Diclofenac potassium

How it works

It non-selectively inhibits cyclo-oxygenase (COX-1 and COX-2), reducing prostaglandin synthesis and thereby its analgesic, anti-inflammatory and antipyretic effects; the potassium salt dissolves quickly for faster onset than the sodium salt.

Prescribing in practice

• Diclofenac carries a higher cardiovascular thrombotic risk than other non-selective NSAIDs and is contraindicated in established ischaemic heart disease, cerebrovascular disease, peripheral arterial disease and heart failure (MHRA advice); use the lowest effective dose for the shortest duration.
• Co-prescribe gastroprotection (e.g. a proton-pump inhibitor) in patients at risk of gastrointestinal ulceration or bleeding, and avoid combining with other NSAIDs including aspirin.
• Avoid in the third trimester of pregnancy and use caution with renal impairment, hypertension and concurrent ACE inhibitors, diuretics or anticoagulants.

Monitoring

Monitor blood pressure, renal function and for signs of gastrointestinal bleeding, particularly in older patients and those on longer courses.

Counselling the patient

• Take with or after food to reduce stomach upset.
• Stop and seek advice if you develop black stools, vomiting blood, or unexplained breathlessness or chest pain.

Evidence & guidelines

Diclofenac is a long-established NSAID whose cardiovascular safety profile is summarised in MHRA/EMA reviews and reflected in NICE guidance on NSAID prescribing.