Comparative Pharmacology
Head-to-head clinical analysis: TERRAMYCIN W POLYMYXIN versus TERRAMYCIN POLYMYXIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: TERRAMYCIN W POLYMYXIN versus TERRAMYCIN POLYMYXIN.
TERRAMYCIN W/ POLYMYXIN vs TERRAMYCIN-POLYMYXIN
Head-to-head clinical comparison of therapeutic indices and safety profiles.
Terramycin (oxytetracycline) is a bacteriostatic tetracycline antibiotic that inhibits protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-tRNA binding. Polymyxin B is a cationic polypeptide that disrupts bacterial cell membranes by interacting with lipopolysaccharides in Gram-negative bacteria.
Terramycin (oxytetracycline) inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing aminoacyl-tRNA attachment. Polymyxin disrupts bacterial cell membrane permeability by binding to lipopolysaccharides, leading to cell death.
Ophthalmic infections (superficial ocular infections)Otic infections (external ear infections)Topical bacterial infections (off-label: skin infections, wound prophylaxis)
Ophthalmic infections caused by susceptible organismsSuperficial ocular infections (conjunctivitis, blepharitis)Prophylaxis of neonatal conjunctivitis due to Neisseria gonorrhoeae or Chlamydia trachomatis
Not applicable: Terramycin (oxytetracycline) and polymyxin B combination is not available for systemic use; topical or ophthalmic preparations only; no standard adult systemic dose.
Adults: 1-2 drops into affected eye(s) every 4 hours, or 1/2-1 inch ribbon of ointment into conjunctival sac 3-4 times daily. For dermatological use: apply sparingly to affected area 2-3 times daily.
None Documented
None Documented
Oxytetracycline: 6-10 hours (normal renal function; prolonged to 50-100 hours in anuria). Polymyxin B: 6-8 hours (normal renal function; prolonged to 24-48 hours in renal impairment).
Terramycin: 6-10 hours (prolonged in renal impairment); polymyxin B: 6-7 hours (prolonged in renal impairment); clinical context: dosing interval adjustment required for renal dysfunction
Not extensively metabolized; primarily excreted unchanged in urine and feces.
Oxytetracycline is primarily excreted unchanged in urine; minimal hepatic metabolism. Polymyxin is not metabolized hepatically; primarily renally excreted.
Renal: Oxytetracycline ~70% unchanged; Polymyxin B ~60% unchanged. Fecal: Oxytetracycline ~20-30% (biliary and unabsorbed); Polymyxin B ~40% (biliary).
Renal (terramycin: ~70% unchanged in urine; polymyxin B: ~60% unchanged in urine), biliary/fecal (terramycin: ~20-30% in feces; polymyxin B: ~40% fecal elimination)
Oxytetracycline: 20-35% (bound to albumin). Polymyxin B: ~80% (bound to plasma proteins, including albumin).
Terramycin: ~25-35% bound to plasma proteins (mainly albumin); polymyxin B: ~80-90% bound to plasma proteins (albumin, α-1-acid glycoprotein)
Oxytetracycline: 0.9-1.4 L/kg (distributes widely, except CSF). Polymyxin B: 0.5-1.0 L/kg (mostly extracellular, limited CNS penetration).
Terramycin: 1.3-1.8 L/kg (distributes widely, including pleural fluid, ascites, bile); polymyxin B: 0.3-0.5 L/kg (limited distribution, primarily extracellular)
IM: Oxytetracycline ~100% (aqueous solution); Polymyxin B ~100% (IM). Oral: Not applicable (polymyxin B not absorbed; oxytetracycline ~70-80% oral but not in this product). Topical: Minimal systemic absorption.
Terramycin: oral ~60-80% (food decreases absorption), IM ~70-80%; polymyxin B: not absorbed orally (0.1-0.3%), IM ~100%, IV 100%
Not applicable: No systemic dosing; topical use does not require adjustment.
Terramycin-Polymyxin (oxytetracycline/polymyxin B) is primarily used topically; systemic absorption is minimal. No specific GFR-based dose adjustments required for topical use. For rare systemic use, oxytetracycline requires adjustment if GFR <50 mL/min: prolong dosing interval to every 12-24 hours. Polymyxin B: adjust if GFR <30 mL/min, reduce dose by 50% or increase interval to 12-24 hours.
Not applicable: No systemic dosing; contraindicated in severe hepatic impairment if systemic absorption occurs (e.g., extensive burns).
No specific Child-Pugh based adjustments required for topical use. For systemic oxytetracycline, use with caution in severe hepatic impairment; consider dose reduction or alternative therapy. Polymyxin B is not hepatically metabolized; no adjustment needed.
Not applicable: Safety and efficacy not established; contraindicated in children <8 years due to teeth discoloration and bone growth retardation.
Children ≥2 years: same as adult dosing for ophthalmic and topical use. For infants <2 years: use only if clearly needed; no specific weight-based dosing established for topical forms.
Not applicable: No systemic dosing; use with caution if renal impairment present due to potential nephrotoxicity from polymyxin B with topical application on denuded skin.
No specific dose adjustments needed for topical ophthalmic or dermatologic use. Use caution with systemic administration due to potential renal impairment; monitor renal function and adjust accordingly.
No FDA black box warning for this combination product.
None
["Hypersensitivity reactions including anaphylaxis","Photosensitivity with oxytetracycline","Nephrotoxicity with polymyxin B","Neuromuscular blockade with polymyxin B","Avoid prolonged use","Monitor renal function"]
["Prolonged use may result in overgrowth of nonsusceptible organisms including fungi.","Photosensitivity reactions may occur with oxytetracycline.","Renal impairment may require dose adjustment for polymyxin.","Avoid use in children under 8 years due to tooth discoloration.","Caution in patients with myasthenia gravis due to potential neuromuscular blockade from polymyxin."]
["Hypersensitivity to any component","Myasthenia gravis (due to polymyxin B)","Avoid in otic use if tympanic membrane is perforated"]
["Hypersensitivity to any component","Severe renal impairment (for polymyxin component)","Pregnancy (tetracycline class effects on fetal bone/teeth)","Lactation (tetracycline excreted in milk)"]
Data Pending Review
Data Pending Review
No known food interactions with topical ophthalmic Terramycin with polymyxin B. Systemic absorption is negligible. No dietary restrictions required.
Avoid dairy products (milk, cheese, yogurt), antacids, and iron-fortified foods within 2-3 hours of administration. Calcium, magnesium, aluminum, and zinc can chelate tetracyclines, reducing absorption. Do not take with mineral supplements or laxatives containing magnesium.
Tetracyclines (oxytetracycline) cross the placenta. First trimester: limited evidence of teratogenicity, but use generally avoided due to risk of neural tube defects? Second/third trimester: use contraindicated due to risk of permanent tooth discoloration and enamel hypoplasia in the fetus; also associated with reversible inhibition of fetal bone growth. Polymyxin B: minimal placental transfer; no known teratogenicity in animal studies. Combined product: avoid in pregnancy unless no alternative.
Terramycin (oxytetracycline) is a tetracycline antibiotic that crosses the placenta. Tetracyclines are associated with fetal risk, including permanent tooth discoloration and enamel hypoplasia when used during the second and third trimesters. They may also cause skeletal growth retardation and are contraindicated after the first trimester. Polymyxin B sulfate has limited data; animal studies show no teratogenicity but fetal harm cannot be ruled out. Avoid use during pregnancy unless no safer alternative.
Oxytetracycline is excreted in breast milk in low concentrations (M/P ratio not established for this specific combination). Potential for bone and dental effects in the nursing infant. Polymyxin B is poorly absorbed orally, so infant exposure likely negligible. Caution advised: consider alternative antibiotics during breastfeeding.
Oxytetracycline is excreted into human breast milk in low concentrations; M/P ratio not established. Theoretical risk of dental discoloration and bone growth suppression in nursing infants, but clinical significance is low due to poor oral absorption of tetracyclines bound to milk calcium. Polymyxin B is excreted in milk in trace amounts; oral absorption is negligible. Use with caution; alternative agents preferred.
Pregnancy-induced increases in plasma volume and renal clearance may reduce serum concentrations of oxytetracycline; however, specific dose adjustment recommendations are lacking. Use standard adult dosing with caution, but avoid in pregnancy if possible due to fetal risks.
Pregnancy-induced physiological changes (increased plasma volume, renal clearance) may reduce serum oxytetracycline concentrations; however, dose adjustments are not typically recommended due to risks. Avoid use after first trimester. No specific adjustments for polymyxin B.
Category C
Category C
Terramycin (oxytetracycline) with polymyxin B is a combination ophthalmic ointment used for superficial ocular infections. Oxytetracycline is a bacteriostatic tetracycline inhibiting protein synthesis; polymyxin B is a bactericidal polypeptide disrupting cell membranes. Efficacy covers Gram-positive (Staphylococcus, Streptococcus) and Gram-negative (Pseudomonas, E. coli) pathogens. Avoid prolonged use due to risk of superinfection. Do not use for viral or fungal infections. In patients with renal impairment, monitor for cumulative toxicity from polymyxin B. Discontinue if hypersensitivity or corneal epithelial defects occur. This formulation is not for injection or systemic use.
Terramycin (oxytetracycline) is primarily bacteriostatic, while polymyxin is bactericidal. Monitor renal function in patients receiving polymyxin due to risk of nephrotoxicity. Avoid use in children under 8 years due to tooth discoloration and bone growth inhibition. Caution in patients with myasthenia gravis or porphyria.
Wash hands before and after application.Tilt head back, pull down lower eyelid, and apply a small strip (about 0.5-1 cm) of ointment into the conjunctival sac.Do not touch the tube tip to any surface, including the eye, to avoid contamination.Blurred vision may occur temporarily after application; avoid driving or operating machinery until vision clears.Complete the full course of treatment even if symptoms improve; do not skip doses.Do not use for longer than prescribed to reduce risk of antibiotic resistance.Notify your doctor if symptoms worsen or do not improve within a few days.Remove contact lenses before application; do not wear during treatment unless directed.Store the ointment at room temperature, away from heat and direct sunlight.Keep out of reach of children.
Take on an empty stomach (1 hour before or 2 hours after meals) unless gastrointestinal upset occurs.Avoid dairy products, antacids, iron supplements, and calcium-rich foods within 2-3 hours of dosing.Do not take with magnesium-containing laxatives or bismuth subsalicylate.Complete the full course of therapy even if symptoms improve.Report any signs of superinfection (e.g., oral thrush, vaginal discharge) or persistent diarrhea.Use sunscreen and protective clothing; may cause photosensitivity.Not for use in pregnant women or children under 8 years.Store at room temperature, away from light and moisture.Do not share medication with others.