PHARMACOKINETICS OF RECTAL PARACETAMOL AFTER MAJOR SURGERY IN CHILDREN

Glycogelatin capsular suppositories containing a paracetamol slurry 40 mg . kg(-1) were given PR to 20 children (12 months-17 yrs) after maj or orthopaedic surgery and plasma concentrations of paracetamol measur ed for up to 18 h. The mean maximum concentration (C-max) was 0.115 (s o 0.049) mmol . l(-1). Peak concentration occurred (T-max) at 2.3 (so 1.2) h. Mean concentration was 0.07 (so 0.03) mmol . l(-1) at six h. A pparent paracetamol clearance was 5.8 ml . min(-1). kg(-1). The plasma concentration of paracetamol associated with analgesic effectiveness in children is unknown, but antipyretic effects are seen in the range 0.066-0.130 mmol . l(-1). Paracetamol suppositories 40 mg . kg(-1) giv en perioperatively achieve effective therapeutic antipyretic plasma co ncentrations within 1-2 h. The timing is coincident with the recovery phase of short duration paediatric surgery. The coefficient of varianc e of C-max was 43%. Some individual patients may not achieve a C-max w hich is therapeutic.