Gastrointestinal Toxicity

Gastrointestinal (GI) toxicity can occur in long term use of diclofenac, especially in the elderly

Toxicokinetics

Diclofenac, like other NSAIDs, can cause serious gastrointestinal toxic effects when taken long term.

These include: ^{3, 4, 19}

inflammation
ulcers and bleeding
perforations of the esophagus, stomach, and intestines.

These can be fatal.

These effects are caused by inhibition of COX-1 and COX-2 enzymes. This is to reduce the production of prostaglandins which are key for inflammation. However, the inhibition of COX1 also reduces stomach mucus production, bicarbonate production and platelet aggregation. This is what causes the GI toxic effects ².

Figure 1: created by Amna Khan, adapted from Desia et al ²².

You are more at risk of developing peptic ulcers when taking diclofenac if you are: ²⁴

over 65 years of age
have a history of ulcers
take steroids
are on other painkillers alongside diclofenac
are on certain kinds of antidepressants

Signs and symptoms

Symptoms to look for: ^{3, 4}

Vomiting
Diarrhoea
Blood in vomit or stool.
Severe indigestion or stomach pain.

Prevention

Diclofenac can be taken with paracetamol or codeine but should not be taken with aspirin, ibuprofen or Naproxen. It is advised you take diclofenac with food to avoid gastric irritation. excessive drinking is also not recommended ⁴.
Doctors may not prescribe diclofenac if you have previously had stomach ulcers, have ulcerative colitis, have crohns disease, are on blood thinning medication, are pregnant or breastfeeding ^{3, 4}.
Doctors should prescribe the lowest therapeutic dose ²⁰.

Treatment

Diclofenac should be taken as prescribed. if you suffer any of the symptoms mentioned above you should contact a medical professional ⁴.
Drugs such as Omeprazole, Pantoprazole, Misoprostol, and Thymoquinone can be prescribed alongside Diclofenac to help prevent peptic ulcers ^{23, 25}. However studies have found misoprostol causes side effects that are less well tolerated by patients ²³.
In the case of an overdose, it has been suggested a dose of activated charcoal immediately after ingestion can help prevent absorption ²¹.

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