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Comparative dissolution profiles of representative quinolones in different media.

BACKGROUND
Quinolones have a broad spectrum of activity against bacteria and are a class of synthetic antimicrobial modeled after nalidixic acid.


OBJECTIVE
To determine the dissolution efficiencies of ciprofloxacin and sparfloxacin in 0.1NHCL, deionized water, 0.1 M acetic acid and pH 7.4 phosphate buffer.


METHODS
The in-vitro dissolution profiles of ciprofloxacin (250 mg and 500 mg) and sparfloxacin (200 mg) tablets were studied in the respective media using US Pharmacopoeia (USP) Apparatus II. In order to monitor the comparative rate of dissolution, samples were withdrawn from the medium for quantification over nine pre-determined time points during a total period of two hours. Samples were analyzed by an HPLC method capable of concurrent elution of ciprofloxacin/sparfloxacin.


RESULTS
The medium with most stable release pattern for the representative quinolones was 0.1M acetic acid, followed by 0.1NHCl, distilled water and pH 7.4 buffer respectively. The %Q30 of Ciprofloxacin(CP) and Sparfloxacin(SP) was found to conform entirely to both USP2004 and FDA specifications. Sparfloxacin was found to be unstable due to cloudiness observed in 0.1N HCl medium. The CP and SP showed highest %Q(max) in 0.1M acetic acid compared to other media. This result has implication in the choice of medium for dissolution testing of quinolones, particularly for comparative purposes in the absence of specific monograph recommendations. Furthermore, it supports the change from 0.1N to 0.01NHCI for ciprofloxacin in the USP as a monographic modification.


CONCLUSION
We conclude that there is a need to have a general-purpose dissolution medium for comparing profiles of different quinolones, 0.1M acetic acid may be a suitable candidate. Furthermore, the study may serve as guidance to the drug regulatory authorities in formulation of monographs for the drugs.