Penicillin G (Benzylpenicillin) Drug Overview - PDF

Overview of the Drug Class Prototype: penicillin G (Benzylpenicillin) Category: Penicillin G belongs to the narrow-spectrum class of penicillins. Primary Function: PCN G is active against most gram-positive bacteria, gram- negative cocci, anaerobic bacteria, and sp...

Overview of the Drug Class Prototype: penicillin G (Benzylpenicillin) Category: Penicillin G belongs to the narrow-spectrum class of penicillins. Primary Function: PCN G is active against most gram-positive bacteria, gram- negative cocci, anaerobic bacteria, and spirochetes. PCN G is the first choice for infections caused by sensitive gram-positive cocci. Unique Features: PCN G was the first available PCN and remains the drug of choice for many infections. Mechanism of Action PCNs weaken the bacterial cell wall, causing the organism to take up excessive water and rupture. This bactericidal action is accomplished by two actions: inhibition of transpeptidases and disinhibition of autolysins. These combined actions result in cell lysis and death. PCNs are only active against bacteria undergoing growth and division. Indications and Therapeutic Uses Gram-Positive Cocci Infections: PCN G is the drug of choice for infections caused by gram-positive cocci such as Streptococcus pneumoniae, pharyngitis (caused by Streptococcus pyogenes), and infectious endocarditis (caused by Streptococcus viridans). Gram-Positive Bacilli Infections: PCN G is the preferred agent for infections caused by gram-positive bacilli, such as gas gangrene, tetanus, and anthrax. Meningitis: PCN is the drug of choice for meningitis caused by N. meningitidis. Gonorrhea: PCN is the drug of choice for non-penicillinase producing strains of N. gonorrhoeae (ceftriaxone has replaced PCN as primary treatment for N. gonorrhoeae not of this classification). Syphilis: PCN is the drug of choice for syphilis (T. pallidum). PCN G is used for the prevention of syphilis in exposed sexual partners. Rheumatic Fever: PCN G is used for prophylaxis and treatment of recurrent rheumatic fever. Bacterial Endocarditis: PCN is utilized for prophylaxis of bacterial endocarditis in individuals with prosthetic heart valves, congenital heart disease, acquired valvular heart disease, mitral valve prolapse, and those with a history of bacterial endocarditis. Side Effects and Adverse Reactions Side Effect Description Hypersensitivity The most concerning adverse reaction. Injection Site Pain at the injection site can occur with IM injection. Accidental injection into an Reaction artery can cause gangrene or tissue necrosis. Accidental injection into a peripheral nerve can cause sensory or motor dysfunction. Neurotoxicity With toxicity, seizures, confusion, or hallucinations can occur. Precautions and Contraindications Precautions Clients with a PCN allergy should be considered allergic to all PCN agents. Due to the risk (low at 1%) of cross-sensitivity to cephalosporins, clients with a PCN allergy and immediate, high-intensity immune responses (e.g., anaphylaxis) should avoid cephalosporins. Use of Sodium PCN G should be used with caution in clients on sodium- restricted diets. Drug Interactions Since PCNs are most effective against [actively growing bacteria], concurrent use of [bacteriostatic agents like tetracyclines] could reduce the [bactericidal effects] of PCN and should therefore be avoided. Dosing, Administration, & Client Teaching Dosing Dosing varies based on the condition, severity, and client response. Check drug dosing guidelines for individualized dosing. PCN G is available as four salts: potassium PCN G, procaine PCN G, benzathine PCN G, and sodium PCN G.  All forms of PCN may be administered intramuscularly. Different salts affect the rate of absorption. PCN G is also available for IV administration. PCN G dosing for adults is 1.2 – 24 million units at 4-hour intervals. Administration IM or IV administration. Monitor for hypersensitivity. Client Teaching Clients should be educated on the importance of completing the full course of treatment. Educate clients about side effects, monitoring, and when to report to a provider. Labs to Monitor Basic Metabolic Panel (BMP) Renal impairment causes the half-life of PCN to dramatically increase and may require a reduction in dosage. Monitor renal function (including BUN/Creatine and Creatine Clearance) to assess renal dosing recommendations in clients at high risk of toxicity.