, indinavir, saquinavir or nelfinavir) decreased viral load and increased CD4+ cell counts in patients with HIV infection. Antiviral efficacy was maintained during up to 24 weeks' follow-up. Available data suggest that rash, headache and diarrhoea or loose stools are the most frequent adverse events associated with amprenavir therapy.
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PMID:Amprenavir. 961 98


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