Generic Name

Cefdinir

Brand Names

Omnicef) is a third‑generation oral cephalosporin with high activity against a broad spectrum of gram‑positive and gram‑negative bacteria. It is widely prescribed for respiratory and airway infections in both children and adults due to its favorable safety profile and convenient dosing schedule.

Mechanism

*Cefdinir* inhibits bacterial cell wall synthesis by binding to penicillin‑binding proteins (PBPs), particularly PBP2a and PBP3, thereby blocking transpeptidation of peptidoglycan chains. This leads to cell lysis and death. Its third‑generation structure confers resistance to many β‑lactamases, maintaining efficacy against β‑lactamase–producing organisms (e.g., *Streptococcus pneumoniae*, *Haemophilus influenzae*).

Pharmacokinetics

• Absorption: 77 %–85 % bioavailable following oral administration; not affected by food after 4 h.
• Distribution: 66 % protein binding; extensive tissue distribution (e.g., lung, sinus mucosa).
• Metabolism: Minimal hepatic metabolism; 25 % excreted unchanged in bile, ~70 % renal.
• Elimination half‑life: 5.5 h (childhood), 6–8 h (adults) → steady‑state reached within 2–3 days.
• Renal adjustment: Dose reductions for CrCl <30 mL/min. No dosing adjustment in mild–moderate hepatic impairment.

Indications

• Upper Respiratory Tract Infections (URTI)
• Acute otitis media (unsusceptible hearing loss test)
• Acute sinusitis (culture‑verified or severe cases)
• Community‑acquired pneumonia (CAP)
• Lower Respiratory Tract Infections (LRTI)
• Bacterial bronchitis
• Acute exacerbations of chronic bronchitis
• Pharyngitis (GABHS) – preferred oral β‑lactam when penicillin allergy is not severe
• Skin & Soft Tissue infections – mild–moderate community acquired skin infections
• Non‑bacterial indications – none specified; off‑label use occurs rarely

Contraindications

• Contraindications
• Hypersensitivity to cephalosporins or penicillins (anaphylaxis, urticaria, angioedema)
• Severe renal impairment (CrCl <15 mL/min)
• Warnings
• Clostridioides difficile‑associated diarrhea (CDAD) – similar risk to other β‑lactams; monitor GI symptoms
• Liver dysfunction – rare hepatotoxicity; monitor LFT in prolonged therapy
• Gastrointestinal irritation – avoid in patients with peptic ulcer disease or gastritis
• Adverse drug reactions – consider concomitant anticonvulsants for increased serum levels.

Dosing

• Take on an empty stomach; dose time should be 2 h before/after meals.
• Tableware: Reconstitute in water or coffee; read dosage titration pearls.

Adverse Effects

• Common (≥ 1 %–5 %)
• Nausea, vomiting, diarrhea
• Headache, dizziness
• Rash (maculopapular, urticaria)
• Abnormal liver function tests (transaminitis)
• Serious (≤ < 1 %)
• Anaphylaxis – signs: angioedema, bronchospasm, hypotension
• Severe gastrointestinal: C. difficile infection – watery/purple stools
• Severe skin reactions – Stevens–Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN)
• Hepatotoxicity – hepatic failure, jaundice
• Severe neutropenia – risk of secondary infections

Monitoring

• Renal function – baseline CrCl; repeat if CrCl 7 days.
• Liver Panel – baseline & after 1–2 weeks of prolonged use.
• Clinical signs of CDAD – monitor stools, report any diarrheal episodes.
• Allergy History – detailed history before initial dose.
• Therapeutic Outcomes – resolution of fever, cough, or otalgia by day 3–5.

Clinical Pearls

• Gut‑health friendly dosing – *Cefdinir* has minimal biliary excretion, leading to a lower risk of CDAD compared with other cephalosporins.
• Bacterial coverage – active also against *Streptococcus pneumoniae* with reduced penicillin‑sensitivity; ideal for CAP resistant organisms.
• Children – can use liquid formulation; dose based purely on weight; no binding to NSAIDs.
• Pseudomonas – not active; avoid for Pseudomonas‑predominant infections.
• Drug interaction – co‑administration with antacids can reduce absorption; recommend staggered dosing.
• Allergy cross‑reactivity – consider lower risk of cross‑reactivity with penicillin if 12–24 h interval between exposures.
• Supersaturation – avoid taking multiple cefdinir doses within 24 h to minimize GI irritation.
• Respiratory pipeline – combine with azithromycin only for multi‑drug resistant CAP.

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• Reference: U.S. FDA prescribing information; UpToDate, “Cefdinir – adverse events, warnings, and drug interactions”; Sanford Guide 2024.