Extencilline
Extencilline is a long-acting penicillin antibiotic formulation administered via intramuscular injection. It contains benzathine benzylpenicillin and is primarily used to treat syphilis and certain streptococcal infections, providing sustained antibacterial activity over an extended period.
Extencilline is a brand-name, long-acting injectable penicillin antibiotic used primarily for treating syphilis and certain bacterial infections.
Key facts at a glance
- RxNorm
- 2671688
- Generic
- Extencilline
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Mainly prescribed for the treatment of syphilis (both early and late stages) and other infections caused by susceptible organisms, including streptococcal pharyngitis, rheumatic fever prophylaxis, and yaws.
Contains benzathine benzylpenicillin, which inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, leading to bacterial death. The benzathine formulation creates a depot at the injection site, allowing gradual release of penicillin G over several days.
Administered exclusively by deep intramuscular injection. Patients with penicillin allergy should not receive this medication. May cause injection site reactions and requires reconstitution before use. Effectiveness depends on susceptibility of the target organism.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy