María Segunda Aurora-Prado

Development and validation of a method for quantitative determination of econazole nitrate in cream formulation by capillary zone electrophoresis.

A simple, fast, inexpensive and reliable capillary zone electrophoresis (CZE) method for the determination of econazole nitrate in cream formulations has been developed and validated. Optimum conditions comprised a pH 2.5 phosphate buffer at 20 mmol L(-1) concentration, +30 kV applied voltage in a 31.5 cm x 50 microm I.D. capillary. Direct UV detection at 200 nm led to an adequate sensitivity without interference from sample excipients. A single extraction step of the cream sample in hydrochloric acid was performed prior to injection. Imidazole (100 microg mL(-1)) was used as internal standard. Econazole nitrate migrates in approximately 1.2 min. The analytical curve presented a coefficient of correlation of 0.9995. Detection and quantitation limits were 1.85 and 5.62 microg mL(-1), respectively. Excellent accuracy and precision were obtained. Recoveries varied from 98.1 to 102.5% and intra- and inter-day precisions, calculated as relative standard deviation (RSD), were better than 2.0%. The proposed CZE method presented advantageous performance characteristics and it can be considered suitable for the quality control of econazole nitrate cream formulations.

Dual encapsulation of hydrophobic and hydrophilic drugs in PLGA nanoparticles by a single-step method: drug delivery and cytotoxicity assays

Dual drug encapsulation in biodegradable nanoparticles is always challenging and often requires strenuous optimization of the synthesis–encapsulation processes. This becomes even more difficult when the simultaneous encapsulation of molecules of different polarity is sought. Here we present a modified emulsification–evaporation process to produce polymeric nanoparticles (NPs) made of the biocompatible and biodegradable polymer poly(lactic-co-glycolic acid) (PLGA) and co-encapsulating simultaneously two different drugs, the hydrophobic dexamethasone (DX) and the hydrophilic diclofenac sodium (DS). Three independent processing parameters were systematically modified to promote the incorporation of the different-polarity drugs into PLGA and to control the particle size under 150 nm. The careful selection of the appropriate solvents (ethyl acetate and methanol) was a key requirement for the successful encapsulation of DX and DS. DS and DX release kinetics as well as cytotoxicity assays underlined the therapeutic potential of the dual encapsulation strategy.

Development and validation of a simple and rapid capillary zone electrophoresis method for determination of nnrti nevirapine in pharmaceutical formulations

-1 e 4,3 µg mL -1 , respectivamente. Precisoes intra e inter-dia expressas como desvio padrao relativo foram 1,4% e 1,3%, respectivamente e a recuperacao media foi de 100,81%. O farmaco foi submetido a testes de hidrolises (acida, basica e neutra) e a estresse oxidativo. Nao foi observada interferencia por parte dos produtos de degradacao, nem dos excipients na analise da nevirapina. Este metodo mostrou ser rapido, simples, preciso, exato e economico para a determinacao de nevirapina em produtos farmaceuticos e e apropriado para o controle de qualidade em analise de rotina uma vez que a eletroforese capilar oferece beneficios em termos de desenvolvimento rapido dos metodos e custos muito reduzidos de operacao. A simple and fast capillary zone electrophoresis (CZE) method has been developed and validated for quantification of a non-nucleoside reverse transcriptase inhibitor (NNRTI) nevirapine, in pharmaceuticals. The analysis was optimized using 10 mmol L -1 sodium phosphate buffer pH 2.5, +25 kV applied voltage, hydrodynamic injection 0.5 psi for 5 s and direct UV detection at 200 nm. Diazepam (50.0 µg mL -1 ) was used as internal standard. Under these conditions, nevirapine was analyzed in approximately less than 2.5 min. The analytical curve presented a coefficient of correlation of 0.9994. Limits of detection and quantification were 1.4 µg mL -1 and 4.3 µg mL -1 , respectively. Intra- and inter-day precision expressed as relative standard deviations were 1.4% and 1.3%, respectively and the mean recovery was 100.81%. The active pharmaceutical ingredient was subjected to hydrolysis (acid, basic and neutral) and oxidative stress conditions. No interference of degradation products and tablet excipients were observed. This method showed to be rapid, simple, precise, accurate and economical for determination of nevirapine in pharmaceuticals and it is suitable for routine quality control analysis since CE offers benefits in terms of quicker method development and significantly reduced operating costs.

Determination of Four Nadolol Stereoisomers in Capsules by High-Performance Liquid Chromatography and Circular Dichroism

Nadolol is a blocking agent with activity in β-adrenergic receptors. The objective of this research was to develop and validate an HPLC and circular dichroism method for the quantification of four nadolol stereoisomers in capsules. The HPLC method was validated using a Chiralcel OD column (250 × 4,6 mm, 10 μm). The mobile phase consisted of hexane-ethanol-diethylamine-acetic acid (86 + 14 + 0.3 + 0.3, v/v/v/v), with a flow rate of 0.7 mL/min and temperature of 25 ± 1°C and UV detection carried out at 220 nm. Solutions were prepared in ethanol containing 200 μg/mL nadolol. The method proved to be precise, selective, accurate, and robust and was successfully applied for the determination of the two homologs of four nadolol stereoisomers in capsules.