Tretinoin
Synonyms :
All-trans Retinoic acid, Retinoic acid
Mechanism :
Tretinoin is not a cytolytic agent but instead induces cytodifferentiation and decreased proliferation of APL cells. In APL patients, tretinoin treatment produces an initial maturation of the primitive promyelocytes derived from the leukemic clone, followed by a repopulation of the bone marrow and peripheral blood by normal, polyclonal hematopoietic cells in patients achieving complete remission (CR). The exact mechanism of action of tretinoin in APL is unknown.
Indication :
- Acne
- Acute promyelocytic leukemia
Contraindications :
Contraindicated in patients with a known hypersensitivity to any of its components, or other retinoids, in patients who are sensitive to parabens, which are used as preservatives in the gelatin capsule. Avoid contact with eye, nostrils, mouth and mucous membranes. Do not use simultaneously with peeling agent. Do not use ultraviolet lamps and minimize exposure to sunlight.
Dosing :
Available as 0.025%/10 gm cream or as oral tablet.
Acne:
Apply pea sized amount at bedtime to skin, every day, where acne lesions appear. Use enough to lightly cover that area.
Acute promyelocytic leukemia:
Remission induction: 45 mg/m² in 2 divided doses, daily, orally.
Adverse Effect :
Headache, fever, weakness, and fatigue. With oral therapy: hemorrhage, infections, gastrointestinal hemorrhage, disseminated intravascular coagulation, pneumonia, septicaemia and cerebral hemorrhage. With topical application: erythema, excessive dryness, scaling, pruritus, photosensitivity, edema, hypo/hyperpigmentation, blistering, stinging, initial acne flares up.
Interaction :
Vitamin A: Patients should be advised against taking vitamin supplements containing vitamin A to avoid additive toxic effects.
Tetracyclines: Concomitant treatment with tetracyclines should be avoided because pseudotumor cerebri (benign intracranial hypertension) has been reported.
Hepatic Dose :
Dose adjustment may be required. Elevation of liver function tests can occur in half of patients, hence carefully monitor enzyme levels. If liver function levels are greater than 5 times the upper limit of normal: stop treatment.
If hepatotoxicity occurs during treatment: reduce the dose or discontinue treatment if levels don’t normalise or hepatitis is suspected.