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)

Darunabir, formerly TMC114, is a new protease inhibitor (PI) under clinical development designed to be active against HIV strains resistant to currently available PI. The virological and immunological response to ritonavir-boosted darunabir was assessed in four heavily antiretroviral-experienced patients who had failed enfuvirtide and two or more previous ritonavir-boosted PI regimens, including tipranavir in one instance. All four patients reached undetectable plasma HIV-RNA levels within 8 weeks of therapy and experienced significant CD4 cell count gains.
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PMID:Successful rescue therapy with darunabir (TMC114) in HIV-infected patients who have failed several ritonavir-boosted protease inhibitors. 1684 14

TMC114 (darunavir) is a promising clinical inhibitor of HIV-1 protease (PR) for treatment of drug resistant HIV/AIDS. We report the ultra-high 0.84 A resolution crystal structure of the TMC114 complex with PR containing the drug-resistant mutation V32I (PR(V32I)), and the 1.22 A resolution structure of a complex with PR(M46L). These structures show TMC114 bound at two distinct sites, one in the active-site cavity and the second on the surface of one of the flexible flaps in the PR dimer. Remarkably, TMC114 binds at these two sites simultaneously in two diastereomers related by inversion of the sulfonamide nitrogen. Moreover, the flap site is shaped to accommodate the diastereomer with the S-enantiomeric nitrogen rather than the one with the R-enantiomeric nitrogen. The existence of the second binding site and two diastereomers suggest a mechanism for the high effectiveness of TMC114 on drug-resistant HIV and the potential design of new inhibitors.
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PMID:Ultra-high resolution crystal structure of HIV-1 protease mutant reveals two binding sites for clinical inhibitor TMC114. 1696 36

This open-label, randomized, crossover study investigated the bioavailability, short-term safety, and tolerability of darunavir (TMC114) coadministered with low-dose ritonavir under fasted conditions and after different meal types in HIV-negative healthy volunteers. All volunteers received ritonavir 100 mg twice daily on days 1 to 5, with a single darunavir 400-mg tablet given on day 3 (darunavir/rtv). Pharmacokinetic parameters for darunavir and ritonavir were determined under fasted conditions and following a standard breakfast, a high-fat breakfast, a nutritional protein-rich drink, or a croissant with coffee. Administration of darunavir/rtv in a fasting state resulted in a decrease in darunavir C(max) and AUC(last) of approximately 30% compared with administration after a standard meal. No significant differences in darunavir plasma concentrations were observed between different fed states. Darunavir/rtv should therefore be administered with food, but exposure to darunavir is not affected by the type of meal.
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PMID:The effect of different meal types on the pharmacokinetics of darunavir (TMC114)/ritonavir in HIV-negative healthy volunteers. 1738 57

The XV International HIV Drug Resistance Workshop recorded advances in basic and clinical science of HIV resistance to antiretrovirals as well as new findings on resistance by hepatitis B virus (HBV) and hepatitis C virus (HCV). In the clinical arena, attendees learned of four cases of resistance to lopinavir/ritonavir monotherapy, correlation between low-frequency pretreatment mutations and failure of a first antiretroviral regimen, emergence of non-nucleoside-related mutations in 20% of patients interrupting a suppressive nonnucleoside regimen, and evolution of mutations conferring resistance to an HIV entry inhibitor that is being studied as a vaginal microbicide. New data reported from the POWER 1, 2 and 3 salvage trials suggested that there is a close correlation between darunavir (TMC114) phenotypic susceptibility, the number of baseline protease inhibitor-related resistance mutations and virological response. Scientists exploring the mechanisms of resistance reported of mutations in the carboxy-terminal domain of reverse transcriptase that may further resistance to zidovudine, novel mutations that may contribute to resistance of both nucleoside and non-nucleoside reverse transcriptase inhibitors, and a mechanism that HCV and HIV may share to resist antiviral therapy.
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PMID:Key reports from the XV International HIV Drug Resistance Workshop 2006. 1750 58

Effective combination therapy for HIV/AIDS is now available and has made a major impact on HIV-related mortality and morbidity. The effects of even the most active of antiretroviral drugs are hampered by drug resistance and tolerability issues. Darunavir (TMC114), coadministered with low-dose ritonavir (darunavir/r), is a new HIV-1 protease inhibitor that has been designed to be active against both wild-type and multi-resistant virus. Darunavir/r 600/100 mg b.i.d. in a combination antiretroviral regimen in the POWER trials has provided treatment-experienced patients with substantially greater virological and immunological benefits compared with standard of care. This article reviews the presently available data on darunavir, its pharmacology, pharmacokinetics, drug-drug interactions and clinical trial results, as well as examining darunavir from a health economic perspective.
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PMID:Darunavir (TMC114): a new HIV-1 protease inhibitor. 1769 96

Darunavir (TMC114) is a newly developed HIV-1 protease inhibitor with potent antiviral activity against both wild-type and multidrug resistant HIV-1 strains. The drug is currently approved by the US FDA for antiretroviral treatment-experienced patients with limited therapeutic options. The approved dosage of darunavir is 600 mg in combination with ritonavir 100mg twice daily. Darunavir is rapidly absorbed after oral administration, reaching peak plasma concentrations after 2.5-4 hours. Absorption is followed by a fast distribution/elimination phase and a subsequent slower elimination phase with a terminal elimination half-life of 15 hours in the presence of low-dose ritonavir. Darunavir is approximately 95% plasma protein bound, mainly to alpha(1)-acid glycoprotein. Systemic exposure is increased by 30% when darunavir is taken with a meal. Darunavir is extensively and almost exclusively metabolised by cytochrome P450 (CYP) 3A4. Coadministration with small doses of the strong CYP3A4 inhibitor ritonavir results in an increase in darunavir bioavailability from 37% to 82%. Darunavir and its metabolites are mainly excreted in faeces (79.5%) and, to a lesser extent, in urine (13.9%). With regard to the necessary coadministration with low-dose ritonavir as a potent CYP3A4 inhibitor, coadministration of other substrates of CYP3A4 with darunavir/ritonavir requires caution or is even contraindicated. Guidance is derived from drug-drug interaction trials and experience from comparable ritonavir-boosted protease inhibitor regimens.
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PMID:Clinical pharmacokinetics of darunavir. 1771 72

Antiretroviral drug combinations that include two nucleoside reverse transcriptase inhibitors and a protease inhibitor (PI) can suppress HIV replication to undetectable levels, improving the prognosis of HIV-infected individuals. The aim of therapy is complete virological suppression, with a current goal of <50 copies/mL HIV-1 RNA, in order to minimize the occurrence of drug resistance. Improved understanding of the pharmacology of PIs, primarily the importance of adequate drug exposure, has led to the widespread administration of PIs combined with a low 'boosting' dose of ritonavir. The combination of PIs with ritonavir can improve treatment responses in both treatment-naive and -experienced patients. Boosted PIs are an important therapeutic option for HIV and extensive data exist supporting their use. Use of individual agents should be guided by a resistance test at all stages of treatment from naive through to highly treatment-experienced patients. Currently, seven boosted PIs have both US and European licensing approval: indinavir, saquinavir, lopinavir, fosamprenavir, atazanavir, tipranavir and darunavir (formerly TMC114). The preferred first-line option in the USA is lopinavir. Many of the older PIs are less effective and/or have less favourable tolerability profiles. Emergent PI resistance is a major challenge in treatment, and it can be accelerated by partial suppression of viral load through inappropriate therapy combinations. Using the newer boosted PIs, which have more robust resistance profiles, with an optimized background regimen may increase the likelihood of complete viral suppression. This review discusses the relative strengths and weaknesses of boosted PIs in current practice.
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PMID:Overview of boosted protease inhibitors in treatment-experienced HIV-infected patients. 1789 Feb 81

Our structure-based design strategies which specifically target the HIV-1 protease backbone, resulted in a number of exceedingly potent nonpeptidyl inhibitors. One of these inhibitors, darunavir (TMC114), contains a privileged, structure-based designed high-affinity P2 ligand, 3(R),3a(S),6a(R)-bis-tetrahydrofuranylurethane (bis-THF). Darunavir has recently been approved for the treatment of HIV/AIDS patients harboring multidrug-resistant HIV-1 variants that do not respond to previously existing HAART regimens.
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PMID:Darunavir, a conceptually new HIV-1 protease inhibitor for the treatment of drug-resistant HIV. 1790 Sep 13

The high incidence of cross-resistance between human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) limits their sequential use. This necessitates the development of PIs with a high genetic barrier and a broad spectrum of activity against PI-resistant HIV, such as tipranavir and darunavir (TMC114). We performed a surface plasmon resonance-based kinetic study to investigate the impact of PI resistance-associated mutations on the protease binding of five PIs used clinically: amprenavir, atazanavir, darunavir, lopinavir, and tipranavir. With wild-type protease, the binding affinity of darunavir was more than 100-fold higher than with the other PIs, due to a very slow dissociation rate. Consequently, the dissociative half-life of darunavir was much higher (>240 h) than that of the other PIs, including darunavir's structural analogue amprenavir. The influence of protease mutations on the binding kinetics was tested with five multidrug-resistant (MDR) proteases derived from clinical isolates harboring 10 to 14 PI resistance-associated mutations with a decreased susceptibility to various PIs. In general, all PIs bound to the MDR proteases with lower binding affinities, caused mainly by a faster dissociation rate. For amprenavir, atazanavir, lopinavir, and tipranavir, the decrease in affinity with MDR proteases resulted in reduced antiviral activity. For darunavir, however, a nearly 1,000-fold decrease in binding affinity did not translate into a weaker antiviral activity; a further decrease in affinity was required for the reduced antiviral effect. These observations provide a mechanistic explanation for darunavir's potent antiviral activity and high genetic barrier to the development of resistance.
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PMID:Binding kinetics of darunavir to human immunodeficiency virus type 1 protease explain the potent antiviral activity and high genetic barrier. 1792 44

This was an open-label, crossover study to investigate the pharmacokinetic interaction between darunavir (TMC114), coadministered with low-dose ritonavir (darunavir/ritonavir), and the protease inhibitor saquinavir in HIV-negative healthy volunteers. Thirty-two volunteers were randomized into two cohorts (panel 1 and panel 2). In two separate sessions, panel 1 received 400/100 mg darunavir/ritonavir twice a day and 400/1000/100 mg darunavir/saquinavir/ritonavir twice a day; panel 2 received 1000/100 mg saquinavir/ritonavir twice a day and 400/1000/100 mg darunavir/saquinavir/ritonavir twice a day. All treatments were administered orally under fed conditions for 13 days with an additional single morning dose on day 14. Treatment sessions were separated by a washout period of at least 14 days. Twenty-six volunteers completed the study (n=14, panel 1; n=12, panel 2), whereas six discontinued as a result of adverse events. Coadministration of saquinavir with darunavir/ritonavir resulted in decreases of darunavir area under the curve and maximum and minimum plasma concentrations of 26%, 17%, and 42%, respectively, compared with administration of darunavir/ritonavir alone. Relative to treatment with saquinavir/ritonavir alone, saquinavir exposure was not significantly different with the addition of darunavir. Ritonavir area under the curve12h increased by 34% when saquinavir was added to treatment with darunavir/ritonavir. The coadministration of darunavir/saquinavir/ritonavir was generally well tolerated. Similar findings are expected with the approved 600/100 mg darunavir/ritonavir twice-a-day dose. The combination of saquinavir and darunavir/ritonavir is currently not recommended.
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PMID:Pharmacokinetic interaction between darunavir and saquinavir in HIV-negative volunteers. 1804 78


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