Tretinoin

RETIN-A

What it isRAR agonist retinoid; topical treatment of acne and systemic differentiation therapy for acute promyelocytic leukemia.

Why it mattersThe same molecule is routine acne therapy on skin and lifesaving maturation therapy for malignant promyelocytes.

What it changesTopical use irritates and photosensitizes; systemic use is teratogenic and can cause differentiation syndrome.

FDA-approved for

BOXED WARNING Embryo-fetal toxicity (loss and malformations); Differentiation Syndrome (~26% of APL patients, can be life-threatening or fatal)

FDA dosing	Population	Start	Target	Max
Acute promyelocytic leukemia — induction of remission	Adults and pediatrics ≥1 yr	22.5 mg/m² BID	22.5 mg/m² BID	22.5 mg/m² BID

Renal Undefined

Hepatic Undefined

Discontinue if the t(15;17) translocation or PML/RARα fusion is not identified

Take with a meal
Swallow capsules whole with water; do not chew, dissolve, or open
Discontinue 30 days after complete remission or after 90 days of treatment, whichever occurs first
Do not take a missed dose unless >10 hours until next dose; if vomiting occurs, do not take an extra dose
Negative pregnancy test before initiating; two effective contraceptive methods in females during treatment and for 1 month after; males use effective contraception during and for 1 week after

Differentiation syndrome — start high-dose corticosteroids at first signs
Rapidly evolving leukocytosis (~40%)
Intracranial hypertension (especially pediatric)
Hypercholesterolemia/hypertriglyceridemia
Hepatotoxicity (monitor LFTs)
Venous and arterial thromboembolic events; avoid concomitant antifibrinolytics (e.g., tranexamic acid)
Confirm APL by t(15;17) or PML/RARα

Pregnancy Can cause embryo-fetal loss and malformations; retinoid teratogen — contraindicated intent in pregnancy (boxed warning)

Lactation No data; advise not to breastfeed during treatment and for 1 week after the last dose

NO BOXED WARNINGS

Principal riskIrritation and photosensitivity

Cost, est. cash$10–$300/month

Generic entry1998

Therapeutic safety burden1 / 4

Overdose danger0 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk0 / 4

Legacy pregnancy categoryNot assigned — PLLR-era drug

Defining liabilityLocal irritation or hypersensitivity; systemic toxicity is minimal with correct local use.