MEZLIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MEZLIN (MEZLIN).
Mezlocillin is a ureidopenicillin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), specifically inhibiting transpeptidase activity, leading to cell lysis.
| Metabolism | Primarily excreted unchanged in urine via glomerular filtration and tubular secretion; partially metabolized hepatically to benzylpenicilloyl derivatives. |
| Excretion | Renal (70-80% unchanged via glomerular filtration and tubular secretion); biliary (approximately 2-3%); fecal (minor). |
| Half-life | Terminal elimination half-life is 0.7-1.2 hours in healthy adults; prolonged to 2-5 hours in renal impairment (CrCl <20 mL/min) and up to 10-20 hours in ESRD. |
| Protein binding | 16-50% bound primarily to albumin. |
| Volume of Distribution | 0.2-0.3 L/kg; distributes well into extracellular fluid, bile, and pleural fluid; limited CSF penetration. |
| Bioavailability | IM: approximately 80% absorbed; IV: 100%. |
| Onset of Action | IV: Immediate peak concentrations; IM: 30-60 minutes for therapeutic levels. |
| Duration of Action | Approximately 4-6 hours for susceptible bacteria; requires frequent dosing (q4-6h) due to short half-life. |
3-4 g intravenously every 4-6 hours; maximum 24 g/day.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 3 g every 6 hours; CrCl 10-29 mL/min: 3 g every 8 hours; CrCl <10 mL/min: 2 g every 12 hours. |
| Liver impairment | No specific adjustment recommended; caution in severe hepatic impairment. |
| Pediatric use | Infants >7 days and children: 200-300 mg/kg/day intravenously divided every 4-6 hours; maximum 24 g/day. |
| Geriatric use | Start at lower end of dosing range; monitor renal function and adjust based on creatinine clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MEZLIN (MEZLIN).
| Breastfeeding | Mezlocillin is excreted in human milk in low concentrations. The M/P ratio is unknown. It is considered compatible with breastfeeding due to poor oral bioavailability in infants. However, potential for alteration of infant gut flora and allergic sensitization exists. Use caution in mothers of preterm or jaundiced infants. |
| Teratogenic Risk | Mezlin (mezlocillin) is a penicillin-class antibiotic. Available human data are limited, but penicillins are generally considered low risk in pregnancy. Animal studies have not shown teratogenicity. First trimester: No evidence of fetal harm, but data are insufficient to rule out risk. Second and third trimesters: Considered safe when clinically indicated. Avoid use only if hypersensitivity to penicillins exists. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["History of allergic reaction to penicillins","Hypersensitivity to cephalosporins or other beta-lactam antibiotics (cross-sensitivity)"]
| Precautions | ["Serious and occasionally fatal hypersensitivity reactions (anaphylaxis) have been reported","Clostridium difficile-associated diarrhea (CDAD) may occur","Renal impairment requires dosage adjustment","Prolonged use may result in superinfection","May cause neurotoxicity with high doses or renal failure"] |
Loading safety data…
| Fetal Monitoring | Monitor maternal renal and hepatic function periodically. Observe for signs of hypersensitivity reactions. In prolonged therapy, monitor for superinfection. No specific fetal monitoring required, but assess for adverse effects if given near term. |
| Fertility Effects | No known adverse effects on human fertility. Animal studies have not reported reproductive toxicity at therapeutic doses. |