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. Enhanced Chemical Stability of D‐cycloserine.