Monodox

Action

Unclear. Thought to inhibit bacterial protein synthesis at 30S and 50S ribosomal subunit and to alter cytoplasmic membrane of susceptible organisms.

Availability

Capsules: 50 mg, 100 mg, 150 mg

Capsules (coated pellets): 40 mg, 75 mg, 100 mg

Powder for injection: 100 mg, 200 mg

Powder for oral suspension: 25 mg/5 ml

Syrup: 50 mg

Tablets: 20 mg, 50 mg, 75 mg, 100 mg

Indications and dosages

➣ Rosacea

Adults: 40 mg P.O. daily in the morning

➣ Infections caused by various organisms, including Mycoplasma, Chlamydia, and Rickettsia organisms, and Borrelia burgdorfer

Adults and children weighing more than 45 kg (99 lb): 100 mg P.O. q 12 hours on first day, followed by 100 to 200 mg P.O. once daily; or 50 to 100 mg P.O. q 12 hours; or 200 mg I.V. once daily; or 100 mg I.V. q 12 hours on first day, followed by 100 to 200 mg I.V. once daily; or 50 to 100 mg I.V. q 12 hours

Children weighing 45 kg (99 lb) or less: 2.2 mg/kg P.O. q 12 hours on first day, followed by 2.2 to 4.4 mg/kg/day P.O. once daily; or 1.1 to 2.2 mg/kg P.O. q 12 hours; or 4.4 mg/kg I.V. once daily; or 2.2 mg/kg I.V. q 12 hours on first day, followed by 2.2 to 4.4 mg/kg I.V. once daily; or 1.1 to 2.2 mg/kg I.V. q 12 hours

➣ Gonorrhea in penicillin-allergic patients

Adults and children weighing more than 45 kg (99 lb): 100 mg P.O. q 12 hours for 7 days; or 300 mg P.O. initially, followed by another 300 mg P.O. 1 hour later

➣ Lyme disease

Adults and children weighing more than 45 kg (99 lb): 100 mg P.O. b.i.d. for 10 to 30 days

➣ Periodontitis

Adults and children weighing more than 45 kg (99 lb): 20 mg P.O. b.i.d. for up to 9 months

➣ Anthrax

Adults and children weighing more than 45 kg (99 lb): 100 mg P.O. b.i.d. for 60 days; or 100 mg I.V. q 12 hours for 60 days, changing to oral route when appropriate

Children weighing 45 kg (99 lb) or less: 2.2 mg/kg P.O. b.i.d. for 60 days; or 100 mg I.V. q 12 hours for 60 days, changing to oral route when appropriate

➣ Prevention of malaria caused by Plasmodium falciparum in short-term travelers (less than 4 months)

Adults: 100 mg/day P.O. starting 1 to 2 days before travel begins and continuing during and for 4 weeks after travel

Children: 2 mg/kg/day P.O., up to adult dosage of 100 mg/day, starting 1 to 2 days before travel begins and continuing during and for 4 weeks after travel

Off-label uses

• Traveler's diarrhea

• Pleural effusion

Contraindications

• Hypersensitivity to drug, other tetracyclines, or bisulfites (with some drug products)

Precautions

Use cautiously in:

• renal disease, hepatic impairment, nephrogenic diabetes insipidus, cachexia

• pregnant or breastfeeding patients

• children younger than age 8.

Administration

• Obtain specimens for culture and sensitivity testing, as ordered, before first dose.

☞ Don't give in conjunction with methoxyflurane anesthetic. Severe or fatal kidney damage may result.

• Reconstitute powder for injection with dextrose 5% in water, normal saline solution, lactated Ringer's solution, or dextrose 5% in lactated Ringer's solution.

• Don't infuse solutions with concentrations above 1 mg/ml.

• Infuse 100-mg dose over at least 1 hour.

• Complete infusion within 12 hours of dilution, unless diluted with lactated Ringer's solution or dextrose 5% in lactated Ringer's solution; in this case, complete infusion within 6 hours.

☞ Don't give during last half of pregnancy or to children under age 8 unless other drugs are likely to be ineffective or are contraindicated. Drug may retard bone growth and cause tooth discoloration and malformation.

• Be aware that capsules with coated pellets contain immediate- and delayed-release pellets.

Adverse reactions

CNS: paresthesia, pseudotumor cerebri

CV: phlebitis, thrombophlebitis, pericarditis

EENT: vestibular reactions, hoarseness, pharyngitis

GI: nausea, vomiting, diarrhea, esophagitis, epigastric distress, enterocolitis, anogenital lesions or inflammation, glossitis, oral candidiasis, black hairy tongue, pancreatitis

GU: dark yellow or brown urine, vaginal candidiasis

Hematologic: hemolytic anemia, neutropenia, thrombocytopenia

Hepatic: hepatotoxicity

Musculoskeletal: bone growth retardation (in children younger than age 8)

Skin: photosensitivity, maculopapular or erythematous rash, hyperpigmentation, urticaria

Other: tooth enamel defects, increased appetite, phlebitis at I.V. site, superinfection, hypersensitivity reactions including anaphylaxis

Interactions

Drug-drug. Adsorbent antidiarrheals; antacids; calcium, iron, and magnesium preparations: decreased doxycycline absorption

Barbiturates, carbamazepine, hormonal contraceptives containing estrogen, phenytoin, rifamycin: decreased doxycycline efficacy

Cholestyramine, colestipol: decreased oral absorption of doxycycline

Methoxyflurane: increased nephrotoxicity

Penicillin: decreased penicillin activity

Sucralfate: prevention of doxycycline absorption from GI tract

Warfarin: enhanced warfarin effects

Drug-diagnostic tests. Alkaline phosphatase, alanine aminotransferase, amylase, aspartate aminotransferase, bilirubin, blood urea nitrogen (BUN), eosinophils: increased levels

Hemoglobin, neutrophils, platelets, white blood cells: decreased levels

Urine catecholamines: false elevations

Drug-food. Calcium-containing foods: decreased drug absorption

Drug-behaviors. Alcohol use: decreased anti-infective effect of doxycycline

Sun exposure: increased risk of photosensitivity

Patient monitoring

• Evaluate I.V. site regularly. Apply cool compresses as needed.

☞ Monitor for hypersensitivity reactions, including anaphylaxis.

• Monitor hepatic profile, CBC, BUN, and creatinine levels.

• Assess for hypercoagulability in patients taking warfarin concurrently.

• Monitor for digoxin toxicity in patients taking digoxin concurrently.

Patient teaching

• Advise patient to take with 8 oz of water to ensure passage into stomach.

• Tell patient to take on empty stomach at least 1 hour before meals or 2 hours afterwards.

• Instruct patient to take at least 1 hour before bedtime to prevent esophagitis.

☞ Tell patient to immediately report painful swallowing, abdominal pain, easy bruising or bleeding, or signs of hypersensitivity (such as rash).

• Advise female patient to tell prescriber if she is pregnant.

• Instruct patient to avoid alcohol use and large amounts of calcium-containing foods (such as dairy products and some green leafy vegetables, such as spinach).

• Stress importance of good oral hygiene.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and behaviors mentioned above.