Darunavir

Darunavir is an orally-bioavailable non-peptidic inhibitor of human immunodeficiency virus type 1 (HIV-1) protease that selectively inhibits HIV-1 protease enzyme induced cleavage of gag and gag-pol poly-proteins preventing the maturation of virions and also inhibits the dimerization of HIV-1 protease suppressing proteolytic activity and subsequent replication of HIV-1. Study results have shown that darunavir exhibits potent inhibition against HIV-1 with a value of 50% inhibition concentration IC₅₀ of 0.003 μmol/L in HIV-1 infected MT-2 cells. Darunavir binds to HIV-1 protease with considerably high affinity and fits closely with the substrate envelop leading to its potent ability to inhibit multidrug-resistant HIV strains.

Reference

McKeage K, Perry CM, Keam SJ. Darunavir: a review of its use in the management of HIV infection in adults. Drugs. 2009;69(4):477-503. doi: 10.2165/00003495-200969040-00007.

Interaction of Rifampin and Darunavir-Ritonavir or Darunavir-Cobicistat In Vitro.[Pubmed:28193650]

Antimicrob Agents Chemother. 2017 Apr 24;61(5). pii: AAC.01776-16.

Treatment of HIV-infected patients coinfected with Mycobacterium tuberculosis is challenging due to drug-drug interactions (DDIs) between antiretrovirals (ARVs) and antituberculosis (anti-TB) drugs. The aim of this study was to quantify the effect of cobicistat (COBI) or ritonavir (RTV) in modulating DDIs between Darunavir (DRV) and rifampin (RIF) in a human hepatocyte-based in vitro model. Human primary hepatocyte cultures were incubated with RIF alone or in combination with either COBI or RTV for 3 days, followed by coincubation with DRV for 1 h. The resultant DRV concentrations were quantified by high-performance liquid chromatography with UV detection, and the apparent intrinsic clearance (CLint.app.) of DRV was calculated. Both RTV and COBI lowered the RIF-induced increases in CLint.app. in a concentration-dependent manner. Linear regression analysis showed that log10 RTV and log10 COBI concentrations were associated with the percent inhibition of RIF-induced elevations in DRV CLint.app., where beta was equal to -234 (95% confidence interval [CI] = -275 to -193; P < 0.0001) and -73 (95% CI = -89 to -57; P < 0.0001), respectively. RTV was more effective in lowering 10 muM RIF-induced elevations in DRV CLint.app. (half-maximal [50%] inhibitory concentration [IC50] = 0.025 muM) than COBI (IC50 = 0.223 muM). Incubation of either RTV or COBI in combination with RIF was sufficient to overcome RIF-induced elevations in DRV CLint.app., with RTV being more potent than COBI. These data provide the first in vitro experimental insight into DDIs between RIF and COBI-boosted or RTV-boosted DRV and will be useful to inform physiologically based pharmacokinetic (PBPK) models to aid in optimizing dosing regimens for the treatment of patients coinfected with HIV and M. tuberculosis.

Refining criteria for selecting candidates for a safe lopinavir/ritonavir or darunavir/ritonavir monotherapy in HIV-infected virologically suppressed patients.[Pubmed:28192453]

PLoS One. 2017 Feb 13;12(2):e0171611.

OBJECTIVE: The primary objective of this study was to estimate the incidence of treatment failure (TF) to protease inhibitor monotherapies (PI/r-MT) with lopinavir/ritonavir (LPV/r) or Darunavir/ritonavir (DRV/r). DESIGN: A multicenter cohort of HIV-infected patients with viral load (VL) 100 cells/muL) and residual viremia (aHR = 1.48 [95% CI: 1.01-2.17] vs. undetectable VL) were independently associated to TF. CONCLUSIONS: Residual viremia and nadir CD4+ counts <100 cells/muL should be regarded as the main factors to be taken into account before considering switching to a PI/r-MT.

A rapid validated UV-HPLC method for the simultaneous determination of the antiretroviral compounds darunavir and raltegravir in their dosage form.[Pubmed:28361525]

Rev Esp Quimioter. 2017 Jun;30(3):195-200. Epub 2017 Mar 29.

OBJECTIVE: A rapid, simple and sensitive high-performance liquid chromatography (HPLC) method with ultraviolet detection has been developed for quantification of Darunavir and raltegravir in their pharmaceutical dosage form. METHODS: The assay enables the measurement of both drugs with a linear calibration curve (R2= 0.999) over the concentration range 5-100 mg/L. The determination was performed on an analytical Tracer Excel 120 ODSB (15x0.4.6 cm) column at 35 masculineC. The selected wavelength was 254 nm. The mobile phase was a mixture of 0.037 M sodium dihydrogen phosphate buffer, acetonitrile and methanol (40:50:10, v/v/v) at a flow rate of 2.0 mL/min Nevirapine (50 mg/L) was used as internal standard. RESULTS: Accuracy, intra-day repeatability (n = 5), and inter-day precision (n = 3) were found to be satisfactory, being the accuracy from -4.33 to 3.88% and precisions were intra-day and inter-day, 0.25% and 4.42% respectively in case of Darunavir. Raltegravir intra-day and inter-day precisions lower of 1.01 and 2.36%, respectively and accuracy values bet from -4.02 to 1.06%. CONCLUSIONS: Determination of the Darunavir and raltegravir in their dosage form was done with a maximum deviation of 4%. This analytical method is rapid, easily implantable and offers good results.

TURQUOISE-I Part 1b: Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir with Ribavirin for Hepatitis C Virus Infection in HIV-1 Coinfected Patients on Darunavir.[Pubmed:28329334]

J Infect Dis. 2017 Feb 15;215(4):599-605.

Background: Ombitasvir/paritaprevir/ritonavir with dasabuvir (OBV/PTV/r + DSV) +/- ribavirin (RBV) is approved for hepatitis C virus (HCV) genotype 1 (GT1) treatment in HIV-1 coinfected patients. In healthy controls, coadministration of OBV/PTV/r + DSV + Darunavir (DRV) lowered DRV trough concentration (Ctrough) levels. To assess the clinical significance of this change, TURQUOISE-I, Part 1b, evaluated the efficacy and safety of OBV/PTV/r + DSV + RBV in coinfected patients on stable, DRV-containing antiretroviral therapy (ART). Methods: Patients were HCV treatment-naive or interferon-experienced, had CD4+ lymphocyte count >/=200 cells/microL or >/=14%, and plasma HIV-1 RNA suppression on once-daily (QD) DRV-containing ART at screening. Patients were randomized to maintain DRV 800 mg QD or switch to twice-daily (BID) DRV 600 mg; all received OBV/PTV/r + DSV + RBV for 12 weeks. Results: Twenty-two patients were enrolled and achieved SVR12. No adverse events led to discontinuation. Coadministration had minimal impact on DRV maximum observed plasma concentration and area under the curve; DRV Ctrough levels were slightly lower with DRV QD and BID. No patient experienced plasma HIV-1 RNA >200 copies/mL during treatment. Conclusions: HCV GT1/HIV-1 coinfected patients on stable DRV-containing ART achieved 100% SVR12 while maintaining plasma HIV-1 RNA suppression. Despite DRV exposure changes, episodes of intermittent HIV-1 viremia were infrequent.