1. Measurement of Δ9THC and metabolites in the brain and peripheral tissues after intranasal instillation of a nanoformulation
- Author
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Gunjan Upadhyay, Oksana Fihurka, Connor Habecker, Pranav Patel, and Juan Sanchez-Ramos
- Subjects
Intranasal administration ,Nanoparticles ,Nanoemulsions ,Delta-9-tetrahydrocannabinol (Δ9THC) ,Cannabidiol (CBD) ,Pharmacokinetics ,Pharmacy and materia medica ,RS1-441 ,Plant culture ,SB1-1110 - Abstract
Abstract Background Comparative bioavailability of cannabinoids following their administration by dosing routes has been studied previously, but there are no quantitative reports of distribution of Δ 9 THC, nor its metabolites, across various brain regions following intranasal (i.n.) administration. The aim of the present study was to determine the time course of Δ 9 THC transport from nose to brain and to quantify the distribution of Δ 9 THC and its metabolites in four brain regions. Methods Δ9THC was formulated as a lipophilic nano-emulsion and instilled i.n. to three groups of adult mice and euthanized after 2, 4, and 8 h. Brains were dissected into 4 regions. Sensitive analytical methods (HPLC-MS) were utilized to quantify levels of Δ 9 THC and metabolites in brain regions and peripheral tissues. Data was expressed as mean concentrations (± SEM) of Δ 9 THC and metabolites in brain regions, blood, plasma, urine, and liver. Two-way analysis of variance was performed followed by post hoc multiple comparisons. Results Peak concentrations of Δ 9 THC were reached at 2 h in the brain (15.9 ng/mg), blood (4.54 μg/mL), and plasma (4.56 μg /mL). The percentage of administered dose of Δ 9 THC transported to the brain (5.9%) was greater than in blood (1.7%), plasma (1.6%), urine (0.4%), and liver (0.1%). Concentrations of Δ9THC and its THC-COOH metabolite in the liver reached their highest levels at 8 h. Discussion The present study is the first to report the uptake and distribution across brain regions of Δ 9 THC and its principal metabolites following i.n. administration. The systemic bioavailability (absorption into the blood) of intranasal Δ 9 THC was 1.7% of the administered dose, much lower than that reported by others after oral ingestion (7–10%) and inhalation (20–35%), but those prior studies did not measure the transport of Δ 9 THC into brain regions. Others have reported Δ 9 THC in the whole brain following i.n. instillation in a different species (rats) to be twice (5.9%) that following i.p. injections, while metabolites of Δ 9 THC in rat brain were lower after i.n. administration. Conclusions The intranasal route of a Δ 9 THC nanoformulation is an effective way to deliver cannabinoids to the brain, especially in those who cannot take the medication orally. Going forward, a metered dosing nasal spray will provide accurate and consistent doses.
- Published
- 2023
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