Drug reference

Phenoxymethylpenicillin

Penicillin · Antibiotic

Also known as Penicillin V

PenicillinAntibiotic

CDSCO approvedSchedule H

EXCRETION

—

not curated

INTERACTIONS

1 major

SEVERE in our sources

PREGNANCY

Not known to be harmful

FDA category + note

Top interactions

MethotrexateSevereDatabaseDDInter

Mechanism

Phenoxymethylpenicillin (penicillin V) is an acid-stable penicillin that inhibits bacterial cell wall synthesis by binding to PBPs and blocking peptidoglycan transpeptidation. The phenoxymethyl side chain protects the beta-lactam ring from gastric acid hydrolysis, enabling reliable oral absorption — unlike penicillin G which is degraded in the stomach. Its narrow spectrum covers streptococci, oral anaerobes, and non-penicillinase-producing staphylococci, making it the drug of choice for streptococcal pharyngitis and rheumatic fever prophylaxis.

Indications

Respiratory-tract infections in childrenStreptococcal tonsillitisContinuing treatment after one or more injections of benzylpenicillin sodium when clinical response has begunProphylaxis against streptococcal infections following rheumatic feverProphylaxis against pneumococcal infections following splenectomy or in sickle-cell diseaseOral infectionsOtitis mediaAcute sore throatPrevention of recurrent cellulitis (specialist use only)Prevention of recurrent erysipelas (specialist use only)Prevention of recurrence of rheumatic feverPrevention of secondary case of invasive group A streptococcal infection

Dosing

Adult: Pharyngitis: 500 mg QDS or 1 g BD for 5-10 days. Oral infections: 500 mg every 6h, up to 1 g every 6h. Rheumatic fever prophylaxis: 250 mg BD.
Pediatric: 1-5 years: 125 mg QDS or 250 mg BD. 6-11 years: 250 mg QDS or 500 mg BD. 12-17 years: adult doses. Rheumatic fever prophylaxis: 1-5 years 125 mg BD; 6-17 years 250 mg BD.
Max dose: 4 g/day (1 g QDS)