Does pethidine still have a place in therapy?

Editor, – We read with interest the article 'Does pethidine still have a place in therapy?' (Aust Prescr 2002;25:12-3).The author concluded that pethidine 'can be used to treat acute pain for a short time' and suggests that it results in smaller increases in common bile duct pressures as well as less urinary retention and constipation when compared with morphine.

Our Drug Committee has debated whether or not there was a place for pethidine in acute pain management. We were not convinced that there was any good evidence to suggest that repeated doses (required if analgesia is to be maintained) resulted in clinically significant reductions in bile duct pressures compared with morphine. There was also no good evidence comparing effects on urinary retention and constipation. However, it is known that signs consistent with norpethidine toxicity can be seen within 24 hours of starting treatment with pethidine if higher doses are required.

A review of the use of opioids in pain management also expressed concerns about pethidine's continuing use.¹ It states 'Since use of pethidine is not associated with any specific advantage, it is a poor choice if multiple doses are needed' and that 'there is no good evidence to suggest that pethidine has any advantage at equianalgesic doses over other opioids for biliary or renal colic'.

For these reasons, as well as the problems that can be seen when pethidine is used for chronic pain (as mentioned in the article), our Drug Committee has recommended that hydromorphone become the second-line choice of opioid after morphine for routine acute pain management when parenteral opioids are required. Where intravenous opioids are used, fentanyl may also be a useful alternative, especially in view of its lack of active metabolites.

P. Macintyre
Director, Acute Pain Service

F. Bochner
Chairman, Drug Committee

S. Wiltshire
Project Pharmacist, Drug Committee
Royal Adelaide Hospital
Adelaide

Dr A. Molloy, author of the article, comments:

I concur with the concerns of the Royal Adelaide Hospital Drug Committee regarding the use of pethidine and the fact that norpethidine toxicity can occur after repeated doses within 24 hours if high doses are required. Now that hydromorphone is available, it is certainly reasonable to consider this as a second-line choice if parenteral opioids are required in the acute pain setting. Pethidine, however, should not be taken off the formulary as it still remains a useful drug for short-term treatment of acute pain.