Marcelo Donadel Malesuik

Identification, characterization and cytotoxicity in vitro assay of nitazoxanide major degradation product.

Stress studies of the broad-spectrum antiparasitic nitazoxanide were conducted in order to isolate and elucidate the major degradation product involved in thermal, acid, alkaline, oxidative and photolytic decomposition of the drug in solution and solid state. The major degradation product was identified and characterized using techniques namely LC-DAD, (1)H NMR, (13)C NMR, IR, and MS/MS. The stability of nitazoxanide raw material and nitazoxanide in tablets and in suspension powder was studied under different conditions and the results suggest the formation of the same deacetylated degradation product occur in all cases. This product was also studied in order to determine the preliminary cytotoxicity in vitro with mononuclear cells. Compared with nitazoxanide, the degradation product showed a higher cytotoxicity at a concentration of 40 μg mL(-1) after 48 h of incubation, under tested conditions. Therefore, stress studies showed that special care must be taken during the preparation, manufacture, and storage of this pharmaceutical drug.

Development of a simple, rapid and validated spectrophotometric method for nitazoxanide in pharmaceutical formulations and comparison with HPLC

A rapid, economical, reproducible, and simple direct spectrophotometric method was developed and validated for the assay of nitazoxanide in pharmaceutical formulations. Nitazoxanide concentration was estimated in water at 345 nm and pH 4.5. The method was suitable and validated for specificity, linearity, precision, and accuracy. There was no interference of the excipients in the determination of the active pharmaceutical ingredient. The proposed method was successfully applied in the determination of nitazoxanide in coated tablets and in powders for oral suspension. This method was compared to a previously developed and validated method for liquid chromatography to the same drug. There was no significative difference between these methods for nitazoxanide quantitation.

STABILITY-INDICATING CZE METHOD AND STRESS DEGRADATION STUDIES OF NITAZOXANIDE

A new, simple, and effective stability-indicating CZE method was developed and validated for the determination of nitazoxanide in pharmaceutical formulations, using nimesulide as an internal standard. The optimum separation was carried out on a fused silica capillary (48.5 cm × 75 μm i.d., effective length 40 cm) maintained at 25°C, and a running electrolyte containing sodium acetate buffer (pH 5.2; 30 mM)-acetonitrile (80:20, v/v). The injections of the samples were performed using the pressure mode at 50 mbar for 5 s, with detection at 360 nm using a photo-diode array detector. The method was suitably validated for specificity, linearity, precision, accuracy, limit of detection and quantitation, and robustness. The high sensitivity of the method was proven with the limit of detection (0.05 μg mL−1) and quantitation (0.2 μg mL−1). The stability-indicating capability of the method was proven using stress conditions (acid and basic hydrolysis, oxidation, and photolysis). The proposed method was successfully applied for the determination of nitazoxanide in coated tablets and oral suspension powder.

Stability Study of Finasteride: Stability-Indicating LC Method, In Silico and LC–ESI-MS Analysis of Major Degradation Product, and an In Vitro Biological Safety Study

Stability studies of the pharmaceutically important compound finasteride were conducted in order to evaluate decomposition of the drug under forced degradation conditions. A simple stability-indicating liquid chromatography method was developed and validated for the evaluation of finasteride and degradation products formed in pharmaceutical preparations and the raw material. Isocratic LC separation was achieved on a C18 column using a mobile phase of o-phosphoric acid (0.1% v/v), adjusted to pH 2.8 with triethylamine (10% v/v) and acetonitrile (52:48 v/v), with a flow rate of 1.0 mL min-1. The alkaline degradation kinetics of the drug were also evaluated and could be best described as second-order kinetics under the experimental conditions applied for the tablets and raw material. Based on in silico studies and molecular weight confirmation, a comprehensive degradation pathway for the drug and the identity of its major product could be suggested without complicated isolation or purification processes. Furthermore, a biological safety study was performed to evaluate the effect of the degraded sample in relation to the intact molecule. The results showed that the degraded sample affected the cell proliferation. Therefore, these studies show that special care must be taken during the manipulation, manufacture and storage of this pharmaceutical drug.