Magnesium Hydroxide Nanoparticles Improve the Ocular Hypotensive Effect of Twice Daily Topical Timolol Maleate in Healthy Dogs

• Main Authors: Mizuki Kita, Kazutaka Kanai, Hiroki Mitsuhashi, Tomoki Noguchi, Noriaki Nagai, Mizuki Yamaguchi, Yuya Otaka, Rina Kudo, Yohei Yamashita, Kazuki Tajima
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: Veterinary Sciences
• Subjects: dogs; drug delivery system; glaucoma; magnesium hydroxide nanoparticles; timolol maleate
• Online Access: https://www.mdpi.com/2306-7381/8/8/168

Timolol maleate (TM), a beta-adrenergic receptor antagonist, is widely used for canine antiglaucoma eye drops; however, its bioavailability is <5%. Our previous study revealed that magnesium hydroxide nanoparticles (nMH) have potency in improving the bioavailability of fixed-combined TM in rodent models. This study aimed to investigate whether the fixed combination with nMH improves the ocular hypotensive effect of TM and affects pupil size (PS), heart rate (HR), and mean arterial pressure (MAP) in clinically healthy dogs. Five clinically healthy dogs were administered topical saline, commercial 0.5% TM, and a 0.01% or 0.1% nMH–0.5% TM fixed combination (0.01% or 0.1% nMH–TM) twice daily in one eye for 7 days with at least a 28-day interval. The changes from baseline were calculated and were statistically analyzed for each drug. IOP was significantly reduced in both 0.01% and 0.1% nMH–TM-treated-dogs compared with saline- and TM-treated dogs. Meanwhile, 0.01% and 0.1% nMH did not exacerbate the side effects of TM. From these results, nMH improved the ocular hypotensive effect of TM without enhancing side effects. Topical nMH–TM is potentially more effective for canine ocular hypotensive eye drops than TM.