Tretinoin

This is the acid form of vitamin A and is also called all-trans retinoic acid. The exact method of action is unclear but topical tretinoin decreases binding ability of epithelial cells to adjacent cells. Tretinoin also enhances mitotic activity although the exact method still remains to be elucidated.

• Induction of remission in acute promyelocytic leukaemia.^1,2 It is used in those previously untreated patients, patients that have relapsed and in those resistant to standard therapy.
• Acne vulgaris³
• Photodamage to skin
• Treatment of hair loss (unlicensed use)

• Monitor FBC, INR, liver function and calcium (can cause hypercalcaemia)
• Patients should be advised to monitor for evidence of thrombo-embolism e.g. swollen legs, chest pain
• Monitor lipids
• Renal impairment - monitor renal function
• Liver impairment - monitor liver function
• Avoid using topical preparations in or near eyes, mouth and broken skin

• Tretinoin is teratogenic, so pregnancy is an absolute contraindication and women of child bearing age should avoid getting pregnant (this extends to up to one month after treatment ends)³
• Breast feeding
• History of cutaneous epithelioma for topical preparations

• When used with tetracyclines there is an increased risk of benign intracranial hypertension
• Vitamin A - risk of hypervitaminosis A with retinoids
• Possible reduction in effectiveness of the progestogen only pill (combined oral contraceptive preparations are not effected)

Tretinoin is given orally in leukaemia. In the treatment of acne it is usually applied topically and is available in cream and gel formulations. There is also a solution of tretinoin and erythromycin available for acne.

• Skin irritation - with redness and peeling
• Photosensitivity when used topically
• Retinoic acid syndrome (may be fatal) - fever, SOB, pulmonary infiltrates, oedema, weight gain and may lead to multi-organ failure
• GIT disturbances ranging from nausea to pancreatitis
• Arrhythmias
• Headaches and benign intracranial hypertension
• Hypercalcaemia
• Risk of both arterial and venous thrombosis¹