To address the ongoing shortage of Pfizer’s Bicillin L-A (benzathine penicillin G injectable suspension), the U.S. Food and Drug Administration is allowing the temporary import of a similar drug, penicillin G benzathine (brand name, Extencilline). Extencilline has been determined to be equivalent to Bicillin L-A and is currently authorized and marketed in other countries.

For the treatment of syphilis, the California Department of Public Health advises health care providers to consider the following when using Extencilline:

• Primary, secondary and early latent syphilis: Extencilline 2.4 million units as a single intramuscular (IM) dose.
• Late latent syphilis or syphilis of unknown duration: Extencilline 2.4 million units IM once weekly for 3 weeks.
• Extencilline is safe for use in pregnancy and should be administered following standard protocols for treatment of syphilis in pregnancy (PDF).
• Extencilline is safe for use in neonates and infants and can therefore be used for neonates/infants when Bicillin L-A is otherwise appropriate.
• Extencilline is not interchangeable with aqueous crystalline penicillin G as it has low penetration of the central nervous system, therefore is not appropriate in cases of suspected neuroinvasion or in the presence of pathologic cerebrospinal fluid (CSF) findings.
• Follow-up clinical and serologic evaluation should be performed after treatment at the recommended intervals per the 2021 Centers for Disease Control and Prevention Sexually Transmitted Infections Treatment Guidelines.

For more information

• FDA Announcement on Availability of Extencilline
• CDPH Provider Alert on Powdered Benzathine Benzylpenicillin (Extencilline®) for the Treatment of Syphilis
• CDC STI Treatment Guidelines