The analgesic efficacy of tramadol has been recently reassessed as pan of a new clinical development programme to support an application for registration in the USA. This article reviews the results of single dose and short term studies of oral tramadol 50, 75, 100 and 150mg in various acute pain conditions. In a double-blind single dose study conducted in 161 patients with severe pain following caesarean section, tramadol 75 and 150mg and the combination of paracetamol 650mg with dextropropoxyphene napsylate 100mg were shown to be effective and statistically superior to placebo. The results from this and 17 other similar studies in patients with pain after surgery (n = 1594) or dental extraction (n = 1859) including other comparators were included in a pooled analysis. Tramadol 100mg was the optimal single dose for acute pain and tramadol 50mg showed similar analgesic efficacy to codeine 60mg. Multiple dose short term studies (n = 520) with tramadol 50, 75 and 100mg demonstrated a statistically significant and dose-dependent reduction in the consumption of either ibuprofen or morphine as escape medication. New pharmacokinetic data show that steady-state plasma tramadol concentrations reached after oral administration of 50mg doses every 6 hours are similar to those obtained after administration of a 100mg single oral dose (250 mu g/L). This rationale is supported by the results of long term studies in which the average daily dose of tramadol was approximately 250mg.
