A systematic review and combined analysis of therapeutic drug monitoring studies for oral paliperidone

<b>Introduction</b>: This article includes a combined analysis of therapeutic drug monitoring (TDM) studies and a review of the marketer’s data on pharmacological mechanisms. <b>Areas covered</b>: An article search led to the inclusion of 21 paliperidone studies in the systematic review plus 2 case reports. Paliperidone clearance was calculated from: 1) steady-state studies using concentration/dose (C/D) ratios, and 2) single-dose studies describing 24-h area under the curve calculations. The marketed extended-release formulation has 28% bioavailability. Calculated mean C/D ratios (ng/ml/mg/d) were: 1) 4.09 in 6 studies of 221 non-Korean and non-geriatric adult patients, 2) 2.59 in 2 studies of 100 Korean adult patients, and 3) 6.89 in 1 study with 15 elderly Japanese patients. The limited drug–drug interaction studies indicated that carbamazepine is a clinically relevant inducer requiring three times the dosage, and that valproate, probably an inhibitor, requires half the dosage. Renal impairment markedly decreased paliperidone elimination, and other antipsychotics should be considered. <b>Expert Commentary</b>: We recommend more use of: 1) paliperidone TDM in clinical practice, 2) TDM when moving from oral to long-acting paliperidone, 3) better designs for paliperidone TDM studies, 4) laboratory studies on paliperidone pharmacokinetic mechanisms, and 5) TDM studies comparing paliperidone and risperidone dosing.