RESUMEN

Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables.

Asunto(s)

RESUMEN

An HPLC method was developed and validated for the determination of cetirizine dihydrochloride (CZ) as well as its related impurities in commercial oral solution and tablet formulations. Furthermore, two preservatives associated with the drug formulations, namely, propyl (PP) and butylparabens (BP) were successfully determined by this method. The chromatographic system used was equipped with a Hypersil BDS C18, 5 microm column (4.6 x 250 mm) and a detector set at 230 nm in conjunction with a mobile phase of 0.05 M dihydrogen phosphate:acetonitrile:methanol:tetrahydrofuran (12:5:2:1, v/v/v/v) at a pH of 5.5 and a flow rate of 1 ml min(-1). The calibration curves were linear within the target concentration ranges studied, namely, 2 x 10(2) - 8 x 10(2) microg ml(-1) and 1-4 microg ml(-1) for CZ, 20-100 microg ml(-1) for preservatives and 1-4 microg ml(-1) for CZ related impurities. The limits of detection (LOD) and quantitation (LOQ) for CZ were, respectively, 0.10 and 0.34 microg ml(-1) and for CZ related impurities were in the ranges of 0.08-0.26 microg ml(-1) and 0.28-0.86 microg ml(-1), respectively. The method proved to be specific, stability indicating, accurate, precise, robust and could be used as an alternative to the European pharmacopoeial method set for CZ and its related impurities.

Asunto(s)

RESUMEN

This article studies the compatibility of amlodipine besylate in its solid formulations with various drug excipients. The various factors affecting amlodipine besylate stability were studied using high-performance liquid chromatography (HPLC). It has been found that binary 1:1 mixtures of amlodipine besylate and an excipient are stable at 65 degrees C and 40 degrees C/75% RH. Further investigations were conducted to study the stability of amlodipine besylate in multicomponent mixtures, including mixtures with actual formulations. The study reveals that mixtures of lactose, magnesium stearate, and water induce some instability on amlodipine besylate. The major degradation product confirmed by HPLC-mass spectrometry is amlodipine besylate glycosyl. This is in conformity with the well-known Maillard reaction between primary amines and lactose. Thus, lactose-free amlodipine formulations are recommended from the safety, quality, efficacy, and process cost points of view.

Asunto(s)

RESUMEN

There is a lack of information concerning analysis of terbutaline sulfate and quantification of its related substances particularly in the liquid dosage forms. This work aimed at developing and validating an HPLC method for determination of terbutaline sulfate and its possible degradation products, namely, 3,5-dihydroxybenzoic acid, 3,5 dihydroxybenzaldehyde and 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone that might appear as impurities in the starting material as well as in the solid and liquid formulations. The chromatographic system used consisted a Hypersil 100 C(18,) 150 x 4.6 mm (5 microm) column, a mobile phase of ammonium acetate (0.15 M) and glacial acetic acid (pH of 4.0, 96:4 v/v) with a flow rate of 2 ml min(-1) and a UV detector set at 270 nm. The degree of linearity and the characteristic statistical parameters of the calibration curves including the limit of detection (LOD) and limit of quantitation (LOQ) were estimated for terbutaline sulfate and its degradation products. The method was found to be specific, stability indicating, accurate, precise and robust.

Asunto(s)

RESUMEN

The chemical stability of enalapril maleate in tablet dosage forms consisting of different formulation excipients has been studied in this work. The influence of various parameters such as heat, moisture, light and the drug-matrix was investigated. The degradation of enalapril maleate has been followed by using an HPLC method, which was demonstrated to be specific, stability indicating, accurate and precise. The degradation kinetics of enalalpril maleate in phosphate buffer solutions of pH values in the range of 2.2-10.5 were observed to be psuedo first order throughout the whole pH range studied. Enalapril maleate alone showed high stability for temperature under dry and humid conditions, however it became unstable when mixed with the drug-matrix in its tablet formulations and exposed to the same conditions. The pathway of degradation of enalapril maleate was found to be pH dependent. The extent of degradation of two different enalapril maleate tablet formulations (product A of a basic drug-matrix and product B of an acidic drug-matrix) has been investigated. The degree of degradation of the product with acidic matrix was significantly less than that of the basic matrix under same temperature and humidity conditions. In fact, diketopiperazine and enalaprilat degradants were mainly associated with the degradation of the product with the acidic matrix and that with the basic matrix, respectively. Dry enalapril maleate powder showed some photolysis, which was more significant with daylight (3.3%) compared with that under UV light (0.2%). Although the product with the acidic matrix showed some photolysis but the effect was not pronounced and the % recovery of enalapril was almost complete and within the acceptable experimental errors. However, the product with the basic matrix showed almost no response for photolysis.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)