Overview
To reduce the development of drug-resistant bacteria and maintain the effectiveness of doxycycline and other antibacterial drugs, doxycycline should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. DESCRIPTION Doxycycline is an antibacterial drug synthetically derived from oxytetracycline, and is available as capsules of doxycycline...
Mechanism of Action
CLINICAL PHARMACOLOGY Tetracyclines are readily absorbed and are bound to plasma proteins in varying degree. They are concentrated by the liver in the bile, and excreted in the urine and feces at high concentrations and in a biologically active form. Doxycycline is virtually completely absorbed after oral administration. Following a 200 mg dose, normal adult volunteers averaged peak serum levels of 2.6 mcg/mL of doxycycline at 2 hours, decreasing to 1.45 mcg/mL at 24 hours. Excretion of doxycycline by the kidney is about 40%/72 hours in individuals with normal function (creatinine clearance about 75 mL/min.). This percentage excretion may fall as low as 1- 5%/72 hours in individuals with severe renal insufficiency (creatinine clearance below 10 mL/min.).
Indications
- INDICATIONS AND USAGE To reduce the development of drug-resistant bacteria and maintain effectiveness of doxycycline and other antibacterial drugs, doxycycline should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.
Common Doses
- 200 mg
- 100 mg
- 2.2 mg
- 4.4 mg
Dosage
DOSAGE AND ADMINISTRATION The usual dosage and frequency of administration of doxycycline differs from that of the other tetracyclines. Exceeding the recommended dosage may result in an increased incidence of side effects. Adults: The usual dose of oral doxycycline is 200 mg on the first day of treatment (administered 100 mg every 12 hours) followed by a maintenance dose of 100 mg/day. In the management of more severe infections (particularly chronic infections of the urinary tract), 100 mg every 12 hours is recommended.
Contraindications
- CONTRAINDICATIONS This drug is contraindicated in persons who have shown hypersensitivity to any of the tetracyclines.
Side Effects
- ADVERSE REACTIONS Due to oral doxycycline's virtually complete absorption, side effects of the lower bowel, particularly diarrhea, have been infrequent. The following adverse reactions have been observed in patients receiving tetracyclines: Gastrointestinal: anorexia, nausea, vomiting, diarrhea, glossitis, dysphagia, enterocolitis, inflammatory lesions (with monilial overgrowth) in the anogenital region, and pancreatitis. Hepatotoxicity has been reported rarely. These reactions have been caused by both the oral and parenteral administration of tetracyclines.
Interactions
- Drug Interactions Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage. Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines in conjunction with penicillin. Absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, and iron-containing preparations. Absorption of tetracyclines is impaired by bismuth subsalicylate.