Identification, Isolation, and Structural Characterization of Novel Forced Degradation Products of Darunavir Using Advanced Analytical Techniques Like UPLC-MS, Prep-HPLC, HRMS, NMR, and FT-IR Spectroscopy

Since the stability of the pharmaceuticals plays a crucial role in efficacy and safety while using them in the treatment of disorders, the evaluation of purity and impurity profiling of pharmaceuticals is of utmost importance using efficient analytical techniques. The present study explains the identification, isolation, and characterization of stress degradation products of the anti-human immunovirus drug Darunavir. The degradation study was performed to evaluate the stability profile of Darunavir in different stress conditions like hydrolytic, oxidative, thermal, and photolytic conditions as per the ICH guidelines. Degradation products were identified using ultra-performance liquid chromatography coupled with mass spectrometry, isolated using semi-preparative high-performance liquid chromatography, and structural characterization by HRMS and ¹H, ¹³C NMR (1D, 2D). Darunavir is relatively stable in oxidative, thermal, and photolytic conditions; however, considerable degradation was observed in acid and base hydrolysis. A total of five degradation products were identified and isolated in acid and base degradation. DP-1, DP -2, & DP-3 were observed in acid conditions, whereas in base conditions, along with DP-2, two more DPs, i.e., DP-4 & DP-5, were identified. Among the five DPs, two degradation products, namely DP-1: N-(4-(N-(3-amino-2-hydroxy-4-phenylbutyl)-N-isobutylsulfamoyl) phenyl) acetimidamide. & DP-3: hexahydrofuro[2,3-b]furan-3-yl(4-((4-acetimidamido-N-isobutylphenyl)sulfonamido)-3-hydroxy-1-phenylbutan-2-yl)carbamate, are novel, remaining degradation products DP-2: 4-amino-N-(3-amino-2-hydroxy-4-phenylbutyl)-N-isobutylbenzenesulfonamide, DP-4: 4-amino-N-(((5S)-4-benzyl-2-oxooxazolidin-5-yl) methyl) -N-isobutyl benzenesulfonamide and DP-5: methyl ((3S)-4-((4-amino-N-isobutylphenyl) sulfonamido)-3-hydroxy-1-phenylbutan-2-yl) carbamate are already reported tentatively using a single analytical technique coupled with mass analysis without any evidence from NMR and IR data. Hence, the present study focused on using High-Resolution Mass, 1D, and 2D ¹H, ¹³C NMR data for concrete confirmation of structures for degradation products.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10337-022-04226-z.

Chemo-metric assisted UV-spectrophotometric methods for simultaneous estimation of Darunavir ethanolate and Cobicistat in binary mixture and their tablet formulation

Darunavir ethanolate (DRV) and Cobicistat (CBS) is a combination of antiretroviral drugs used for the treatment of human immunodeficiency virus (HIV) infections. Two Chemo-metric assisted UV-spectrophotometric methods were developed for simultaneous estimation of DRV and CBS in tablet dosage form, namely; partial least square (PLS) and Classical least square method (CLS). The proposed methods were successfully applied for simultaneous determination of DRV and CBS in a laboratory mixture and their tablet formulation to achieve maximum sensitivity and lowest error. The applied methods were validated as per ICH guidelines and found to be linear in the concentration range of 5-30μg/mL for DRV and 5-30μg/mL for CBS. The developed methods were statistically comared with reported UPLC method where no significant difference was found relating to both accuracy and precision. Thus, the proposed methods can be effectively utilized for the routine quality control assessment of these drugs in commercial tablet dosage form.

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.

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.

A critical review of properties of darunavir and analytical methods for its determination

Darunavir is a synthetic non-peptidic protease inhibitor that has been shown to be extremely potent against wild-type HIV, and it is an important component of highly active antiretroviral treatment (HAART), which is considered as one of the most significant advances in the field of HIV therapy. However, there are some concerns about darunavir quality control. Darunavir shows pseudo-polymorphism: in different ambient conditions one pseudo-polymorphic form can change to another. This behavior of darunavir is problematic because the dosage form is exposed to different ambient conditions around the world, since HIV/AIDS is prevalent globally. Issues around differences in the solubility and effects that different forms of darunavir can cause are of concern, and a more stable form is preferable. Important investigations of darunavir such as dissolution behavior, polymorphism, stability and degradation studies, and the impact of that on the quality of the product are being conducted by our working group. A cure for HIV/AIDS remains a long-term commitment, and there is much yet to achieve. This article discusses, by a critical review of the literature, the impact of the use of darunavir in the treatment of HIV-infected patients, its physical-chemical properties, the analytical methods to determine it, and challenges that remain in order to ensure the quality and stability of darunavir.

Simultaneous quantification of related substances of perindopril tert-butylamine using a novel stability indicating liquid chromatographic method

A novel stability indicating gradient reverse-phased high-performance liquid chromatographic method has been developed for the quantification of impurities of perindopril tert-butylamine (PER) in pharmaceutical dosage form. Separation of the active substance and its known (Impurities B, C, D, E, F) and unknown impurities was achieved on a BDS Hypersil C18 column (250 mm × 4.6 mm, 5 µm), thermostated at 70°C, using a mobile phase comprised of aqueous solution of sodium 1-heptanesulfonate adjusted to pH 2 with perchloric acid and acetonitrile. The flow rate was maintained at 1.5 mL min(-1), injection volume of 20 µL was utilized and detection of analytes was performed at 215 nm. The developed method was validated in accordance with current ICH Guidelines for all suggested parameters, including forced degradation studies and proved to be linear, accurate, precise and suitable for the impurity testing of PER, being subsequently applied during on-going stability studies of a newly developed generic formulation.

Stability Study of Darunavir Ethanolate Tablets Applying a New Stability-Indicating HPLC Method

Chemical and physical degradation of drugs may result in altered therapeutic efficacy and even toxic effects. Therefore, the aim of this work was to study the stability of darunavir and to develop and validate a liquid chromatography (LC) method to determine darunavir in raw material and tablets in the presence of degradation products. The novel method showed to be linear from 6.0 to 21.0 μg/mL, with high precision (CV < 2%) and accuracy (recuperation of 99.64%). It is simple and reliable, free of placebo interferences. The robustness of the method was evaluated by a factorial design using seven different parameters. Forced degradation study was done under alkaline, acidic, and oxidative stress at ambient temperature and by heating. The LC method was able to quantify and separate darunavir and its degradation products. Darunavir showed to be unstable under alkaline, acid, and oxidative conditions. The novelty of this study is understanding the factors that affect darunavir ethanolate stability in tablets, which is the first step to unravel the path to know the degradation products. The novel stability-indicating method can be used to monitor the drug and the main degradation products in low concentrations in which there is linearity.