CLOXACILLIN SODIUM
Clinical safety rating: safe
Human studies have proved safety
Cloxacillin is a beta-lactam antibiotic that binds to penicillin-binding proteins (PBPs) located on the bacterial cell wall, inhibiting transpeptidases and thus preventing the cross-linking of peptidoglycan chains. This leads to cell lysis and death, primarily mediated by autolytic enzymes. It is resistant to penicillinase (beta-lactamase) produced by staphylococci.
| Metabolism | Primarily hepatic, with about 30% excreted unchanged in urine. Metabolism involves hepatic enzymes, though specific CYP pathways are not well defined. |
| Excretion | Renal (70-80% unchanged via glomerular filtration and tubular secretion); biliary/fecal (small amount, <10%) |
| Half-life | 0.5-1.1 hours in adults with normal renal function; prolonged in neonates, elderly, and renal impairment (up to 2-4 hours in anuria) |
| Protein binding | 90-94% bound to serum albumin |
| Volume of Distribution | 0.1-0.25 L/kg; low, reflecting limited extravascular distribution |
| Bioavailability | Oral: 37-50% (reduced by food); IM: ~70-80% |
| Onset of Action | Oral: 30-60 minutes; IM: 15-30 minutes; IV: immediate (within minutes) |
| Duration of Action | 4-6 hours for bacterial growth suppression; dose adjustment may be needed for severe infections or renal impairment |
250-500 mg orally every 6 hours on an empty stomach; 250 mg - 2 g IV/IM every 4-6 hours depending on severity; maximum 12 g/day for serious infections.
| Dosage form | FOR SOLUTION |
| Renal impairment | CrCl > 50 mL/min: no adjustment; CrCl 10-50 mL/min: no adjustment; CrCl < 10 mL/min: dose no adjustment needed but avoid in anuria; not significantly removed by hemodialysis. |
| Liver impairment | Mild to moderate hepatic impairment (Child-Pugh A/B): no adjustment needed; severe hepatic impairment (Child-Pugh C): use with caution, consider 50% dose reduction. |
| Pediatric use | Oral: 12.5-25 mg/kg/day divided every 6 hours; IV/IM: 25-50 mg/kg/day divided every 6 hours; severe infections: up to 100 mg/kg/day. Maximum 4 g/day. |
| Geriatric use | No specific dose adjustment required; monitor renal function due to age-related decline; start at lower end of dosing range; careful administration to avoid dehydration. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Probenecid may decrease excretion Serious and occasionally fatal hypersensitivity reactions have been reported.
| Breastfeeding | Excreted in breast milk in low levels; M/P ratio approximately 0.05. Considered compatible with breastfeeding due to poor oral bioavailability in infants, but monitor for diarrhea or rash. |
| Teratogenic Risk | Pregnancy Category B. Animal studies have not demonstrated fetal risk, and no adequate human studies exist. Risk cannot be ruled out but appears low across all trimesters. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Common Effects | Diarrhea |
| Serious Effects |
["Hypersensitivity to cloxacillin, other penicillins, or any component of the formulation.","Use is contraindicated in patients with a history of immediate-type hypersensitivity reactions (e.g., anaphylaxis) to beta-lactam antibiotics."]
| Precautions | ["Severe and occasionally fatal hypersensitivity (anaphylactoid) reactions have been reported.","Prolonged use may result in superinfection due to overgrowth of non-susceptible organisms, including Clostridioides difficile.","Use with caution in patients with renal impairment, as dose adjustment may be necessary.","Leukopenia, neutropenia, and thrombocytopenia have been associated with high doses or prolonged therapy."] |
Loading safety data…
| Routine maternal monitoring of renal function, hepatic function, and complete blood count due to potential hematologic adverse effects. Fetal monitoring as per standard obstetric care; no specific fetal monitoring required. |
| Fertility Effects | No known adverse effects on fertility in animal studies. No human data available. |