INTRODUCTION: Doses of acetaminophen 15mg/ kg intravenous and 40 mg/kg rectally produce similar effect-site concentrations. However, the clinical effectiveness of these routes has not been compared. The aim of this study was to compare the efficacy of analgesia (in terms of duration of analgesia and effect on pain intensity) in children following adenotonsillectomy after acetaminophen either 15 mg/ kg IV or 40 mg/ kg rectally. METHODS: Fifty children, aged between 5 and 14 yrs., undergoing

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... ive adenotonsillectomy were randomly allocated into two groups. Group IV received 15mg/kg intravenous acetaminophen and Group PR received 40mg/kg rectal acetaminophen. Blood pressure, heart rate, respiratory rate and oxygen saturation were continuously monitored. Postoperative pain was assessed by visual analogue scale (VAS) and rescue analgesia provided if scores were 4 or greater. The primary outcome measure was time to first rescue analgesia. RESULTS: The time to first rescue analgesia was significantly longer in children receiving rectal acetaminophen (8.96 ± 3.46) compared with those receiving IV acetaminophen (6.00 ± 1.63) (P-value 0.000). Only one child in IV Group required rescue analgesia within first 6 hours with differences between the groups being most prominent in the period from 6 to 10 hours. Vitals did not show any difference in both groups peri-operatively. Postoperative pain assessment by VAS at various time intervals showed no significant difference between the groups. CONCLUSIONS: Rectal acetaminophen 40 mg/ kg provides longer analgesia for moderately painful procedures when compared with 15 mg/ kg acetaminophen IV. However, efficacy of intravenous paracetamol has no superiority to rectal administration.