Analysis of erythromycin

Spectrophotometric Investigations of Macrolide Antibiotics: A Brief Review

Macrolides, one of the most commonly used class of antibiotics, are a group of drugs produced by Streptomyces species. They belong to the polyketide class of natural products. Their activity is due to the presence of a large macrolide lactone ring with deoxy sugar moieties. They are protein synthesis inhibitors and broad-spectrum antibiotics, active against both gram-positive and gram-negative bacteria. Different analytical techniques have been reported for the determination of macrolides such as chromatographic methods, flow injection methods, spectrofluorometric methods, spectrophotometric methods, and capillary electrophoresis methods. Among these methods, spectrophotometric methods are sensitive and cost effective for the analysis of various antibiotics in pharmaceutical formulations as well as biological samples. This article reviews different spectrophotometric methods for the determination of macrolide antibiotics.

Spectrofluorimetric analysis of certain macrolide antibiotics in bulk and pharmaceutical formulations

The macrolides (erythromycin, erythromycin esters, azithromycin dihydrate, clarithromycin and roxithromycin) can be analyzed by a simple spectrofluorimetric method based on the oxidation by cerium(VI) in the presence of sulphuric acid and monitoring the fluorescence of cerium(III) formed at lambda(ex) 255 nm and lambda(em) 348 nm. All variables affecting the reaction conditions as cerium(VI), sulphuric acid concentrations, heating time, temperature and dilution solvents were carefully studied. Linear calibration graphs were obtained in the range of 42.6-1200 ng ml(-1) with a percentage relative standard deviation in the range of 0.014-0.058%. Quantitation and detection limits were calculated. The method was applied successfully for the assay of the studied drugs in pure and pharmaceutical dosage forms as tablets, capsules and suspension. Recovery experiments revealed recovery of 98.3-100.8%. The effect of potential interference due to common ingredients as glucose, sucrose, lactose, citric acid, and propylene glycol was investigated. Applying standard addition method shows a recovery of 97.7-100.9% macrolide antibiotics from their corresponding dosage forms.

Selective spectrophotometric method for the determination of erythromycin and its esters in pharmaceutical formulations using gentiana violet

A simple and selective method for the determination of erythromycin and its stearate and succinate esters in their pure forms and in pharmaceutical formulations is described. The procedure is based on the formation of a blue-coloured (lambda max = 633 nm) complex with gentiana violet in alkaline medium. Different variables affecting the colour development were studied and optimized. The method was used to determine 2.5-25 micrograms ml-1 of erythromycin in the final measured solution. The simplicity of the method permits rapid analysis and it is thus suitable for routine control. The method is highly specific for the determination of stearate and succinate esters in pharmaceutical formulations. The reliability of the method was established by parallel determinations against the official British Pharmacopoeial method.

Extraction-spectrofluorimetric method for the determination of erythromycin and its esters in pharmaceutical formulations using manual and flow-injection procedures

A sensitive and rapid extraction-spectrofluorimetric method for the determination of erythromycin, based on the formation of an ion pair with Erythrosine B, is described. The calibration graph resulting from the measurement of the fluorescence of the chloroform extract (10 cm3) at 560 nm with excitation at 544 nm is linear over the range 10-600 micrograms of erythromycin per 20 cm3 of total volume of aqueous phase, with a relative standard deviation (RSD) of 1.5% for 3.7 micrograms cm-3 erythromycin. The method can be successfully adapted to an unsegmented flow system, the peak height being proportional to erythromycin concentration over the range 0.65-5.88 micrograms of erythromycin per 400 mm3 of sample solution injected. Up to 45 samples h-1 can be processed with an RSD of 2.9-3.8%. Manual and flow-injection methods were satisfactorily applied to the determination of erythromycin in pharmaceutical preparations.

[Chemical analysis of veterinary drugs in food. 1. General methods and gas chromatographic procedures]

A review is presented that in the first section describes current techniques for preparation, extraction and clean up of food samples for the determination of veterinary drug residues by chemical methods. The second section gives an overview of gas chromatographic methods published up to 1983 for the analysis of meat, liver, kidney, egg and milk for residues of antibiotics and chemotherapeutic agents. Discussed are stability of the compounds, derivatization, detection and particular aspects of their metabolism. The structural formula is given for all drugs mentioned. The procedures for determination are summarized in a table, together with the most important analytical parameters.