Tretinoin

Tretinoin, also known as all-trans-retinoic acid, is a naturally occurring derivative of vitamin A (retinol). Retinoids such as tretinoin are important regulators of cell reproduction, proliferation and differentiation and are used to treat acne and photodamaged skin as well as cornification disorders such as ichthyosis and keratosis follicularis. Tretinoin is also used in the treatment of acute promyelocytic leukemia. It is used as a topical formulation to treat acne and as an oral formulation to treat leukemia.

Pharmacodynamics

For use in the treatment of acute promyelocytic leukemia, the exact mechanism of action is unknown. However, laboratory tests have shown that tretinoin forces the degenerate cells to differentiate and prevents them from proliferating.

In the treatment acne, it leads to normalization of proliferation and multiplication of keratinocytes in the skin, resulting in a decrease in the formation of blackheads and pustules.

Pharmacokinetics

Tretinoin is 1-31% absorbed when applied to the skin. Plasma protein binding is approximately 95%. Metabolism occurs in the liver. The average half-life is 0.5-2 hours.

Side effects

Common side effects when used on the skin are limited to the site of application and include skin redness, peeling, and sensitivity to sunlight.

When used by mouth, the most common side effects are shortness of breath, headache, numbness, depression, skin dryness, itching, hair loss, vomiting, muscle pain, and vision problems.

Other serious side effects include increased white blood cell count and blood clots. Use during pregnancy is contraindicated because of the risk of birth defects.

Toxicological data

LD50 (rat, oral): 2000 mg-kg-1