Doxycycline Hyclate
Common Brand Names: Vibramycin
Therapeutic Class: A semisynthetic tetracycline antibiotic
Common Injectable Dosage Forms:
Powder for Injection: 100 mg vials
Dosage Ranges:
The usual adult and children 8 years of age weighing more than 45 kg IV dosage is 200 mg the first day given 1-2 doses followed by 50-100 mg every 12 hours.
The usual dose for children 8 years of age weighing less than 45 kg is 4.4 mg/kg the first day and 2.2-4.4 mg/kg daily thereafter.
Administration and Stability: 100 mg vials should be diluted with 10 mL of sterile water. Each 100 mg of drug should be further diluted for administration with a compatible solution (D5W, NS) to 100-1000 mL providing a concentration of 0.1-1 mg/mL. Depending on the dose, infusions are given over 1-4 hours, with a 100 mg dose (0.5 mg/mL) recommended to be given over at least 1 hour. Stable at 0.1-1 mg/mL for 48 hours at room temperature and 72 hours when refrigerated and protected from light. pH 1.8-3.3
Pharmacology/Pharmacokinetics: Tetracyclines are usually bacteriostatic in nature but may act bactericidal in high concentrations or against highly susceptible organisms. They exert their action by reversibly binding to the 30S and 50S ribosomal subunits. Susceptible organisms generally include Rickettsia, Chlamydia, Mycoplasma, spirochetes, and many uncommon gram-negative and gram-positive bacteria. They are widely distributed to various body fluids and tissues, including pleural, ascites, and synovial fluids plus the CNS, bone, and teeth. Doxycycline is hepatically metabolized and excreted via the urine, with an elimination half-life of 12-15 hours.
Drug and Lab Interactions: May potentiate the effects of oral anticoagulants by impairing utilization of prothrombin or by decreasing vitamin K production by intestinal bacteria. May antagonize the bactericidal actions of aminoglycosides and penicillins when used concomitantly. Decreased serum levels of doxycycline are seen with concomitant use of barbiturates, phenytoin, and carbamazepine. Causes false-positive results in urine glucose determinations using cupric sulfate reagent (Benedict’s reagent, Clinitest), and false-negative results using glucose oxidase reagent (Clinistix, Tes-Tape). Also generally interferes with fluorimetry of urinary catecholamines resulting in falsely increased values.
Contraindications/Precautions: Use with caution in patients with renal and/or hepatic dysfunction and monitor serum levels carefully with prolonged use. Prolonged exposure to sunlight or ultraviolet light may lead to photosensitivity reactions. Increased muscle weakness in patients with myasthenia gravis is sometimes associated with parenteral tetracycline therapy. The possibility of bacterial overgrowth and superinfections should always be considered with broad-spectrum antibiotic therapy. Pregnancy Category D.
Monitoring Parameters: Liver function tests
Adverse Effects: Adverse effects noted with doxycycline therapy include tooth discoloration (especially in pediatric patients), photosensitivity, nausea, and thrombophlebitis. Tetracyclines have also caused nephrotoxicity and hepatotoxicity.
Common Clinical Applications: Effective in the treatment of certain pneumonias, GI infections, non-gonococcal urethritis, and Lyme disease.
