The Effect of Methyl-Cellulose on Responses to Solutions of Pilocarpine*

Effects of Drug Vehicles on Ocular Contact Time

“…Radioactive sodium pentechnetate Tc 99m was added to commonly used ophthalmic drug vehicles of saline, 1% methylcellulose, 1.4% polyvinyl alcohol, and a 6:4 mixture of white petrolatum-mineral oil ointment. These drug vehicles containing 99mTc were placed on both rabbit and human eyes and the rate of disappearance of the radioactivity determined.…”

Concentration of Fluorescein in Tear Fluid after Instillation as Eye-Drops

“…b). This suggests a greater drug resorption for the former, which has indeed been demonstrated in a number of investigations [Miiller andDeardorff, 1956: Haas andMerrill, 1962;Wang andHammarhind, 1970: Borgmann andWurster, 1973], The larger area under the curve for the older age group for both types of eye-drops ( fig. 3c, d) must be ascribed to diminished tear production at higher ages, which would result in less dilution and drainage of instilled drugs.…”

Vehicle Effects on Ocular Drug Bioavailability II: Evaluation of Pilocarpine

“…Previous work with pilocarpine showed that viscous polymer solutions (5,9,13) are only moderately successful in enhancing its corneal penetration. Attempts to increase the corneal drug penetration often begin by increasing the viscosity of the vehicle to delay this loss.…”

“…Thus, most topically applied ocular vehicles have included viscous polymers such as hydroxypropylcellulose (2)(3)(4), methylcellulose (5)(6)(7)(8)(9)(10)(11)(12), and polyvinyl al-Detailed studies of the drainage loss rate of these vehicles also have been performed (3,5,13,16,17) to permit selection of vehicles exhibiting cohol (2)(3)(4)(6)(7)(8)(13)(14)(15). Because of an inadequate understanding of the interplay between drug-vehicle-precorneal area properties, the primary thrust of much research has been directed toward prolonging the presence of the instilled dose in the precorneal area, usually referred to as increasing the contact time.…”

“…Tear samples were removed at 0, 1, 2, 3,4, and 5 min postinstillation using [1][2][3][4][5][6][7][8][9][10][11] disposable capillary pipets4. Isotonic 0.14 M l4C-glycerin solutions were prepared using Sorenserts buffer at pH 5 and 8, and 25-p1 doses were topically instilled as in the aqueous humor studies.…”