Penicillin G Benzathine CAS 41372-02-5
Benzathine benzylpenicillin is a white crystalline powder. Very slightly soluble in water, freely soluble in dimethylformamide and in formamide, slightly soluble in ethanol (96 per cent). It is an ...
Category：Active Pharmaceutical Ingredients
Introduction
Benzathine benzylpenicillin is a white crystalline powder. Very slightly soluble in water, freely soluble in dimethylformamide and in formamide, slightly soluble in ethanol (96 per cent). It is an antibiotic medicine used to control streptococcal infection and prevent rheumatic fever, suitable for mild or moderate infections caused by bacteria sensitive to penicillin, such as pneumonia, scarlet fever, tonsillitis, otitis media, gonorrhea, etc.
Molecular Formula：(C16H18N2O4S)2·C16H20N2·4H2O
Molecular Weight:981.19
CAS No.: 41372-02-5
Description
Penicillin G benzathin is a white crystalline powder. It is an antibiotic useful for the treatment of a number of bacterial infections.
Application
Penicillin antibiotics, used for mild or moderate infections caused by penicillin-sensitive bacteria, such as pneumonia, scarlet fever, tonsillitis, otitis media, gonorrhea, etc. It is mainly used to prevent rheumatic fever, treat syphilis in different stages, and control the prevalence of streptococcal infection.
Packing
25kg/bag or as per customer’s requirements.
Storage
Preserve in tight containers.
Minimum Order
One package
Penicillin G Benzathine Introduction
| Item | Details |
| Generic Name | Penicillin G Benzathine |
| CAS Number | 41372 – 02 – 5 |
| Trade Names | Bicillin L – A, Permapen, etc. |
| Classification | Penicillin – class antibiotic |
| Chemical Structure | Penicillin G benzathine has a beta – lactam ring fused to a thiazolidine ring, which is characteristic of penicillins. The molecular formula is (C₁₆H₁₈N₂O₄S)₂·C₁₆H₂₀N₂. It consists of two molecules of penicillin G linked to a benzathine moiety. The benzathine part helps to slow down the release of penicillin G in the body, resulting in a long – acting formulation. The beta – lactam ring and other functional groups such as the carboxyl and sulfhydryl groups are crucial for its antibacterial activity and binding to penicillin – binding proteins (PBPs) in bacteria. |
| Pharmacological Action | Penicillin G benzathine, upon hydrolysis in the body, releases penicillin G. Penicillin G then binds to PBPs in the bacterial cytoplasmic membrane. This binding inhibits the transpeptidation reaction, which is essential for the cross – linking of peptidoglycan chains in the bacterial cell wall. As a result, the cell wall weakens, and the bacteria become more vulnerable to osmotic pressure, leading to cell lysis and death. It has a narrow – spectrum antibacterial activity mainly against Gram – positive bacteria. It is highly effective against Streptococcus pyogenes (the causative agent of streptococcal pharyngitis), Streptococcus pneumoniae, and some strains of Staphylococcus aureus (but not methicillin – resistant Staphylococcus aureus). It also has activity against Neisseria meningitidis and Treponema pallidum, the causative agent of syphilis. |
| Clinical Applications | 1. Streptococcal Infections: – The primary use is in the treatment and prevention of streptococcal pharyngitis. A single intramuscular injection of penicillin G benzathine can provide long – term antibacterial activity, effectively eradicating Streptococcus pyogenes from the throat. – It can also be used for the prevention of rheumatic fever in patients with a history of streptococcal infections, as streptococcal infections are a major trigger for rheumatic fever. 2. Syphilis: – In the treatment of early – stage syphilis (primary, secondary, and latent syphilis of less than 1 year duration), penicillin G benzathine is the drug of choice. A single intramuscular injection is usually sufficient for early – stage syphilis. For late – stage syphilis (latent syphilis of more than 1 year duration or tertiary syphilis), multiple injections at specific intervals are required. 3. Other Infections: – In some cases, it may be used for the treatment of mild to moderate infections caused by susceptible Gram – positive bacteria, especially when a long – acting antibiotic is desired to ensure continuous antibacterial coverage over an extended period. |
| Dosage and Administration | Adults: – For streptococcal pharyngitis, the typical dose is 1.2 million units (equivalent to approximately 900 mg of penicillin G) given as a single intramuscular injection. – For early – stage syphilis, the dose is also 2.4 million units (equivalent to approximately 1800 mg of penicillin G) given as a single intramuscular injection. – For late – stage syphilis, 2.4 million units are given as intramuscular injections at weekly intervals for 3 doses. Children: – For streptococcal pharyngitis in children weighing less than 27 kg, the dose is 600.000 units (equivalent to approximately 450 mg of penicillin G) given as a single intramuscular injection. – For children with early – stage syphilis, the dose is adjusted based on body weight, typically 50.000 units/kg given as a single intramuscular injection, not to exceed 2.4 million units. The intramuscular injection should be given deep into a large muscle mass, such as the gluteus maximus or vastus lateralis, to ensure proper absorption and minimize pain at the injection site. |
| Adverse Reactions | 1. Injection – Site Reactions: Pain, swelling, and induration at the injection site are common. These reactions are usually self – limiting and resolve within a few days. 2. Allergic Reactions: Allergic reactions can occur, ranging from mild rashes, itching, and hives to severe anaphylactic shock. Patients with a known history of allergy to penicillins are at a higher risk. The risk of anaphylaxis is relatively low but can be life – threatening. 3. Gastrointestinal Effects: Although less common compared to some other penicillins, nausea, vomiting, and diarrhea may occur in some patients. 4. Jarisch – Herxheimer Reaction: In the treatment of syphilis, especially early – stage syphilis, the Jarisch – Herxheimer reaction can occur. This is an acute febrile reaction that may be accompanied by headache, myalgia, and exacerbation of syphilitic lesions. It is thought to be due to the release of endotoxins from dying spirochetes. |
| Drug Interactions | 1. With Probenecid: Probenecid inhibits the renal tubular secretion of penicillin G (released from penicillin G benzathine), increasing its plasma concentration and half – life. This may enhance the antibacterial effect but also increase the risk of side effects. 2. With Other Antibiotics: Combining penicillin G benzathine with bacteriostatic antibiotics, such as tetracyclines or macrolides, may lead to antagonistic effects, as penicillin is most effective against actively growing bacteria, and bacteriostatic drugs inhibit bacterial growth. 3. With Oral Contraceptives: There is some evidence that penicillin G may reduce the effectiveness of oral contraceptives by interfering with the normal gut flora that recycles estrogen conjugates. Women using oral contraceptives should be advised to use additional contraceptive methods during treatment with penicillin G benzathine. |
| Special Population Considerations | 1. Pregnant Women: Penicillin G benzathine is generally considered safe for use during pregnancy, especially for the treatment of syphilis. It is important to treat syphilis during pregnancy to prevent congenital syphilis in the fetus. However, as with all medications, it should only be used when clearly needed. 2. Breastfeeding Women: It is excreted in breast milk in small amounts. Although it is usually considered safe for breastfeeding infants, close monitoring for any adverse effects in the infant is recommended. 3. Patients with Renal Impairment: Since penicillin G is mainly excreted by the kidneys, in patients with significant renal impairment, the plasma concentration of penicillin G may increase, and close monitoring may be required. However, due to the long – acting nature of penicillin G benzathine, the dosing interval may not need to be adjusted as frequently as with shorter – acting penicillin formulations. 4. Elderly Patients: Elderly patients may be more sensitive to the drug’s side effects, especially allergic reactions and injection – site reactions. Close monitoring and appropriate dosing adjustments are needed. |
| History and Development | Penicillin G benzathine was developed as a long – acting formulation of penicillin G. The addition of the benzathine moiety was a significant advancement as it allowed for less frequent dosing while maintaining effective antibacterial levels over an extended period. This was particularly useful for diseases like syphilis and streptococcal pharyngitis, where continuous antibacterial coverage is important. Since its introduction, it has played a crucial role in the treatment and prevention of these infections, especially in areas where patient compliance with multiple – dose regimens may be a challenge. |
