Doxycycline

doxycycline (dox i sye' kleen) Adoxa, Apo-Doxy (CAN), Doryx, Doxy 100, Doxy 200, Doxycin (CAN), Doxytec (CAN), Novo-Doxylin (CAN), Nu-Doxycycline (CAN), Periostat, Vibra-Tabs, Vibramycin Pregnancy Category D Drug classes

Antibiotic Tetracycline antibiotic Therapeutic actions

Bacteriostatic: Inhibits protein synthesis of susceptible bacteria, causing cell death. Indications

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Infections caused by rickettsiae; M. pneumoniae; agents of psittacosis, ornithosis, lymphogranuloma venereum and granuloma inguinale; B. recurrentis; H. ducreyi; P. pestis; P. tularensis; B. bacilliformis; Bacteroides; V. comma; V. fetus; Brucella; E. coli; E. aerogenes; Shigella; A. calcoaceticus; H. influenzae; Klebsiella; D. pneumoniae; S. aureus When penicillin is contraindicated, infections caused by N. gonorrhoeae, T. pallidum, T. pertenue, L. monocytogenes, Clostridium, B. anthracis, Chlamydia psittaci, C. trachomatis Oral tetracyclines used for acne, uncomplicated adult urethral, endocervical, or rectal infections caused by C. trachomatis Acute intestinal amebiasis Reduction of incidence and progression of disease following exposure to anthrax Malaria prophylaxis for malaria due to Plasmodium falciparum for short-term use in travelers Treatment of periodontal disease as an adjunct to scaling and root planing Unlabeled use: Prevention of "traveler's diarrhea" commonly caused by enterotoxigenic E. coli

Contraindications and cautions

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Contraindicated with allergy to tetracyclines Use cautiously with renal or hepatic dysfunction, pregnancy, lactation.

Available forms

Tablets—50, 75, 100 mg; capsules—50, 100 mg; coated pellets, capsules—75, 100 mg; powder for oral suspension—25 mg; syrup—50 mg; powder for injection—100, 200 mg Dosages ADULTS General guidelines

200 mg IV in one or two infusions (each over 1–4 hr) on the first treatment day, followed by 100–200 mg/day IV, depending on the severity of the infection, or 200 mg PO on day 1, followed by 100 mg/day PO. • Primary or secondary syphilis: 300 mg/day IV for 10 days; or 100 mg q 12 hr PO on the first day, followed by 100 mg/day as one dose or 50 mg q 12 hr PO. • Acute gonococcal infection: 200 mg PO, then 100 mg at bedtime, followed by 100 mg bid for 3 days; or 300 mg PO followed by 300 mg in 1 hr. • Primary and secondary syphilis: 300 mg/day PO in divided doses for at least 10 days. • Traveler's diarrhea: 100 mg/day PO as prophylaxis. • Malaria prophylaxis: 100 mg PO daily. • Anthrax prophylaxis: 100 mg PO bid for 60 days. • CDC recommendations for STDs: 100 mg bid PO for 7–10 days. • Periodontal disease: 20 mg PO bid, following scaling and root planing. PEDIATRIC PATIENTS

> 8 yr and < 100 lb: 4.4 mg/kg, IV in one or two infusions, followed by 2.2– 4.4 mg/kg/day IV in one or two infusions; or 4.4 mg/kg, PO in two divided doses the first day of treatment, followed by 2.2–4.4 mg/kg/day on subsequent days. > 8 yr and > 100 lb: Use adult dosage. • Malaria prophylaxis: 2 mg/kg/day PO, up to 100 mg/day. • Anthrax prophylaxis: 2.2 mg/kg PO bid for 60 days. GERIATRIC PATIENTS OR PATIENTS WITH RENAL FAILURE

IV doses of doxycycline are not as toxic as other tetracyclines in these patients. Pharmacokinetics Route Oral IV

Onset Varies Rapid

Peak 1.5–4 hr End of infusion

Metabolism: T1/2: 15–25 hr Distribution: Crosses placenta; enters breast milk Excretion: Urine and feces IV facts

Preparation: Prepare solution of 10 mg/mL, reconstitute with 10 mL (100-mg vial): 20 mL (200 mg vial) of sterile water for injection; dilute further with 100–1,000 mL (100-mg vial) or 200–2,000 mL (200-mg vial) of sodium chloride injection, 5% dextrose injection, Ringer's injection, 10% invert sugar in water, lactated Ringer's injection, 5% dextrose in lactated Ringer's, Normosol-M in D5W, Normosol-R in D5W, or Plasma-Lyte 56 or 148 in 5% Dextrose. If mixed in lactated Ringer's or 5% dextrose in lactated Ringer's, infusion must be completed within 6 hr after reconstitution; otherwise, may be stored up to 72 hr if refrigerated and protected from light, but infusion should then be completed within 12 hr; discard solution after that time. Infusion: Infuse slowly over 1–4 hr. Adverse effects

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Dental: Discoloring and inadequate calcification of primary teeth of fetus if used by pregnant women, discoloring and inadequate calcification of permanent teeth if used during period of dental development Dermatologic: Phototoxic reactions, rash, exfoliative dermatitis (more frequent and more severe with this tetracycline than with any others) GI: Fatty liver, liver failure, anorexia, nausea, vomiting, diarrhea, glossitis, dysphagia, enterocolitis, esophageal ulcer Hematologic: Hemolytic anemia, thrombocytopenia, neutropenia, eosinophilia, leukocytosis, leukopenia Local: Local irritation at injection site Other: Superinfections, nephrogenic diabetes insipidus syndrome

Interactions

Drug-drug • Decreased absorption with antacids, iron, alkali • Decreased therapeutic effects with barbiturates, carbamazepine, phenytoins • Increased digoxin toxicity with doxycycline • Increased nephrotoxicity with methoxyflurane • Decreased activity of penicillins Drug-food • Decreased effectiveness of doxycycline if taken with food, dairy products Drug-lab test • Interference with culture studies for several days following therapy Nursing considerations Assessment

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History: Allergy to tetracyclines, renal or hepatic dysfunction, pregnancy, lactation Physical: Skin status, R and sounds, GI function and liver evaluation, urinary output and concentration, urinalysis and BUN, liver and renal function tests; culture infected area before beginning therapy

Interventions

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Administer the oral medication without regard to food or meals; if GI upset occurs, give with meals; patients being treated for periodontal disease should receive tablet at least 1 hr before morning and evening meals. Protect patient from light and sun exposure.

Teaching points

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Take drug throughout the day for best results; if GI upset occurs, take drug with food. If being treated for periodontal disease, take at least 1 hr before morning and evening meals. Avoid pregnancy while using this drug; using barrier contraceptives is advised. These side effects may occur: Sensitivity to sunlight (wear protective clothing, use sunscreen), diarrhea.

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Report rash, itching, difficulty breathing, dark urine or light-colored stools, pain at injection site.

Adverse effects in Italic are most common; those in Bold are life-threatening.