Benzathine Penicillin
Synonym :
Penicillin Benzathine
Mechanism :
Penicillin G exerts a bactericidal action against penicillin-sensitive microorganisms during the stage of active multiplication. It acts through the inhibition of biosynthesis of cell-wall mucopeptide. It is not active against the penicillinase-producing bacteria, which include many strains of staphylococci. Since it is a long acting penicillin, it is given every 1-3 weekly.
Indication :
- Streptococcus infections (Group A Strep): Infections of the upper respiratory tract (e.g., pharyngitis).
- Venereal infections: syphilis, yaws, bejel, and pinta.
- Prophylaxis
- Rheumatic fever and/or chorea
- Prophylactic therapy for rheumatic heart disease and acute glomerulonephritis
Contraindications :
A history of a previous hypersensitivity reaction to any of the penicillin’s is a contraindication. Do not inject into or near an artery or nerve.
Dosing :
Intramuscular.
Streptococcal Group A: Upper respiratory infections (e.g., pharyngitis):
Older children: A single dose of 1.2 million IU.
Children and infants under 27 kg: A single dose of 600000 IU.
Syphilis: Primary, secondary, and latent:
Primary: 50000 IU/kg single dose, max: 2.4 million Units/dose.
Late (tertiary and neurosyphilis): 50000 IU/kg at 7-day intervals for 3 doses, max: 2.4 million Units/dose.
Congenital: Under 2 years of age: 50000 IU/kg single dose, max: 2.4 million Units/dose.
Yaws, Bejel, and Pinta:
A single dose of 1.2 million IU.
Prophylaxis for rheumatic fever and glomerulonephritis:
>27 kg:
1.2 million IU once a month.
<27 kg:
600000 IU once a month.
Adverse Effect :
Maculopapular eruptions, exfoliative dermatitis, urticaria, Jarisch-Herxheimer reaction, anaphylaxis, laryngeal edema, serum-sickness like reactions (chills, fever, edema, arthralgia, prostration, eosinophilia), hemolytic anemia, leukopenia, thrombocytopenia.
Interaction :
Tetracycline: May antagonize the bactericidal effect of penicillin, and concurrent use of these drugs should be avoided.
The rate of excretion of the penicillin’s is decreased by concomitant administration of probenecid; probenecid prolongs, as well as increases, blood levels of the penicillins.
Laboratory Tests: In prolonged therapy with penicillin and particularly with high-dosage schedules, periodic evaluation of the renal and hematopoietic systems is recommended.
Laboratory Test Interactions: Penicillin’s can interfere with the copper sulfate reagent method of testing for glycosuria, resulting in falsely elevated or falsely decreased readings. Such interference does not occur with the glucose oxidase method.
Hepatic Dose :
No dosage adjustments are recommended.