Abstract

Metronidazole suspension is available in most developed countries as a prescription only medicine and in the form of an extemporaneous preparation of 90 days shelf-life. In Nigeria, it is available on the shelf with shelf lives of 2 - 4 years. It is available from at least 20 local manufacturers. This work has determined the shelf life of two brands of metronidazole suspension using accelerated stability testing method. A relatively simple analytical method has been utilized for stability studies of metronidazole suspension because of known research constraints in the laboratories of most developing countries. The analytical procedure employed for quantization of metronidazole in the suspension involved; liquid-liquid extraction followed by the use of ultraviolet/visible Spectrophotometry. This method has been successfully used for the determination of the shelf-life of two branded metronidazole suspensions. The technique offers the advantage of simplicity, rapidity and sensitivity without the need for very expensive equipment. The shelf lives calculated for Brand 1 at the temperatures of 25 and 30°C were 4.96 and 3.86 years, respectively; while that for Brand 2 was 7.7 and 5.87 years, respectively. The labeled shelf life for Brand 1 was 2 years while that for Brand 2 was 3 years.

Key words: Metronidazole suspension, accelerated stability testing, shelf-life, spectrophotometric assay method.