Retinoids are highly potent drugs and should only be prescribed under specialist supervision.
Major concern: teratogenicity (strict pregnancy prevention protocols are essential).
Always check the BNF or UpToDate for prescribing advice, monitoring, and contraception guidance.

🧬 Mode of Action

Act via nuclear retinoic acid receptors altering gene transcription.
They are vitamin A analogues.
Tretinoin promotes differentiation of malignant promyelocytes → crucial in treatment of APL (M3 subtype AML).

📋 Indications

Severe scarring acne (often resistant to antibiotics; may worsen initially).
Severe or refractory psoriasis.
Acute promyelocytic leukaemia (APL, M3) – induces remission.
Photo-damaged skin (dermatology use).

🚫 Contraindications

Absolute: Pregnancy (teratogenic).
Relative: Renal or hepatic impairment, hyperlipidaemia, uncontrolled psychiatric illness.

💊 Dosing (examples)

Tretinoin (oral): APL induction therapy; dose guided by haematology protocol.
Isotretinoin (oral, Accutane): Single 15–20 week course often results in prolonged acne remission.
Topical tretinoin: Used in acne and photo-aged skin.
Etretinate/Acitretin: Used in severe psoriasis (now rarely first-line due to long half-life and teratogenicity).

⚠️ Cautions & Monitoring

Pregnancy prevention: Must prove not pregnant (documented LMP + pregnancy test before treatment, repeated as per guidelines).
Contraception: Two reliable forms recommended (e.g., combined pill + barrier). Continue contraception after stopping (6 weeks for isotretinoin; 3 years for etretinate due to long half-life).
Baseline and periodic: FBC, LFTs, fasting lipids, calcium, clotting profile.
Monitor for benign intracranial hypertension (headache, papilloedema, visual changes).

❗ Side Effects

Teratogenicity – absolute contraindication in pregnancy.
Neurological: Benign intracranial hypertension (esp. if combined with tetracyclines).
Mucocutaneous: Severe dryness of lips, skin, eyes, nose.
APL-specific: Retinoic acid syndrome (~25% of APL cases): fever, dyspnoea, pulmonary infiltrates, pleural/pericardial effusions, weight gain.
Metabolic: Dyslipidaemia, hypertriglyceridaemia, pancreatitis (rarely fatal).
Psychiatric: Depression, mood swings, suicidal ideation (monitor mental health closely).
GI/Hepatic: Nausea, hepatitis, worsening IBD.
MSK/Ocular: Arthralgia, hyperostosis, corneal opacities, impaired night vision.
CV: Thrombotic events, stroke (rare).

🔗 Drug Interactions

Avoid vitamin A supplements (risk of toxicity).
Tetracyclines, corticosteroids: ↑ risk of benign intracranial hypertension.
Progesterone-only pill: Less effective – use combined or barrier contraception.
Avoid St John’s Wort (reduces contraceptive efficacy via CYP induction).

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Retinoids 💊

⚠️ About (Always check the BNF or local formulary)