Doxycycline 100 mg (Vibramycin)

• Generic name: Doxycycline Calcium, Hyclate, Monohydrate
• Trade names: Doryx, Doxy, Vibramycin (Pfizer), Vibra-Tabs, Periostat
• Dosages: 100 mg capsules
• Pharmacologic category: Tetracycline antibiotic
• FDA approved: 1967
• 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
• Gingivitis (Periostat)
• Acne
• Sexually transmitted diseases (STDs) such as gonorrhea and chlamydia
• Prophylactic treatment of anthrax due to Bacillus anthracis
• Plague (due to Yersinia pestis), including naturally occurring or endemic bubonic, septicemic, or pneumonic plague
• Malaria (due to Plasmodium falciparum)
• Tickborne Rickettsial diseases
• Lyme disease, bartonellosis
• Trachoma (chronic infections of the eye)
• Anti-infective prophylaxis in sexual assault victims

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
• expired 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 [1]
• Sarcoidosis [9]

Doxycycline blocks 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. 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
• 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.
• 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.
• 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.
• 5. Zele-Starcevic' L, Plecko Vanda, 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.
• 6. Borg R, Dotevall L, Hagberg L, Maraspin Vera, 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 for Lyme disease associated with erythema migrans. J Am Acad Dermatol. 1995 Feb;32(2 Pt 1):223-7.
• 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.
• 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.
• 10. Mosam A, Morar N. Recalcitrant cutaneous sarcoidosis: an evidence-based sequential approach. J Dermatolog Treat. 2004 Dec;15(6):353-9.
• 11. Ragnar Norrby S. Atypical pneumonia in the Nordic countries: aetiology and clinical results of a trial comparing fleroxacin and doxycycline. J Antimicrob Chemother. 1997 Apr;39(4):499-508. PubMed