Which of the following statement about Penicillin G is true?: (A) It is commonly administered orally, (B) It has a broad spectrum of antibacterial activity, (C) It can be used for the treatment rat bite fever, (D) Concomitant probenecid decreases its duration of action
Answer is C. Prophylactic uses (a) Rheumatic fever: Low concentrations of penicillin prevent colonization by streptococci responsible for rheumatic fever. Benzathine penicillin 1 .2 MU every 4 weeks till 18 years of age or 5 years after an attack, whichever is more. (b) Bacterial endocarditis: Dental extractions, endoscopies, catheterization, etc. cause bacteremia which in patients with valvular defects can cause endocarditis. PnG can afford protection, but amoxicillin is preferred now. (c) Agranulocytosis patients: Penicillin may be used alone or in combination with an aminoglycoside antibiotic to prevent respiratory and other acute infections. Pharmacokinetics: Penicillin G is acid labile-destroyed by gastric acid. As such, less than 1 /3rd of an oral dose is absorbed in the active form. Absorption of sod. PnG from i.m. site is rapid and complete; peak plasma level is attained in 30 min. It is distributed mainly extracellularly; reaches most body fluids, but penetration in serous cavities and CSF is poor. However, in the presence of inflammation (sinovitis, meningitis, etc.) adequate amounts may reach these sites. About 60% is plasma protein bound. It is little metabolized because of rapid excretion. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:697,699