Levobunolol hydrochloride

To the above toluenic solution containing levobunolol as free base, 16 ml ethanol and the stoichiometric amount of hydrogen chloride were added. The stirred mixture was cooled below 10°C and kept at this temperature for one hour. The precipitated solid was filtered, washed with toluene, recrystallized twice from 43 ml ethanol and dried to give 10.0 g (51% yield) of (-)-3,4-dihydro-5-(3-(tert-butylamino)-2-hydroxypropoxy)-l(2H)-naphthalenone hydrochloride (levobunolol hydrochloride) having a rotary power at 25°C below -19°. 

In a recent study carried out in the laboratory of the present author,30 the effect of different agents, known for their capacity of altering the permeability of biological membranes, was tested on in vitro permeation through rabbit corneas of three ophthalmic drugs possessing different lipophilic character timolol maleate (TM), levobunolol hydrochloride (LB) and cyclopentolate hydrochloride (CY). (Octanol/water distribution coefficients = 0.051,0.197 and 0.247, respectively). 

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