Paracetamol plus supplementary doses of codeine. An analgesic study of repeated doses

A double-blind, multicentre analgesic trial was carried out in patients suffering from pain after removal of an impacted lower wisdom tooth. 266 patients were evaluated after random allocation to treatment with paracetamol 500 mg, paracetamol 500 mg plus codeine 20 mg, paracetamol 500 mg plus codeine 30 mg, or paracetamol 500 mg plus codeine 40 mg. On the day of surgery the patients assessed their own pain intensity hourly on a visual analogue scale. The analysis of the results was carried out according to the method which considered repeated dose intake. A statiscally significant dose-response relationship was obtained between the supplementary doses of codeine and analgesic efficacy. In the comparison of side effects, their frequency increased with increasing amounts of codeine. In clinical practice codeine 30 mg appeared to be the optimal supplement for paracetamol 500 mg.