About topical medicines

Topical medicines are designed to be applied to a body surface, such as the skin or mucous membranes and common examples of topical preparations are skin creams, ointments, lotions, inhalers, eye and ear drops. In this context it also includes steroid injections into joints and local anaesthetics in small amounts and products applied to the external genitalia.

Internal products

Products designed to be internalised, such as suppositories, pessaries and foams are not included as absorption with these can be significant.

Type of porphyria

The type of porphyria an individual has and whether it is acute or non-acute can affect treatment choice with topical medicines.

Acute porphyria

Almost all topical preparations are considered safe in people with an acute form of porphyria (acute intermittent porphyria, aminolevulinate dehydratase deficiency porphyria, hereditary coproporphyria, variegate porphyria), when applied to intact skin or mucosa.

Oestrogen and progestogen-containing gels may not be appropriate for some people with an acute porphyria and advice should be sought from a porphyria specialist before prescribing them.

Absorption considerations

Regardless of the region of application, the extent to which a medicine is absorbed (taken up) through the skin can be increased by factors such as:

• as coverage of a large area
• sealing/occluding a medicine under a dressing
• the skin being broken or tissue not being intact

Consideration need to be given to this before prescribing and/or administering a topical treatment and if there is a risk that the medicine may be absorbed in large amounts, then a porphyria specialist should be contacted for advice.

Non-acute (cutaneous) porphyria

All medicines are safe to use in the cutaneous porphyrias (congenital erythropoietic porphyria, erythropoietic protoporphyria or porphyria cutanea tarda).

However, oestrogen and progestogen-containing gels may not be appropriate for some people with porphyria cutanea tarda and advice should be sought from a porphyria specialist before prescribing them.

Useful links

• A list of medicines that are safe in the acute porphyrias is produced by the UK Porphyria Medicines Information Service (UKPMIS). They can also be contacted for specialist porphyria advice on choosing medicines by telephone on 029 21842251. This service is available to healthcare professionals and people with porphyria living in the UK.
• British and Irish Porphyria Network (BIPNET)
• British Porphyria Association (BPA)