A comparison of rectal and intramuscular codeine phosphate in children following neurosurgery

Abstract

Codeine is frequently used for postoperative analgesia in children. Intramuscular injections are not ideal and the rectal route may be preferable. We compared rectal and intramuscular codeine administered following neurosurgery. 20 children (over 3 months) undergoing elective neurosurgical procedures, were randomized to receive either rectal or intramuscular codeine phospate (1 mg.kg-1) at the end of the procedure. Serum levels of codeine and morphine were assayed at intervals following administration (0, 30, 60, 120, 240 min). Fentanyl was the intraoperative analgesic and postoperative rescue analgesia was paracetamol, diclofenac and intramuscular codeine. The Children's Hospital of Eastern Ontario Pain Scale was used to assess analgesia. Peak codeine levels in both groups were observed at 30 min and morphine levels were consistently low. The plasma codeine levels were significantly greater at 30 and 60 min following intramuscular injection, and were associated with slightly better analgesia scores, but did not reach statistical significance. However, the peak plasma level occurred at similar times in both groups. Codeine is absorbed as rapidly via the rectal route compared with the intramuscular route but the peak levels are lower.

Codeine phosphate in paediatric medicine

“…and rectal codeine in children aged 3 months to 12 yr for post-operative analgesia, peak plasma levels of codeine were achieved as expected between 30 and 60 min in both groups but rectal bioavailability was found to be lower. 72 In another study of rectal codeine for post-operative analgesia in infants and children aged between 6 months and 4 yr, the mean initial half-life was 2.6 h, but in the infants of the lowest body weight, the half life was over 2 h longer than this mean value. 92 In addition, plasma drug concentration data indicate that a rectal dose of codeine of 0.5 mg kg ±1 in children can result in similar, or slightly greater, plasma concentrations of codeine and its metabolites than after 60 mg orally in adults.…”

Acute and chronic pain following craniotomy: a review

“…For non‐ventilated patients in the immediate postoperative period appropriate analgesia consists of oral, rectal or intramuscular codeine phosphate, 30–60 mg 4‐hourly. Codeine [27, 28] has been traditionally the opiate of choice because it has a ceiling to its respiratory depressant effects and it does not mask pupillary signs. Paracetamol 1 g 6‐hourly will give a synergistic effect with the codeine.…”

Symptom control in cancer patients: the clinical pharmacology and therapeutic role of suppositories and rectal suspensions

“…Raising the pH of rectal codeine phosphate solutions from 4.3 to 9 enhances the bioavailability and rate of absorption. Codeine phosphate per rectum is as rapidly absorbed as by parenteral injection, but produces lower peak levels [100]. Alkaline solutions per rectum have a relatively short T-max of 0.4 h and a C-max of 170 µg/l, which is better than the corresponding values for similar oral doses.…”