The Toxicity and Therapeutic Efficacy of Mefenamic Acid and its Hydroxyethyl Ester in Mice: In Vivo Comparative Study: A promising Drug Derivative

Background: Hydroxyethyl Ester of Mefenamic acid (HEMA), which is an available derivative of mefenamic acid (MFA) in the literature, was shown to exert a strong resistance to enzymatic hydrolysis in various buffer solutions as well as in the plasma. However, there are no studies yet that investigate the biological effects of HEMA as a possible active drug in-vivo. This study provides an in-vivo investigation of the efficacy and toxicity of HEMA in comparison to those of a related drug, MFA, that has a similar chemical structure. 
Methods: Acute toxicity evaluations were conducted in various groups of mice following administration of high equimolar doses of HEMA and MFA and were measured at various parameters including the percentage of catalepsy, seizure score, percentage of clonic-tonic seizure and death, grimace scale score (GSS) and locomotor activity. In addition, the anti-inflammatory and anti-nociceptive effects of HEMA were evaluated in the carrageenan-induced paw edema test and acetic acid-induced writhing test, respectively. 
Results: The findings of this study revealed that the percentage of catalepsy, clonic-tonic seizure and death as well as seizure and grimace scale scores were lower in mice treated with HEMA than those treated with equimolar doses of MFA. In addition, treatment with HEMA caused a comparable anti-inflammatory activity in the carrageenan-induced paw edema test and a significantly (p<0.05) higher anti-nociceptive effect in the acetic acid-induced writhing test than that of MFA. 
Conclusion: Results obtained from this study may indicate that HEMA has superior therapeutic advantages for the management of acute and inflammatory events with a less potential risk of neuromuscular adverse effects.