Cefpodoxime

Cefpodoxime is an oral third-generation cephalosporin, given as the proxetil prodrug, with better staphylococcal activity than cefixime. It is used for respiratory, urinary, skin and throat infection and as step-down therapy after ceftriaxone.

Classification. Beta-lactam, third-generation cephalosporin, oral prodrug.

Mechanism. Blocks penicillin-binding proteins; stable to many beta-lactamases but not to ESBLs.

Spectrum. Streptococci, pneumococci (penicillin-susceptible), MSSA (moderate), Haemophilus, Moraxella, Neisseria, and non-ESBL Escherichia coli, Klebsiella and Proteus. Not active against MRSA, enterococci, Pseudomonas or anaerobes.

Pharmacokinetics. Oral bioavailability about 50%, increased by food. Half-life 2 to 3 hours. About 30 to 40% excreted unchanged in urine. Absorption falls by about 30% with antacids or H2-receptor antagonists.

No loading dose. Maximum 800 mg daily in adults.

Adults. - Pharyngitis and tonsillitis: 100 mg every 12 hours for 5 to 10 days. - Acute sinusitis: 200 mg every 12 hours for 10 days. - Community-acquired pneumonia and exacerbation of chronic bronchitis: 200 mg every 12 hours for 5 to 14 days depending on severity. - Skin and soft tissue infection: 400 mg every 12 hours for 7 to 14 days. - Uncomplicated cystitis: 100 mg every 12 hours for 3 days. - Uncomplicated gonorrhoea: 200 mg as a single oral dose (use only if susceptibility is confirmed).

Children 2 months to 12 years. 5 mg/kg every 12 hours (maximum 200 mg a dose); for pharyngitis maximum 100 mg a dose; for skin infection up to 10 mg/kg every 12 hours (maximum 400 mg a dose).

Alternatives. Cefixime, cefuroxime, amoxicillin clavulanate, azithromycin.

Contraindications. Cephalosporin hypersensitivity.

Adverse effects. Diarrhoea, nausea, vaginal candidiasis, rash, headache, Clostridioides difficile infection. Serious: anaphylaxis, severe skin reactions, interstitial nephritis, haemolytic anaemia, cytopenias, hepatitis, seizures in renal failure.

Interactions. Antacids and H2-receptor antagonists reduce absorption; probenecid raises levels; nephrotoxic drugs; oral typhoid vaccine.

Common prescribing errors. Giving tablets without food, giving at the same time as antacids, and using it for MRSA or severe infection.

Special groups. - Pregnancy and breastfeeding: acceptable. - Older adults: reduce by kidney function. - Kidney impairment: creatinine clearance under 30 mL/min give the usual dose every 24 hours; haemodialysis give three times weekly after the session. - Liver impairment: no adjustment in cirrhosis. - Region: availability in East Africa varies.

Formulations. Tablets 100 mg and 200 mg; suspension 50 mg and 100 mg in 5 mL. Take tablets with food.

Baseline and monitoring. - Baseline: allergy history, creatinine if risk of kidney disease. - During treatment: review at 48 to 72 hours; creatinine and full blood count in courses over 14 days. - No therapeutic drug monitoring.

Stop rules. Stop for anaphylaxis, severe rash, or persistent diarrhoea with fever.

Referral and escalation. Refer for treatment failure, suspected resistant organisms and complications of respiratory infection.