Generic Name

Cefadroxil

Brand Names

*Cefadex*, *Cefadex FX*, etc.) is a first‑generation, oral β‑lactam cephalosporin. It is widely used for uncomplicated skin and soft‑tissue infections, urinary tract infections, and mild upper‑respiratory tract infections.

Mechanism

• Bacterial cell‑wall inhibition: Cepadroxil binds selectively to membrane‑anchored penicillin‑binding proteins (PBPs) (especially PBP‑3, PBP‑4, PBP‑5), blocking peptidoglycan cross‑linking.
• Result: Increased cell‑wall permeability, osmotic lysis, and bacterial death.
• β‑lactamase resistance: It is moderately resistant to common β‑lactamases produced by gram‑positive cocci but is susceptible to extended‑spectrum β‑lactamases.

Pharmacokinetics

• Route: Oral; capsules or tablets.
• Absorption: ~70 % bioavailability; peak plasma levels at ~2 h.
• Distribution: Low plasma protein binding (<15 %); penetrates skin, soft tissues, bone, and the kidneys efficiently.
• Metabolism: Not metabolized; excreted unchanged.
• Elimination: Renal via glomerular filtration and tubular secretion; half‑life ≈ 2 h in normal renal function.
• Drug interactions: No clinically significant interactions; caution with nephrotoxic agents (e.g., aminoglycosides).

Indications

• Skin & soft‑tissue infections: cellulitis, abscesses, dermatitis, erysipelas (benign, uncomplicated).
• Urinary tract infections: cystitis, pyelonephritis when organisms are susceptible.
• Upper‑respiratory tract infections: pharyngitis, sinusitis, mild otitis media (when no other antibiotic is indicated).
• Dental infections: periapical abscess, periodontal abscess.
• Special Indication: prophylaxis for H. pylori eradication regimens (combination therapy).

Contraindications

• Allergy: Hypersensitivity to cephalosporins, penicillin (especially severe anaphylaxis or systemic reactions).
• Renal impairment: Severe CKD (CrCl <30 mL/min) – dose adjustments or alternative therapy required.
• Pregnancy/Lactation: Category B; routine use is acceptable in pregnancy; lactation is considered safe.
• Warnings:
• Potential for *Clostridioides difficile* colitis, especially with prolonged therapy.
• Rare allergic skin reactions (rash, urticaria, anaphylaxis).
• Crystalluria may occur in fasting or dehydrated patients; advise adequate fluid intake.

Dosing

• Administration: Oral, preferably on an empty stomach for optimal absorption.
• Duration: 7–14 days for uncomplicated infections; may be extended to 21 days for pyelonephritis.

Adverse Effects

• Common:
• Gastrointestinal upset (nausea, vomiting, diarrhea).
• Mild rash or urticaria.
• Headache, dizziness.
• Serious (rare):
• Severe hypersensitivity reactions (anaphylaxis).
• Clostridioides difficile toxic megacolon.
• Hematologic: neutropenia, thrombocytopenia.
• Myocarditis, pericarditis (very rare).

Monitoring

• Renal function: Serum creatinine, BUN, CrCl at baseline, then weekly (if therapy >7 days).
• Complete blood count: Once at baseline; repeat at 2–4 weeks if prolonged therapy.
• Liver function tests: Baseline for patients with hepatic disease.
• Signs of toxicity: Monitor for allergic reactions, GI disturbances, or signs of C. difficile colitis (watery diarrhea, abdominal pain).

Clinical Pearls

1. Bioavailability Advantage – Cefadroxil’s oral bioavailability (≈70 %) far exceeds that of many other first‑generation cephalosporins, allowing effective serum and tissue concentrations without IV formulation.
2. “Safe‐Second‑Line” for Mild Infections – Because of its narrow spectrum, cefadroxil is an excellent oral option for uncomplicated dermatologic or urinary infections when broad‐spectrum agents are not warranted, helping to curb unnecessary antimicrobial exposure.
3. Crystalluria Prevention – In patients with risk factors (fasting, dehydration, high dose), advise adequate oral fluids and consider splitting the dose to reduce peak serum concentration and crystal formation.
4. Synergy with Clindamycin – For MSSA bacteremia or wound infections, a combination of cefadroxil & clindamycin can provide rapid bactericidal activity plus suppression of toxin production; valuable in post‑traumatic or post‑surgical infections.
5. Minimize Cross‑Reacticity – Though cross‑reactivity with penicillin is reported in <5 % of patients, cefadroxil can be cautiously used in patients with a known non‑severe allergy to penicillin; however, in patients with prior anaphylaxis, avoid altogether.
6. Prophylactic Use in H. pylori Regimens – Cefadroxil is often part of a 3‑drug triple therapy for H. pylori eradication (amoxicillin‑based). Its predictable PK and low cost make it a staple in many clinical laboratories.

*Prepared for medical students and healthcare professionals seeking a quick yet comprehensive reference on cefadroxil.*