PHARMACOLOGICAL EVALUATION OF A NEW TIMOLOL PILOCARPINE FORMULATION/

A new formulation (HYA) based on timolol hyaluronate and pilocarpine h yaluronate salts has been shown to improve the bioavailability of the drugs and to extend the duration of their action. Extent of the intrao cular pressure lowering effect, duration of action and aqueous bioavai lability of timolol and pilocarpine of HYA were compared with a commer cial preparation. Ocular hypertension in the rabbit was induced by alp ha-chymotrypsin or by water loading. The hypotensive effect of HYA tre atment was significantly greater and longer than that observed in rabb it eyes treated with the commercial preparation both in the normotensi ve and in the hypertensive animals. Furthermore, we evaluated the miot ic response; due to pilocarpine, normotensive rabbits showed a greater miotic response and an extended duration when the eyes were treated w ith HYA. The new formulation increased the aqueous availability of tim olol and pilocarpine compared to the commercial preparation as determi ned by HPLC. The pharmacodynamic and pharmacokinetic profiles of HYA i ndicate an increase in efficacy and duration of action along with an i ncrease in bioavailability of timolol and pilocarpine in comparison wi th the commercial preparation.