Diclofenac

How it works

It inhibits cyclo-oxygenase (COX-1 and COX-2), reducing prostaglandin synthesis, which relieves pain and, in ureteric colic, lowers intraureteric pressure and renal pelvic pressure.

Prescribing in practice

• Avoid in significant renal impairment, hypovolaemia, or dehydration because NSAIDs can precipitate acute kidney injury in the obstructed or volume-depleted patient.
• It carries gastrointestinal bleeding and cardiovascular thrombotic risks and is contraindicated in established cardiovascular disease, so use the lowest effective course.
• Use with caution alongside anticoagulants, other NSAIDs, and drugs affecting renal perfusion per the SPC.

Monitoring

Monitor renal function and blood pressure with repeated or prolonged use and remain alert to gastrointestinal symptoms.

Counselling the patient

• Take with or after food to reduce stomach upset.
• Report black stools, vomiting blood, or significant indigestion promptly.
• Use for the shortest time needed to control colic pain.

Evidence & guidelines

Recommended as first-line analgesia for renal colic on the basis of trials showing NSAIDs provide effective pain relief with less need for rescue analgesia than opioids.