BENZYLPENICILLIN INJECTION BP
Benzylpenicillin is indicated for the treatment of serious infections caused by susceptible micro-organisms which require high concentrations of the drug. Therapy should be guided by bacteriological studies (including sensitivity tests) and by clinical response.
The indications include
Pneumonia, Bacteraemia, emphysema, pericarditis, endocarditis, meningitis, anthrax, clostridial infections (e.g tetanus), Diphtheria, Rat-bite-fever, etc.
Benzylpenicillin is contraindicated in patients having history of hypersensitivity to any of the penicillins.
Method of reconstitution
Benzylpenicillin is meant for parenteral administration by intramuscular or intravenous route. For intramuscular administration the contents of 0.5 mega units (300mg), 1 mega units (600mg) & 5 mega units (3g) vials should be diluted with 2ml, 2ml and 10ml of sterile water for injection respectively and injected into a suitable muscle mass. For intravenous administration the required dose should be reconstituted with an appropriate volume of sterile isotonic sodium chloride for injection and administered slowly intravenously. Higher doses can be given by constant intravenous infusion.
For the treatment of severe infection due to susceptible strains of Streptococci, Pneumococci and Staphylococci such as bactaraemia, pneumonia, endocarditis, pericarditis, emphysema and other severe infections a minimum dose of 5million units per day must be administered.
For treatment of meningococcal meningitis, actinomycosis, clostridial infections, listeriosis, fusospirochaetal infections and rat-bite-fever, a usual daily dose of 15 to 20 million units is required.
Depending on severity of infection and state of renal function, a dose of 50,000 units to 200,000 units/kg body weight may be administered on divided doses per day or by constant intravenous infusion.
Intravenous or intramuscular infusion can be given every 2,4 or 6 hours by calculating the required daily dose and dividing it suitably. Alternatively a loading dose can be given followed by constant intravenous drip. Hence the necessary precautions should be taken before administering the drug and patient should be checked for the history of allergy to penicillins and non-reactiveness to test doses.
The necessary precautions must always be observed regardless of the number of times the patient may have received penicillin without incident in the past.
Penicillin should be used with caution in individual with a history of significant allergies and/or asthma. Particular care should be taken with I.V administration because of the possibility of thrombophlebitis. Prolonged use of benzylpenicillin may result in overgrowth of non-susceptible organisms. Constant observation of the patient is essential. Aqueous Penicillin G by the intravenous route (about 10mllion units) should be administered slowly because of the adverse effects of electrolyte imbalance from either the potassium or sodium content of the penicillin.
Pregnancy category B. reproduction studies performed in the mouse, rat and rabbit had revealed no evidence of impaired fertility or harm to the foetus due to benzylpenicillin. Human experience with the penicillin during pregnancy has not shown any positive evidence of adverse effects on the foetus. There are, however, no adequate and well controlled studies in pregnant women showing conclusively that harmful effects of the drugs on the foetus can be excluded.
Penicillins are excreted in human milk. Caution should be exercised when benzylpenicillin is administered to a nursing woman.
Administration of tetracycline is known to antagonize the antibacterial action of penicillin and must be avoided. Probenecid raises and prolongs the plasma concentrations of penicillins.
Hypersensitivity reactions: these are common and hypersensitivity reactions or sensitization is usually the result of previous treatment with penicillin. The following hypersensitivity reactions have been reported.
Skin rashes ranging from maculopapular eruptions to exfoliative dermatitis, urticaria and reactions resembling serum sickness, including chills, fever, edema, arthralgia and prostration. Severe and occasionally fatal anaphylaxis have occurred.
Jarich-Herxheimer reactions have been reported to occur in patients treated for syphilis, features include malaise, chills, fever, sore throat, myalgia, headache and tachycardia.
Haemolytic anaemia, thrombocytopenia, leucopenia, nephropathy and neuropathy are rarely observed adverse reactions and are usually associated with high intravenous dosage.
Some patients may develop antibiotic associated pseudomembraneous colitis, caused by Clostridium difficile toxin, during or following administration of penicillins.
Neurological adverse reactions, including convulsions, may occur with the attainment of high Cerebro spinal fluid (CSF) level of beta-lactams. In case of overdosage, discontinue medication, treat symptomatically and institute supportive measures as required. Benzylpenicillin sodium is haemoddialzable.
Store below 30°C in a dry place