Cefazolin

# Cefazolin ## Overview - **Classification**: First-generation Cephalosporin antibiotic - **Mechanism**: Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to bacterial cell lysis. ## Primary Indications 1. **Surgical Prophylaxis**: Prevention of surgical site infections. 2. **Skin and Soft Tissue Infections**: Treatment of mild to moderate infections (e.g., cellulitis, erysipelas). 3. **Bone and Joint Infections**: Treatment of osteomyelitis and septic arthritis. 4. **Urinary Tract Infections**: Treatment of acute uncomplicated UTIs. 5. **Endocarditis Prophylaxis**: For certain dental or surgical procedures in high-risk patients. ## Adult Dosing ### Standard Dosing **Surgical Prophylaxis** - **Dose**: **1-2 g** IV - **Frequency**: Administer **30-60 minutes prior to incision**. - **Route**: Intravenous (IV) - **Duration**: May repeat dose every **2-4 hours** intraoperatively for prolonged procedures. - **Special Considerations**: For patients >120 kg, consider **3 g** IV. **Mild to Moderate Infections (e.g., uncomplicated cellulitis, UTI)** - **Dose**: **250 mg - 1 g** IV or IM - **Frequency**: Every **6 to 8 hours** - **Route**: Intravenous (IV), Intramuscular (IM) - **Maximum Dose**: Typically **6 g/day** **Severe Infections (e.g., endocarditis, osteomyelitis, septicemia)** - **Dose**: **1 g - 2 g** IV - **Frequency**: Every **6 to 8 hours** - **Route**: Intravenous (IV) - **Maximum Dose**: Up to **12 g/day** (in life-threatening situations) ### Dose Adjustments - **Renal Impairment**: Adjust frequency based on Creatinine Clearance (CrCl). - CrCl **50-20 mL/min**: Administer standard dose every **8 hours**. - CrCl **19-10 mL/min**: Administer standard dose every **12 hours**. - CrCl **<10 mL/min**: Administer standard dose every **18-24 hours**. - **Hemodialysis**: Administer standard dose post-dialysis; supplemental doses may be needed. - **Hepatic Impairment**: No specific dose adjustment generally needed. - **Elderly Patients**: Adjust based on renal function (CrCl) due to age-related decline. ## Pediatric Dosing ### Neonates (0-28 days) - **Mild to Moderate Infections** - **< 7 days old (<2000 g)**: **25 mg/kg/dose** IV - **Frequency**: Every **12 hours** - **< 7 days old (>2000 g)**: **25 mg/kg/dose** IV - **Frequency**: Every **8 hours** - **7-28 days old (<2000 g)**: **25 mg/kg/dose** IV - **Frequency**: Every **8 hours** - **7-28 days old (>2000 g)**: **25 mg/kg/dose** IV - **Frequency**: Every **6 hours** - **Maximum**: **100 mg/kg/day** for treatment, or up to **50 mg/kg/day** for prophylaxis. - **Special Notes**: Use cautiously; immature renal function increases risk of accumulation. ### Infants (1-12 months) - **Mild to Moderate Infections**: **25-50 mg/kg/day** IV or IM - **Frequency**: Divided every **8 hours** - **Severe Infections**: **100 mg/kg/day** IV or IM - **Frequency**: Divided every **6-8 hours** - **Maximum**: **6 g/day** ### Children (1-12 years) - **Mild to Moderate Infections**: **25-50 mg/kg/day** IV or IM - **Frequency**: Divided every **8 hours** - **Severe Infections**: **100 mg/kg/day** IV or IM - **Frequency**: Divided every **6-8 hours** - **Maximum**: **6 g/day** (or adult maximum dose, whichever is less) ### Adolescents (13-18 years) - **Dose**: Generally follows **adult dosing** guidelines. - **Maximum**: Up to **12 g/day** (for severe infections), otherwise **6 g/day**. ## Safety Information ### Contraindications - **Absolute**: Known serious **hypersensitivity** to cefazolin or any other cephalosporin antibiotics. - **Absolute**: History of immediate and severe **hypersensitivity reaction to penicillin** (e.g., anaphylaxis, Stevens-Johnson syndrome). - **Relative**: History of non-severe penicillin allergy (monitor closely for cross-reactivity). ### Common Adverse Effects - **Common (1-10%)**: - **Gastrointestinal**: Nausea, vomiting, diarrhea. - **Injection site**: Pain, tenderness, phlebitis (IV), induration (IM). - **Hypersensitivity**: Rash, pruritus. - **Hematologic**: Eosinophilia, leukopenia. - **Serious but Rare**: - **Anaphylaxis**: Severe allergic reaction, angioedema. - **Clostridioides difficile-associated diarrhea (CDAD)**: Pseudomembranous colitis. - **Seizures**: Especially with high doses in renal impairment. - **Nephrotoxicity**: Acute interstitial nephritis. - **Hematologic**: Neutropenia, thrombocytopenia, hemolytic anemia. ### Key Drug Interactions - **Warfarin**: May **increase INR** and bleeding risk; monitor INR closely. - **Nephrotoxic Agents (e.g., aminoglycosides, loop diuretics)**: Concomitant use may **increase risk of renal toxicity**; monitor renal function. - **Probenecid**: **Decreases renal clearance** of cefazolin, leading to higher and more prolonged serum concentrations. ## Monitoring & Follow-up - **Before Treatment**: - Obtain **allergy history** (especially to beta-lactams). - Assess **renal function** (CrCl) to guide dosing. - **During Treatment**: - Monitor for **signs of allergic reaction** (e.g., rash, dyspnea). - Monitor for **gastrointestinal side effects** (e.g., diarrhea, abdominal pain). - Monitor **renal function** in patients with pre-existing impairment or on concurrent nephrotoxic drugs. - Monitor for **superinfection** (e.g., oral candidiasis, vaginal yeast infection, CDAD). - Assess **clinical response** to therapy. - **Clinical Signs**: Watch for persistent fever, new rash, significant diarrhea, decreased urine output, or neurological changes. ## Clinical Pearls - 💡 **Gram-positive Coverage**: Excellent activity against many **Gram-positive cocci**, including methicillin-susceptible *Staphylococcus aureus* (MSSA) and streptococci. - 💡 **Surgical Prophylaxis Staple**: It's a first-line choice for preventing infections in many surgical procedures due to its spectrum and favorable safety profile. - 💡 **Administration**: Administer **IV or IM only**; no oral formulation. Ensure proper IV dilution and infusion rate. - 💡 **Penicillin Allergy**: Cross-reactivity with penicillin is generally **low (about 1%)** for first-generation cephalosporins, but caution is warranted with severe penicillin allergy. - 💡 **Renal Dosing**: Always **dose adjust in renal impairment** to prevent accumulation and potential adverse effects like seizures. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.