Indications: syphilis; penicillin-sensitive infections, active against some gram positive organisms and against few gram negative organisms e.g. Neisseria gonorrhoea.

Cautions: avoid intravascular route since ischaemic reactions may occur.

Contra-indications: hypersensitivity to penicillin.

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), interst haemolytic anaemia, leucopenia, thrombocytopenia, and coagulation disorders; also reported diarrhoea (including antibiotic-associated colitis)

Dose: deep IM injection in usual dose of 900 mg for treatment of streptococcal infections Children may be given IM doses of 225-675 mg according to body weight To prevent recurrences of acute rheumatic fever, 900 mg IMevery 4 weeks.

Note: 900 mg of Benzathine penicillin = 720 mg of Benzylpenicillin (1.2 million units) approximately.