All medicines that are listed on the UK Porphyria Medicines Information Service (UKPMIS) ‘Drugs that are considered to be safe for use in the acute porphyrias’ may be used.
Local expert opinion is that all topical preparations are considered safe in patients with porphyria, when applied to intact skin or mucosa. In this context, ‘topical preparations’ include skin creams, ointments, lotions, inhalers, eye drops, ear drops, steroid injections into joints and local anaesthetics in small amounts, lice treatments, and creams for use on the external genitalia.
Absorption of products that are designed to be internalised such as suppositories, pessaries and rectal foams may be significant. Additional advice on safety should be sought before using these types of products.
Regardless of the application site, absorption is increased by occlusion, coverage of a large area, and when the skin is broken or the membranes are not intact. These factors should be considered prior to prescribing and/or administering a topical preparation. If there is a risk of substantial absorption and metabolism, seek specialist advice.
Senior Information Pharmacist, Welsh Medicines Information Centre