Cephalexin
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Trade Name
Keflex (primary brand name); generic cephalexin
Classification
First-generation cephalosporin antibiotic; beta-lactam
Dosage/Route
- * Dosage:
- – Capsules: 250 mg, 500 mg, 750 mg
- – Suspension: 125 mg/5 mL, 250 mg/5 mL
- – Tablets: 250 mg, 500 mg
- * Route: Oral (PO)
Usual Dosage
- * Adults: 250-500 mg PO every 6 hours (QID) or 500 mg every 12 hours (BID); max 4 g/day
- * Children: 25-50 mg/kg/day PO divided QID or BID; max 4 g/day
- * Severe Infections: Up to 100 mg/kg/day in kids or 1 g QID in adults
- * Duration: 7-14 days (e.g., 10 days for strep throat)
Mechanism of Action
Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, disrupting peptidoglycan cross-linking. Bactericidal against gram-positive bacteria (e.g., Streptococcus, Staphylococcus) and limited gram-negative bacteria (e.g., E. coli, Klebsiella)
Side Effects & Adverse Effects
- * Side Effects: Diarrhea, nausea, rash, abdominal pain
- * Adverse Effects:
- – Hypersensitivity (rash, anaphylaxis; ~5-10% cross-reactivity with penicillin allergy)
- – Clostridioides difficile-associated diarrhea (CDAD)
- – Rare: Hematologic (e.g., neutropenia), nephrotoxicity
Nursing Management (Implications & Teachings)
- * Implications:
- – Assess for penicillin/cephalosporin allergy (anaphylaxis risk) before first dose
- – Monitor GI symptoms (diarrhea = CDAD) and rash (hypersensitivity)
- – Culture/sensitivity before starting if possible (confirm susceptibility)
- – Give with food if GI upset occurs; suspension stable at room temp
- * Teachings:
- – Finish full course; don’t skip doses
- – Report hives, swelling, or severe diarrhea
- – Shake suspension well; take evenly spaced (e.g., 6 AM, noon, 6 PM, midnight)
- – Store capsules in cool, dry place
Indication for This Patient
* Bacterial infections:
- – Skin/soft tissue (e.g., cellulitis, impetigo; S. aureus, non-MRSA)
- – Respiratory (e.g., strep throat, tonsillitis)
- – UTI, bone infections (susceptible organisms)
Time
- * Timing: Every 6 or 12 hours (QID or BID)
- * Onset: Symptom relief in 1-3 days
- * Duration: 7-14 days (infection-specific)
