Tetracyclines And Acne

Tetracyclines are the drugs of choice for the treatment of acne and are usually given in divided doses of 1 gram or less a day. They work in three ways:

1. They suppress the growth of the acne bacteria, P. acnes.
2. They inhibit the action of P. acnes enzymes which break down sebum to fatty acids and cause inflammation.
3. They suppress the migration of white cells (pus cells) to the areas of inflammation.

They are particularly effective in acne because they are accumulate in the sebaceous gland and secreted with the sebum.

Tetracyclines are relatively safe drugs. They cause nausea and diarrhoea in some cases and, rarely, skin allergies. These side effects are relatively uncommon when you think of the large amounts of tetracyclines that are prescribed everyday. Tetracyclines are deposited in developing bones and teeth and may affect bone and teeth development, causing a yellowish discolouration of teeth. They should not therefore be used in women who are pregnant or who are contemplating pregnancy, and in children under the age of eight years. Tetracyclines may also cause photosensitivity, a sensitivity to sunlight causing an increased tendency to sunburn. Except for doxycycline and minocycline, all other tetracyclines should not be used in individuals with abnormal kidney functions.

A main disadvantage of tetracyclines is that their absorption is impaired by food, diary products, calcium, magnesium, iron and antacids (medicines which are prescribed to reduce the acidity of stomach secretions). Tetracyclines have therefore, to be taken one hour before food or two hours after the last meal and this may be difficult to fit into your diet routine.

The newer tetracyclines such as minocycline and doxycycline are not appreciably affected by food and milk, but are still affected by iron, magnesium and antacids. Remember, some multivitamins often contain mineral such as iron and magnesium and should not be taken with all tetracyclines. Minocycline and doxycycline are convenient especially for teenagers who seem to be eating all the time. Minocycline is accumulated in large amounts in the sebaceous gland and is secreted in sebum. It is highly effective in acne and is also effective in patients who were previously resistant to other tetracyclines. Doxycycline has not been extensively evaluated in the treatment of acne. Gastric and intestinal disturbances occur with both drugs but is less frequent than with other tetracyclines because they are more completely absorbed. Minocycline may cause dizziness, and a slateblue pigmentation of the skin. It does not apparently cause photosensitivity.


NO MORE PIMPLES, A SELF-CARE GUIDE, DR. LIM KAH-BENG