Evaluation of Combined Strategy to Reduce the Pain of Penicillin G Benzathine Injection in Primary Syphilis

Abstract

Background: Intramuscular (IM) injection of penicillin G Benzathine (PGB) is widely recognized as the primary treatment for patients at all stages of syphilis. However, the discomfort and induration associated with PGB injections are often a challenge for patients. While lidocaine is already known to reduce injection pain and is standard practice in some countries, the added value of combining lidocaine with the z-track technique has not been thoroughly investigated. This study aims to observe the use of combining lidocaine with the Z-track technique in the treatment of syphilis, and to explore less painful methods of administering IM PGB for the treatment of syphilis in adult patients.

Methods: 32 syphilis patients requiring penicillin treatment were injected with 1.2 million units of penicillin on both sides of the buttocks. The left side was injected using the traditional method with 0.9% saline as the solvent (control Group), while the right side was injected using a "z" injection method with 0.2% lidocaine as the solvent (experimental Group). The success rate of the single injection, the intensity and duration of the post-injection pain and the induration reaction were observed and recorded.

Results: There was no statistically significant difference in single injection success rate and immediate post injection pain score between the two sides (P>0.05). However, the right side had a lower pain score at 30 minutes post injection and fewer induration reactions, showing a statistically significant difference between the two sides (P<0.05). Chi-squared analysis showed that age, gender and BMI had no significant effect on pain scores 30 minutes after injection in either the control or intervention groups. (P>0.05).

Conclusion: The lidocaine + Z-track penicillin method can reduce delayed pain and induration reactions in patients with syphilis, and provides an additional approach to improving patient comfort beyond the standard use of lidocaine alone. This method merits clinical promotion.

Keywords: PGB; intramuscular injection; penicillin G benzathine; syphilis.

Figure 1

The scale of the visual analogue scale (VAS): (A) shows the immediate pain scores (red is the experimental buttock, the blue is the controls), and (B) shows the 30-minute pain scores (ed is the experimental buttock, the blue is the controls). ****P < 0.001.