Mass Spectrometry Imaging Demonstrates the Regional Brain Distribution Patterns of Three First-Line Antiretroviral Drugs

Abstract

HIV in the central nervous system (CNS) contributes to the development of HIV-associated neurological disorders (HAND), even with chronic antiretroviral therapy. In order for antiretroviral therapy to be effective in protecting the CNS, these drugs should have the ability to localize in brain areas known to be affected by HIV. Consequently, this study aimed to investigate the localization patterns of three first-line antiretroviral drugs, namely, efavirenz, tenofovir, and emtricitabine, in the rat brain. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) were utilized to assess the pharmacokinetics and brain spatial distribution of the three drugs. Each drug was administered (50 mg/kg) to healthy female Sprague-Dawley rats via intraperitoneal administration. LC-MS/MS results showed that all three drugs could be delivered into the brain, although they varied in blood-brain barrier permeability. MALDI-MSI showed a high degree of efavirenz localization across the entire brain, while tenofovir localized mainly in the cortex. Emtricitabine distributed heterogeneously mainly in the thalamus, corpus callosum, and hypothalamus. This study showed that efavirenz, tenofovir, and emtricitabine might be a potential drug combination antiretroviral therapy for CNS protection against HAND.

Figure 1

MRM chromatogram: (1) TFV (t_R: 1.3 min), (2) FTC (t_R: 3.3 min), (3) ZDV (t_R: 3.7 min), (4) ADV (t_R: 4.4 min), (5) CBB (t_R: 5.8 min), and (6) EFV (t_R: 6.6 min).

Figure 2

Concentration–time profiles of EFV, TFV, and FTC in plasma (A) and brain (B) homogenates following a single dose of 50 mg/kg to the rats via IP administration (n = 3, mean ± SEM).

Figure 3

MALDI-MS images of coronal rat brain sections showing a time-dependent spatial distribution of three antiretroviral drugs. (A) Ion images for EFV (m/z 316.673) generated from 0 to 20% of maximum intensity, (B) for TFV (m/z 288.121) generated from 0 to 20% of maximum intensity, and (C) for FTC (m/z 248.463) generated from 0 to 50% of maximum intensity. Ion intensities for the three drugs were normalized against the TIC. Spatial resolution of 100 μm and a scale bar of 5 mm. The H&E staining with regional labels and the regions of interest (ROIs) were confirmed using the rat brain atlas.

Figure 4

Relative ion abundance of the three drugs in different brain regions. Images were obtained at a spatial resolution of 100 μm and a scale bar of 2 mm. The sum ion intensities (a.u.) are presented for each drug at 0.5 h post-dose for EFV (m/z 316.673) and 0.25 h post-dose for both TFV (m/z 288.121) and FTC (m/z 248.463).