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Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD

GENERIC NAME: doxycycline

BRAND NAME: Vibramycin, Oracea, Adoxa, Atridox and others

DRUG CLASS AND MECHANISM: Doxycycline is a synthetic (man-made) antibiotic derived from tetracycline. Doxycycline works by interrupting the production of proteins by bacteria. It is effective against a wide variety of bacteria, such as Hemophilus influenzae, Streptococcus pneumoniae, Mycoplasma pneumoniae, Chlamydia psittaci, Chlamydia trachomatis, Neisseria gonorrhoea, and many others.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Capsules: 40, 50, 75, and 100 mg. Tablets: 50, 75, 100, and 150 mg. Suspension: 25 mg/teaspoon. Syrup: 50 mg/teaspoon. Powder for injection: 42.5, 100, and 200 mg.

STORAGE: Tablets, capsules, syrup and suspension should be kept at room temperature 15-30°C (59-86°F) in tight, light resistant containers.

Powder for injection should be stored at or below 25°C (77°F) and protected from light.

Atridox should be stored at 2° to 8°C (36° to 46°F).

PRESCRIBED FOR: Doxycycline is used for many different types of infections, including respiratory tract infections due to Hemophilus influenzae, Streptococcus pneumoniae, or Mycoplasma pneumoniae. It also is used for the treatment of nongonococcal urethritis (due to Ureaplasma), Rocky mountain spotted fever, typhus, chancroid, cholera, brucellosis, anthrax, syphilis, and acne.

DOSING: The absorption of doxycycline is not markedly affected by food, and therefore, it can be taken with meals. For most infections, doxycycline is taken once or twice daily for 7 to 14 days. For adult infections, the usual dose of oral doxycycline is 200 mg on the first day of treatment (100 mg every 12 hours) followed by a dose of 100 mg/day as a single dose or 50 mg twice daily.

DRUG INTERACTIONS: It is recommended that doxycycline not be taken at the same time as aluminum, magnesium, or calcium based antacids, such as Mylanta, Maalox, Tums, or Rolaids because, like food, these medications bind doxycycline in the intestine and prevent its absorption. Similarly, doxycycline should not be taken with minerals (such as calcium or iron) or with bismuth subsalicylate (Pepto Bismol).

Doxycycline may enhance the activity of warfarin (Coumadin) and cause excessive "thinning" of the blood leading to exaggerated bleeding, necessitating a reduction in the dose of warfarin. Phenytoin (Dilantin), carbamazepine (Tegretol), and barbiturates (such as phenobarbital) may enhance the metabolism (destruction) of doxycycline thus making it less effective.

PREGNANCY: Tetracycline antibiotics, such as doxycycline, can have toxic effects on development of bone in the fetus. Therefore, tetracyclines are not recommended during pregnancy unless there is no other appropriate antibiotic.

NURSING MOTHERS: Doxycycline is secreted into breast milk but the extent of absorption by the breastfed infant is not known. Since tetracyclines can cause toxic effects on bone, the use of tetracyclines in nursing mothers is of concern. The physician must decide whether to recommend that a nursing mother discontinue nursing during treatment with tetracyclines or change to a different antibiotic.

SIDE EFFECTS: Doxycycline is generally well-tolerated. The most common side effects are diarrhea or loose stools, nausea, abdominal pain, and vomiting. Tetracyclines, such as doxycycline, may cause tooth discoloration if used in persons below 8 years of age. Exaggerated sunburn can occur with tetracyclines; therefore, sunlight should be minimized during treatment.

Reference: FDA Prescribing Information