TETRACHEL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TETRACHEL (TETRACHEL).
Tetracycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the mRNA-ribosome complex.
| Metabolism | Tetracycline is primarily metabolized in the liver via glucuronidation and undergoes enterohepatic circulation. Minor metabolism may involve microsomal enzymes. |
| Excretion | Renal 60% (glomerular filtration), fecal 40% (biliary excretion of active drug and metabolites). |
| Half-life | 6-11 hours (prolonged in renal impairment; up to 57 hours in anuria). |
| Protein binding | 65% (primarily albumin). |
| Volume of Distribution | 1.3 L/kg (extensive tissue penetration, including bone and teeth). |
| Bioavailability | Oral: 77-96% (decreased by food, dairy, antacids). |
| Onset of Action | Oral: 1 hour; IV: immediate; Topical: 2-3 days. |
| Duration of Action | Oral: 12 hours; IV: 12 hours; Topical: up to 12 hours after application. |
500 mg orally once daily for 28 days; for severe infections, 500 mg twice daily for 14 days.
| Dosage form | CAPSULE |
| Renal impairment | CrCl >50 mL/min: no adjustment. CrCl 30-50 mL/min: 250 mg once daily. CrCl <30 mL/min: 125 mg once daily. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: 250 mg once daily. Child-Pugh C: 125 mg once daily. |
| Pediatric use | Children ≥8 years: 5 mg/kg orally once daily (max 500 mg) for 28 days. |
| Geriatric use | Initiate at low end of dosing range; monitor renal function and adjust dose based on CrCl. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TETRACHEL (TETRACHEL).
| Breastfeeding | Tetracycline is excreted into human milk, with milk-to-plasma ratio (M/P) approximately 0.5-0.8. Low levels of tetracycline are found in breast milk; however, due to potential for serious adverse reactions (e.g., permanent tooth discoloration and bone growth inhibition) in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. Alternative antibiotics with better safety profiles in lactation are preferred. |
| Teratogenic Risk | Tetracyclines, including Tetrachel, are classified as FDA Pregnancy Category D. They can cause fetal harm when administered to a pregnant woman. Use during the second and third trimesters (weeks 13 to 40) is associated with permanent discoloration of teeth (yellow-gray-brown) and enamel hypoplasia in the child. Additionally, there is a risk of retarded skeletal growth and potentially reversible inhibition of bone growth. Use during the first trimester is generally discouraged unless no alternative therapy is available, as there may be a small risk of teratogenicity (e.g., neural tube defects, cardiovascular malformations) based on some observational studies, though evidence is conflicting. |
■ FDA Black Box Warning
Tetracycline can cause fetal harm when administered to a pregnant woman. Use during tooth development (last half of pregnancy, infancy, and children up to 8 years) may cause permanent discoloration of teeth (yellow-gray-brown). It should not be used in this age group unless other drugs are not likely to be effective or are contraindicated.
| Serious Effects |
["Hypersensitivity to tetracyclines or any component of the formulation.","Pregnancy (especially second and third trimesters) and lactation.","Children under 8 years of age (except for specific infections like anthrax or where no alternative exists).","Severe hepatic impairment."]
| Precautions | ["Photosensitivity: exaggerated sunburn reaction; avoid direct sunlight and UV light.","Hepatotoxicity: may cause liver damage, especially in patients with renal impairment or receiving high doses.","Renal impairment: accumulation may occur; dosage adjustment required.","Superinfection: use of tetracycline may result in overgrowth of non-susceptible organisms, including fungi.","Pseudomembranous colitis: Clostridium difficile-associated diarrhea has been reported.","Intracranial hypertension: bulging fontanelles in infants and benign intracranial hypertension in adults.","Tissue irritation: avoid extravasation; thrombophlebitis risk with IV administration."] |
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| Fetal Monitoring | Pregnant women receiving tetracycline should have baseline and periodic liver function tests (LFTs) and renal function tests (serum creatinine, BUN) due to risk of hepatotoxicity and nephrotoxicity in the mother. In prolonged therapy, monitor for signs of superinfection and C. difficile diarrhea. Fetal monitoring includes ultrasound assessment for skeletal abnormalities if used in the second/third trimester, and postpartum dental examination of the infant for enamel hypoplasia and tooth discoloration. |
| Fertility Effects | Tetracycline has been shown to impair fertility in animal studies; effects on human fertility are not well-established. It may reduce sperm motility and concentration in men, and in women, it may cause reversible inhibition of spermatogenesis or ovarian function. Clinical significance is considered low with short-term use, but prolonged therapy may warrant fertility counseling. |