Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0021051 (immunodeficiency)
71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Patients with human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome have high rates of psychiatric illness. The effective management of these psychiatric conditions can improve a patient's quality of life and may improve antiretroviral adherence. Care providers for patients with HIV infection frequently encounter clinical situations in which psychotropic medications are needed or are being used. Those clinical situations require familiarity with the broad category of medications termed "psychotropic." That familiarity should include a basic understanding of indications, adverse effects, and drug interactions. In particular, it is very important to recognize the many potential interactions based on cytochrome P450 metabolism, which is common to many psychotropics, the protease inhibitors, and the nonnucleoside reverse-transcriptase inhibitors. In a brief review of the use of psychotropic medications in patients with HIV infection, we discuss indications, adverse effects, and drug interactions for commonly used antidepressants, mood stabilizers, anxiolytics, antipsychotics, psychostimulants, and drugs of abuse.
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PMID:Psychotropic medications and HIV. 1658 91

The human immunodeficiency virus (HIV) was discovered in 1982, but treatment strategies were not introduced until 5 years later. Early regimens consisted of one or two drugs and often led to treatment failure. Since the advent in 1995 of highly active antiretroviral therapy (HAART), which consists of at least three agents, a dramatic improvement has been seen in the number of patients attaining undetectable viral loads, improved CD4 counts, and improved survival. However, early HAART often consisted of drugs with complex dosing schedules, strict food requirements, treatment-limiting adverse effects, and the need to take 16-20 pills/day. These treatment barriers often led to patient nonadherence, with subsequent treatment failure and development of resistant strains. The CD4 count and viral load are the most important surrogate markers used to determine if treatment is indicated. Current guidelines suggest starting treatment in patients who are symptomatic with an acquired immunodeficiency syndrome-defining illness regardless of CD4 count or viral load, as well as in asymptomatic patients with a CD4 count of 350 cells/mm(3) or below. In patients with CD4 counts above 350 cells/mm(3) and viral loads above 100,000 copies/ml, some clinicians prefer to defer treatment, whereas others will consider starting therapy; treatment is deferred in patients with CD4 counts above 350 cells/mm(3) and viral load s below 100,000 copies/ml. If therapy is started, the selection of appropriate agents is based on comorbidities (liver disease, depression, cardiovascular disease), pregnancy status, adherence potential (dosage regimen, pill burden, dosing frequency), food restrictions (dosing with regard to meals), adverse drug effects, and potential drug-drug interactions. Within the last 8 years, newer antiretroviral agents have focused on ways to improve adherence, such as convenient dosing (fewer pills), pharmacokinetic and formulation changes to reduce dosing frequency or pill burden, and coformulated dosage forms that contain two or three drugs in one convenient pill. Other improvements include increased potency of newer agents, agents sensitive to a highly resistant virus, improved adverse-effect profile (e.g., less gastrointestinal effects, improved lipid profiles), as well as protease inhibitor boosting with ritonavir, which takes advantage of the potent cytochrome P450 inhibitory action of ritonavir. This review focuses on the concepts of antiretroviral therapy, barriers to successful antiretroviral treatment, developments to limit treatment barriers, and new drug entities for the treatment of HIV.
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PMID:An update and review of antiretroviral therapy. 1686 88

Concurrent use of natural health products (NHPs) with antiretroviral drugs (ARVs) is widespread among human immunodeficiency virus-infected patients. This article reviews the clinical pharmacokinetic and pharmacodynamic interactions between NHPs and ARVs. Many NHPs are complex mixtures and are likely to contain organic compounds that may induce and/or inhibit drug metabolizing enzymes and drug transporters. Although the weight of evidence for the effects of certain NHPs varies and many studies of these products lack scientific rigor, it has been observed that St. John's wort clearly induces cytochrome P450 3A4 and P-glycoprotein and reduces protease inhibitor and nonnucleoside reverse-transcriptase inhibitor concentrations, thereby increasing the likelihood of therapeutic failure. Limited clinical research suggests that intake of garlic and vitamin C results in reductions in ARV concentrations. The intake of milk thistle, Echinacea species, and goldenseal inhibits cytochrome P450 enzymes in vitro and may increase ARV concentrations, but by clinically unimportant amounts. Intake of fish oil reduces ARV-induced hypertriglyceridemia without significantly affecting lopinavir concentrations. Before recommending the use of NHPs as adjuncts to ARV use, studies should first exclude significant pharmacokinetic interactions and ensure that ARV efficacy is maintained.
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PMID:Interactions between natural health products and antiretroviral drugs: pharmacokinetic and pharmacodynamic effects. 1698 20

Many drug interactions with drugs used for the therapy of human immunodeficiency virus (HIV) occur at the level of different cytochrome P450 isozymes. Increasing evidence suggests that antiretrovirals may also modify activity and expression of active drug transport systems. Such interactions may alter drug absorption, elimination, and also drug distribution and reach clinical importance if thereby access to the target site is affected. Beyond P-glycoprotein, the family of multidrug resistance-related proteins (MRP/ABCC) substantially contributes to the elimination of numerous drugs and their metabolites. Because the interaction of MRPs with non-HIV protease inhibitor antiretrovirals has not been studied thoroughly, we investigated whether important non-nucleoside reverse transcriptase inhibitors (NNRTI) (delavirdine, efavirenz, and nevirapine), nucleoside reverse transcriptase inhibitors (NRTI) (abacavir, emtricitabine, and lamivudine), and tenofovir as a nonnucleotide reverse transcriptase inhibitor can interact with MRP1, MRP2, and MRP3 in vitro. Inhibition of these ABC transporters was quantified by confocal laser-scanning microscopy using the 5-chloromethylfluorescein diacetate assay. With the exception of abacavir, which had no effect on MRP3, all the test compounds increased intracellular 5-chloromethylfluorescein fluorescence in a concentration-dependent manner, and this effect was observed in all the overexpressing cell lines but not in the parental cell line, indicating inhibition of MRP1, MRP2, and MRP3. In conclusion, the present study provides the first evidence for a significant and concentration-dependent inhibition of MRPs by NNRTI, NRTI, and tenofovir, which was most pronounced for delavirdine, efavirenz, and emtricitabine, suggesting that this might contribute to some of the known drug interactions impairing HIV therapy and also to the superior effectiveness of combination pharmacotherapy.
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PMID:Inhibition of MRP1/ABCC1, MRP2/ABCC2, and MRP3/ABCC3 by nucleoside, nucleotide, and non-nucleoside reverse transcriptase inhibitors. 1717 11

Although highly active antiretroviral therapy (HAART) has revolutionized the treatment of human immunodeficiency virus (HIV)-positive patients, malignancies in the setting of HIV infection remain an appreciable problem. We evaluated the changing epidemiology of HIV-related malignancies, optimal neoplastics and their effect on viral dynamics, and evidence regarding drug interactions between chemotherapy and antiretrovirals. A MEDLINE search (January 1966-June 2006) was performed to identify clinical trials, review articles, and meta-analyses; abstracts from HIV conferences were also searched. Survival of patients with HIV-related malignancies has substantially improved since the advent of HAART. Chemotherapy for malignancies in the HIV-positive population generally resembles that for the HIV-negative population, with trials revealing an elevated frequency of toxicities in HIV-positive patients. Studies of antineoplastics have shown no long-term adverse effects on viral dynamics in terms of immunologic or virologic HIV markers. Limited pharmacokinetic data with antineoplastics and antiretrovirals suggest possible changes in some pharmacokinetic parameters, but these results should be interpreted cautiously because of the small numbers of patients enrolled in the trials. Researchers also report an increased frequency of chemotherapy-related toxicities when HAART was coadministered with antineoplastics. This increase was likely due to impairment of cytochrome P450 metabolism of antineoplastics by protease inhibitors. Because of the survival benefits of HAART, the integration of antiretrovirals with chemotherapy is now preferred for patients with HIV-related malignancies. However, because the metabolic pathways of many of these agents are similar, the effectiveness of antineoplastic therapy and its related toxicities should be vigilantly monitored in this patient population.
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PMID:Oncologic complications of human immunodeficiency virus infection: changing epidemiology, treatments, and special considerations in the era of highly active antiretroviral therapy. 1719 66

Tipranavir is a nonpeptidic protease inhibitor that has activity against human immunodeficiency virus strains resistant to multiple protease inhibitors. Tipranavir 500 mg is coadministered with ritonavir 200 mg. Tipranavir is metabolized by cytochrome P450 (CYP) 3A and, when combined with ritonavir in vitro, causes inhibition of CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A in addition to induction of glucuronidase and the drug transporter P-glycoprotein. As a result, drug-drug interactions between tipranavir-ritonavir and other coadministered drugs are a concern. In addition to interactions with other antiretrovirals, tipranavir-ritonavir interactions with antifungals, antimycobacterials, oral contraceptives, statins, and antidiarrheals have been specifically evaluated. For other drugs such as antiarrhythmics, antihistamines, ergot derivatives, selective serotonin receptor agonists (or triptans), gastrointestinal motility agents, erectile dysfunction agents, and calcium channel blockers, interactions can be predicted based on studies with other ritonavir-boosted protease inhibitors and what is known about tipranavir-ritonavir CYP and P-glycoprotein utilization. The highly complex nature of drug interactions dictates that cautious prescribing should occur with narrow-therapeutic-index drugs that have not been specifically studied. Thus, the known interaction potential of tipranavir-ritonavir is reported, and in vitro and in vivo data are provided to assist clinicians in predicting interactions not yet studied. As more clinical interaction data are generated, better insight will be gained into the specific mechanisms of interactions with tipranavir-ritonavir.
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PMID:Mechanisms of pharmacokinetic and pharmacodynamic drug interactions associated with ritonavir-enhanced tipranavir. 1754 71

The potent induction of hepatic cytochrome P450 3A isoforms by rifampin complicates therapy for coinfection with human immunodeficiency virus (HIV) and Mycobacterium tuberculosis. We performed an open-label, single-arm study to assess the safety and pharmacokinetic interactions of the HIV protease inhibitor atazanavir coadministered with rifampin. Ten healthy HIV-negative subjects completed pharmacokinetic sampling at steady state while receiving 300 mg atazanavir every 12 h without rifampin (period 1), 300 mg atazanavir every 12 h with 600 mg rifampin every 24 h (period 2), and 400 mg atazanavir every 12 h with 600 mg rifampin every 24 h (period 3). During period 1, the mean concentration of drug in serum at 12 h (C(12 h)) was 811 ng/ml (range, 363 to 2,484 ng/ml) for atazanavir, similar to historic seronegative data for once-daily treatment with 300 mg atazanavir boosted with 100 mg ritonavir. During periods 2 and 3, the mean C(12 h) values for atazanavir were 44 ng/ml (range, <25 to 187 ng/ml) and 113 ng/ml (range, 39 to 260 ng/ml), respectively, well below historic seronegative data for once-daily treatment with 400 mg atazanavir without ritonavir. Although safe and generally well tolerated, 300 mg or 400 mg atazanavir administered every 12 h did not maintain adequate plasma exposure when coadministered with rifampin.
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PMID:Effect of concomitantly administered rifampin on the pharmacokinetics and safety of atazanavir administered twice daily. 1757 25

Human immunodeficiency virus protease inhibitors (PIs) modestly affect the plasma pharmacokinetics of tenofovir (TFV; -15% to +37% change in exposure) following coadministration with the oral prodrug TFV disoproxil fumarate (TDF) by a previously undefined mechanism. TDF permeation was found to be reduced by the combined action of ester cleavage and efflux transport in vitro. Saturable TDF efflux observed in Caco-2 cells suggests that at pharmacologically relevant intestinal concentrations, transport has only a limited effect on TDF absorption, thus minimizing the magnitude of potential intestinal drug interactions. Most tested PIs increased apical-to-basolateral TDF permeation and decreased secretory transport in MDCKII cells overexpressing P-glycoprotein (Pgp; MDCKII-MDR1 cells) and Caco-2 cells. PIs were found to cause a multifactorial effect on the barriers to TDF absorption. All PIs showed similar levels of inhibition of esterase-dependent degradation of TDF in an intestinal subcellular fraction, except for amprenavir, which was found to be a weaker inhibitor. All PIs caused a dose-dependent increase in the accumulation of a model Pgp substrate in MDCKII-MDR1 cells. Pgp inhibition constants ranged from 10.3 microM (lopinavir) to >100 microM (amprenavir, indinavir, and darunavir). Analogous to hepatic cytochrome P450-mediated drug interactions, we propose that the relative differences in perturbations in TFV plasma levels when TDF is coadministered with PIs are based in part on the net effect of inhibition and induction of intestinal Pgp by PIs. Combined with prior studies, these findings indicate that intestinal absorption is the mechanism for changes in TFV plasma levels when TDF is coadministered with PIs.
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PMID:Effects of human immunodeficiency virus protease inhibitors on the intestinal absorption of tenofovir disoproxil fumarate in vitro. 1766 27

Drug-induced liver injury (DILI) encompasses a spectrum of clinical disease ranging from mild biochemical abnormalities to acute liver failure. The majority of adverse liver reactions are idiosyncratic, occurring in most instances 5-90 days after the causative medication was last taken. The diagnosis of DILI is clinical, based on history, probability of the suspect medication as a cause of liver injury and exclusion of other hepatic disease. DILI can be hepatocellular (predominant rise in alanine transaminase), cholestatic (predominant rise in alkaline phosphatase) or mixed liver injury. An elevated bilirubin level more than twice the upper limit of normal in patients with hepatocellular liver injury implies severe DILI, with a mortality of approximately 10% and with an incidence rate of 0.7-1.3 per 100,000. Although acute liver failure is rare, 13-17% of all acute liver failure cases are attributed to idiosyncratic drug reactions. Response to drug withdrawal may be delayed up to 1 year with cholestatic liver injury with occasional subsequent progressive cholestasis known as the vanishing bile duct syndrome. Overall, chronic disease may occur in up to 6% even if the offending drug is withdrawn. Antibiotics and NSAIDs are the most common cause of DILI. Statins rarely cause significant liver injury whereas antiretroviral therapy is associated with hepatotoxicity in 10% of treated patients. Multiple mechanisms of DILI have been implicated, including TNF-alpha-activated apoptosis, inhibition of mitochondrial function and neoantigen formation. Risk factors for DILI include age, sex and genetic polymorphisms of drug-metabolising enzymes such as cytochrome P450. In patients with human immunodeficiency virus, the presence of chronic viral hepatitis increases the risk of antiretroviral therapy hepatotoxicity. Over the next decade, the combination of accurate case ascertainment of DILI via clinical networks and the application of genomics and proteomics will hopefully lead to accurate prediction of risk of DILI, so that pharmacotherapy can be optimised with avoidance of adverse hepatic events.
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PMID:Idiosyncratic drug-induced liver injury: an overview. 1796 56

P-glycoprotein (P-gp), multiple drug resistance associated proteins (MRPs), and cytochrome P450 3A4 together constitute a highly efficient barrier for many orally absorbed drugs. Multidrug regimens and corresponding drug-drug interactions are known to cause many adverse drug reactions and treatment failures. Available literature, clinical reports, and in vitro studies from our laboratory indicate that many drugs are substrates for both P-gp and CYP3A4. Our primary hypothesis is that transport and metabolism of protease inhibitors (PIs) and NNRTIs will be altered when administered in combination with azole antifungals, macrolide, fluroquinolone antibiotics, statins, cardiovascular agents, immune modulators, and recreational drugs [benzodiazepines, cocaine, lysergic acid dithylamide (LSD), marijuana, amphetamine (Meth), 3,4-methylenedioxymethamphetamine (MDMA), and opiates] due to efflux, and/or metabolism at cellular targets. Therefore, such drug combinations could be a reason for the unexpected and unexplainable therapeutic outcomes. A number of clinical reports on drug interaction between PIs and other classes (macrolide antibiotics, azole antifungals, cholesterol lowering statins, cardiovascular medicines, and immunomodulators) are discussed in this article. MDCKII-MDR1 was employed as an in vitro model to evaluate the effects of antiretrovirals, azole antifungals, macrolide, and fluroquinolone antibiotics on efflux transporters. Ketoconazole (50 muM) enhanced the intracellular concentration of (3)H ritonavir. The inhibitory effects of ketoconazole and MK 571 on the efflux of (3)H ritonavir were comparable. An additive effect was observed with simultaneous incorporation of ketoconazole and MK 571. Results of (3)H ritonavir uptake studies were confirmed with transcellular transport studies. Several fluroquinolones were also evaluated on P-gp-mediated efflux of (3)H cyclosporin and 14C erythromycin. These in vitro studies indicate that grepafloxacin, levofloxacin, and sparfloxacin are potent inhibitors of P-gp-mediated efflux of 14C erythromycin and (3)H cyclosporin. Simultaneous administration of fluoroquinolones and macrolides could minimize the efflux and metabolism of both of the drugs. Effects of erythromycin and ketoconazole on carbamazepine metabolism were examined. Formation of 10,11-epoxy carbamazepine, a major CBZ metabolite, was significantly inhibited by these agents. Therefore, drug efflux proteins (P-gp, MRPs) and metabolizing enzyme (CYP450) are major factors in drug interactions. Overlapping substrate specificities of these proteins result in complex and sometimes perplexing pharmacokinetic profiles of multidrug regimens. Drug-drug interactions with PIs and other coadministered agents for human immunodeficiency virus (HIV) positive population have been discussed in light of efflux transporters and metabolizing enzymes. This article provides an insight into low and variable oral bioavailability and related complications leading to loss of therapeutic activity of MDR and CYP 450 substrates.
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PMID:MDR- and CYP3A4-mediated drug-drug interactions. 1804 Aug 9


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