Quantification of controlled release leuprolide and triptorelin in rabbit plasma using electromembrane extraction coupled with HPLC-UV

An electromembrane extraction followed by HPLC-UV technique was developed and validated for quantification of leuprolide and triptorelin in rabbit plasma. The influencing parameters on the extraction efficiency were optimized using experimental design methodology. The optimized conditions were found to be; supported liquid membrane: a mixture of 1-octanol and 2-ethyl hexanol (1:1) containing 10% v/v di(2-ethylhexyl) phosphate, applied voltage: 5 V, extraction time: 5 min, pH of the donor phase: 4.5 and pH of the acceptor phase: 1.0. The optimized method was validated for linearity, intraday and interday precision, and accuracy in rabbit plasma. The range of quantification for both peptides was 0.5-1000 ng/mL with regression coefficients higher than 0.994. Relative recoveries of leuprolide and triptorelin were found to be 80.3 and 75.5%, respectively. Limits of quantification and detection for both peptides were found to be 0.5 and 0.15 ng/mL, respectively. The validated method was successfully applied to pharmacokinetic study of the 1-month depot formulations of each peptide after subcutaneous administration to rabbits.