cefadroxil
Duricef

Available forms
Available by prescription only
Capsules: 500 mg
Suspension: 125 mg/5 ml, 250 mg/5 ml, 500 mg/ 5 ml
Tablets: 1 g

Indications and dosages
 Urinary tract, skin, and soft-tissue infections caused by susceptible organisms; pharyngitis; tonsillitis. Adults: 1 to 2 g P.O. daily, depending on the infection treated. Usually given once or twice daily.
Children: 30 mg/kg P.O. daily in two divided doses.
≡ Dosage adjustment. Adjust dosage, based on creatinine clearance, as shown in below. Because drug is dialyzable, patients receiving treatment with hemodialysis may require dosage adjustment.

Creatinine clearance (ml/min) Dosage interval (hr) 25-50 12 10-25 24 < 10 36

Pharmacodynamics
Antibacterial action: Cefadroxil is primarily bactericidal; it also may be bacteriostatic. Activity depends on the organism, tissue penetration, dosage, and rate of organism multiplication. It acts by adhering to bacterial penicillin-binding proteins, thereby inhibiting cell wall synthesis.
Cefadroxil is active against many gram-positive cocci, including penicillinase-producing Staphylococcus aureus and Staphylococcus epidermidis; Streptococcus pneumoniae, group B streptococci, and group A beta-hemolytic streptococci; and susceptible gram-negative organisms, including Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis.

Pharmacokinetics
Absorption: Absorbed rapidly and completely from the GI tract after oral administration.
Distribution: Distributed widely into most body tissues and fluids, including the gallbladder, liver, kidneys, bone, bile, sputum, and pleural and synovial fluids; CSF penetration is poor. Drug crosses the placental barrier; it’s 20% protein-bound.
Metabolism: Not metabolized.
Excretion: Excreted primarily unchanged in urine by way of glomerular filtration and renal tubular secretion; small amounts may appear in breast milk. End-stage renal disease prolongs half-life to 25 hours. Drug can be removed by hemodialysis.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug or other cephalosporins. Use cautiously in breast-feeding women and patients with impaired renal function or penicillin allergy.

Interactions
Drug-drug. Bacteriostatic drugs (chloramphenicol, erythromycin, tetracyclines): May interfere with bactericidal activity. Use cautiously.
Loop diuretics, nephrotoxic drugs (aminoglycosides, colistin, polymyxin B, vancomycin): May increase risk of nephrotoxicity. Monitor patient closely.
Probenecid: Competitively inhibits renal tubular secretion of cephalosporins, resulting in higher, prolonged serum levels of these drugs. Use together cautiously.

Adverse reactions
CNS: seizures, fever.
GI: pseudomembranous colitis, nausea, vomiting, diarrhea, glossitis, abdominal cramps, oral candidiasis.
GU: genital pruritus, candidiasis, vaginitis, renal dysfunction.
Hematologic: transient neutropenia, eosinophilia, leukopenia, anemia, agranulocytosis, thrombocytopenia.
Respiratory: dyspnea.
Skin: maculopapular and erythematous rashes, urticaria.
Other: hypersensitivity reactions (serum sickness, anaphylaxis, angioedema).

Effects on lab test results
• May increase ALT, AST, alkaline phosphatase, bilirubin, GGT, and LDH levels.
• May increase eosinophil count. May decrease hemoglobin. hematocrit, and neutrophil, WBC, granulocyte, and platelet counts.

Overdose and treatment
Overdose may cause neuromuscular hypersensitivity; seizures may follow high CNS levels.
 Remove cefadroxil by hemodialysis. Other treatment is supportive.

Special considerations
• Longer half-life of this drug permits once- or twice-daily dosing.
• With large doses or prolonged therapy, monitor patient for superinfection, especially if high-risk.
• In patients with suspected renal impairment, monitor renal function tests before and during therapy.
• Cefadroxil causes false-positive results in urine glucose tests using cupric sulfate (Benedict’s reagent or Clinitest); use glucose oxidase test (Chemstrip uG, Diastix, or glucose enzymatic test strip) instead. Cefadroxil causes false elevations in serum or urine creatinine levels in tests using Jaffe reaction.
• Positive Coombs’ test results occur in about 3% of patients taking cephalosporins.
Breast-feeding patients
• Drug appears in breast milk; use cautiously in breast-feeding women.
Pediatric patients
• Serum half-life is prolonged in neonates and infants younger than age 1.
Geriatric patients
• Reduce dosage in elderly patients with diminished renal function.

Patient education
• Inform patient of potential adverse reactions.
• Instruct patient to take medication with food to lessen GI discomfort.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use