Contraindications & Hypersensitivity

Patients who have previously shown hypersensitivity to NSAIDs or asprin, as well as those who are prone to asthma attacks or angioedema, should avoid Diclofenac.

Why are Asthma patients contraindicated?

Figure 3: Effects of Diclofenac in contraindicated asthma patients ⁵⁰

Other mechanisms for Diclofenac contraindications with Asthma

Inhibition of the COX pathway, leads to upregulation of the Lipoxygenase (LOX) pathway.
The LOX pathway leads to increased Leukotriene synthesis; Leukotriene is an inflammatory chemical which may also lead to bronchospasms, or exacerbate the effects of asthma ^,51

How can Diclofenac lead to Angioedema?

Increased Leukotriene production from upregulation of the LOX pathway leads to increased vascular permeability.
Increased vascular permeability allows fluid to build up and this causes swelling^,52

Treatment of Diclofenac induced Asthma or Angiodema

Cessastion of Diclofenac treatment will reverse the effects
Leukotriene receptor antagonists may be prescribed to reduce the effects of Leukotriene in the above mechanisms^,52

Hypersensitivity to Diclofenac

Figure 4: An IgE mediated Type I hypersensitivity reaction ⁵³

Anaphylactic Shock^,53

A hypersensitivity reaction can lead to anaphylactic shock in the individual whereby a flood of chemicals is released because of contact with the allergen.
This can result in a rash, low blood pressure, difficulty in breathing and extreme drowsiness.
Prevention from Anaphylactic shock includes avoiding known triggers of hypersensitive reactions
In emergency situations, patients in anaphylactic shock are administered with intravenous adrenaline to reduce the symptoms.
Antihistamine may also be administered to counter the effects of the high levels of histamine in the body
Fluids and Oxygen may be given to stabilize and treat the patient^,53

Due to genetic polymorphisms and differences, some individuals may experience hypersensitivity to NSAIDs, or specifically Diclofenac^53,54.
The process relating to hypersensitivity on the left, is considered a 'Type I' hypersensitivity reaction
Hypersensitivity reactions are more common in those with autoimmune diseases, or those who report previous hypersensitivity to other NSAIDs^,53,54

Other contraindications & cautions³

Those who have active Gastrointestinal bleeding, or ulcers should specifically avoid Oral Diclofenac^3,
Proctitis (Inflammation of the Rectum) is a contraindication as well as an adverse effect of Diclofenac Suppositories. Hence in healthy individuals suppositories should not be used for more than 48hrs³ .
When applying topical Diclofenac, the eyes and areas of broken skin should be avoided. Type IV Hypersensitivity (Contact allergy with red, itchy, blisters at point of application) is a recognised adverse effect and a past history is a contraindication for use⁵⁵.
Large amounts of topical application can still result in hypersensitivity and systemic effects.

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