Syphillis 

Parenteral penicillin G remains the drug of choice for treating all stages of syphilis. Primary, secondary or latent syphilis known to be of less than one year's duration should be treated with an intramuscular injection of benzathine penicillin G, a repository formula-tion. Doxycycline is also usually effective if compliance is assured. A longer course of treatment, preferably with intramuscular penicillin Genzathine, is required for late syphilis (more than one year's duration) other than neurosyphilis.