Periocular Tissue Concentrations of Propranolol after Ocular Instillation of a Gel-Forming Solution

The aim of this study was to determine the concentrations of propranolol in periocular tissues and plasma after ocular instillation of 0.5% propranolol gel-forming solution (GFS) as compared to 0.5% propranolol non-gelforming solution (non-GFS) for potential use in the treatment of periocular capillary hemangiomas.

A GFS prepared in 1% sodium alginate or a non-GFS in phosphatebuffered saline was instilled into the eyes of rabbits. At predetermined time intervals after dosing, blood was withdrawn, rabbits were euthanized, and periocular tissues were dissected.

Ocular instillation of the GFS resulted in higher concentrations of propranolol in the outer layers of both the upper and lower eyelids (in the range of 9.9-36.9 μg/g) and maintained higher levels of propranolol in these tissues for 24 h after dosing, as compared to the ocular instillation of the non-GFS (in the range of 3.4-15.1 μg/g). While the concentrations of propranolol in the other periocular tissues were generally similar for GFS and non-GFS at 1 h after dosing, the concentrations of propranolol in the extraocular muscles and periocular fat were higher for GFS than those for non-GFS between 4-24 h after dosing. Lower level of propranolol in plasma was observed at 1 h with GFS as compared with non-GFS.

The use of the propranolol gel-forming solution can prolong drug retention on the ocular surface and increase its distribution to the outer layers of the eyelids while decreasing systemic exposure to the drug.