Liquid Chromatographic Separation of Darunavir Enantiomers on Coated and Immobilized Amylose Tris(3, 5-Dimethylphenylcarbamate) Chiral Stationary Phases: LIQUID CHROMATOGRAPHIC SEPARATION OF DARUNAVIR ENANTIOMERS ON COATED AND IMMOBILIZED CHIRAL STATIONARY PHASES

Darunavir: A comprehensive profile

Darunavir: (3R,3aS,6aR)-hexahydrofuro[2,3-b]furan-3-yl [(2S,3R)-4-{[(4-aminophenyl)sulfonyl] (isobutyl)amino}-3-hydroxy-1-phenyl-2-butanyl]carbamate is a synthetic non-peptide protease inhibitor. On June 2006, it was first approved by the Food and Drug administration (FDA) for treatment of resistant type-1 of the human immunodeficiency virus (HIV). In July 2016, the FDA expanded the approval for use of darunavir in pregnant women with HIV infection. Darunavir prevents the replication of HIV virus by inhibiting the catalytic activity of the HIV-1 protease enzyme, and selectively inhibits the cleavage of HIV encoded Gag-Pol polyproteins in virus-infected cells, which prevents the formation of mature infectious virus particles. Darunavir is unique among currently available protease inhibitors because it maintains antiretroviral activity against a variety of multidrug-resistant HIV strains. This article discusses, by a critical extensive review of the literature, the description of darunavir in terms of its names, formulae, elemental composition, appearance, and use in the treatment of HIV-infected patients. The article also discusses the methods for preparation of darunavir, its physical-chemical properties, analytical methods for its determination, pharmacological properties, and dosing information.

Enantioseparation of isoxazolines with functionalized perphenylcarbamate cyclodextrin clicked chiral stationary phases in HPLC

The enantioseparations of 12 isoxazoline racemates were explored with four perphenylcarbamate cyclodextrin (CD) clicked chiral stationary phases (CSPs) in high performance liquid chromatography (HPLC). The results demonstrated that the functionalities on phenylcarbamate moiety greatly determined the chiral separation ability of CD clicked CSPs. Among of them, per(3-chloro-4-methylphenylcarbamate) CD clicked CSP (CCC3M4-CSP) exhibited the best enantioseparation ability, affording 4ClPh-OPr with a chiral resolution over 20 in ternary eluent mobile phases. The optimization of CSPs structures provided wide platform for their chiral separations towards multi-mode HPLC.

Eluent Tolerance and Enantioseparation Recovery of Chiral Packing Materials Based on Chitosan Bis(Phenylcarbamate)-(n-Octyl Urea)s for High Performance Liquid Chromatography

The goal of the present work was to study the influence of the swelling of chitosan derivatives on the enantioseparation and the separation performance recovery of chiral stationary phases (CSPs) based on these derivatives. Therefore, six chitosan bis(phenylcarbamate)-(n-octyl urea)s were synthesized, which were coated on macroporous 3-aminopropyl silica gel affording new CSPs. Most of the CSPs demonstrated strong enantioseparation capability for the tested chiral compounds. The swelling capacity of the chitosan bis(phenylcarbamate)-(n-octyl urea)s in ethyl acetate, acetone and tetrahydrofuran (THF) was evaluated. Among the chitosan derivatives, the chitosan bis(3,5-dichlorophenylcarbamate)-(n-octyl urea) polymer showed the highest swelling capacity in ethyl acetate and THF. The polymer-based CSPs could be utilized with pure ethyl acetate and a normal phase containing 70% THF, but was damaged by pure THF. On the other hand, the separation performance of the damaged CSP could be recovered after it was allowed to stand for a period of time. The observations are important for the development and application of polysaccharide derivative-based CSPs.

Characterization of the Oxidative Degradation Product of Darunavir by LC-MS/MS

A rapid, selective, and reliable LC-MSⁿ method has been developed and validated for the isolation and structural characterization of the degradation product of darunavir (DRV). DRV, an HIV-1 protease inhibitor, was subjected to intrinsic oxidative stress conditions using 30% hydrogen peroxide and the degradation profile was studied. The oxidative degradation of DRV resulted in one degradation product. The unknown degradation product was separated on a Hibar Purospher C₁₈ (250 mm × 4.6 mm; 5 µm) column by using 0.01 M ammonium formate (pH 3.0) and acetonitrile as mobile phase in the ratio of 50:50, v/v. The eluents were monitored at 263 nm using a UV detector. The isolated degradation product was characterized by UPLC-Q-TOF and its fragmentation pathway was proposed. The proposed structure of the degradation product was confirmed by HRMS analysis. The developed stability-indicating LC method was validated with respect to accuracy, precision, specificity/selectivity, and linearity. No prior reports were found in the literature about the oxidative degradation behavior of DRV.

Dried blood spot analysis of (+) and (-) darunavir enantiomers on immobilized amylose tris-(3, 5-dimethylphenylcarbamate) LC and its application to pharmacokinetics

Dried blood spot analysis is an innovative novel blood sampling technique gaining interest in drug discovery and development processes owing to its inherent advantages over the conventional whole blood, plasma or serum sample collection. The present manuscript describes the development and validation of a highly sensitive and precise method of evaluation of pharmacokinetics of (+) and (-) darunavir enantiomers on rat dried blood spots. The enantiomers on rat dried blood spots were extracted into methanol and separated by LC on a Chiralpak IA column using hexane and ethanol containing 0.1% DEA (75:25, v/v) as a mobile phase at 20°C; both the enantiomers were detected at 266 nm using a photodiode array detector. The method was validated in terms of selectivity, linearity, accuracy, precision and stability as per the US Food and Drug and Administration guidelines. The hematocrit effect on extraction recovery was evaluated and the mean recoveries of (-) and (+) enantiomers of darunavir from dried blood spots were found to be 85.76 and 88.91% respectively. The intra- and inter-day precision and accuracy were 3.1-8.4 and 0.8-4.8% respectively. The developed method was successfully applied to a pharmacokinetic study of (+) and (-) enantiomers of darunavir on rat dried blood spots.

Synthesis and characterization of cellulose 3,5-dimethylphenylcarbamate silica hybrid spheres for enantioseparation of chiral β-blockers

A cellulose derivative-based chiral stationary phase (CSP) is considered one of the most widely applied CSPs due to its powerful enantioseparation ability. The high loading capacity and mechanical strength of CSPs are crucial for their application in preparative chromatography, such as a simulated moving bed. Compared to traditional cellulose-based CSPs that have been adsorbed onto chromatographic supports, organic-inorganic hybrid CSPs exhibit a potentially higher loading capacity and mechanical strength by increasing the density of chiral recognition groups. A hybrid cellulose 3,5-dimethylphenylcarbamate chiral stationary phase (organic/inorganic: 70/30, w/w) was prepared via a sol-gel method and characterized with several analytical techniques, including Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and (29)Si cross polarization/magic angle spinning nuclear magnetic resonance ((29)Si CP/MAS NMR). In addition, the as-synthesized hybrid chiral silica spheres were treated with an end-capping process to mask the residual silica hydroxyl groups. Compared to a commercial Chiralpak IB column, better separation of β-blocker drugs, including pindolol (selectivity of 5.55), metoprolol (2.30), propranolol (1.96), bisoprolol (1.74) and atenolol (1.46), on the end-capped CSP was achieved using liquid chromatography, which suggests that the packing material synthesized in this work has sufficient chiral discriminating ability for the effective separation of β-blocker drugs.