It is unfortunate that the use of antibiotics in acne developed by serendipity. Twenty years ago it was thought that acne was possibly infectious and, by chance, tetracycline was discovered to be effective. It was subsequently believed that acne was not in fact infectious and in the early 1960s it was thought that, since small doses were useful and sometimes worked well, tetracycline's mechanism of action was probably nonbacterial.

Thus, for some years either 250 mg or 500 mg tetracycline was the dosage of choice. (Fifteen years ago this author's department contributed to this myth of the use of low-dose antibiotics in acne.) This idea should now be totally forgotten..

Dose-response studies were nonexistent until a few years ago and it is only in the last four years that a new and sensible approach has allowed the logical use of oral antibiotics in acne. Tetracycline, however, still remains and should remain the first choice.

Minocycline is an expensive, and doxycycline a less expensive, alternative. Erythromycin is also used and certainly would be the drug of choice in a patient sensitive to tetracycline, in a female who is contemplating pregnancy or in the treatment of a pregnant patient who required oral therapy. Co-trimoxazole is occasionally used, especially in patients with Gram-negative folliculitis.

Trimethoprim is a preferred alternative since it has fewer side-effects than co-trimoxazole..

Trimethoprim should also be considered in patients nonresponsive to tetracycline and erythromycin or in those who are intolerant of such preparations. Clindamycin is an excellent drug but is contraindicated because of the risk of pseudomembraneous colitis. Tetracycline Tetracycline is the first choice in oral therapy and, like erythromycin, must be given Vi-\ hour before food with a sip of water.

If the patient is on iron or antacids those therapies must be taken after food. The practitioner should initially use the cheaper forms of tetracycline, such as tetracyline or oxytetracycline. We have shown, as will be indicated later (see page 282) that the recommended dose is 1 g/day.42 There is no justification in giving smaller doses.

Erythromycin Erythromycin has been shown to be as effective as tetracycline (Table 16.3).42 It is less affected by food so Doxycycline A further alternative in the tetracycline group is doxycycline..

Studies have shown it to be equal in effect to minocycline.47 in those individuals where the taking of tablets Vi—\ hour before food is impossible, as is occasionally the case, then erythromycin would be the drug of choice.43 It is, however, somewhat more expensive than ordinary tetracycline, though less expensive than minocycline.

Minocycline Minocycline, a variant of tetracycline, is very well absorbed compared with ordinary tetracycline and can be taken with food.44 Recent work has indicated that an even greater effect is obtained if it is taken half an hour before food with water.45 Minocycline has a more rapid effect in the resolution of certain acne lesions and a greater effect on the skin surface P. acnes than tetracycline..

However, in controlled studies at 100 or 200mg/day in the average acne patient, it is no better than 1 g tetracycline.

Thus minocycline should not be the first choice for the average acne patients though it should be considered in a patient not responding to conventional therapy. It is expensive. Co-trimoxazole Co-trimoxazole is indicated in those patients intolerant of tetracycline or erythromycin or in patients who have shown no response with other therapies.48 It is also a useful drug in Gram-negative folliculitis..

They are much more common in the elderly than in younger, healthy acne patients. Trimethoprim Studies have shown trimethoprim to be as effective as tetracycline in the average acne patient.49 Limited personal observations - totally uncontrolled - indicate it to be as effective as co-trimoxazole in Gram-negative folliculitis.

The recommended dose of trimethoprim is 300 mg twice daily..

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