Cephalexin

General

Keflex, Biocef, and others
Antibiotic, cephalosporin (first generation)

No	Yes	1	B

Key

Caps and tabs: 250, 500 mg

Oral suspension: 125 mg/5 mL, 250 mg/5 mL (100, 200 mL)

Dosing

Infant and child: 25–100 mg/kg/24 hr PO ÷ Q6 hr. Less frequent dosing (Q8–12 hr) can be used for uncomplicated infections. Total daily dose may be divided Q12 hr for streptococcal pharyngitis (>1 yr) and skin/skin structure infections.

Adult: 1–4 g/24 hr PO ÷ Q6 hr

Max. dose (all ages): 4 g/24 hr

Bacterial endocarditis prophylaxis for dental and upper respiratory procedures:
Infant and child: 50 mg/kg PO (max. dose: 2 g) 1 hr before procedure
Adult: 2 g PO 1 hr before procedure

Notes

Some cross-reactivity with penicillins. Use with caution in renal insufficiency. May cause GI discomfort, false-positive urine reducing substance (Clinitest and other copper reduction method tests) and Coombs’ test; false elevation of serum theophylline levels (HPLC method); and false urinary protein test. Probenecid increases serum cephalexin levels and concomitant administration with cholestyramine may reduce cephalexin absorption. May increase the effects of metformin.

Administer doses on an empty stomach; 2 hr prior or 1 hr after meals. Adjust dose in renal failure (seeChapter 31).