Abstract
The quantification of the HIV integrase inhibitor raltegravir in blood plasma is described using solid phase extraction (SPE) coupled with an accurate high-performance liquid chromatography assay with ultraviolet (UV) detection. The method was validated over the range of 20-10,000 ng/mL using simple sample preparation and chromatography. The SPE method was optimized to be selective and highly efficient. The buffer's ionic strength and pH were optimized for retaining RAL and the internal standard on the column, the percentage of methanol was optimized in the cleaning step to remove unwanted plasma contaminants, and the type and amount of acid was optimized for complete elution of the compounds. This method has no interference with other potentially co-administered antiretrovirals or common drugs. Average recoveries for the extraction method were consistently high: 90% for raltegravir and 90% for the internal standard diazepam. This method was found to be accurate and precise. Within day (n=6) and between day (n=18) accuracies ranged from 97.5 to 104.4%. Within-day (n=6) and between-day (n=18) precision ranged from 1.4 to 3.8%, and from 2.4 to 7.9%, respectively. This is the first published method to use simple UV technology and reliable SPE extraction methodology for the quantification of raltegravir in human plasma. This method can be easily implemented in most bioanalytical laboratories.