Isotretinoin

It is an isomer of tretinoin.

Indications

Systemic treatment of nodulo-cystic and conglobate acne, severe acne, acne which has not responded to adequate course of systemic antibacterial or acne associated with psychological problems.

Dosage

Adults : Initially 500mcg/kg daily (in 1-2 divided doses) with food, for 4 weeks. If good response, continue for further 8-12 weeks; if little response increase to 1mg/kg daily 8-12 weeks. If intolerant, reduce dose to 100-200 mcg/kg daily. Usually given for 16 weeks, repeat course is not normally required. Children : Not recommended

Contra-Indications

Renal or hepatic impairment, hypervitaminosis A, hyperlipidaemia.

Special Precautions

Exclude pregnancy. Avoid blood donation during treatment and at least one month after treatment; history of depression. Monitor hepatic function and lipids before treatment, one month after starting treatment and then every three months. Diabetes, dry eye syndrome. Avoid keratolytics.

Side Effects

Nausea, headache, malaise, drowsiness, sweating. Benign intracranial hypertension (avoid concomitant use of tetracycline). Myalgia, arthralgia. Dryness of skin, epidermal fragility; rarely acne fulminans, facial hyperpigmentation. Dryness of lips, nasal mucosa, pharyngeal mucosa, conjunctiva. Visual disturbances, Hair thinning. Raised serum creatinine, plasma triglycerides, cholesterol.

Drug Interactions

Alcohol, antibacterials, warfarin, antiepileptics, cytotoxic drugs, oestrogens and progestogens, vitamins.