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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Probenecid may decrease cephalosporin excretion Nephrotoxicity may occur with concurrent use of potent diuretics.
| FDA category | Human |
| Breastfeeding | Cefazolin is excreted into breast milk in low concentrations (M/P ratio approximately 0.1-0.3). It is considered compatible with breastfeeding; however, potential for infant gut flora alteration and diarrhea is minimal. Monitor infant for gastrointestinal symptoms. |
| 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. |
■ FDA Black Box Warning
There is no FDA black box warning for cefazolin.
| Common Effects | Diarrhea |
| Serious Effects |
["Known hypersensitivity to cefazolin or any cephalosporin","Severe immediate allergic reactions to penicillins (cross-reactivity possible)"]
| 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. |
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| 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. |