Indications: throat infections, otitis media, endocarditis, meningococcal disease, pneumonia, cellulitis; anthrax; prophylaxis in limb amputation.

Caution history of allergy; false-positive urinary glucose (if tested for reducing substances); renal impairment.

Contra-indications: penicillin hypersensitivity.

Side Effects: hypersensitivity reactions including urticaria, fever, joint pains, rashes, angioedema, anaphylaxis, serum sickness-like reaction; rarely CNS toxicity including convulsions (especially with high doses or in severe renal impairment), interstitial nephritis, haemolytic anaemia, leucopenia, thrombocytopenia, and coagulation disorders; also reported diarrhoea (including antibiotic-associated colitis).

Dose: By intramuscular or by slow intravenous injection or by infusion, 2.4–4.8 g daily in 4 divided doses, increased if necessary in more serious infections (single doses over 1.2 g intravenous route only); PRETERM NEONATE and NEONATE under 1 week, 50 mg/kg daily in 2 divided doses; NEONATE 1–4 weeks, 75 mg/kg daily in 3 divided doses; CHILD 1 month–12 years, 100 mg/kg daily in 4 divided doses; intravenous route recommended in neonates and infants.

Endocarditis (in combination with another antibacterial if necessary), by slow intravenous injection or by infusion, 7.2 g daily in 6 divided doses, increased if necessary (e.g. in enterococcal endocarditis or if benzyl penicillin used alone) to 14.4 g daily in 6 divided doses.

Anthrax (in combination with other antibacterial, by slow intravenous injection or by infusion, 2.4 g every 4 hours; CHILD 150 mg/kg daily in 4 divided doses.

Intrapartum prophylaxis against group B streptococcal infection, by slow intravenous injection or by infusion, initially 3 g then 1.5 g every 4 hours until delivery.

Meningococcal disease, by slow intravenous injection or by infusion, 2.4 g every 4 hours; PRETERM NEONATE and NEONATE under 1 week, 100 mg/kg daily in 2 divided doses; NEONATE 1–4 weeks, 150 mg/kg daily in 3 divided doses; CHILD 1 month–12 years, 180–300 mg/kg daily in 4–6 divided doses.

Important: If bacterial meningitis and especially if meningococcal disease is suspected: a single injection of benzylpenicillin by intravenous injection (or by intramuscular injection) followed by continuous monitoring at the hospital. Suitable doses are:

ADULT 1.2 g; INFANT under 1 year 300 mg; CHILD 1–9 years 600 mg, 10 years and over as for adult.

By intrathecal injection, not recommended.