Turpentine oil induced inflammation decreases absorption and increases distribution of phenacetin without altering its elimination process in rats

Plasma concentrations and pharmacokinetics of phenacetin, a CYP1A2 substrate were determined in normal and experimentally induced inflamed rats by turpentine oil to know the role of inflammation on the pharmacokinetics of phenacetin and formation of its active metabolite (paracetamol) by CYP1A2 in wistar albino rats, weighing about 200–250 g that were randomly divided into two groups consisting six in each group. Rats in group I (control) received phenacetin (150 mg kg −1 , PO) where as group II received phenacetin 12 h after induction of inflammation by turpentine oil (0.4 mL, i.m). Blood samples were collected from retro orbital plexus at pre-determined time intervals prior to and at 0.166, 0.33, 0.67, 1.5, 2, 4, 8 and 12 h post-administration of phenacetin. Plasma was separated and analyzed for phenacetin and its metabolite paracetamol by HPLC assay. Based on plasma concentrations of phenacetin and its metabolite paracetamol, the pharmacokinetic parameters were determined by compartmental methods. C max of phenacetin was significantly ( p