Among first-line anti-tuberculosis drugs, which agent penetrates the blood-brain barrier best and achieves therapeutic cerebrospinal fluid concentrations regardless of meningeal inflammation?

• A Rifampicin
• B Ethambutol
• C Streptomycin
• D Isoniazid ✓

Explanation

Isoniazid crosses the blood-brain barrier readily even when the meninges are uninflamed, achieving CSF levels close to serum levels. This property, combined with its potent early bactericidal activity against rapidly dividing bacilli, makes it the single most important drug in tuberculous meningitis. Rifampicin penetrates inflamed meninges only, ethambutol penetration is poor and unreliable, and streptomycin enters CSF only with active inflammation.

Reference: Katzung Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.