LIMIT Trial - Lidocaine With Intramuscular Injection of Benzathine Penicillin G for Treponema Pallidum Treatment

The purpose of the study is to test the question of: Does the addition of 0.5ml 1% lidocaine compared to 0.5 ml normal saline solution to 1.2 million units of benzathine penicillin G affect the pain experienced by individuals being treated for Treponema pallidum (syphilis) infections at 10 minutes and 24 hours post injection?

Background

Prior Literature and Studies, and Rationale for this Study

There is evidence to suggest that lidocaine can help reduce the pain associated with intramuscular injections of benzathine penicillin G or bicillin, used to treat syphilis infections. A study published in the Journal of Pediatric Infectious Diseases in 1998 found that the use of lidocaine as a diluent of BPG significantly reduced the pain of injection. Another study by Estrada et al in 2019 looked at the addition of 1% mepivicaine as diluent for PGB vs PGB alone and showed that mepivicaine significantly decreased pain experienced by participants. Per the IUSTI European Guidelines for Syphilis management, lidocaine is used as a diluent for benzathine penicillin G since 1998. No studies have been performed thus far looking at prefilled benzathine penicillin G syringes and the possibility of inserting lidocaine to the injection to decrease the pain experienced by individuals being treated for syphilis infections, instead of using lidocaine as a diluent which is not possible for the BPG formulations present here in the US.

Study Objectives

Primary Aim To see if there is any benefit of adding 0.5 ml 1% lidocaine to prepackaged Benzathine Penicillin G, with respect to pain, compared to standard of care, in the treatment of Treponema pallidum infections, both 10 minutes and 24 hours after injection.

Secondary Aim To see if there are any adverse effects of adding 0.5 ml 1% lidocaine to prepackaged Benzathine Penicillin G and to assess use of other pain medications 24 hours post injection.

Dose Rationale and Risk/Benefits Use of 0.5 ml 1% lidocaine was decided upon based off the size of the prefilled BPG syringe and the room for additional liquid within the syringe. 1% lidocaine is commonly used as a pain relief measure in clinical settings for injections and other procedures.

Overview or Design Summary This study is a double blinded randomized placebo control trial of addition of the effect on pain of the addition of 0.5ml 1% lidocaine solution to prepackaged benzathine Penicillin G injection, compared to addition of 0.5 ml normal saline solution, in adults being treated for syphilis (Treponema pallidum) infections, within the Infectious Diseases Clinic at Washington University in St. Louis.

Inclusion criteria

• Adults 18 years of age or above
• Confirmed syphilis diagnosis (reactive RPR with confirmatory treponemal testing)
• Receiving first injection in series if patient requires 3x weekly injections for syphilis treatment

Exclusion criteria

• Penicillin allergy (anaphylaxis)
• Lidocaine allergy (anaphylaxis)
• Second or third injection in series if patient requires 3x weekly injections for syphilis treatment
• Pregnancy