Medicine for acne: Oral antibiotics: Minocycline

Minocycline.
Minocycline (50-mg and 100-mg capsules and scored tablets) is a tetracycline derivative that has proved valuable in cases of pustular acne that have not responded to conventional oral antibiotic therapy. Minocycline is very expensive; generic forms are now available. One study comparing minocycline (50 mg three times a day) with tetracycline (250 mg four times a day) revealed that minocycline resulted in significant improvement in patients who did not respond to tetracycline. Patients who responded to tetracycline had significantly advanced improvement when switched to minocycline. The inhibitory effect on gastrointestinal absorption with food and milk is significantly greater for tetracycline than for minocycline. Food causes a 13% inhibition of absorption with minocycline and a 46% inhibition with tetracycline, milk a 27% inhibition with minocycline and a 65% inhibition with tetracycline. The simpler regime and early onset of clinical improvement are likely to result in better patient compliance. There is therefore justification for the use of minocycline as first-line oral therapy.
DOSING.
The usual initial dosage is 50 to 100 mg twice each day. The dosage is tapered when a significant decrease in the number of lesions is observed, usually in 3 to 6 weeks.
ADVERSE EFFECTS.
Minocycline is highly lipid-soluble and readily penetrates the cerebrospinal fluid, causing dose-related ataxia, vertigo, nausea, and vomiting in some patients. In susceptible individuals, central nervous system (CNS) side effects occur with the first few doses of medication. If CNS adverse reactions persist after the dosage is decreased or after the capsules are taken with food, alternative therapy is indicated. A blue-gray pigmentation of the skin, oral mucosa, nails, and thyroid gland has been found in some patients, usually those taking high dosages of minocycline for extended periods. Skin pigmentation has been reported in depressed acne scars, at sites of cutaneous inflammation, as macules resembling bruises on the lower legs, and as a generalized discoloration suggesting an off-color suntan. Pigmentation may persist for long periods after minocycline has been discontinued. The consequences of these deposits are unknown. Tooth staining (lasting for years) located on the incisal one half to three fourths of the crown has been reported in adults, usually after years of minocycline therapy. In contrast, tooth staining produced by tetracycline occurs on the gingival third of the teeth in children treated before age 7.