indication

For the treatment of severe recalcitrant nodular acne

pharmacology

Isotretinoin, a retinoid, is indicated in the treatment of severe recalcitrant nodular acne. Nodules are inflammatory lesions with a diameter of 5 mm or greater. The nodules may become suppurative or hemorrhagic. "Severe," by definition, means "many" as opposed to "few or several" nodules. Clinical improvement in nodular acne patients occurs in association with a reduction in sebum secretion. The decrease in sebum secretion is temporary and is related to the dose and duration of treatment with Accutane, and reflects a reduction in sebaceous gland size and an inhibition of sebaceous gland differentiation.

mechanism of action

Isotretinoin noticeably reduces the production of sebum and shrinks the sebaceous glands. It stabilises keratinization and prevents comedones from forming. It also reduces inflammation in moderate-severe inflammatory acne. The exact mechanism of action is unknown, however it is known that it alters DNA transcription.

toxicity

Isotretinoin is teratogenic. It also causes mucocutaneous side effects suck as cheilitis, dry skin, and dry eyes.

half life

17-50 hours

route of elimination

Isotretinoin and its metabolites are further metabolized into conjugates, which are then excreted in urine and feces. The metabolites of isotretinoin and any conjugates are ultimately excreted in the feces and urine in relatively equal amounts (total of 65% to 83%).

drug interactions

Carbamazepine: Isotretinoine decreases the effect of carbamazepine

Demeclocycline: Increased risk of intracranial hypertension

Doxycycline: Increased risk of intracranial hypertension

Methacycline: Increased risk of intracranial hypertension

Minocycline: Increased risk of intracranial hypertension

Oxytetracycline: Increased risk of intracranial hypertension

Rolitetracycline: Increased risk of intracranial hypertension

Tetracycline: Increased risk of intracranial hypertension

Vitamin A: Isotretinoin increases the risk of vitamin A toxicity. Avoid vitamin A supplementation while taking isotretinoin.