capsaicin: clinical use

Prescribing considerations

• Confirm peripheral neuropathic pain and whether symptoms are sufficiently localised for topical treatment.
• Patch application requires trained staff, ventilation and protective handling.
• Assess cardiovascular risk before patch treatment where hypertension is unstable or poorly controlled, or cardiovascular disease is present.
• For diabetic neuropathy, examine the feet for lesions, neuropathy-related injury and vascular insufficiency.
• The cream is unsuitable for children; patch safety and efficacy below adulthood have not been established.

Contraindications and cautions

• Hypersensitivity to capsaicin or formulation excipients
• Cream application to broken or irritated skin
• Patch application to broken, irritated or wet skin; avoid the face, scalp above the hairline and areas near mucous membranes

Monitoring

• Monitor blood pressure during patch treatment.
• Monitor application-site pain and inspect promptly if it is severe because chemical burns have occurred.
• Assess sensory deficits before patch treatment and reconsider treatment if sensory loss develops or worsens.
• For diabetic neuropathy, continue visual foot assessment at later visits.

Clinical pharmacology

Capsaicin is a selective TRPV1 agonist. Initial nociceptor activation releases vasoactive neuropeptides and causes heat and erythema; subsequent reversible desensitisation reduces responsiveness to painful stimuli. Systemic patch absorption is low and temporary.

Formulation and product differences

• The cream is self-applied to localised painful areas and licensed for post-herpetic neuralgia after skin healing and painful diabetic peripheral polyneuropathy.
• The cutaneous patch is licensed broadly for peripheral neuropathic pain in adults and requires healthcare-professional application.
• Patch risks include treatment-related pain, temporary blood-pressure elevation, sensory change and rare serious burns.
• The cream contains benzyl alcohol and cetyl alcohol, which may cause local irritation or contact dermatitis.

Cream

Route: Cutaneous

Strengths: 0.025% w/w, 0.075% w/w