Effect of freezing, long-term storage and microwave thawing on the stability of tramadol in 5% dextrose infusion in polyvinyl chloride bags.

Tramadol hydrochloride (Contramal) is often used as infusions for hospitalized patients to manage or prevent acute or chronic pain that requires analgesia at opioid level. Advance preparation of intravenous solutions of tramadol hydrochloride could be useful to improve quality assurance, time management and cost savings of drug delivery; but little is known about their stability after freezing followed by microwave thawing. The purpose of this study was to investigate how freezing, long-term storage and microwave thawing can affect the stability of tramadol in 5% dextrose infusion.