<prompt> Drug of choice for primary syphilis isAmpicillinBenzathine penicillinErythromycinTetracycline  <response>: Ans. b Benzathine penicillin. Ref. Pharmacology KD Tripathi 5th657, 673, 688; Harrisons Medicine 16th980Rx of SyphilisEarly latent syphilisLate syphilis1.2 MU Procaine penicillin x 10 daysOR2.4 MU benzathine penicillin 1-3 weeklyBenzathine penicillin2.4 MU weekly for 4 weeksDrug used for treatment of syphilis Penicillin Erythromycin Tetracycline Cephalosporins. 