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Benzathine benzylpenicillin (CAS: 1538-09-6), also known as benzathine penicillin G, is a long-acting antibiotic combining penicillin G with benzathine. Administered via deep intramuscular injection, it slowly releases penicillin G over 2–4 weeks from a poorly soluble depot at the injection site, killing bacteria by inhibiting cell wall synthesis.
Its primary uses include first-line treatment of all stages of syphilis (no documented resistance ever reported), secondary prophylaxis of rheumatic fever and rheumatic heart disease, streptococcal pharyngitis, diphtheria prophylaxis, and prevention of poststreptococcal glomerulonephritis.
Key selling points include its unmatched extended duration of action eliminating daily dosing, zero documented Treponema resistance, WHO Essential Medicine status, exceptional cost-effectiveness (~$0.27–$1.71 per course), proven safety in pregnancy (Category B), simplified single-injection regimens improving compliance, broad gram-positive coverage, and well-established global manufacturing under strict pharmacopoeial standards.
Specifications of Benzathine benzylpenicillin CAS 1538-09-6 COA:
Items | Specifications | Results |
Appearance | White or almost white,slightly hygroscopic powder. | White powder |
Identification | The infrared absorption spectrum is concordant with the spectrum obtained with benzathine benzylpenicillin CRS. | Complies |
Acidity or alkalinity | Meet the requirements | Complies |
Related substances | Impurity A≤0.2 % Impurity B≤0.2 % Impurity C≤2.0 % Impurity D≤0.2 % Impurity E≤0.3 % Impurity F≤0.3 % Impurity G≤0.2 % Impurity H≤0.2 % Impurity I≤0.2 % Impurity J≤0.5 % Impurity K≤1.0 % Any other impurity≤0.2% Total impurities≤3.5% | Not detected Not detected 0.1% Not detected Not detected Not detected Not detected Not detected Not detected Not detected Not detected 0.03% 0.2% |
Water | 5.0%~8.0% | 6.7% |
Residual solvent | Ethanol≤5000ppm | 252 ppm |
Bacterial endotoxins | <0.13IU/ml | <0.010 IU/ml |
Sterility | Meet the requirements | Complies |
Assay (Calculated on anhydrous basis) | Benzathine 24.0% ~ 27.0% | 26.3% |
Benzathine benzylpenicillin 94.5%~102.0% | 101.1% | |
Conclusion | The product conforms to the above specifications. | |
Product Name:Benzathine benzylpenicillin
CAS:1538-09-6
MF:C48H56N6O8S2
Melting point :123-124℃
form:powder
color:White
Uses:
Benzathine benzylpenicillin (CAS: 1538-09-6), also known as benzathine penicillin G (BPG) or long-acting penicillin, is a long-acting antibiotic formulation created by combining penicillin G (benzylpenicillin) with N,N'-dibenzylethylenediamine (benzathine). Its molecular formula is (C₁₆H₁₈N₂O₄S)₂·C₁₆H₂₀N₂ with a molecular weight of approximately 909.14 g/mol.
It appears as a white crystalline powder and is very slightly soluble in water, which is the key to its prolonged action. When administered via deep intramuscular injection, it forms a poorly soluble deposit at the injection site that slowly releases penicillin G into the bloodstream over 2–4 weeks, maintaining sustained therapeutic levels with a single dose.
Its mechanism of action is bactericidal — it inhibits bacterial cell wall biosynthesis by targeting and irreversibly binding to penicillin-binding proteins (PBPs), which are transpeptidase enzymes essential for cross-linking the peptidoglycan layer. This disruption leads to osmotically unstable cell walls, bacterial lysis, and death.
It is listed on the WHO Model List of Essential Medicines and is marketed under trade names such as Bicillin L-A (Pfizer), Permapen, and others.
Primary Uses
1. Treatment of Syphilis and Treponemal Infections (First-Line Therapy)
Benzathine benzylpenicillin is the gold-standard, first-line treatment for all stages of syphilis (primary, secondary, latent, and congenital), as endorsed by the CDC and WHO. A single intramuscular dose of 2.4 million units is sufficient for early syphilis, while late latent syphilis requires weekly injections for 3 weeks. It is also the drug of choice for yaws, bejel, and pinta — endemic treponematoses caused by related Treponema species.
Notably, no documented resistance of Treponema pallidum to benzathine penicillin G has ever been reported, making it an exceptionally reliable therapeutic agent.
2. Prevention of Rheumatic Fever and Rheumatic Heart Disease
One of its most critical public health roles is the secondary prophylaxis of acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Monthly intramuscular injections (every 3–4 weeks) prevent recurrent Group A streptococcal infections that trigger autoimmune damage to heart valves. This long-term prophylaxis — often lasting years or decades — significantly reduces the risk of progressive cardiac valve damage.
3. Treatment of Streptococcal Infections
It is used to treat Group A β-hemolytic streptococcal pharyngitis (strep throat) and tonsillitis, particularly in settings where oral adherence is a concern. A single IM injection achieves cure rates comparable to a full 10-day course of oral penicillin V.
4. Prophylaxis of Poststreptococcal Glomerulonephritis
By preventing recurrent streptococcal infections, it also serves as prophylaxis against acute poststreptococcal glomerulonephritis, a serious kidney complication.
5. Diphtheria Prophylaxis
It is used for primary and secondary prophylaxis of diphtheria in close contacts of confirmed cases.
6. Other Infections
It is effective against mild-to-moderate infections caused by penicillin-sensitive organisms, including certain respiratory tract infections, and has been used in cardiac valve surgery prophylaxis.
Key Selling Points
1. Unmatched Extended Duration of Action
The defining advantage of benzathine benzylpenicillin is its sustained-release pharmacokinetic profile. After a single deep IM injection, therapeutic blood levels persist for 2–4 weeks, with detectable concentrations lasting up to 21 days. Peak plasma levels are reached at 24–48 hours, and the drug is gradually hydrolyzed from the injection-site depot. This eliminates the need for daily dosing and dramatically improves patient compliance — a critical factor in long-term prophylactic regimens.
2. No Documented Bacterial Resistance (Treponema pallidum)
Remarkably, since its introduction in the 1950s, no resistance of Treponema pallidum to penicillin has ever been documented. This makes benzathine benzylpenicillin an irreplaceable therapeutic agent for syphilis, especially in an era of rising antimicrobial resistance across other pathogen classes.
3. WHO Essential Medicine Status & Global Public Health Impact
Listed on the WHO Model List of Essential Medicines, benzathine benzylpenicillin is recognized as one of the most effective and safe medicines needed in a health system. It plays an indispensable role in global efforts to control syphilis, prevent rheumatic heart disease (a leading cause of acquired heart disease in low- and middle-income countries), and manage streptococcal disease burden.
4. Cost-Effectiveness
Benzathine benzylpenicillin is remarkably affordable. The wholesale cost in developing countries is approximately $0.27–$1.71 USD per treatment course, making it one of the most cost-effective antibiotics available. In China, a 1.2 million unit vial costs approximately ¥10–50 RMB, placing it well within reach of public health programs and resource-limited settings.
5. Proven Safety Profile in Pregnancy
Benzathine benzylpenicillin is classified as FDA Pregnancy Category B (no risk demonstrated in animal studies), making it safe for use during pregnancy. This is particularly important for preventing congenital syphilis — a single dose administered to the mother effectively treats the fetus and prevents severe birth defects.
6. Simplified Treatment Regimens
For early syphilis, a single injection of 2.4 million units achieves cure — compared to multi-day oral regimens required with alternative antibiotics. For rheumatic fever prophylaxis, monthly injections replace the burden of daily oral medication, significantly improving adherence rates in long-term prevention programs.
7. Broad Activity Against Gram-Positive Organisms
Beyond Treponema, it demonstrates potent activity against β-hemolytic streptococci (Groups A, B, C, G, H, L, and M), Streptococcus pneumoniae, Corynebacterium diphtheriae, Bacillus anthracis, Clostridium species, Actinomyces, and various spirochetes — providing versatile coverage for multiple infection types.
8. Well-Established Manufacturing & Quality Standards
Manufactured globally by major pharmaceutical companies including Pfizer (Bicillin L-A), North China Pharmaceutical Group, and CSPC Pharma, benzathine benzylpenicillin is produced under stringent pharmacopoeial standards (USP, BP, Chinese Pharmacopoeia). Available in standardized strengths of 600,000, 1,200,000, and 2,400,000 units, it ensures consistent dosing and reliable quality.
9. Versatile Formulation Options
Available as a sterile powder for reconstitution (for IM injection) and as pre-filled syringes (e.g., Bicillin L-A), it offers flexibility for different clinical settings — from large hospitals to remote field clinics in mass treatment campaigns.
Also, if you have any other questions, you can contact us
FAQ From Wuhan Fortuna Chemical Co.,Ltd
Q1: Can I get a sample for free ?
A: For small QTY and low value product, we can provide sample for free exclude shipping cost. For high value sample, we will charge the basic sample cost, but we can refund all the cost if customers place order after sample test.
Q2: How to confirm the product quality before placing orders ?
A: Most of our products confirm to international standards like USP/EP/BP/JP/CP. We will provide COA/TDS/MSDS for customers to confirm the specification before placing order.
Q3: What is the payment you accept?
A: For small and low value order, we accept CreditCard, MaterCard,VISA,Western Union and T/T.For large order, we can do T/T and L/C. Any pay on delivery or pay-after are not available for us.
Q4: What is your shipment way ?
A: For less than 100kg gross weight order will ship with courier like FedEx or UPS, we support customers to place courier orders remotely by their account, we will package the goods well and wait for pick up.For more than 100kg goods, we will transport by Air or Sea according to customers' requirement.
Q5: How long is your after-sales service?
A: We accept customer’s quality complaint in three month after customer received the goods. We provide tech.support for all-life if customer place order from our company.
Q6: How do you treat quality complaint ?
A: We support customer to provide our products to any rightful third party testing organization to test our products according to the COA specification, if the test result is confirm with COA, we will take all the loss for customers.
Name:Wuhan Fortuna Chemical Co.,Ltd
Category:Others
Trade Category: Trading Company
Employees: 11 - 50 People
Address: Room 2015, No.2 Building, Kaixin Mansion No.107
Company Information: Wuhan Fortuna Chemical Co.,Ltd established in 2006, is a big integrative chemical enterprise being engaged in Pharmaceutical and Intermediates, Food and Feed additives, Fine chemicals,Biochemical and Reagent, which is the members of Hubei E-commerce Chamber.
Our company has professional persons who major in chemical R&D and sicentific management, supply fine chemical products with high quality and close service, also supply custom-tailored products according to our clients' requirement.
We have a positive and self-motivated management work team with a common philosophy, caring and commitment through teamwork, our team strive to achieve success in delighting our clients and ourselves.
Since Wuhan Fortuna Chemical Co., Ltd founded, we continuously innovate our products and improve our service, sales network. Hence, we initiate the first sale mode on net in China, which is the retail trade of small package bring along wholesale of diversified management modes. Our products are exported widely to South Korea, Vietnam, Australia, Europe and South America, highly recommended by our clients.We insist on the management creed “Market is our compass, Quality is our life, Credit is our soul”. Clients’ trust is our forward power, their satisfaction is our struggling goal.
Wuhan Fortuna Chemical Co.,Ltd is a professional manufacturer which provide Benzathine benzylpenicillin with good quality and best price, welcome to contact us to get COA/TDS/MSDS of Benzathine benzylpenicillin.
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