Δ9-Tetrahydrocannabinol Derivative-Loaded Nanoformulation Lowers Intraocular Pressure in Normotensive Rabbits

Pranjal S Taskar; Akash Patil; Prit Lakhani; Eman Ashour; Waseem Gul; Mahmoud A ElSohly; Brian Murphy; Soumyajit Majumdar

doi:10.1167/tvst.8.5.15

Δ⁹-Tetrahydrocannabinol Derivative-Loaded Nanoformulation Lowers Intraocular Pressure in Normotensive Rabbits

Transl Vis Sci Technol. 2019 Sep 19;8(5):15. doi: 10.1167/tvst.8.5.15. eCollection 2019 Sep.

Authors

Pranjal S Taskar^{1

2}, Akash Patil^{1

2}, Prit Lakhani^{1

2}, Eman Ashour^{1

2}, Waseem Gul³, Mahmoud A ElSohly^{1

2

3}, Brian Murphy⁴, Soumyajit Majumdar^{1

2}

Affiliations

¹ Department of Pharmaceutics and Drug Delivery, University of Mississippi, Oxford, MS, USA.
² Research Institute of Pharmaceutical Sciences, University of Mississippi, Oxford, MS, USA.
³ ElSohly Laboratories Inc., Oxford, MS, USA.
⁴ Emerald Bioscience Inc., Costa Mesa, CA, USA.

Abstract

Purpose: Δ⁹-Tetrahydrocannabinol-valine-hemisuccinate, a hydrophilic prodrug of Δ⁹-tetrahydrocannabinol, synthesized with the aim of improving the ocular bioavailability of the parent molecule, was investigated in a lipid-based nanoparticle dosage form for ocular delivery.

Methods: Solid lipid nanoparticles (SLNs) of Δ⁹-tetrahydrocannabinol-valine-hemisuccinate and Δ⁹-tetrahydrocannabinol, along with a nanoemulsion of Δ⁹-tetrahydrocannabinol-valine-hemisuccinate, were tested for glaucoma management in a normotensive rabbit model by using a multiple-dosing protocol. Marketed formulations of timolol maleate and pilocarpine HCl were also tested for their pharmacodynamic profile, post-single dose administration.

Results: A peak intraocular pressure (IOP) drop of 30% from baseline was observed in rabbits treated with SLNs loaded with Δ⁹-tetrahydrocannabinol-valine-hemisuccinate at 90 minutes. Treated eyes of rabbits receiving Δ⁹-tetrahydrocannabinol-valine-hemisuccinate SLNs had significantly lower IOP than untreated eyes until 360 minutes, whereas the group receiving the emulsion formulation showed a drop in IOP until 90 minutes only. In comparison to marketed pilocarpine and timolol maleate ophthalmic solutions, Δ⁹-tetrahydrocannabinol-valine-hemisuccinate SLNs produced a greater effect on IOP in terms of both intensity and duration. In terms of tissue concentrations, significantly higher concentrations of Δ⁹-tetrahydrocannabinol-valine-hemisuccinate were observed in iris-ciliary bodies and retina-choroid with SLNs.

Conclusion: Δ⁹-Tetrahydrocannabinol-valine-hemisuccinate formulated in a lipid-based nanoparticulate carrier shows promise in glaucoma pharmacotherapy.

Translational relevance: Glaucoma therapies usually focus on decreased aqueous humor production and increased outflow. However, such therapy is not curative, and there lies a need in preclinical research to focus efforts on agents that not only affect the aqueous humor dynamics but also provide neuroprotection. Historically, there have been bench-scale studies looking at retinal ganglion cell death post-axonal injury. However, for a smooth translation of this in vitro activity to the clinic, animal models examining IOP reduction, i.e., connecting the neuroprotective activity to a measurable outcome in glaucoma management (IOP), need to be investigated. This study investigated the IOP reduction efficacy of cannabinoids for glaucoma pharmacotherapy in a normotensive rabbit model, bringing forth a new class of agents with the potential of IOP reduction and improved permeation to the back of the eye, possibly providing neuroprotective benefits in glaucoma management.

Keywords: glaucoma; intraocular pressure; normotensive; solid lipid nanoparticles; tetrahydrocannabinol.