Class: First-Generation Cephalosprin
Dosage Forms. Powder for Suspension: 125 mg/5 mL, 250 mg/5 mL; Tablet: 250 mg, 500 mg; Capsule: 250 mg, 500 mg, 750 mg
Common FDA Label Indication, Dosing, and Titration.
1. Infection of skin and/or subcutaneous tissue: Adults, 500 mg po q12h; Children, 25-50 mg/kg/d po divided q12h
2. Osteomyelitis: Adults, 250 mg-1 g po q6h; Children, 25-100 mg/kg/d po divided q6h, max 4 g/d
3. Otitis media, respiratory tract infection, urinary tract infection: Adults, 250 mg-1 g po q6h; Children: 25-100 mg/kg/d po divided q6h, max 4 g/d
4. Streptococcal pharyngitis: Adults, 500 mg po q12h × 10 d; Children, 25-50 mg/kg/d po divided q6h × 10 d, max 4 g/d
1. Bacterial endocarditis; prophylaxis for high-risk patients; dental, respiratory, or infected skin/skin structure or musculoskeletal tissue procedures: Adults, 2 g po 30-60 min prior to procedure; Children, 50 mg/kg 30-60 min prior to procedure
MOA. Cephalexin is a first-generation cephalosprin that inhibits bacterial wall synthesis of actively dividing cells by binding to one or more penicillin-binding proteins (PBPs). Most Gram-positive bacteria, including non-penicillinase and penicillinase-producing staphylococci, and streptococci. Activity against Gram-negative bacteria is less than that observed with the second- and third-generation cephalosporins and is primarily restricted to Escherichia coli, Klebsiella, and Proteus mirabilis.
Drug Characteristics: Cephalexin
Medication Safety Issues: Cephalexin
Drug Interactions: Cephalexin
Adverse Reactions: Cephalexin
Efficacy Monitoring Parameters. Resolution of signs and symptoms of infection.
Toxicity Monitoring Parameters. Seek medical attention if decreased urination, blistering skin rash or extreme fatigue, unusual bruising or bleeding, shortness of breath.
Key Patient Counseling Points. Seek medical attention if rash develops. Complete full course of therapy. For the suspension, shake well and store in the refrigerator. Note short expiration after reconstitution. Avoid mixing suspension with food or beverages, but food can be taken afterward. Symptoms should improve within 2-3 d; if they worsen, seek follow-up with healthcare practitioner.
Clinical Pearls. May resume normal activities after 24 h of antibiotics and if afebrile. Ten percent of patients allergic to penicillins are also allergic to cephalosporins; use with caution in penicillin-allergic patients.