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The Pharmaceutical Journal Vol 263 No 7074 p891
December 4, 1999 Clinical

Acetylcysteine may be useful for ichthyosis

Topical application of acetylcysteine may be useful for the skin condition ichthyosis, Dr Pedro Redondo (University clinic of Navarra, Pamplona, Spain) reports. In a research letter to the Lancet (1999;354:1880), he describes the case of a woman with lamellar ichthyosis (a severe form of the condition) who was successfully treated with acetylcysteine.
The woman was given two solutions - one to apply to the inside of each arm twice a day. Both solutions were a water in oil emulsion, one of which contained 10 per cent acetylcysteine and the other (with no additions) was a placebo. The regimen was followed thoroughly. After five weeks, there had been an "outstanding improvement" to the actively treated arm and no change in the arm treated with placebo, Dr Redondo says (see picture).
Ichthyosis is a condition caused by an overproduction of keratin resulting in scaly, thickened skin. It is usually present from birth. The affected skin is unable to retain water and consequently dries out. Ichthyosis is treated with emollients (creams, ointments and bath oils), keratolytic agents and retinoids.

photo of ichthyosis treatment
The appearance of the patient's forearms after five weeks: topical acetylcysteine was applied to the arm on the left and placebo was applied on the right

The emulsion used in the experiment improved the stability of acetylcysteine, which breaks down to release malodorous sulphur-containing compounds, the author says.
Prior to its use in this patient, a cell culture experiment was used to show that acetylcysteine had an antiproliferative effect on human keratinocytes (the cells that make keratin). The experiment also showed that this inhibition of proliferation was not due to the cytotoxic effect of the drug.
Dr Redondo concludes that because acetylcysteine is an atoxic and hypoallergenic amino acid derivative with successful therapeutic uses and rare side effects, "it may be useful in the treatment of hyperproliferative skin disorders."
The author comments that acetylcysteine has also been used as an antidote for paracetamol overdose and as a mucolytic.