A patient with AIDS and cryptococcal meningitis is treated with amphotericin B. Liposomal amphotericin B (AmBisome) is preferred over conventional amphotericin B deoxycholate because:

• A Liposomal formulation increases free drug concentrations in CSF enhancing fungicidal activity
• B Liposomal amphotericin binds ergosterol with 10-fold higher affinity than conventional form
• C Phospholipid coating prevents amphotericin B from crossing the blood-brain barrier reducing CNS side effects
• D Liposomal delivery preferentially concentrates drug in reticuloendothelial system and infected tissues while reducing delivery to proximal tubular cells, decreasing nephrotoxicity ✓

Explanation

Conventional amphotericin B deoxycholate causes profound nephrotoxicity via direct tubular toxicity and renal vasoconstriction. Liposomal formulations encapsulate the drug within phospholipid vesicles that are taken up preferentially by phagocytic cells (macrophages in spleen, liver, and infected tissues) where fungal organisms reside, achieving high drug concentrations at infection sites. Liposomal encapsulation simultaneously reduces direct uptake by renal tubular cells, lowering the incidence and severity of nephrotoxicity and infusion-related reactions while maintaining antifungal efficacy.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.