A group of drugs used for skin conditions such as acne, psoriasis, and sun damage
Retinoid drugs are used to treat a number of skin conditions, including acne, psoriasis, and sun damage. These drugs are related chemically to vitamin A, which is needed to maintain healthy skin. Tretinoin and isotretinoin are used mainly in the treatment of severe acne. In addition, tretinoin may be used to treat mottling, fine wrinkles, and roughness in sun-damaged skin. However, the effects are only temporary, and the drug is not effective on deep wrinkles. Acitretin is used mainly to treat some types of severe psoriasis, a condition in which the skin becomes red, thickened, and scaly.
How do they work?
Retinoid drugs act on cells in the outer layers of the skin. The precise way in which tretinoin and isotretinoin work is unknown, but both drugs increase the rate at which the outer layers of skin are shed. This action helps to prevent acne by unblocking hair follicles clogged by sebum (oil) that might develop into blackheads or whiteheads. Isotretinoin also reduces the production of sebum by sebaceous glands in the skin.
Acitretin reduces the rate of production of keratin, a protein found in the outer layer of the skin. Keratin is produced in excessive amounts in the skin of people with psoriasis. Acitretin also has anti-inflammatory properties and may help to relieve the inflammation of the joints that is sometimes experienced by people who have severe psoriasis.
How are they used?
Topical tretinoin preparations should be applied as a liquid, gel, or cream once or twice daily in a thin layer over the affected area. Skin affected by acne will probably improve after 2–3 weeks, although the maximum effect may not be apparent for 8–12 weeks. Skin that has been damaged by exposure to strong sunlight is treated with a cream preparation. You will probably notice an improvement in your skin’s condition after 2–4 weeks, but treatment may last up to 6 months.
Isotretinoin is available in capsule form and is prescribed by a specialist only when acne is very severe. It should be taken daily with food. After 4 weeks, your doctor may adjust the dose, depending on how your skin has responded to the treatment. A 12–16 week course of the drug often clears up acne entirely. A repeat course is not usually recommended.
Acitretin, which is used to treat psoriasis, is only taken orally. If your doctor prescribes acitretin, it will have to be taken daily, and you will usually see an improvement in your skin after about 2–4 weeks. The full benefit is usually seen after 4–6 weeks. Your doctor will prescribe acitretin for no longer than 6 months, but treatment may resume after a 3–4 month break.
What are the side effects?
Using topical preparations that contain tretinoin may cause your skin to peel and become red and inflamed.
If you are taking isotretinoin or acitretin, your skin may become dry, flaky, and itchy, and you may experience sore lips and eyes, nosebleeds, and hair loss. Acitretin and isotretinoin can also affect the liver, and your blood will be tested regularly during treatment to monitor liver function. Women who are taking these drugs may find that their periods become irregular.
All retinoid drugs can cause severe birth defects, and this effect persists for some time after stopping treatment. For this reason, any woman who is pregnant (or thinks she might be) or who is planning a pregnancy should tell her doctor, who will be able to advise about suitable contraception. Long-term treatment with retinoid drugs may lead to pain in the joints and bones. In very rare cases, the treatment may also result in thinning or thickening of the bones in the spine, knees, and ankles.
Retinoid drugs can damage a developing fetus. You should discuss your contraception needs with your doctor before starting treatment.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.