Celecoxib: a COX-2 anti-inflammatory for arthritis

The UK product information describes celecoxib as indicated in adults for symptomatic relief in osteoarthritis, rheumatoid arthritis and ankylosing spondylitis. It does not cure those conditions; it eases pain and stiffness.

It is a selective cyclooxygenase-2 inhibitor. Cyclooxygenase makes prostaglandins, and COX-2 is the form associated with pain, inflammation and fever. Because celecoxib does not appreciably block COX-1 at normal doses, it lacks the antiplatelet effect that aspirin has, so it is not a substitute for aspirin when aspirin is prescribed to prevent clots.

Celecoxib is taken by mouth as capsules, with or without food. Prescribers are told to use the shortest duration and lowest effective dose and to review the need for it periodically, because cardiovascular risk may rise with dose and duration. The leaflet says that if there is no extra benefit after two weeks of a higher dose, other options should be considered.

Older people are started on the lower dose, particularly if they weigh under 50kg. People known to be slow CYP2C9 metabolisers, and those with moderate liver impairment, are started on reduced amounts. Anyone who finds capsules hard to swallow should follow the leaflet guidance rather than improvising.

The contraindications in the product information include allergy to celecoxib or to sulfonamides; an active stomach ulcer or gut bleeding; asthma, rhinitis, nasal polyps, angioedema or hives triggered by aspirin or other NSAIDs; severe liver disease; kidney function below the stated threshold; inflammatory bowel disease; congestive heart failure; and established ischaemic heart disease, peripheral artery disease or cerebrovascular disease.

Because the list is long and relates to heart and circulation, a prescriber normally reviews blood pressure and cardiovascular risk factors such as smoking, diabetes and high cholesterol before choosing it. Blood pressure should be monitored when starting and during treatment.

The product information groups effects by frequency. Reactions that include sinusitis, upper respiratory infection, insomnia, dizziness, headache, abdominal pain, diarrhoea, indigestion and rash can occur. More serious effects include heart attack, stroke, heart failure, raised blood pressure, stomach bleeding and ulcers, kidney problems, severe liver reactions, and serious allergic or skin reactions.

Seek urgent help for chest pain, breathlessness, weakness on one side, slurred speech, black stools or vomiting blood, yellowing of the skin or eyes, or swelling of the face or throat. Fluid retention and swelling of the ankles are also reported, which matters for people with heart or kidney conditions.

Celecoxib is contraindicated in pregnancy and in women of childbearing potential who are not using effective contraception. Animal studies showed malformations and, in the second or third trimester, NSAIDs can affect the baby's kidneys and reduce amniotic fluid. If pregnancy occurs during treatment it should be stopped. The product information also says women taking it should not breastfeed.

As with other NSAIDs, celecoxib may delay or prevent rupture of ovarian follicles, which has been associated with reversible infertility in some women.

Anticoagulants such as warfarin need closer INR monitoring, particularly at the start or when the dose changes. NSAIDs can blunt blood pressure medicines (ACE inhibitors, angiotensin receptor blockers, diuretics, beta-blockers) and raise the risk of kidney problems in dehydrated or older people. Renal function should be checked when combined with ciclosporin or tacrolimus.

Celecoxib inhibits CYP2D6, so levels of medicines cleared by that enzyme, such as some antidepressants, antipsychotics and heart-rhythm medicines, can rise. Using it with another non-aspirin NSAID should be avoided. Low-dose aspirin can be taken with it, but the stomach risk is higher.

Celecoxib may have a minor effect on driving; anyone who feels dizzy, has vertigo or is drowsy should not drive or use machinery. Do not change or stop a prescribed medicine without talking to your prescriber, who can discuss alternatives such as paracetamol, topical NSAIDs, other oral NSAIDs with stomach protection, exercise and physiotherapy.