TERRAMYCIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TERRAMYCIN (TERRAMYCIN).
Inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-tRNA from binding to the A site.
| Metabolism | Primarily excreted unchanged in urine and feces. Undergoes enterohepatic circulation. Not extensively metabolized; minor hepatic metabolism via glucuronidation. |
| Excretion | Renal (primarily glomerular filtration, 20-60% unchanged in urine), biliary/fecal (10-30% via bile into feces). |
| Half-life | Terminal elimination half-life: 8-10 hours in normal renal function; prolonged to 20-40 hours in severe renal impairment (creatinine clearance <10 mL/min). |
| Protein binding | 20-40% bound primarily to serum albumin. |
| Volume of Distribution | 1.3-1.7 L/kg; distributes extensively into tissues including bone, liver, and bile; does not penetrate cerebrospinal fluid significantly. |
| Bioavailability | Oral: 70-80% (fasting); reduced by food or divalent cations; Intramuscular: 80-100%. |
| Onset of Action | Oral: 1-2 hours; Intravenous: immediate; Intramuscular: 0.5-1 hour. |
| Duration of Action | Approximately 6-8 hours after oral dose; 12-24 hours after IV or IM administration; clinical effect correlates with serum levels >1-2 mcg/mL. |
| Molecular Weight | 496.9 Da (as oxytetracycline hydrochloride; base: 460.4 Da) |
| Action Class | Tetracyclines |
| Brand Substitutes | TM 500mg Capsule, Oticycline 500mg Capsule, Oxy 500mg Capsule, TM 250mg Capsule, T M SF Capsule, Oticycline 250mg Capsule, T M 250mg Capsule |
250-500 mg orally every 6 hours or 1-2 g intravenously every 12 hours. Maximum oral dose: 2 g/day.
| Dosage form | SYRUP |
| Renal impairment | For GFR 10-50 mL/min: administer every 12-24 hours; for GFR <10 mL/min: administer every 24 hours and consider therapeutic drug monitoring. |
| Liver impairment | No specific Child-Pugh based dose adjustment is established; use with caution in severe hepatic impairment (Child-Pugh C) and monitor liver function. |
| Pediatric use | Children >8 years: 25-50 mg/kg/day orally divided every 6 hours; maximum 2 g/day. Intravenously: 10-20 mg/kg/day divided every 12 hours; maximum 1 g/day. |
| Geriatric use | Start at lower end of dosing range (250 mg orally every 6 hours or 500 mg IV every 12 hours) due to possible renal impairment; adjust based on renal function. |
| 1st trimester | Avoid. Oxytetracycline crosses the placenta and may cause interference with bone development and tooth discoloration in the fetus. Use only if no safer alternative. |
| 2nd trimester | Avoid. Risk of tooth discoloration and inhibition of bone growth in the fetus. Use only if clearly needed. |
| 3rd trimester | Avoid. Significant risk of permanent tooth discoloration and reversible inhibition of bone growth. Contraindicated after the 4th month of pregnancy. |
Clinical note
Comprehensive clinical and safety monograph for TERRAMYCIN (TERRAMYCIN).
| Placental transfer | Oxytetracycline crosses the placenta readily. Fetal serum levels reach 50-70% of maternal serum levels. Accumulates in fetal bones and teeth due to chelation with calcium. |
| Breastfeeding | Oxytetracycline is excreted into breast milk in small amounts. Potential for dental staining and bone growth inhibition in the nursing infant. The American Academy of Pediatrics considers it compatible with breastfeeding, but caution is advised. Monitor infant for gastrointestinal disturbances and rash. |
■ FDA Black Box Warning
Use during tooth development (last half of pregnancy, infancy, and children up to 8 years) may cause permanent discoloration of teeth (yellow-gray-brown) and enamel hypoplasia. Not recommended for use during pregnancy or in children under 8 years except for anthrax, plague, or other serious infections.
| Serious Effects |
Hypersensitivity to tetracyclinesSevere hepatic impairmentSystemic lupus erythematosus (may exacerbate)Pregnancy (after first trimester; absolute contraindication after 4th month)Lactation (relative contraindication; avoid in nursing mothers of infants with known sensitivity)
| Precautions | Photosensitivity, Superinfection, CNS effects (pseudotumor cerebri), Hepatotoxicity, Renal toxicity (in patients with renal impairment), Antianabolic effects (elevated BUN), Pancreatitis, Esophageal ulceration, Tetracycline-antacid interaction, Use in pregnancy category D, Use in nursing mothers |
| Food/Dietary | Dairy products (milk, cheese, yogurt) and calcium-fortified foods significantly reduce absorption; avoid within 2 to 4 hours of dosing. High-iron foods (e.g., spinach, red meat) may also reduce absorption if taken simultaneously. Alcohol does not directly interact, but may increase risk of hepatotoxicity if abused. |
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| Lactation Rating | L2 - Limited data indicate moderate safety; use with caution. |
| Teratogenic Risk | Terramycin (oxytetracycline) is a tetracycline antibiotic. Tetracyclines can cause fetal harm when administered to a pregnant woman. Use during the second and third trimesters may cause permanent discoloration of teeth (yellow-gray-brown) and enamel hypoplasia. Additionally, they can inhibit fetal skeletal growth. Use during the first trimester is associated with a slightly increased risk of neural tube defects, though data are limited. Therefore, use is contraindicated in pregnancy unless no alternative exists. |
| Fetal Monitoring | Monitor maternal renal and hepatic function due to potential toxicity. In pregnancy, consider fetal ultrasound to monitor for skeletal abnormalities if used during second/third trimester. Also monitor for signs of maternal superinfection or gastrointestinal disturbances. |
| Fertility Effects | Tetracyclines have been shown to cause reduced fertility in animal studies. In humans, no definitive evidence of impaired fertility has been reported, but due to potential ovarian and testicular toxicity, caution is advised in patients attempting conception. |
| Clinical Pearls | Terramycin (oxytetracycline) is a broad-spectrum tetracycline antibiotic. Due to widespread resistance, it is rarely used as first-line therapy except for specific indications like brucellosis, chlamydial infections, and acne. It chelates with divalent and trivalent cations, so avoid concurrent administration with dairy products, antacids, or iron supplements. Photosensitivity is common; patients should avoid prolonged sun exposure. Hepatotoxicity and nephrotoxicity can occur, especially in pregnancy and renal impairment. Drug interactions include increased risk of pseudotumor cerebri with isotretinoin and oral retinoids. |
| Patient Advice | Take this medication on an empty stomach, at least 1 hour before or 2 hours after meals, with a full glass of water. · Avoid dairy products, antacids, iron, calcium, magnesium, and zinc supplements within 2 to 4 hours of taking this medication. · Wear sunscreen and protective clothing and avoid prolonged sun exposure, as this drug can make your skin more sensitive to sunlight. · Do not take this medication if you are pregnant, planning to become pregnant, or breastfeeding, as it can cause permanent teeth discoloration and bone growth problems in the fetus or infant. · Complete the full course of therapy even if you feel better; stopping early may lead to bacterial resistance. · Store at room temperature away from moisture and heat. |