Multiple-reaction monitoring (MRM) LC–MS/MS quantitation of venlafaxine and its O-desmethyl metabolite for a preclinical pharmacokinetic study in rabbits

Preclinical pharmacokinetic (PK) studies in animal models during the formulation development phase give preliminary evidence and near clear picture of the PK behavior of drug and/or its dosage forms before clinical studies on humans and help in the tailoring of the dosage form according to the expected and requisite clinical behavior. The present work reports a first of its kind preclinical PK study on extended-release (ER) solid oral dosage forms of venlafaxine (VEN) in New Zealand White rabbits. The VEN is a highly prescribed and one of the safest and most effective therapeutic agents used in the treatment of different types of depression disorders worldwide. The multiple-reaction monitoring (MRM) LC–MS/MS method developed for this purpose demonstrated enough reliability in simultaneously quantitating VEN and its equipotent metabolite O-desmethylvenlafaxine (ODV) in rabbit plasma. The method described uses solid-phase extraction for sample preparation followed by an ultrafast LC–MS/MS analysis. The chromatographic separation was achieved isocratically with a predominantly polar mobile phase by employing RPLC. The triple quadrupole LC/MS/MS system operated in MRM mode used an ESI probe as an ion source in positive polarity. The validation results are within the permissible limits of US FDA recommendations and acceptance criteria for bioanalytical method validation.