Two low-molecular-weight fractions of sodium hyaluronate (Na-HA), denominated Hyalastin® and Hyalectin®, were investigated as potential adjuvants for ophthalmic vehicles containing pilocarpine nitrate (PiN). Tests were also performed on an ionic complex (HA/PiB) prepared from hyaluronic acid (derived from Hyalastin®) and pilocarpine base. The performance of the vehicles under study was verified by miosis and ocular retention tests carried out on albino rabbits, against a series of reference vehicles, three of which contained a high-molecular-weight fraction of Na-HA (Healon®). The group of 14 reference and test preparations exhibited Newtonian or pseudoplastic flow characteristics and encompassed a wide range of apparent viscosities (1 to 1054 mPa s). The results indicate that the HA/PiB salt and the high-MW Na-HA can significantly increase the bioavailability of pilocarpine with respect to reference vehicles of comparable viscosity: an effect that can be reasonably attributed to muco-adhesive effects. Conversely, in the present rabbit tests, the low-MW fractions of Na-HA performed poorly as adjuvants for the PiN solutions.
Evaluation of high- and low-molecular weight fractions of sodium hyaluronate and an ionic complex as adjuvants for topical ophthalmic vehicles containing pilocarpine
CHETONI, PATRIZIA;MONTI, DANIELA
1991-01-01
Abstract
Two low-molecular-weight fractions of sodium hyaluronate (Na-HA), denominated Hyalastin® and Hyalectin®, were investigated as potential adjuvants for ophthalmic vehicles containing pilocarpine nitrate (PiN). Tests were also performed on an ionic complex (HA/PiB) prepared from hyaluronic acid (derived from Hyalastin®) and pilocarpine base. The performance of the vehicles under study was verified by miosis and ocular retention tests carried out on albino rabbits, against a series of reference vehicles, three of which contained a high-molecular-weight fraction of Na-HA (Healon®). The group of 14 reference and test preparations exhibited Newtonian or pseudoplastic flow characteristics and encompassed a wide range of apparent viscosities (1 to 1054 mPa s). The results indicate that the HA/PiB salt and the high-MW Na-HA can significantly increase the bioavailability of pilocarpine with respect to reference vehicles of comparable viscosity: an effect that can be reasonably attributed to muco-adhesive effects. Conversely, in the present rabbit tests, the low-MW fractions of Na-HA performed poorly as adjuvants for the PiN solutions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
