13-cis isomer of retinoic acid. Reduces sebaceous-gland size + sebum production ~90%; induces keratinocyte differentiation; anti-inflammatory. Only agent that produces durable acne remission (single course cures many). Severe teratogenicity (FDA iPLEDGE mandatory contraception for females of reproductive potential).
Half-Life (t½)
PO: 20h
Dosing Guidelines
PO: Typical 0.667 mg (Range: 0.5–1 mg)
Target Organ Systems
reproductive
integumentary
immune-hematologic
Interactions
Vitamin A (contraindicated): Additive hypervitaminosis A — isotretinoin and preformed vitamin A share RAR/RXR-mediated mucocutaneous, hepatic, and CNS (pseudotumor cerebri) toxicity; supplemental vitamin A is contraindicated during a course. [Silverman 1987]
Tretinoin (topical) (caution): Do not combine topical tretinoin with oral isotretinoin — additive irritation without incremental benefit.