It is an isomer of tretinoin.

Indications: severe forms of nodulo-cystic acne which are resistant to previous therapy, particularly cystic acne and conglobate acne especially when the lesions involve the trunk.

Cautions: liver function should be checked before and one month after the start of treatment, and subsequently at three month intervals; serum lipids should also be checked.

Contra-indications: blood donation by patients who are treated (one or two weeks) with the drug to women of child-bearing age is contra-indicated; pregnancy; hepatic and renal insufficiency; hypervitaminosis A; patients with excessively elevated blood lipid values; hypersensitivity to the drug; concurrent use of other keratolyses or exfoliative acne drugs; exposure to sun; UV exposure.

Side Effects: dryness of the skin, nasal mucosa and conjunctiva; visual disturbances; malaise and drowsiness; change in blood picture; mood changes and depression.

Drug Interactions: possible increased risk of benign intracranial hypertension when retinoids given with tetracyclines; risk of hypervitaminosis A when given with vitamin A; it possibly reduces plasma concentration of carbamazepine.

Dose: Initially, 500 mcg/kg daily; after 4 weeks the dose is adjusted within the range of 0.1-1.0 mg/kg daily. The max. dose of 1 mg/kg daily should be given for only a limited period of time.

Treatment lasts for 16 weeks. There is often an improvement after the discontinuation of the treatment and thus a period of at least 8 weeks is needed before restarting the treatment.