If you're a psoriasis sufferer, chances are you've been offered Zorac (tazarotene). It's one of the first retinoids (vitamin A derivative) that can be applied directly to the skin. As such, it's being marketed heavily by its manufacturer, Allergan, as a successful treatment of mild to moderate plaque psoriasis.
One important element of its marketing is a recently completed study involving 300 patients, who were given 0.1 per cent or 0.05 per cent tazarotene gel once a day, or the steroid cream fluocinonide twice a day.
Overall improvement was similar among both treatments, but fewer of the tazarotene group suffered a relapse 12 weeks after the therapy had finished.
Although, as a gel, it's easy to apply, it also seems to be less well tolerated than some of its competitors. More in the tazarotene group had to drop out because of side effects, which included irritation, burning and erythema (skin reddening) (J Am Acad Dermatol 1998; 38: 705-11).
To this can be added the adverse reactions noted in earlier trials, such as pruritus (itching), experienced by up to a quarter of all patients, and a worsening of the condition, which was reported by up to 10 per cent of all patients.
Not surprisingly, reaction is associated with higher concentrations of the gel. The higher concentration gel of 0.1 per cent can cause up to 5 per cent more cases of severe skin irritation than the lower concentration, especially during the first four weeks of use, the manufacturer warns.
Pregnant women and breastfeeding mothers should not use the gel, nor should any woman thinking of becoming pregnant. Its safety among patients under the age of 18 has not been proven.