Dihydrocodeine in postoperative pain

Clinical bottom line:
A single 30 mg oral dose of dihydrocodeine does not provide effective analgesia. A 60 mg dose is significantly less effective than ibuprofen 400 mg. Quality data do not exist for a placebo comparison. Patients should be offered a more effective analgesic in the treatment of postoperative pain.

Adverse effects were mild and transient.

Dihydrocodeine is a synthetic opioid analgesic which was developed in the early 1900s. Its structure and pharmacokinetics are similar to codeine, and it is used for the treatment of postoperative pain and as an antitussive. Nearly one tenth of all analgesic preparations issued in England were for dihydrocodeine in 1995.

Systematic review

HJ McQuay, RA Moore. An evidence-based resource for pain relief. Oxford University Press March 1998 ISBN 0-19-262718-X.

Date review completed: February 1997
Number of trials included: 4
Number of patients: (97 active vs. 97 placeb; 80 active vs. 80 active control).
Control group: placebo (3 trials) / ibuprofen (1 trial)
Main outcomes: 4-6 hours TOTPAR or SPID; number-needed-to-treat (NNT) for 50% pain relief (with 95% confidence intervals); relative benefit (with 95% confidence intervals).

Inclusion criteria were full journal publication of trials of dihydrocodeine in acute postoperative pain; single oral dose; postoperative administration; randomised; placebo-controlled; double-blind; moderate to severe baseline pain; adult populations.

For each trial the mean TOTPAR or SPID values for dihydrocodeine and placebo groups were converted to the percent of maximum total pain relief based on the categorical pain scales (%maxTOTPAR or %maxSPID). These values were then converted to dichotomous information on the proportion, and then the number of patients, who achieved at least 50%maxTOTPAR. A number-needed-to-treat for at least 50% pain relief and the relative benefit of the treatment were then calculated.

Findings

Oral dihydrocodeine vs. placebo

Dihydrocodeine 60 mg data were not available from the included trials. Dihydrocodeine 30 mg (dihydrocodeine tartrate) was not significantly different from placebo.

Oral dihydrocodeine vs. ibuprofen

Ibuprofen was significantly more effective than dihydrocodeine 30 mg and 60 mg.

Figure: At least 50% pain relief for dihydrocodeine compared with placebo and ibuprofen

Table: NNTs for comparisons of dihydrocodeine versus placebo and ibuprofen

Number of trials	Dose of dihydrocodeine	Dihydrocodeine >50% pain relief/total	Placebo >50% pain relief/total	Relative benefit (95% CI)	NNT (95% CI)
vs. placebo
3	30 mg	29/97	19/97	1.7 (0.7 to 4.0)	not calculated
	Dose of dihydrocodeine	Dihydrocodeine >50% pain relief/total	Ibuprofen >50% pain relief/total	Relative benefit (95% CI)	NNT (95% CI)
vs. ibuprofen
1	30 mg	3/40	18/40	0.2 (0.1 to 0.5)	-2.7 (-1.8 to -5)
1	60 mg	6/40	18/40	0.3 (0.2 to 0.8)	-3.3 (-2.1 to -9)
Negative NNTs in the comparison with ibuprofen mean that ibuprofen was better than dihydrocodeine.

Adverse effects