CEFAZOLIN IN DEXTROSE
Clinical safety rating: safe
Probenecid may decrease cephalosporin excretion Nephrotoxicity may occur with concurrent use of potent diuretics.
Cefazolin is a first-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), thereby disrupting peptidoglycan cross-linking.
| Metabolism | Cefazolin is not significantly metabolized; it is primarily excreted unchanged in urine via glomerular filtration and tubular secretion. |
| Excretion | Renal: 80-90% unchanged by glomerular filtration and tubular secretion. Biliary: minor (<1%). Fecal: negligible. |
| Half-life | 1.8 hours in normal renal function. Prolonged to 12-24 hours in end-stage renal disease (CrCl <10 mL/min). |
| Protein binding | 80-86% bound to albumin. |
| Volume of Distribution | 0.12-0.14 L/kg; primarily extracellular fluid, low CNS penetration unless inflamed meninges. |
| Bioavailability | IM 100% (complete absorption). IV 100%. |
| Onset of Action | IV: immediate; IM: peak serum concentration at 1-2 hours. |
| Duration of Action | 6-8 hours for susceptible organisms in normal renal function. Extended in renal impairment; reduce dosing interval. |
| Molecular Weight | 476.5 |
1-2 g IV every 8 hours. For serious infections, up to 2 g IV every 6 hours.
| Dosage form | SOLUTION |
| Renal impairment | CrCl >55 mL/min: no adjustment; CrCl 35-54 mL/min: 1-2 g IV every 8 hours; CrCl 11-34 mL/min: 500 mg-1 g IV every 12 hours; CrCl ≤10 mL/min: 500 mg-1 g IV every 24 hours. |
| Liver impairment | No dosage adjustment required for hepatic impairment; cefazolin is primarily renally eliminated. |
| Pediatric use | Children >1 month: 25-50 mg/kg/day IV divided every 8 hours; severe infections: 100 mg/kg/day IV divided every 6-8 hours. Maximum 6 g/day. |
| Geriatric use | Based on renal function; CrCl ≥35 mL/min: 1-2 g IV every 8 hours; CrCl 11-34 mL/min: 500 mg-1 g IV every 12 hours; CrCl ≤10 mL/min: 500 mg-1 g IV every 24 hours. Monitor renal function. |
| 1st trimester | Crosses placenta; no evidence of risk in animal studies; human data limited but considered safe if indicated. |
| 2nd trimester | Generally considered safe; no known teratogenic effects. |
| 3rd trimester | Safe; used for perioperative prophylaxis and infections during pregnancy. |
Clinical note
Probenecid may decrease cephalosporin excretion Nephrotoxicity may occur with concurrent use of potent diuretics.
| FDA category | Human |
| Placental transfer | Crosses placenta; achieves therapeutic concentrations in fetal tissues and amniotic fluid. |
| Breastfeeding | Cefazolin is excreted into breast milk in low concentrations (less than 1% of maternal dose). It is considered compatible with breastfeeding due to low oral bioavailability in infants and minimal risk of adverse effects. Monitor for potential gastrointestinal disturbances (e.g., diarrhea, candidiasis) in the infant. |
■ FDA Black Box Warning
There is no FDA black box warning for cefazolin.
| Common Effects | Diarrhea |
| Serious Effects |
Hypersensitivity to cephalosporinsSevere hypersensitivity to penicillins (immediate type)
| Precautions | Hypersensitivity reactions (including anaphylaxis) in patients with penicillin or cephalosporin allergy, Clostridioides difficile-associated diarrhea (CDAD), Renal impairment: dose adjustment required, Coagulation abnormalities (rarely vitamin K deficiency in malnourished patients), Prolonged use may cause superinfection |
| Food/Dietary | None known with food. However, avoid alcohol during treatment and for 72 hours after completion to prevent disulfiram-like reaction. |
Loading safety data…
| Lactation Rating | L1 (Compatible) |
| Teratogenic Risk | Cefazolin is classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and there are no adequate and well-controlled studies in pregnant women. First trimester: No evidence of teratogenicity; crosses placenta but considered safe. Second and third trimesters: No known fetal risks; used commonly for surgical prophylaxis and treatment of infections. Avoid only if hypersensitivity exists. |
| Fetal Monitoring | No specific fetal monitoring required. Standard maternal monitoring for adverse effects (e.g., allergic reactions, injection site reactions). If used for preterm premature rupture of membranes or intrapartum prophylaxis, monitor for signs of infection in mother and neonate. |
| Fertility Effects | No known adverse effects on fertility in animal studies. Human data limited; no evidence of impaired fertility or reproductive performance. |
| Clinical Pearls | Cefazolin in dextrose is a first-generation cephalosporin. Use with caution in penicillin-allergic patients due to ~10% cross-reactivity. Dose adjustment required in renal impairment (CrCl <55 mL/min). Monitor for superinfection with prolonged use. Contains dextrose; caution in diabetes mellitus. |
| Patient Advice | Complete the full course even if you feel better. · Report any signs of allergic reaction (rash, itching, swelling, difficulty breathing). · This medication may cause diarrhea; inform your doctor if severe or persistent. · Avoid alcohol while on this medication and for 72 hours after stopping. · Inform your doctor about all other medications, especially blood thinners and oral contraceptives. |