Preformulation Studies for a Parenteral Solution of Memantine

Preformulation studies regarding a physico-chemical evaluation of memantine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, are presented in this work. This characterization of memantine is pre-required for the formulation of a parenteral solution. The water solubility, the thermal behavior and the chemical stability in aqueous solution, depending on the pH, temperature, UV light and the presence of oxidizing or isotonising agents were determined. A LC/MS/MS analytical method for memantine hydrochloride quantification was developed and validated. It was determined that memantine hydrochloride has a water solubility of 47.035 mg/mL (20C). Thermal analysis revealed that it is an anhydrous substance, presenting a crystalline form, with the melting point at 297.16C. In aqueous solution memantine hydrochloride is stable at room temperature (20C), regardless the pH of medium, UV light, isotonising agent or oxidizing agent and at 80oC, at acidic pH value. These results indicate that memantine hydrochloride has appropriate physico-chemical properties for a parenteral solution formulation.