Currently two effective ways are used with the administration of a metronidazole composition. A single, large dose is given as a bolus to the patient which is clinically effective but a major drawback to the administration of single large dose of metronidazole is the occurrence of significant and undesirable side effects. A second and more generally accepted treatment entails orally administering smaller dose of metronidazole three time a day. The lower dosage of metronidazole over a period of a week significantly reduces the occurrence and severity of side effect but patient compliance is a problem can inadvertently forget to take one or more doses during the course of treatment, causing the plasma metronidazole level drop to bellow an acceptable therapeutic level for a period of several hours or more. Hence extended release formulation of metronidazole could be suitable alternative for reducing the number of daily doses needed to treat a microbial infection, while maintaining the benefit of making bioavailable effective amount of drug over an extended time period.