The purpose of this study is to evaluate and compare the relative bioavailability of Quinine Sulfate 324 mg capsules, manufactured by the Mutual Pharmaceutical Company, to Quinine Sulphate 300 mg tablets, manufactured by the Government Pharmaceutical Organization, Bangkok Metropolis, Thailand, after single oral dose administration under fasting conditions. An additional purpose of this study is to evaluate the effect of food on the Mutual Pharmaceutical Company product.