Saliva versus Plasma Therapeutic Drug Monitoring of Pregabalin in Jordanian Patients

Abstract

The objective is using saliva instead of plasma for pregabalin therapeutic drug monitoring (TDM) since saliva reflects the free non-protein bound drug concentration, simple and noninvasive sampling, cheaper and does not require the expertise of drawing blood. Forty four patients participated in this study, two samples of saliva and another two of blood were taken from each patient; first sample of both saliva and blood is the trough sample and was taken just before the first dose of the day and second sample is the peak sample and was taken 1 h after taking the first dose of the day. Descriptive statistics and t-testing after log transformation were done using Excel, p-value=0.05 was adopted for significant difference. Optimized effective intestinal permeability of pregabalin was estimated by PK-Sim program version 7. This study for the first time revealed that pregabalin is excreted in saliva and classified as class 1 based on Salivary Excretion Classification System (SECS). A good correlation of 0.71-0.83 between Cmin and Cmax of plasma and saliva pregabalin was observed respectively which indicate that saliva sampling is a good alternative matrix for pregabalin TDM. C/D-ratios were calculated to demonstrate pharmacokinetic variability of Pregabalin; the results showed that C/D-ratio was higher in women, elderly and in those patients who had Scr.≥0.9 mg/dl. Proposed pregabalin therapeutic ranges are 0.7 to 1.84 µg/ml in plasma and 0.055 to 0.145 µg/ml in saliva, for neuropathic pain, diabetic neuropathy and disc prolapse patients.