An LC-MS-MS Method for the Simultaneous Quantitation of Acyclovir and Valacyclovir in Human Plasma

A simple, sensitive and selective LC-MS-MS method has been developed for the simultaneous determination of acyclovir and valacyclovir in human plasma. Acyclovir and valacyclovir in plasma were concentrated by solid phase extraction and chromatographed on a C18 column using a mobile phase of 0.1% formic acid: methanol (30:70% v/v). The method was validated over a linear range of 47-10,255 and 5-1,075 ng mL(-1) for acyclovir and valacyclovir respectively. The LOQs were 47.6 and 5.0 ng mL(-1). The validated method was applied for the quantitation of acyclovir and valacyclovir from plasma samples in a pharmacokinetic study.