Pharmacology Dosage and drug of choice for primary syphilis: September 2012 A Amoxicillin (500 mg for 5 days) B Benzathine penicillin (2.4 mega units deep IM) C Erythromycin (2 gm daily for 2 weeks) D Doxycycline (100 mg daily for 2 weeks) 💡 Explanation Dosage and drug of choice for primary syphilis: September 2012 ✓ Correct Answer: B. Benzathine penicillin (2.4 mega units deep IM)