How oral antibiotics can be used to treat acne

Severe acne has the potential to scar and permanently disfigure young adults with resultant psychological and social damage especially when the face is involved. Such lesions therefore should be promptly treated. Oral antibiotic treatment is one of the best systemic therapies available. Tetracycline, and its second generation derivatives minocycline and doxycycline, are among the most common oral antibiotics used in systemic treatment.

Indications

• Acne is of a moderate to severe type.
• Acne is not cured by topical treatment.
• Acne covers a large part of the body, particularly the chest back and shoulders.

Mechanism of action

Antibiotics suppress Propionibacterium acnes growth and also have anti-inflammatory properties. They thus reduce the number of comedones. The effectiveness of these drugs depends on their ability to penetrate the micro environment of the pilosebaceous follicles where the propionibacterium resides. The more penetration the better is the efficacy of the oral antibiotic. Clinical experience and data available to date show that minocycline and doxycycline are more effective than tetracycline.

Course

Oral antibiotics are a long term therapy in acne, the normal duration of treatment being 4 to 6 months. For women with acne, a combined therapy of oral antibiotics and hormonal treatment, where oral contraceptives are used, is recommended. The common view that oral antibiotics reduce the efficacy of the oral contraceptives is largely unfounded, since the failure rates of the contraceptives with or without antibiotics is almost the same according to published research studies.

Tetracycline

Tetracycline is often effective in previously untreated cases of severe acne. Studies have shown 50% to 60% rate of improvement in inflammatory acne. Treatment failures occur because of poor compliance, inadequate treatment duration, folliculitis development, bacterial resistance or high sebum secretion. It is one of the least expensive antibiotic drugs which make it a popular choice. The main disadvantage of tetracycline is that it needs to be taken on an empty stomach since its absorption, and therefore its effectiveness, is reduced by any intake of food.

Side effects of tetracycline are nausea, vomitting, vaginal candidiasis and photosensitivity (i.e. sensitivity to sunlight). These drugs can also cause permanent bone and teeth pigmentation in children and adolescents and are teratogenic in pregnancy. They are not therefore recommended for pregnant women and children below 12 years of age. A general complaint is frequent abdominal problems.

Minocycline

Minocycline tends to be the most popular antibiotic since it has the highest penetration of all antibiotics and therefore its effect is quicker. Unlike tetracycline, minocycline can be taken with meals as food affects its absorption less. Nausea, vomiting and diarrhea are also much less compared to those caused by tetracycline because minocycline is absorbed better when given orally.

Unfortunately it is one of the most expensive drugs and has significant side effects. These include headaches, vertigo, and hyperpigmentation of the skin. It can also cause some allergic reactions, and very rarely autoimmune disorders like autoimmune hepatitis, hypersensitivity reactions like hepatitis and pneumonitis and also death due to hepatoxicity and myocardial necrosis! Hence patients on minocycline should be checked every 3 to 4 months for liver function and antinuclear factor in their blood.

It is for these reasons that Minocycline is not considered first line therapy by many.

Doxicycline

Doxicycline can be taken with meals as this drug also penetrates the pilosebaceous follicles as well as minocycline. Like minocycline, Doxicycline causes less gastrointestinal problems than tetracycline, but is more likely to cause dose dependent photosensitivity reactions.

The use of doxicycline in lower doses in inflammatory acne has been found to be not only effective, but also safe since side effects are fewer and risk of developing bacterial resistance is lower compared to tetracycline and minocycline.

Bacterial resistance

A disturbing development in recent years in antibiotic treatment of acne has been a marked increase in bacterial resistance to these drugs. Ccompared to other antibiotics, such as erythromycin, resistance is less common with tetracycline and doxicycline and rare with minocycline. Strategies for reducing resistance with oral antibiotics include minimizing use of antibiotics, discontinuing oral antibiotics when acne control is achieved, and prescribing the same oral antibiotic for re-treatment.