Enhanced Chemical Stability of D-Cycloserine via Tablet Form Containing Magnesium Oxide as an Alkali Stabilizer

The purpose of this study was to improve the chemical stability of D-cycloserine via tablet form containing an alkali stabilizer. The influence of alkalizing agents on the stability of D-cycloserine was investigated at 60 °C/75% RH for 2 days. The drug stability was evaluated with the D-cycloserine-loaded tablets prepared with various amounts of magnesium oxide using direct compression method. Compared to D-cycloserine powder and a commercial D-cycloserine-loaded product, the long-term drug stability on the chosen tablet was assessed at 40, 60, and 40 °C/75% RH during 6 months. Amongst the stabilizers investigated, magnesium oxide most improved the stability of D-cycloserine at the accelerated stress condition. The magnesium oxide/drug ratio of 1 and 2 showed higher remaining drug concentrations than those less than 0.5; however, two formers gave no significant difference in the remaining drug concentrations. Amongst the tablets tested, the formulation composed of D-cycloserine, magnesium oxide, and talc at the weight ratio of 250/250/5 most increased the stability of D-cycloserine. Additionally, due to the alkali and water-proofing property of magnesium oxide, this tablet improved the stability of D-cycloserine compared to the drug powder and commercial product. Hence, this novel tablet with enhanced drug stability would be a candidate for oral pharmaceutical product of D-cycloserine.