Parenteral versus oral route increases paracetamol efficacy

The analgesic efficacy and tolerability of parenteral versus oral paracetamol 1g were compared in 323 patients immediately after a hallux valgus plasty performed with local anaesthesia (31 men, 292 women, mean age 52 years). Using a multicentre, double-blind, double-placebo, randomised, parallel-group design, the effects of a single dose of propacetamol (PR) 2g [= paracetamol (PA) 1g], oral PA 1g and placebo (PL) were compared in the recovery room 5 hours (mean) after surgery in three parallel groups of patients with at least moderate pain on a 5-point verbal scale. Efficacy was assessed on pain scores rated on a 5-point verbal scale before administration (T0) and 0.25, 0.5, 0.75, 1, 2, 3, 4, 5 and 6 hours after administration and with an overall efficacy 5-point verbal score. Any adverse effects were recorded throughout the duration of the study. PR was statistically superior to PL on pain intensity difference (PID) from T30 minutes to T6 hours (Dunnett test), on maximum pain intensity difference (MAXPID) [p < 0.05] and summed pain intensity difference (SPID) [p < 0.05]. PA was statistically superior to PL at T1, T2, T4, T5 hours (Dunnett test), on MAXPID (p < 0.05) and SPID (p < 0.10). PR was statistically superior to PA on PID from T30 minutes to T4 hours, on MAXPID (p < 0.03) and SPID (p < 0.01). Overall efficacy was found by the patients to be superior with PR vs PA (p < 0.01), PR vs PL (p < 0.05), and PA vs PL (p < 0.10). The remedication time was significantly different between the three groups (p < 0.05). 10 patients experienced 1 adverse effect, PR: 3 (injection site pain, headache, vomiting), PA: 6 [nausea, tremor, injection site pain (3), malaise], PL: 1 (injection site pain). In conclusion, PR 2g (i.e. PA 1g) provided a significantly greater and longer analgesic effect than the same dosage in oral form.