10. Why is minocycline (U.S. brand name Minocin) the most commonly used antibiotic in AP? Are there others?

Minocycline is a second-generation tetracycline, originally synthesized by Lederle Laboratories in 1967, approved by the FDA in 1971, became available for use and has been sold under the brand name, Minocin, in a pelleted capsule, since 1972. Minocin was last distributed through Onset Dermatologics, but its parent company, PreCision Dermatology Inc., was purchased by Valeant Pharmaceutical International, Inc.  in February 2014. Brand-name Minocin is costly, but a number of effective generic minocycline versions are available today. Although Dr. Brown used both tetracycline and doxycycline, minocycline later became the favored choice as a bacteriostatic antibiotic due to its greater lipid solubility (ability to cross cell walls) and hence superior absorption. Simply put, in many cases, it seems to work faster. Unlike bacteriocidal antibiotics, which target cell-walled pathogens, bacteriostatic antibiotics are intended for use against intracellular pathogens (those that parasitize host cells) and cell-wall-deficient bacteria (such as mycoplasma, that do not have a cell wall but rather just an outer lipid layer).

Minocycline’s spectrum of activity is broader than that of other tetracyclines within the same class; it has a longer half-life and is classified as long-acting. Serum levels may reach two to four times those of more water-soluble tetracyclines and so less is needed to achieve the same result. Absorption of minocycline is also less likely to be affected by food.

Tetracycline and doxycycline have also proven to be effective for the treatment of rheumatic disease. Doxycycline achieves much higher tissue concentrations than tetracycline, while minocycline penetrates tissue far more effectively than doxycycline. Tetracycline is the least expensive and oldest member of this family of antibiotics. It is more apt to react with foods and should be taken on an empty stomach with a full glass of water, three hours before or after consumption of food (especially foods high in mineral content, such as dairy products). Supplements and medications containing minerals, such as magnesium, calcium, zinc and iron, should also be avoided within this time frame. Doxycycline (the second drug to be developed in this family) is sold in the United States under the brand names Doryx and Vibramycin (brand names vary internationally) and is often given to patients who do not tolerate minocycline well and sometimes to those with lupus.

Dr. Brown found that when the tetracyclines cannot be used due to drug allergy, other classes of antibiotics could also be effective, including those with similar bacteriostatic properties, such as azithromycin or clarithromycin. Clindamycin may also be used and is most often administered intravenously as an adjunct to tetracycline therapy. When a patient has a high ASO (Antistreptolysin O titer) or has a strong history of streptococcal infection, even when the ASO test result is within range, penicillins such as amoxicillin or ampicillin may also be needed. While tetracycline therapy was most commonly used as the core therapy of AP, Dr. Brown used a variety of different classes of antibiotics, depending upon a patient’s pathogen load and individual needs.

To Learn More:

  • Drugs.com, search tool (enter the name of the antibiotic in the search window on the home page)
  • Drugs.com, Drug Interaction Checker (lets you check for interactions with other drugs you are taking)
  • Wikipedia, Minocycline (provides further information on the properties, spectrum of activity, side effects, and potential drug and supplement interactions of minocycline)

Note: For more detailed information on alternative antibiotics that Dr. Brown used when patients experienced allergy or some other type of sensitivity to the tetracyclines, refer to The New Arthritis Breakthrough, by Henry Scammell (pages 250 to 251).