Usage
Cefadroxil, a first-generation cephalosporin antibiotic, is primarily prescribed for treating bacterial infections susceptible to its action. These include:
- Upper respiratory tract infections: Pharyngitis, tonsillitis (caused by Streptococcus pyogenes)
- Lower respiratory tract infections: Bronchopneumonia, bacterial pneumonia (Streptococcus pneumoniae, Streptococcus pyogenes, Klebsiella pneumoniae, Staphylococcus aureus)
- Urinary tract infections: Cystitis, pyelonephritis (Escherichia coli, Proteus mirabilis, Klebsiella species)
- Skin and soft tissue infections: Abscesses, furunculosis, impetigo, erysipelas, pyoderma, lymphadenitis (Staphylococcus aureus, Streptococcus pyogenes)
Pharmacological Classification: Antibiotic, specifically a first-generation cephalosporin.
Mechanism of Action: Cefadroxil inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs). This binding disrupts the transpeptidation process, ultimately leading to bacterial cell death.
Alternate Names
Cefadroxil is also known as cefadroxil monohydrate (the monohydrate form) or cefadroxil hemihydrate. Brand names include Duricef and Ultracef.
How It Works
Pharmacodynamics: Cefadroxil exerts its bactericidal effect by disrupting the synthesis of the bacterial cell wall. It preferentially targets actively growing bacteria.
Pharmacokinetics:
- Absorption: Cefadroxil is rapidly absorbed after oral administration, reaching peak plasma concentrations within 70-90 minutes. Administration with food may enhance absorption and reduce gastrointestinal side effects.
- Distribution: Cefadroxil has a volume of distribution of approximately 0.31 L/kg and is about 20% protein-bound. It achieves therapeutic concentrations in various tissues and fluids, including urine.
- Metabolism: Cefadroxil is primarily excreted unchanged in the urine. Minimal metabolism occurs.
- Elimination: Cefadroxil is predominantly eliminated via renal excretion (>90% within 24 hours), with a half-life of 1-2 hours in adults with normal renal function, 1.3-1.8 hours in children, and significantly prolonged (up to 24 hours) in adults with renal failure. Hemodialysis can remove a substantial portion of the drug.
Mode of Action: Cefadroxil binds to specific PBPs located on the inner bacterial cell membrane. These PBPs are crucial enzymes involved in the final stages of peptidoglycan synthesis, an essential component of the bacterial cell wall. By inhibiting PBPs, cefadroxil weakens the cell wall, leading to cell lysis and bacterial death.
Elimination Pathways: Primarily renal excretion of the unchanged drug.
Dosage
Standard Dosage
Adults:
- Most infections: 1-2 g/day orally, given as a single dose or divided every 12 hours.
- Pharyngitis/Tonsillitis: 1 g/day for 10 days.
- Urinary Tract Infections: Up to 2g/day given as a single or in divided doses.
Children:
- Most infections: 30 mg/kg/day orally, given in a single dose or divided every 12 hours. Maximum dose: Generally not exceeding 1 g/day, but up to 2 g/day has been used for certain indications.
- Pharyngitis, Tonsillitis, Impetigo: 30 mg/kg/day, given once daily or divided every 12 hours for 10 days.
Special Cases:
- Elderly Patients: Dosage adjustment may be necessary based on renal function.
- Patients with Renal Impairment: Dosage adjustment is crucial.
- CrCl >50 mL/min: No adjustment needed.
- CrCl 25-50 mL/min: Administer every 12 hours.
- CrCl 10-25 mL/min: Administer every 24 hours.
- CrCl <10 mL/min: Administer every 36 hours. Hemodialysis patients require supplemental doses.
- Patients with Hepatic Dysfunction: No dosage adjustment typically needed.
- Patients with Comorbid Conditions: Monitor closely. Consider dose adjustments depending on interactions with other medications.
Clinical Use Cases
Cefadroxil is not typically the preferred agent for intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations requiring rapid bacterial control. These scenarios often call for intravenous antibiotics offering broader coverage and rapid onset of action. Cefadroxil’s use is generally restricted to mild-moderate infections treatable with oral administration.
Dosage Adjustments
See “Special Cases” under “Standard Dosage”. Dosage modifications are crucial for patients with renal impairment, with adjustments based on creatinine clearance.
Side Effects
Common Side Effects:
- Diarrhea
- Nausea
- Vomiting
- Rash
- Abdominal pain/discomfort
- Vaginal itching or discharge
Rare but Serious Side Effects:
- Clostridium difficile-associated diarrhea (pseudomembranous colitis)
- Stevens-Johnson Syndrome
- Toxic epidermal necrolysis
- Allergic reactions (including anaphylaxis)
- Serum sickness
- Hemolytic anemia
- Agranulocytosis
- Thrombocytopenia
- Seizures (especially in patients with renal impairment)
Long-Term Effects:
- Superinfection (overgrowth of resistant organisms)
- Renal dysfunction
Adverse Drug Reactions (ADR):
Any signs of severe allergic reaction, skin reactions (SJS/TEN), C. difficile colitis require immediate medical attention. Seizures and signs of blood dyscrasias also warrant prompt intervention.
Contraindications
- Known hypersensitivity to cephalosporins or penicillins
Drug Interactions
- Probenecid: Increases cefadroxil serum concentrations.
- Anticoagulants (warfarin): May enhance anticoagulant effects.
- Oral contraceptives: Efficacy of oral contraceptives may be reduced.
- Nephrotoxic drugs (aminoglycosides, certain diuretics): Increased risk of renal toxicity.
- BCG and typhoid vaccines: Cefadroxil can interfere with the immune response.
Pregnancy and Breastfeeding
- Pregnancy: Cefadroxil is generally considered safe during pregnancy, but its use should be carefully weighed against potential risks. Consult guidelines for updated safety information.
- Breastfeeding: Cefadroxil passes into breast milk in low concentrations, posing minimal risk to infants. However, monitor infants for diarrhea or thrush.
Drug Profile Summary
- Mechanism of Action: Inhibits bacterial cell wall synthesis by binding to PBPs.
- Side Effects: Diarrhea, nausea, rash; rarely serious allergic reactions, C. difficile colitis, skin reactions.
- Contraindications: Hypersensitivity to cephalosporins or penicillins.
- Drug Interactions: Probenecid, anticoagulants, oral contraceptives, nephrotoxic drugs.
- Pregnancy & Breastfeeding: Generally considered safe; consult current guidelines.
- Dosage: Adults: 1-2 g/day; Children: 30 mg/kg/day; adjust for renal impairment.
- Monitoring Parameters: Renal function, signs of allergic reaction, superinfection.
Popular Combinations
Cefadroxil is typically used as monotherapy. Combinations are generally not recommended unless specifically indicated by the clinical situation.
Precautions
- Assess for allergy to cephalosporins and penicillins.
- Evaluate renal function, especially in elderly patients.
- Monitor for signs of superinfection.
- Caution in patients with a history of gastrointestinal disorders.
- Driving may be impaired due to side effects like dizziness or fatigue.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Cefadroxil?
A: Adults: 1-2 g/day; Children: 30 mg/kg/day. Dosage adjustments are needed for renal impairment.
Q2: What infections does Cefadroxil treat?
A: Primarily skin and soft tissue infections, urinary tract infections, and upper/lower respiratory tract infections caused by susceptible bacteria.
Q3: What is the mechanism of action of Cefadroxil?
A: Cefadroxil inhibits bacterial cell wall synthesis by binding to and inactivating penicillin-binding proteins.
Q4: Is Cefadroxil safe in pregnancy?
A: Generally considered safe, but consult latest guidelines for updated recommendations.
Q5: What are the most common side effects of Cefadroxil?
A: Diarrhea, nausea, vomiting, rash.
Q6: What are the serious side effects of Cefadroxil?
A: Allergic reactions (including anaphylaxis), Stevens-Johnson syndrome, C. difficile-associated diarrhea, seizures.
Q7: Does Cefadroxil interact with other medications?
A: Yes. Important interactions occur with probenecid, anticoagulants, and oral contraceptives.
Q8: How is Cefadroxil eliminated from the body?
A: Primarily through renal excretion.
Q9: Should dosage be adjusted in patients with kidney disease?
A: Yes, dosage adjustment is essential in patients with renal impairment, based on creatinine clearance.
Q10: What is the duration of treatment for strep throat with Cefadroxil?
A: At least 10 days to prevent rheumatic fever.
