Acceptability and Compliance With Daily Injections of Procaine Penicillin in the Outpatient Treatment of Syphilis-Treponemal Infection

Background: In the United Kingdom, it is recommended that syphilis should be treated with intramuscular daily procaine penicillin with or without oral probenecid for 8 to 21 days. However, it has been argued that this regimen would be unacceptable to patients in terms of daily attendance and volume of drug administered, resulting in poor compliance. Goal: To assess the acceptability of and compliance with daily procaine penicillin for 10 to 17 days in patients attending an East London Genito-Urinary Medicine Clinic with a diagnosis of syphilis-treponemal infection. Study Design: The notes of 210 consecutive patients attending with syphilis-treponemal infection who had been offered treatment with daily procaine penicillin, with or without oral probenecid for 10 to 17 days, were reviewed retrospectively. Results: Of 210 patients who were offered daily procaine penicillin, 42 (20%) declined and were given oral doxycydine, amoxicillin, or depot penicillin injections. Of 168 patients who accepted daily procaine penicillin, depending on the stage of infection, 90 (54%) had 1.8 g of daily procaine penicillin together with oral probenecid 500 mg every 6 hours for 17 days (highdose regimen), 57 (34%) had 0.6 g of daily procaine penicillin for 10 to 17 days (low-dose regimen), and 21 (12%) had mixeddose regimens ranging from 0.5 to 2.4 g. Of the 90 who had high-dose regimen, 76 (84%) complied with treatment compared with 50 (88%) of 57 who had low-dose regimen. All 21 patients who had mixed-dose regimens complied fully. Conclusions: Daily procaine penicillin is a well-accepted outpatient regimen with excellent compliance (88% overall) and minimal side effects. Because the high-dose regimen has been shown to achieve treponemicidal levels of penicillin in the cerebrospinal fluid, it is recommended for patients with neurosyphilis or those in whom neurosyphilis cannot be excluded. It also could be considered for patients with concomitant human immunodeficiency virus infection in view of the possible progression to neurosyphilis in those treated with depot penicillin.