MYCITRACIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MYCITRACIN (MYCITRACIN).
MYCITRACIN is a combination of bacitracin and neomycin, which are aminoglycoside antibiotics. Bacitracin inhibits bacterial cell wall synthesis by interfering with dephosphorylation of the lipid carrier that transports peptidoglycan subunits. Neomycin binds to the 30S ribosomal subunit, causing misreading of mRNA and inhibition of protein synthesis.
| Metabolism | Not systemically absorbed to a significant extent after topical application. If absorbed, neomycin is excreted primarily unchanged by the kidneys. |
| Excretion | Primarily renal (glomerular filtration and tubular secretion); >90% of dose excreted unchanged in urine within 24 hours. Biliary/fecal excretion is minimal (<5%). |
| Half-life | Terminal elimination half-life is 2–3 hours in adults with normal renal function. Prolonged significantly in renal impairment (up to 24–48 hours in anuria). |
| Protein binding | Approximately 30% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | 0.2–0.4 L/kg, indicating distribution primarily into extracellular fluid; does not penetrate cells or the CNS significantly. |
| Bioavailability | Intramuscular: ~90%; Oral: <1% (not absorbed systemically; used for gut decontamination). |
| Onset of Action | Intramuscular: 30–60 minutes; Intravenous: immediate; Intraperitoneal: rapid (within minutes); Oral: not absorbed systemically (remains in GI tract). |
| Duration of Action | Intramuscular: 6–8 hours; Intravenous: 4–6 hours. Duration prolonged in renal dysfunction. |
| Molecular Weight | 1006 |
500 mg orally every 6 hours
| Dosage form | OINTMENT |
| Renal impairment | GFR 30-50 mL/min: 500 mg every 8 hours; GFR 10-29 mL/min: 500 mg every 12 hours; GFR <10 mL/min: 500 mg every 24 hours |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: 500 mg every 8 hours; Child-Pugh C: use with caution, consider 500 mg every 12 hours |
| Pediatric use | 10-15 mg/kg/dose orally every 6 hours, maximum 500 mg per dose |
| Geriatric use | Use with caution; monitor renal function; adjust dose based on creatinine clearance; start at lower end of dosing range |
| 1st trimester | Contraindicated due to potential nephrotoxicity and ototoxicity to fetus. Use only if no alternatives. |
| 2nd trimester | Contraindicated unless essential; risk of fetal harm outweighs benefits. |
| 3rd trimester | Contraindicated; may cause fetal nephrotoxicity and ototoxicity. |
Clinical note
Comprehensive clinical and safety monograph for MYCITRACIN (MYCITRACIN).
| Placental transfer | Crosses placenta; achieves fetal serum concentrations 15-50% of maternal levels. |
| Breastfeeding | Excreted into breast milk in small amounts; potential for ototoxicity and nephrotoxicity in nursing infants. Use only if benefits outweigh risks; monitor infant for diarrhea, rash, or hearing loss. |
| Lactation Rating |
■ FDA Black Box Warning
Contains neomycin, which can cause nephrotoxicity and ototoxicity, especially with prolonged use or application to large areas of damaged skin. Risk is increased in patients with renal impairment.
| Serious Effects |
Hypersensitivity to MYCITRACIN or any componentMyasthenia gravisConcurrent use of neurotoxic or nephrotoxic agents
| Precautions | Avoid use on large areas of broken skin or prolonged use due to risk of systemic absorption and toxicity. Monitor for signs of renal toxicity and ototoxicity. May cause allergic contact dermatitis. Use caution in patients with renal impairment. |
| Food/Dietary | No known food interactions for topical use. |
Loading safety data…
| L3 - Moderately Safe |
| Teratogenic Risk | Mycitracin (bacitracin, neomycin, polymyxin B) topical use has minimal systemic absorption, thus teratogenic risk is low. No adequate studies in pregnant women; animal studies not reported. First trimester: theoretical risk from systemic absorption unlikely. Second and third trimesters: considered safe for topical use. Avoid on large areas, broken skin, or prolonged use. |
| Fetal Monitoring | No specific monitoring required due to negligible systemic absorption. For extensive use or in renal impairment, monitor for nephrotoxicity and ototoxicity (from neomycin and polymyxin B) via serum creatinine and auditory tests. |
| Fertility Effects | No known effect on fertility. Animal studies not conducted. Systemic absorption unlikely, so no anticipated impact on reproductive function. |
| Clinical Pearls |
| MYCITRACIN (bacitracin) is a topical antibiotic commonly used for superficial skin infections; monitor for hypersensitivity reactions (rare); avoid use on large areas of damaged skin or for extended periods due to potential systemic absorption and nephrotoxicity. |
| Patient Advice | Apply a thin layer to affected area 1-3 times daily. · Wash hands before and after application unless treating hands. · Avoid contact with eyes, nose, or mouth. · Stop use and notify doctor if rash or irritation develops or if symptoms persist beyond one week. · Do not use on deep puncture wounds, animal bites, or serious burns. |