Desmopressin combined with diclofenac sodium provides significantly better pain relief than diclofenac monotherapy for acute renal colic, a trial has shown.

A study from Iran looked at 150 patients aged 15-65 years (65 is the upper limit for the licence of intranasal desmopressin) presenting with acute renal colic. Patients were randomised, double blind, to receive either a 100mg diclofenac sodium suppository plus 40ųg intranasal desmopressin (group 1), or diclofenac suppository plus placebo saline spray (group 2).

If analgesia was not sufficient at

30 minutes, intramuscular pethidine was administered.

There was no significant difference in demographics or baseline pain scores between the two groups. However, significant differences were seen at 15 and 30 minutes with an improvement in pain scores in the desmopressin group versus NSAID alone (p<0.05).

In group 1, 37.3% of patients did not achieve adequate pain control and received pethidine. However, the number requiring pethidine was almost double in group 2, 69.3%, suggesting a significant additive effect of desmopressin plus NSAID.

Patients with renal colic are commonly encountered in primary care. One of the key roles of the GP is to provide sufficient analgesia for this severely painful condition. Successful pain control may allow the patient to be managed in the community, preventing an acute hospital admission.

Traditionally, the mainstay of analgesia has been NSAIDs, sometimes combined with opiates, but over recent years the search has been undertaken for novel agents to assist NSAIDs in controlling pain. This has included the use of alpha-blockers and calcium channel blockers, and synthetic ADH in the form of intranasal desmopressin. It is postulated that ADH causes a decreased renal diuresis and thus contributes to a rapid decrease in pain levels.

While further research is still required, it would appear that intranasal desmopressin may have a role in the acute management of renal colic. In particular, it may significantly reduce the number of patients requiring opiates, which at the doses required to aid with pain relief in this condition are commonly associated with significant side effects, particularly nausea and vomiting.

Desmopressin may offer an alternative, rapid acting analgesic

and warrants further research to clarify its role.