Cephalexin

cephalexin

(sef a lex' in)

cephalexin

Apo-Cephalex (CAN), Biocef, Keflex, Novo-Lexin (CAN), Nu-Cephalex (CAN)

Pregnancy Category B

Drug classes

Antibiotic

Cephalosporin (first generation)

Therapeutic actions

Bactericidal: Inhibits synthesis of bacterial cell wall, causing cell death.

Indications

·        Respiratory tract infections caused by Streptococcus pneumoniae, group A beta-hemolytic streptococci

·        Skin and skin structure infections caused by staphylococcus, streptococcus

·        Otitis media caused by S. pneumoniae, Haemophilus influenzae, streptococcus, staphylococcus, Moraxella catarrhalis

·        Bone infections caused by staphylococcus, Proteus mirabilis

·        GU infections caused by Escherichia coli, P. mirabilis, Klebsiella

Contraindications and cautions

·        Contraindicated with allergy to cephalosporins or penicillins.

·        Use cautiously with renal failure, lactation, pregnancy.

Available forms

Capsules—250, 500 mg; tablets—250, 500 mg, 1 g; oral suspension—125, 250 mg/5 mL

Dosages

ADULTS

1–4 g/day in divided doses; 250 mg PO q 6 hr usual dose.

·        Skin and skin structure infections: 500 mg PO q 12 hr. Larger doses may be needed in severe cases; do not exceed 4 g/day.

PEDIATRIC PATIENTS

25–50 mg/kg/day PO in divided doses.

·        Skin and skin structure infections: Divide total daily dose, and give q 12 hr. Dosage may be doubled in severe cases.

·        Otitis media: 75–100 mg/kg/day PO in four divided doses.

Pharmacokinetics

Route	Peak	Duration
PO	60 min	8–10 hr

Metabolism: T_1/2: 50–80 min

Distribution: Crosses the placenta, enters breast milk

Excretion: Urine

Adverse effects

·        CNS: Headache, dizziness, lethargy, paresthesias

·        GI: Nausea, vomiting, diarrhea, anorexia, abdominal pain, flatulence, pseudomembranous colitis, liver toxicity

·        GU: Nephrotoxicity

·        Hematologic: Bone marrow depression

·        Hypersensitivity: Ranging from rash to fever to anaphylaxis; serum sickness reaction

·        Other: Superinfections

Interactions

Drug-drug

·        Increased nephrotoxicity with aminoglycosides

·        Increased bleeding effects with oral anticoagulants

·        Disulfiram-like reaction may occur if alcohol is taken within 72 hr after cephalexin administration.

Drug-lab test

·        Possibility of false results on tests of urine glucose using Benedict's solution, Fehling's solution, Clinitest tablets; urinary 17-ketosteroids; direct Coombs' test.

Nursing considerations

Assessment

·        History: Penicillin or cephalosporin allergy, pregnancy, or lactation

·        Physical: Renal function tests, respiratory status, skin status; culture and sensitivity tests of infected area

Interventions

·        Arrange for culture and sensitivity tests of infection before and during therapy if infection does not resolve.

·        Give drug with meals; arrange for small, frequent meals if GI complications occur.

·        Refrigerate suspension, discard after 14 days.

Teaching points

·        Take this drug with food. Refrigerate suspension; discard any drug after 14 days.

·        Complete the full course of this drug even if you feel better.

·        This drug is prescribed for this particular infection; do not self-treat any other infection.

·        You may experience these side effects: Stomach upset, loss of appetite, nausea (take drug with food); diarrhea; headache, dizziness.

·        Report severe diarrhea with blood, pus, or mucus; rash or hives; difficulty breathing; unusual tiredness, fatigue; unusual bleeding or bruising.

Adverse effects in Italic are most common; those in Bold are life-threatening.