Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rifabutin (ansamycin; LM427), a semisynthetic rifamycin derivative, inhibits the replication of human immunodeficiency virus type 1, the virus etiologically linked to acquired immunodeficiency syndrome. The inhibition of virus production was observed in human immunodeficiency virus type 1-infected peripheral blood mononuclear cells both by reverse transcriptase assay and virus-antigen assay. In addition, rifabutin effectively reduced human immunodeficiency virus type 1-associated cytopathic effect to OKT4-positive cells. Virion-associated reverse transcriptase was also markedly inhibited by rifabutin. The inhibitory dose of rifabutin was nontoxic to lymphoid cells, which further suggests that it might serve as a useful agent in the therapeutic modalities of acquired immunodeficiency syndrome.
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PMID:Interaction between rifabutin and human immunodeficiency virus type 1: inhibition of replication, cytopathic effect, and reverse transcriptase in vitro. 245 33

Rifabutin is a derivative of rifamycin S with activity against mycobacteria including atypical organisms such as Mycobacterium avium and M. intracellulare, also referred to as Mycobacterium avium-intracellulare complex (MAC). To date, rifabutin is the only drug to have been studied in large prospective placebo-controlled trials that has been shown to significantly reduce the incidence of disseminated MAC infection when administered prophylactically as a single agent to patients with acquired immune deficiency syndrome (AIDS). Initial studies also indicate that rifabutin may be a useful component of multiple drug regimens for the treatment of MAC infection, although further studies combining rifabutin with other recently available antimycobacterial drugs are required to determine the most effective regimens. When rifabutin is combined with at least two other antimycobacterial drugs, the combination appears to be of similar efficacy to rifampicin (rifampin)-containing regimens in patients with newly diagnosed pulmonary tuberculosis. Since available therapy for MAC infection in patients with AIDS is still suboptimal, rifabutin, at present the only first-line agent for prophylaxis against disseminated MAC infection in patients with advanced human immunodeficiency virus (HIV) infection, has the potential to make a valuable contribution to the continuing attempts to preserve the quality of life of patients with AIDS.
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PMID:Rifabutin. A review of its antimicrobial activity, pharmacokinetic properties and therapeutic efficacy. 752 34

It has been suggested that didanosine (ddI) may undergo hepatic metabolism. Rifabutin is an inducer of drug metabolism. Fifteen human immunodeficiency virus-infected patients whose conditions were stabilized on twice-daily doses of ddI participated in a Phase I, open-label, pharmacokinetic and safety drug interaction study between rifabutin and ddI. Twelve patients completed the study. All patients received their regular ddI dose (167-375 mg) on day 1. On days 2-13 they received once-daily rifabutin (600 mg, three patients; 300 mg, nine patients) with their regular twice-daily ddI regimen. On days 14-16 they received rifabutin alone. Serial blood and urine samples were collected for 12 h on day 1 and for 24 h on days 13 and 16, and safety evaluations were made throughout the study. Average day 1/day 13 ddI pharmacokinetic ratios and 95% confidence interval values for Cmax, AUC0-infinity, Cls/F, and t 1/2, lambda z were 1.17 (0.96-1.38), 1.13 (0.99-1.27), 0.91 (0.81-1.01), and 0.97 (0.79-1.15), respectively (p > 0.05 for all comparisons; paired t test). A 20% difference in AUC0-infinity could be detected with 90% power. Also, there were no significant changes in laboratory values or electrocardiograms, or in rifabutin pharmacokinetic parameters when the two agents were coadministered. Based on the safety and pharmacokinetic assessments, rifabutin did not appear to interact with ddI.
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PMID:A phase I evaluation of concomitant rifabutin and didanosine in symptomatic HIV-infected patients. 778 25

Prevention of opportunistic infections is an integral part of caring for patients infected with human immunodeficiency virus. Mycobacterium avium complex (MAC) bacteremia can cause severe morbidity and excess mortality among these patients. Controlled trials of rifabutin for the prophylaxis of MAC bacteremia have been completed. Rifabutin reduced the incidence of MAC bacteremia by approximately one-half and, when disseminated disease due to MAC (DMAC) did develop, reduced the frequency of associated clinical symptoms. Moreover, prophylaxis with rifabutin was well tolerated. Prophylaxis of MAC bacteremia with macrolide antibiotics is currently being investigated, but no data from large-scale prospective trials are yet available. On the basis of trials completed thus far, the U.S. Public Health Service has recently recommended the use of rifabutin (300 mg/d) as prophylaxis for MAC bacteremia in patients with fewer than 100 CD4+ lymphocytes/mm3. The widespread use of this prophylactic regimen could reduce the rates of morbidity and mortality caused by DMAC. However, rifabutin must be administered only after careful consideration of the circumstances of individual patients. Potential drug interactions, cost, and compliance are important factors in the decision about which patients should receive prophylaxis.
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PMID:Prophylaxis of Mycobacterium avium complex bacteremia in patients with AIDS. 820 74

Patients with advanced human immunodeficiency virus (HIV) disease are at risk for infections caused by protozoa, fungi, viruses, bacteria, and mycobacteria. Chemoprophylaxis is being used increasingly to prevent a growing number of opportunistic infections that occur in HIV-infected patients. Multiple opportunistic pathogen prophylaxis (MOPP) is based on the concept that use of antimicrobial agents with activity against a variety of opportunistic pathogens will result in better patient compliance, reduced toxicity, fewer drug interactions, and lower cost than does the use of numerous single agents focused on only one infection. The antimycobacterial agent rifabutin is a potential candidate for use as MOPP because of its current status as a prophylactic agent for Mycobacterium avium complex infection. Rifabutin is likely to prevent other mycobacterial infections, including tuberculosis. The possible efficacy of rifabutin therapy for bacterial infections and toxoplasmosis deserves further study. We discuss approaches to the evaluation of rifabutin in MOPP regimens, the characteristics that make it potentially useful as prophylaxis for tuberculosis, and the potential limitations associated with its use for this indication.
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PMID:Potential role of rifabutin in prophylaxis for tuberculosis and infections due to multiple opportunistic pathogens. 892 40

Recent advances in the drug therapy of localized and disseminated infection with Mycobacterium avium complex (MAC) are reviewed. MAC infection is the most commonly reported bacterial infection in patients with AIDS, and the frequency of this infection in patients negative for the human immunodeficiency virus (HIV) is increasing. The main portals of entry for MAC are the gastrointestinal and respiratory tracts. Localized MAC infection is more common in HIV-negative than HIV-infected patients. The symptoms of disseminated MAC disease are those typical of advanced HIV disease. The most reliable diagnosis is provided by blood cultures; radiometric culturing techniques are favored. The overall treatment of MAC infection has improved greatly with the introduction of new agents during the past 15 years; survival time has been extended. Clarithromycin and azithromycin have proven effective against both localized and disseminated MAC infection. Clarithromycin is the cornerstone of therapy for disseminated infection. Ciprofloxacin has been successfully used to treat disseminated infection as part of a four-drug regimen including rifampin, ethambutol, and clofazimine. Rifabutin has substantial efficacy when combined with other agents. Liposomal aminoglycosides, such as amikacin, and interferon gamma have shown some initial promise. Rifabutin is currently recommended for the prevention of MAC disease in HIV-infected patients. Clarithromycin and azithromycin have also shown efficacy for prophylaxis, and fluoroquinolones may play a preventive role as well. New drug therapies are improving the outlook for persons infected with MAC.
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PMID:New trends in the drug therapy of localized and disseminated Mycobacterium avium complex infection. 916 32

We conducted a prospective observational study to determine the feasibility and impact of rifabutin prophylaxis (300 mg daily) for human immunodeficiency virus-infected patients whose CD4 cell counts were <100/mm3. Three hundred seventy-one patients (65.2% of all patients with CD4 cell counts of <100/mm3 [mean +/- SD, 30 +/- 25/mm3]) received rifabutin prophylaxis for a mean duration +/- SD of 35.5 +/- 34.2 weeks; 198 patients (mean CD4 cell count +/- SD, 51.6 +/- 32/mm3) did not receive prophylaxis. Rifabutin prophylaxis for 8.4% of patients was interrupted because of adverse events. Mycobacterium avium complex (MAC) bacteremia developed in 17 (4.6%) of 371 patients receiving rifabutin prophylaxis and in 22 (11.1%) of 198 patients not receiving rifabutin prophylaxis. The mean CD4 cell count +/- SD at the diagnosis of MAC bacteremia was lower in patients receiving prophylaxis than in those not receiving prophylaxis (11.5 +/- 6.8/mm3 vs. 34.7 +/- 36/mm3, respectively; P < .01). MICs for MAC strains isolated from patients receiving prophylaxis were less than or equal to those for strains isolated from patients not receiving prophylaxis.
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PMID:Clinical and bacteriologic impact of rifabutin prophylaxis for Mycobacterium avium complex infection in patients with human immunodeficiency virus infection. 911 83

Rifabutin and fluconazole are often given concomitantly as therapy to prevent opportunistic infections in individuals infected with the human immunodeficiency virus. Recent reports have shown increased levels of rifabutin and its 25-desacetyl metabolite, LM565, in plasma when rifabutin is administered with fluconazole. Since fluconazole is known to inhibit microsomal enzymes, this study was undertaken to determine if this rifabutin-fluconazole interaction was due to an inhibition of human hepatic enzymes. The metabolism of both rifabutin and LM565 was evaluated in human liver microsomes and recombinant human cytochrome P-450 (CYP) 3A4 in the presence of fluconazole and other probe drugs known to inhibit CYP groups 1A2, 2C9, 2D6, 2E1, and 3A. The concentrations of rifabutin (1 microg/ml), LM565 (1 microg/ml), and fluconazole (10 and 100 microg/ml) used were equal to those observed in plasma after the administration of rifabutin and fluconazole at clinically relevant doses. High-performance liquid chromatography was used to assess the metabolism of rifabutin and LM565. Rifabutin was readily metabolized to LM565 by human microsomes, but the reaction was independent of NADPH and was not affected by the P-450 inhibitors. No rifabutin metabolism by recombinant CYP 3A4 was found to occur. LM565 was also metabolized by human microsomes to two products, but metabolism was dependent on NADPH and was affected by certain P-450 inhibitors. In addition, LM565 was readily metabolized by the recombinant CYP 3A4 to the same two products found with its metabolism by human microsomes. Therefore, rifabutin is metabolized by human microsomes but not via cytochrome P-450 enzymes, whereas LM565 is metabolized by CYP 3A4.
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PMID:Metabolism of rifabutin and its 25-desacetyl metabolite, LM565, by human liver microsomes and recombinant human cytochrome P-450 3A4: relevance to clinical interaction with fluconazole. 914 45

Didanosine (ddI) is currently used in the management of patients infected by the human immunodeficiency virus. Rifabutin (RBT) is being extensively used for prophylaxis against Mycobacterium avium complex (MAC) infections. Due to its acid-labile characteristics, ddI must be administered with a buffer. Recent reports have indicated that absorption of ketoconazole, ciprofloxacin, and dapsone, etc., in the gut is altered by concomitant ddI dosing. We have assessed whether concomitant dosing of ddI as antiretroviral therapy modifies RBT absorption in the gut, its steady-state pharmacokinetics, and/or safety in 15 patients with AIDS. Of the 15 patients enrolled, 12 completed the study and 3 receiving 600 mg of RBT with concomitant ddI administration withdrew prematurely from the study. Steady-state RBT pharmacokinetics were assessed on day 13 (ddI plus RBT) and day 16 (RBT alone). The ddI doses (adjusted for body weight) were 167 to 375 mg twice daily, while RBT was administered as a single 300- or 600-mg daily dose. No statistically significant (P > 0.05) differences were seen in RBT absorption parameter estimates between days 13 and 16: maximum concentration in plasma (Cmax; 511 +/- 341 ng/ml versus 525 +/- 254 ng/ml) and the time at which Cmax was observed (3.0 versus 2.5 h). The mean RBT estimates for area under the concentration-time curve from 0 to 24 h (AUC(0-tau)) (5,650 versus 5,023 ng x h/ml) and for oral clearance (1.28 versus 1.18 liter/h/kg) on both study days were also similar. Assessment based on urinary recovery of RBT (3.1 versus 3.7 mg) and its predominant deacetyl metabolite, LM565 (1.6 versus 1.4 mg), showed no apparent effect of ddI. The fraction of the RBT dose converted to LM565, as suggested by the ratio of AUC of the metabolite to AUC of the parent drug, was also unaltered (0.15 versus 0.12). A ratio analysis (day 13/day 16) of the RBT pharmacokinetic estimates showed that the 95% confidence intervals for all parameters were inclusive of one. Furthermore, the brief interruption of ddI therapy over this short study period at steady state produced no clinically significant changes in body weight, hematology, and renal and pancreatic functions. Therefore, concomitant administration of ddI appears not to affect RBT absorption in the gut and its disposition or safety in patients with AIDS.
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PMID:Rifabutin absorption in the gut unaltered by concomitant administration of didanosine in AIDS patients. 921 Jun 86

Rifabutin is an effective drug in the treatment of Mycobacterium avium complex (MAC). Rare adverse effects have been described in non immunocompromised patients. We report the case of a 35 year-old woman, negative for the human immunodeficiency virus (HIV), who had an isolated pulmonary infection caused by MAC. Under Rifabutin (600 mg/day), Clarithromycin and Ethambutol, an uveitis, associated with a pseudojaundice and polyarthralgia, appeared, while pulmonary infection improved. Improvement of adverse effects was obtained with non-steroid anti-inflammatory drugs, local steroid treatment for uveitis and lower doses of Rifabutin (300 mg/day). Those adverse effects have not been previously described with this dose of Rifabutin in a non HIV patient. The mechanism remained unknown. The decrease of Rifabutin doses associated with symptomatic treatments allow the preservation of an effective treatment for MAC infection.
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PMID:[Uveitis, arthralgia and pseudo-jaundice in a HIV seronegative patient due to rifabutin]. 960 93


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