Doxycycline 100 mg (Vibramycin)

• Generic name: Doxycycline Calcium, Hyclate, Monohydrate
• Brand/Trade names: Doryx, Doxy, Vibramycin (Pfizer), Vibra-Tabs, Periostat
• Dosages: 100 mg capsules
• Pharmacologic category: Tetracycline antibiotic
• FDA approved: 1967
• Habit forming? No
• Pregnancy risk factor: D

Doxycycline is a broad-spectrum tetracycline antibiotic that is commonly prescribed to treat infections. Doxycycline is derived from and related to oxytetracycline. It differs from other tetracyclines in that it is more completely absorbed and more lipid-soluble; it also has a longer plasma half-life.

Doxycycline indicated uses include:

• urinary tract infections
• respiratory tract infections
• gum disease
• acne
• sexually transmitted diseases (STDs) such as gonorrhea and chlamydia
• as a prophylactic treatment for infection by Bacillus anthracis (anthrax)
• effective against Yersinia pestis, the infectious agent of bubonic plague, and malaria
• Lyme disease
• trachoma (chronic infections of the eye)

• The usual dose of doxycycline is 200 mg on the first day of treatment (100 mg every 12 hours) followed by a maintenance dose of 100 mg per day. The maintenance dose may be taken as a single dose or as 50 mg every 12 hours. Your doctor may prescribe 100 mg every 12 hours for severe infections such as chronic urinary tract infection.
• For Uncomplicated Gonorrhea: The usual dose is 100 mg by mouth, twice a day for 7 days. An alternate, single-day treatment is 300 mg, followed in 1 hour by a second 300-mg dose.
• For Prevention of Malaria: The usual dose is 100 mg a day. Treatment should begin 1 to 2 days before travel to the area where malaria is found, then continue daily during travel in the area and 4 weeks after leaving.
• For Inhalational Anthrax: To prevent or combat infection after exposure, the usual dose is 100 mg taken by mouth twice a day for 60 days.

The usual dose of oral doxycycline for treating acne is 50 mg or 100 mg, twice daily. This tetracycline class antibiotic presumably works by decreasing the population of the skin bacterium, Propionibacterium acnes.

The research suggests other potential actions of doxycycline, including down-regulation of inflammatory mediators and inhibition of P. acnes-derived lipase, with a resultant reduction in follicular free fatty acid levels. These medicinal effects can occur at doses of doxycycline that are too low to kill bacteria.

• Metabolism: not hepatic; partially inactivated in GI tract by chelate formation.
• Elimination half-life: 12-15 hours (usually increases to 22-24 hours with multiple doses);
• Excretion: Feces (30%); urine (23%)

• one of the most potent antibiotics
• anti-inflammatory effects [2, 4]
• blood and tissue levels are equivalent whether the drug is administered orally or intravenously [3]
• first line drug for the treatment of chlamydial infections [5]
• strong antimalarial properties
• active against the most common bacterial cause of community-acquired pneumonia: Streptococcus pneumoniae, Mycoplasma pneumoniae, and Chlamydia pneumoniae [11]
• although tetracyclines are usually avoided in the young child, up to 2 weeks of doxycycline therapy can be given safely without risking dental staining

• contraindicated during pregnancy (pregnancy category D)
• risk of photosensitivity reaction
• expaired doxycycline is dangerous and may cause kidney damage
• risk of esophageal ulceration (if the capsules for some reason do not reach the stomach but remain in the oesophagus)
• prolonged IV use may result in thrombophlebitis

• Enterococcus infections resistant to vancomycin
• Lyme disease [6, 7]
• Human ehrlichiosis [8]
• Rosacea [12]
• Sarcoidosis [9]

Doxycycline block protein synthesis by preventing the binding of aminoacyl-tRNA to the ribosome. Its action is bacteriostatic (preventing the growth of bacteria) rather than killing (bactericidal).

Doxycycline inhibits the nitric oxide synthesis. This activity is a possible pathway by which tetracyclines may function as anti-inflammatory compounds.

• 1. U.S. Food and Drug Administration. Doxycycline (Vibramycin) U.S. Prescribing Information. Available at (PDF format): Prescribing Information
• 2. Borderie D, Hernvann A, Hilliquin P, Lemarchal H, Kahan A, Ekindjian OG. Tetracyclines inhibit nitrosothiol production by cytokine-stimulated osteoarthritic synovial cells. Inflamm Res. 2001 Aug;50(8):409-14. PubMed
• 3. Bocker R, Estler CJ, Maywald M, Weber D. Comparison of distribution of doxycycline in mice after oral and intravenous application measured by a high-performance liquid chromatographic method. Arzneimittelforschung. 1981;31(12):2116-7. PubMed
• 4. Krakauer T, Buckley M. Doxycycline is anti-inflammatory and inhibits staphylococcal exotoxin-induced cytokines and chemokines. Antimicrob Agents Chemother. 2003 Nov;47(11):3630-3. PubMed
• 5. Zele-Starcevic' L, Plecko V, Budimir A, Kalenic' S. Choice of antimicrobial drug for infections caused by Chlamydia trachomatis and Chlamydophila pneumoniae. Acta Med Croatica. 2004;58(4):329-33. PubMed
• 6. Borg R, Dotevall L, Hagberg L, Maraspin V, Lotric-Furlan S, Cimperman J, Strle F. Intravenous ceftriaxone compared with oral doxycycline for the treatment of Lyme neuroborreliosis. Scand J Infect Dis. 2005;37(6-7):449-54. PubMed
• 7. Nowakowski J, Nadelman RB, Forseter G, McKenna D, Wormser GP. Doxycycline versus tetracycline therapy for Lyme disease associated with erythema migrans. J Am Acad Dermatol. 1995 Feb;32(2 Pt 1):223-7. PubMed
• 8. Aguero-Rosenfeld ME, Horowitz HW, Wormser GP, McKenna DF, Nowakowski J, Mun~oz J, Dumler JS. Human granulocytic ehrlichiosis: a case series from a medical center in New York State. Ann Intern Med. 1996 Dec 1;125(11):904-8. PubMed
• 9. El Sayed F, Dhaybi R, Ammoury A. Subcutaneous nodular sarcoidosis and systemic involvement successfully treated with doxycycline. J Med Liban. 2006 Jan-Mar;54(1):42-4. PubMed
• 10. Mosam A, Morar N. Recalcitrant cutaneous sarcoidosis: an evidence-based sequential approach. J Dermatolog Treat. 2004 Dec;15(6):353-9. PubMed
• 11. Ragnar Norrby S. Atypical pneumonia in the Nordic countries: aetiology and clinical results of a trial comparing fleroxacin and doxycycline. Nordic Atypical Pneumonia Study Group. J Antimicrob Chemother. 1997 Apr;39(4):499-508. PubMed
• 12. Quarterman MJ, Johnson DW, Abele DC, Lesher JL Jr, Hull DS, Davis LS. Ocular rosacea. Signs, symptoms, and tear studies before and after treatment with doxycycline. Arch Dermatol. 1997 Jan;133(1):49-54. PubMed