Balraj Saini

Thermal characterization and compatibility studies of itraconazole and excipients for development of solid lipid nanoparticles

The current study was performed to investigate possible interactions between triazole antifungal drug itraconazole (ITR) with selected excipients commonly used for development of solid lipid nanoparticles. The excipients included common lipids (glyceryl behenate (Compritol 888 ATO™), glyceryl monostearate, stearic acid, and cetyl palmitate), charge inducers (dicetyl phosphate and stearlyamine), and surfactants (sodium cholate and sodium deoxycholate). Differential scanning calorimetry, isothermal stress testing, Fourier transform infrared spectral analysis, optical microcopy, and X-ray powder diffraction analysis were performed for assessing the compatibility between the drug and the excipients. Results of the study suggest that the stearic acid exhibited drug–excipient interactions, whereas all other excipients used in the study were found to be compatible with ITR.

Isolation and characterization of a degradation product in leflunomide and a validated selective stability-indicating HPLC-UV method for their quantification

Leflunomide (LLM) is subjected to forced degradation under conditions of hydrolysis, oxidation, dry heat, and photolysis as recommended by International Conference on Harmonization guideline Q1A(R2). In total, four degradation products (I–IV) were formed under different conditions. Products I, II and IV were formed in alkaline hydrolytic, acidic hydrolytic and alkaline photolytic conditions. LLM and all degradation products were optimally resolved by gradient elution over a C18 column. The major degradation product (IV) formed in hydrolytic alkaline conditions was isolated through column chromatography. Based on its 1H NMR, IR and mass spectral data, it was characterized as a British Pharmacopoeial impurity B. The HPLC method was found to be linear, accurate, precise, sensitive, specific, rugged and robust for quantification of LLM as well as product IV. Finally, the method was applied to stability testing of the commercially available LLM tablets.

Degradation Study on Sulfasalazine and a Validated HPLC-UV Method for its Stability Testing

Sulfasalazine (SSZ) was subjected to degradation under the conditions of hydrolysis (acid, alkali, and water), oxidation (30% H2O2), dry heat, and photolysis (UV-VIS light) in accordance with the ICH guidelines. An RP-HPLC method was developed to study the degradation behavior. No degradation was noted under any condition except alkaline hydrolysis where SSZ was degraded to a single minor product. SSZ was optimally resolved from this product on an XTerra® RP18 column with a mobile phase composed of methanol and an ammonium acetate buffer (10 mM, pH 7.0) (48:52, v/v) delivered at a rate of 0.8 mL/min in an isocratic mode. The method was validated and found to be linear (r2=0.99945), precise (%RSD <2), robust, and accurate (94–102%) in the concentration range of 0.5–50 μg/mL of SSZ. The PDA analysis of the degraded sample revealed the SSZ peak purity to be 998.99 and the drug peak eluted with a resolution factor of >2 from the nearest resolving peak, indicating the method to be selectively stability-indicating for the drug analysis. The method was applied successfully for the stability testing of the commercially available SSZ tablets that were under varied ICH-prescribed conditions. An explanation for the unusual stability of the drug when exposed to acidic hydrolysis, despite the presence of the sulfonamide linkage, is also discussed.

Characterization of four new photodegradation products of hydroxychloroquine through LC-PDA, ESI-MSn and LC-MS-TOF studies

ICH recommended forced degradation on HCQ was carried out under the conditions of hydrolysis, oxidation, dry heat and photolysis. Six degradation products (I-VI) were formed under photolytic conditions in alkaline medium. The products were characterized through +ESI-MS(n), LC-MS-TOF and LC-PDA studies. The product III was identified as N-de-ethylated HCQ which is a known impurity. It was also found to form in trace amounts under acidic and alkaline hydrolytic conditions. The products I, II, IV and V characterized as N-dehydroxyethyl-7-dechloro-7-hydroxy HCQ, dechlorinated HCQ, N-dealkylated HCQ and HCQ N-oxide, respectively were identified as new degradation products of HCQ. The product VI was not characterized due to its trace levels and insufficient mass spectral data. The most probable mechanisms of degradation of HCQ to these products were outlined and discussed.

A validated direct spectrofluorimetric method for quantification of mirtazapine in human whole blood

A spectrofluorimetric method for estimation of mirtazapine in human whole blood was developed and validated. The recovery efficiency of the processing method was 95–98%. The analytical method was linear over drug concentration of 10–200 ng/ml. The limit of quantification was 10 ng/ml. The method was precise with %RSD for intra-day and inter-day precision being <3.0 and 1.5, respectively. Excellent recoveries (97.87–99.69%) were achieved during accuracy studies. The method was robust to small changes in processing method and instrumental parameters. The present method can be employed for direct fluorimetric determination of mirtazapine in human whole blood during clinical studies.

Identification of Four New Degradation Products of Epirubicin Through Forced Degradation, LC–UV, MSn and LC–MS–TOF Studies

Epirubicin (EPI) was subjected to International Conference on Harmonization recommended forced degradation under the conditions of hydrolysis, oxidation, dry heat and photolysis to characterize its possible impurities and/or degradation products. The drug was found highly unstable to alkaline hydrolysis even at room temperature, unstable to acid hydrolysis at 80°C and to oxidation at room temperature. The hydrolytic and oxidative degradation products were resolved on an Agilent RP8 (150 mm × 4.6 mm; 5 µm) column with isocratic elution using mobile phase composed of ammonium formate (10 mM, pH 3.0), acetonitrile and methanol. The drug degraded to four oxidative products (O-I, O-II, O-III and O-IV) and to one acid hydrolyzed product (A-I). Purity of each peak in liquid chromatography-ultraviolet (LC-UV) chromatogram was ascertained through photodiode array (LC-PDA) analysis. The products were characterized through electrospray ionization-mass spectrometry (+ESI-MS(n)) studies on EPI and liquid chromatography-time of flight mass spectrometry (LC-MS-TOF) studies on degraded drug solutions. The products, O-I-O-IV, were characterized as 2-hydroxy-8-desacetylepirubicin-8-hydroperoxide, 4-hydroxy-8-desacetylepirubicin-8-hydroperoxide, 8-desacetylepirubicin-8-hydroperoxide and 8-desacetylepirubicin, respectively, and product A-I was characterized as deglucosaminylepirubicin. While A-I was found to be a pharmacopoeial impurity, all oxidative products were found to be new degradation impurities. The mechanisms and pathways of degradation of EPI were discussed and outlined.