COACTIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for COACTIN (COACTIN).
Coactin (mecillinam) is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding protein 2 (PBP2) in gram-negative bacteria, leading to the formation of spheroplasts and cell lysis.
| Metabolism | Coactin is not significantly metabolized; it is excreted largely unchanged in the urine via glomerular filtration and tubular secretion. |
| Excretion | Renal: approximately 70-80% as unchanged drug via glomerular filtration and tubular secretion; biliary/fecal: less than 10% as metabolites and unchanged drug. |
| Half-life | Terminal elimination half-life: 1.0-1.5 hours in adults with normal renal function; prolonged to 2-6 hours in renal impairment; clinically requires frequent dosing or dose adjustment in renal failure. |
| Protein binding | Approximately 30-40% bound to serum albumin; low binding reduces displacement interactions. |
| Volume of Distribution | 0.2-0.4 L/kg; indicates limited extravascular distribution, mainly in extracellular fluid; clinically relevant for dosing in edema or ascites. |
| Bioavailability | Intravenous: 100%; intramuscular: approximately 70-80%; oral: negligible (<5%) due to acid instability; not used orally. |
| Onset of Action | Intravenous: within minutes; intramuscular: 30-60 minutes; oral: not administered orally due to poor bioavailability. |
| Duration of Action | Intravenous: 4-6 hours for susceptible organisms; dosing interval typically 4-6 hours; prolonged in renal impairment. |
| Molecular Weight | 466.5 |
400 mg orally every 6-8 hours with a full glass of water.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 400 mg every 8-12 hours; CrCl 10-29 mL/min: 400 mg every 12-24 hours; CrCl <10 mL/min: 400 mg every 24 hours. |
| Liver impairment | No adjustment required for mild to moderate hepatic impairment. Contraindicated in severe hepatic impairment (Child-Pugh class C). |
| Pediatric use | For children >6 months: 10-15 mg/kg every 6 hours, not to exceed 400 mg per dose. |
| Geriatric use | Start at lower end of dosing range; monitor renal function and adjust based on CrCl. |
| 1st trimester | Data limited; avoid in 1st trimester unless benefit outweighs risk. Possible teratogenicity based on animal studies. |
| 2nd trimester | Use only if clearly needed; no well-controlled human studies. Potential fetal harm. |
| 3rd trimester | Avoid near term due to risk of kernicterus in neonates (displaces bilirubin from albumin). |
Clinical note
Comprehensive clinical and safety monograph for COACTIN (COACTIN).
| Placental transfer | Crosses placenta; achieves fetal serum concentrations 50-100% of maternal levels. |
| Breastfeeding | Excreted into breast milk in low concentrations; risk of kernicterus in infants with G6PD deficiency or hyperbilirubinemia. Use with caution. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Serious Effects |
History of hypersensitivity to co-trimoxazole or sulfonamidesSevere hepatic or renal impairmentPorphyriaMegaloblastic anemia due to folate deficiencyConcomitant use with methotrexateInfants <2 months old
| Precautions | Hypersensitivity reactions including anaphylaxis; cross-allergenicity with other beta-lactams; use with caution in patients with renal impairment; superinfection with prolonged use; pseudomembranous colitis; seizure potential in high doses or with renal insufficiency. |
| Food/Dietary | There are no known significant food interactions with Coactin. However, taking with food may reduce gastrointestinal upset. Avoid alcohol during therapy. |
Loading safety data…
| L3 (Moderately Safe) |
| Teratogenic Risk | COACTIN (amdinocillin) is a penicillin-class antibiotic. FDA pregnancy category B: Animal reproduction studies have not demonstrated fetal risk, but there are no adequate and well-controlled studies in pregnant women. First trimester: Low risk based on animal data; human data limited. Second and third trimesters: Considered safe for use when indicated, as penicillins are generally regarded as low risk. No evidence of teratogenicity in clinical use. |
| Fetal Monitoring | Maternal: Monitor for signs of hypersensitivity reactions, gastrointestinal disturbance, and Clostridioides difficile diarrhea. Fetal/Neonatal: No specific fetal monitoring required; routine antenatal care applies. Observe neonate for potential allergic reactions or gastrointestinal effects if given near delivery. |
| Fertility Effects | No known adverse effects of amdinocillin on male or female fertility in animal studies or clinical reports. Penicillins are not associated with fertility impairment. No specific data on amdinocillin; however, class effect suggests no impact. |
| Clinical Pearls |
| Coactin (mecillinam) is an amidinopenicillin with activity against gram-negative organisms, particularly Enterobacteriaceae. It is primarily used for urinary tract infections. Note that it is not active against Pseudomonas aeruginosa or anaerobic bacteria. Renal dosing adjustment is necessary in patients with creatinine clearance <30 mL/min. Cross-allergenicity with other penicillins exists. |
| Patient Advice | Take this medication exactly as prescribed, even if you feel better. · Complete the full course of treatment. · Notify your doctor if you develop a rash, diarrhea, or signs of an allergic reaction. · This medication may cause diarrhea; if it is severe or contains blood/mucus, contact your doctor. · Avoid alcohol while taking this medication. |