Treatment of secondary syphilis

There are few studies of therapy for secondary syphilis which are adequate by modern standards of scientific design. Penicillin has been the best documented, effective antibiotic, although not all forms and regimens are equally effective. Although both aqueous penicillin G and procaine penicillin G in oil with aluminum monostearate (PAM) appear effective, these are not practical penicillin forms. The first requires injections every 2 to 4 hours for 7 to 10 days and the latter is no longer available in the United Sates. Aqueous procaine penicillin G (APPG) regimes have been evaluated in limited trials, but do appear effective. However, APPG requires daily injections and is impractical for widespread use in the treatment of secondary syphilis. The injection of 2.4 million units of benzathine penicillin G appears to be an effective single session regimen. Although tetracycline is widely accepted as the drug of choice for patients allergic to penicillin, this drug has been less rigorously evaluated for treatment of secondary syphilis. Other antibiotics have been even less well evaluated and none has been clearly shown to be highly effective.