Development and validation of a sensitive HPLC method for the quantification of HI-6 in guinea pig plasma and evaluated in domestic swine

A rapid and small volume assay to quantify HI-6 in plasma was developed to further the development and licensing of an intravenous formulation of HI-6. The objective of this method was to develop a sensitive and rapid assay that clearly resolved HI-6 and an internal standard in saline and plasma matrices. A fully validated method using ion-pair HPLC and 2-PAM as the internal standard fulfilled these requirements. Small plasma samples of 35 μL were extracted using acidification, filtration and neutralization. Linearity was shown for over 4 μg/mL to 1 mg/mL with accuracy and precision within 6% relative error at the lower limit of detection. This method was utilized in the pharmacokinetic analysis HI-6 dichloride (2Cl) and HI-6 dimethane sulfonate (DMS) in anaesthetized guinea pigs and domestic swine following an intravenous bolus administration. From the resultant pharmacokinetic parameters a target plasma concentration of 100 μM was established and maintained in guinea pigs receiving an intravenous infusion. This validated method allows for the analysis of low volume samples, increased sample numbers and is applicable to the determination of pharmacokinetic profiles and parameters.