WHO Model Prescribing Information: Drugs Used in the Treatment of Streptococcal Pharyngitis and Prevention of Rheumatic Fever
(1999; 18 pages) View the PDF document
Table of Contents
View the documentPreface
View the documentIntroduction
Open this folder and view contentsManagement of group a streptococcal upper respiratory tract infection
View the documentTable 1. Treatment of Group a Streptococcal Pharyngitis (Primary Prevention of Rheumatic Fever).
View the documentTable 2. Prevention of Recurrences of Rheumatic Fever by Prevention of Group A Streptococcal Infections in Individuals who have had an initial attack of Rheumatic Fever (Secondary Prophylaxis).
Close this folderDrug Data sheets
View the documentBenzathine Benzylpenicillin
View the documentPhenoxymethylpenicillin
View the documentErythromycin
View the documentSulfadiazine or Sulfisoxazole

Benzathine Benzylpenicillin

powder for injection 1.44 g (2.4 million IU) in 5 ml vial

Benzylpenicillin is a natural substance derived from Penicillium notatum. It consists of a thiazolidone ring connected to a beta-lactam ring. It is bactericidal against streptococci, neisseriae, many anaerobes and spirochaetes.

After intramuscular injection, peak plasma concentrations are usually reached within 12-24 hours and are usually detectable for 1- 4 weeks. It is widely distributed throughout the body and is excreted mainly in the urine.

Uses: Streptococcal pharyngitis. Primary and secondary prophylaxis of rheumatic fever.

Dosage and administration:

Primary prophylaxis:

Children < 30 kg 600,000 IU, a single injection


Children 30 kg and adults


1,200,000 IU, a single injection

Secondary prophylaxis:

Children < 30 kg 600,000 IU, every 3-4 weeks


Children 30 kg and adults


1,200,000 IU, every 3-4 weeks

The vial is diluted in sterile water to allow for a homogeneous suspension to be obtained to avoid obstruction of the injecting needle. A needle gauge of #19 or #20 is preferred. Smaller bore needles have been noted to be more easily obstructed. The injection should be deep into the gluteus maximus muscle. More superficial injections allow the benzathine benzylpenicillin to remain in the subcutaneous tissue leading to decreased absorption and lower serum levels. Care should be taken that the whole content of the vial is fully removed and injected.

Contraindications: Known hypersensitivity to penicillin or cefalosporins.

Precautions: Facilities should be available for treating anaphylaxis whenever penicillin is used. A careful history should be taken with regard to previous allergic reactions.

If skin rashes develop, the patient another antimicrobial should be given.

Important caution: Many hypersensitivity reactions are reported with penicillin ranging from skin rashes to immediate anaphylaxis which may be fatal. The overall incidence of hypersensitivity reactions is from 2 to 5 %. Anaphylaxis is very rare and occurs in about 1/10 000 injections. Death has been reported in about 1/30 - 50 000 injections. It should be emphasized that many anaphylactic reactions occur in severely ill rheumatic heart disease patients who are at risk of life-threatening arrhythmias. They may have an arrhythmia associated with shock mimicking anaphylaxis.

Use in pregnancy: There is no evidence of teratogenicity with benzathine benzylpenicillin. It can be used during pregnancy.

Adverse reactions: The most common adverse effect of these substances are hypersensitivity reactions that range in severity from skin rashes to immediate anaphylaxis.

Pain and sterile inflammation can occur at the site of intramuscular injection.

Accidental injection into a peripheral nerve causes pain and dysfunction.

Nephropathy manifested as interstitial nephritis has been reported.

Neutropenia and thrombocytopenia have occurred rarely.

Storage: Powder for injection should be stored at temperatures between 2 and 8° C and protected from moisture.

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