Tetracyclines

ByBrian J. Werth, PharmD, University of Washington School of Pharmacy
Reviewed/Revised May 2024
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Tetracyclines are bacteriostatic antibiotics that bind to the 30S subunit of the ribosome, thus inhibiting bacterial protein synthesis. Specific tetracyclines are

Pharmacokinetics of Tetracyclines

Tetracyclinedoxycycline and minocycline.

Tetracycline and minocycline

Indications for Tetracyclines

Tetracyclines are active against infections caused by the following:

About 5 to 10% of pneumococcal strains and many group A beta-hemolytic streptococci, many gram-negative bacillary uropathogens, and penicillinase-producing gonococci are resistant.

S. aureus infections.

for all of the following because it is better tolerated and can be given twice a day:

Contraindications to Tetracyclines

Tetracyclines are contraindicated in patients who have had an allergic reaction to them.

doxycycline acceptable for all ages (1). A study of children < 8 years of age who were treated with a short course of doxycycline for suspected Rocky Mountain spotted fever found no evidence of tooth staining or enamel defects compared to children who had not received doxycycline (2, 3).

Contraindications references

  1. 1. Stultz JS, Eiland LS: Doxycycline and Tooth Discoloration in Children: Changing of Recommendations Based on Evidence of Safety. Ann Pharmacother 53(11):1162-1166, 2019. doi: 10.1177/1060028019863796

  2. 2. Todd SR, Dahlgren FS, Traeger MS, et al: No visible dental staining in children treated with doxycycline for suspected Rocky Mountain spotted fever. J Pediatr 166(5):1246–1251, 2015. doi: 10.1016/j.jpeds.2015.02.015

  3. 3. Centers for Disease Control and Prevention (CDC): Research on doxycycline and tooth staining. Accessed February 20, 2024.

Use of Tetracyclines During Pregnancy and Breastfeeding

Hepatotoxicity may occur in pregnant women, particularly after IV administration and in those with azotemia or pyelonephritis. Taking high doses during pregnancy can lead to fatty degeneration of the liver, which may be fatal.

Adverse Effects of Tetracyclines

Adverse effects of tetracyclines include

  • Gastrointestinal disturbances

  • Candidiasis

  • Photosensitivity

  • Bone and dental effects in children

  • Fatty liver

All oral tetracyclines cause nausea, vomiting, and diarrhea and can cause candidal superinfections. If not swallowed with water, tetracyclines can cause esophageal erosions.

Photosensitivity due to tetracyclines may manifest as an exaggerated sunburn reaction.

Contraindications), hypoplasia of dental enamel, and abnormal bone growth in children < 8 years. In infants, tetracyclines may cause idiopathic intracranial hypertension and bulging fontanelles.

Excessive blood levels due to use of high doses or renal insufficiency may lead to fatal acute fatty degeneration of the liver, especially during pregnancy.

minocycline has been associated with development of autoimmune disorders such as systemic lupus erythematosus and polyarteritis nodosa, which may be reversible. Minocycline may also cause drug reaction with eosinophilia and systemic symptoms (DRESS), which is characterized by fever, rash, lymphadenopathy, hepatitis, atypical lymphocytosis, eosinophilia, and thrombocytopenia.

Tetracyclines (except for doxycycline) can exacerbate azotemia, hyperphosphatemia, and metabolic acidosis in patients with renal insufficiency. Although doxycycline

Expired tetracycline pills can degenerate and, if ingested, cause Fanconi syndrome. Patients should be instructed to discard the antibiotics when they expire.

Dosing Considerations for Tetracyclines

Tetracyclines may decrease the effectiveness of oral contraceptives and potentiate the effects of oral anticoagulants.

Drugs Mentioned In This Article
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