A 40-year-old man is diagnosed with symptomatic neurosyphilis. He has no drug allergies. Which regimen is recommended?
- A Aqueous crystalline penicillin G 3 to 4 million units IV every 4 hours for 10 to 14 days ✓
- B Benzathine penicillin G 2.4 million units IM weekly for 3 weeks
- C Procaine penicillin 1.2 million units IM daily for 28 days
- D Azithromycin 500 mg orally daily for 10 days
Correct answer: A. Aqueous crystalline penicillin G 3 to 4 million units IV every 4 hours for 10 to 14 days
Explanation
Neurosyphilis requires aqueous crystalline penicillin G given intravenously at 18 to 24 million units per day in divided doses every 4 hours for 10 to 14 days to achieve treponemicidal levels in cerebrospinal fluid. Benzathine penicillin, adequate for early and latent syphilis, does not reach sufficient CSF concentrations and would fail here. Procaine penicillin alone is not the standard neurosyphilis regimen, and azithromycin resistance in Treponema pallidum precludes its use.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.