Synthesis, Biological Evaluation and Pharmacokinetic Studies of Mefenamic Acid - N-Hydroxymethylsuccinimide Ester Prodrug as Safer NSAID

Background: Non steroidal anti-inflammatory drugs are the most widely prescribed drugs to manage pain and inflammatory conditions, but their long term use is associated with gastrointestinal toxicity. Objectives: The study aimed to synthesize an ester-based prodrug of a non steroidal anti-inflammatory agent, mefenamic acid in order to improve the therapeutic index vis a vis to overcome the side effects such as gastrointestinal irritation and bleeding associated with the use of mefenamic acid. Methods: The ester prodrug (MA-NH) was prepared by condensing mefenamic acid with N-hydroxymethylsuccinimide in the presence of Phosphorus oxychloride. The pharmacokinetic profile, including stability and release of mefenamic acid and N-hydroxymethylsuccinimide from the ester prodrug (MA-NH) was studied by RP- HPLC in acidic medium (pH 1.2), basic medium (pH 7.4), 80 % v/v human plasma, 10 % w/v rat intestinal homogenate and 10 % w/v rat liver homogenate (pH 7.4). Results: The chemical structure of the title compound was characterized by using modern spectroscopic techniques. The prodrug was found to be stable in acid medium, but it hydrolyzed and released sufficient quantities of the drug in alkaline medium. The prodrug produced lesser number of ulcers and showed improved analgesic and anti-inflammatory activity as compared to the parent drug. Conclusion: The results indicate that the synthesized prodrug (MA-NH) is better in terms of analgesic and antiinflammatory activities and with less GI toxicity than the parent drug.