when r 1 and / or r 2 in formula i is alkanoyl containing 1 - 22 carbon atoms , there are included both unbranched and branced alkenoyl , for example , formyl , acetyl , propionyl , butyryl , isobutyryl , valeryl , isovaleryl , 2 - methylbutanoyl , pivalyl , 3 - methylpentanoyl , 3 , 3 - dimethylbutanoyl , 2 , 2 - dimethylpentanoyl , doco - sanoyl , and 7 , 7 - dimethyloctanoyl . the branched alkanoyl groups are preferred over the unbranched alkanoyl groups . when r 1 and / or r 2 in formula i is alkenoyl having one or two double bonds and having 4 - 22 carbon atoms , there are included , for example , crotonyl , 9 - octadecenoyl , 2 , 5 - hexadienoyl , 3 , 6 - octadienoyl , 10 , 13 - octadecadienoyl , and 5 , 13 - docosadienoyl . when r 1 and / or r 2 in formula i is ## str5 ## there are included for example the cycloalkanecarbonyl and cycloalkanealkanoyl groups : cyclopropanecarbonyl , 1 - methylcyclopropanecarbonyl , cyclopropaneacetyl , alpha - methylcyclopropaneacetyl , 1 - methylcyclopropaneacetyl , 2 - amylcyclopropaneacetyl , cyclopropanepropionyl , alpha - methylcyclopropanepropionyl , 2 - isobutylcyclopropanepropionyl , 2 - hexylcyclopropanecarbonyl , cyclobutanepropionyl , 2 - methylcyclobutanecarbonyl , 1 , 3 - dimethylcyclobutanecarbonyl , 3 , 3 - dimethylcyclobutanecarbonyl , cyclobutaneacetyl , 2 , 2 - dimethyl - 3 - ethylcyclobutaneacetyl , cyclobutanepropionyl , cyclopentanecarbonyl , 1 - methyl - 3 - isopropyl , cyclopentanecarbonyl , cyclopentanepropionyl , cyclohexanecarbonyl , cyclohexaneacetyl , 4 - methylcyclohexaneacetyl , cycloheptanecarbonyl , 4 - methylcycloheptaneacetyl , and cycloheptanepropionyl . when r 1 and / or r 2 in formula i is ( phenyl or substituted ## str6 ## there are included for example benzoyl , phenylacetyl , alpha - phenylpropionyl , beta - phenylpropionyl , p - toluyl , m - toluyl , o - toluyl , o - ethylbenzoyo , p - tert - butylbenzoyl , 3 , 4 - dimethylbenzoyl , 2 - methyl - 4 - ethylbenzoyl , 2 , 4 , 6 - trimethylbenzoyl , m - methylphenylacetyl , p - isobutylphenylacetyl , beta -( p - ethylphenyl )- propionyl , p - anisoyl , m - anisoyl , o - anisoyl , m - isopropxybenzoyl , p - n - butoxybenzoyl , 3 - methoxy - 4 - ethoxybenzoyl , 3 , 4 , 5 - trimethoxybenzoyl , 2 , 4 , 6 - triethoxybenzoyl , p - methoxyphenylacetyl , m - isobutoxyphenylacetyl , 3 , 4 - diethoxyphenylacetyl , beta -( 3 , 4 , 5 - trimethoxyphenyl ) o - iodobenzoyl , m - bromobenzoyl , p - chlorobenzoyl , p - flourobenzoyl , 2 - bromo4 - chlorobenzoyl , 2 , 4 , 6 - trichlorobenzoyl , p - chlorophenylacetyl , alpha -( m - bromophenyl )- propionyl , p - trifluoromethylbenzoyl , 2 , 4 - di -( trifluoromethyl )- benzoyl , m - trifluoromethylphenylacetyl , beta -( p - trifluoromethyl - phenyl ) propionyl , 2 - methyl - 4 - methoxybenzoyl , 3 - chloro4 - ethoxybenzoyl , beta -( 3 - methyl - 4 - chlorophenyl ) propionyl , p - dimethylaminobenzoyl , m - diethylaminobenzoyl , p - dibutylaminobenzoyl , p -( n - methyl - n - ethylamino ) benzoyl , 0 - acetamidobenzoyl , m - propionamidobenzoyl , p - hexanoylaminobenzoyl , 3 - chloro - 4 - acetamidophenylacetyl , and p - acetamidophenylpropionyl . when r 1 and / or r 2 in formula i is napthhalenecarbonyl , there are included 1 - naphthalenecarbonyl and 2 - naphthalenecarbonyl . when r 1 and / or r 2 in formula i is pyridinecarbonyl , there are included picolinoyl ( 2 - pyridinecarbonyl ), nicotinoyl ( 3 - pyridinecarbonyl ), and isonicotinoyl ( 4 - pyridinecarbonyl ), and the opthalmologically acceptable acid - addition salts thereof . while all of the compounds within formula i suffice for the purposes of this application , a preferred group of compounds having exceptional activity at minimal concentration exists as noted below : other aspects of this invention include practicing the method of the invention with a pharmaceutically acceptable ophthalmological carrier as well as typical and coventional polymeric inserts or soft contact lenses . topical administration of a compound of formula i to the eye of a warm - blooded animal effectively lowers intraocular pressure without the concomitant appearance of any significant undesirable side effects associated with the prior art . in accordance with the present invention , the compound of formula i or an ophthalmologically acceptable acid addition salt thereof is applied topically to the eye in an effective opthalmologically acceptable amount , thereby providing a therapeutic useful reduction in intraocular pressure . it is to be understood that the term &# 34 ; effective ophthalmologically acceptable amount &# 34 ; as used herein generally refers to the quantity of the active ingredient necessary to effect a lowering of intraocular pressure without causing any concomitant side effects associated with the prior art as heretofore described . while the administered dose , whether a single dose or a daily dose , will , of course , vary with the individual treated , the dose administered is not subject to definite bounds . however , generally , the dose administered will usually be an effective amount , or the equivalent on a molar basis of the pharmacologically active form produced upon the metabolic release of the active drug to achieve its desired pharmacological and physiological effect , i . e ., a lowering of intraocular pressure . normally , however , a dose of from 50 to 100 μ1 of a solution contaning from 0 . 01 to 2 % once every 6 to 12 hours will suffice to reduce intraocular pressure . the term &# 34 ; ophthalmologically acceptable acid addition salts &# 34 ; as used herein in describing the salts of the compound of formula i is intended to define those salts which are nontoxic and nonirritating on topical application to the eye , stable when stored , and otherwise generally acceptable for ophthalmic formulation . by way of example , there can be mentioned those salts derived from organic or inorganic acids which are nonirritating to the ophthalmic membrane such as hydrochloric , hydrobromic , sulfuric , phosphoric , methanesulfonic , acetic , citric , malic , succinic , lactic , tartaric , benzoic and the like . when the compound of formula i is administered topically to the eye of a warm - blooded animal , it is preferred to maintain the same in an aqueous isotonic vehicle such as a 0 . 9 % sodium chloride solution . normally , one to four drops of such solution is sufficient for reducing intraocular pressure . naturally , other vehicles and additional active ingredients may be included , provided they do not hinder the therapeutic activity of the main active drug , the compound of formula i . in practicing the method of the present invention , ophthalmologically acceptable acid addition salts of the compound of formula i which are exceptionally water soluble , such as the tartrate , bitartrate , sulfate or hydrochloride salts are preferred . without further elaboration , it is believed that one of ordinary skill in the art can , using the preceding description , utilize the present invention to its fullest extent . consequently , the following specific embodiments are , therefore , to be construed as merely illustrative , and not limitative , of the remainder of the specification and claims in any way whatsoever . to a methanol solution containing 44 . 7 g ( 0 . 099 mol ) m , p - dipivalyladrenalone hydroperchlorate at 0 ° was added dropwise with stirring a methanol solution containing 16 . 7 g ( 0 . 099 mol ) cesium chloride . after stirring for 0 . 5 hr . at 0 ° , the cesium perchlorate was removed by filtration and the methanol filtrate was concentrated under reduced pressure to a light yellow solid . recrystallization of isopropanol gave 23 . 1 g ( 0 . 060 mol ), 60 %, m , p - dipivalyladrenalone hydrochloride , mp 201 ° - 203 ° , tlc ( silica gel / chloroform : methanol : formic acid : 30 : 10 : 1 ( viv )) rf = 0 . 65 ; uv ( methanol ): λmax 254 nm , λ280 nm ( sh ); ir ( kbr ) 2980 , 2770 , 1750 , 1685 , 1260 , 1100 and 840 cm - 1 ; pmr ( cd 3 cocd 3 . d 2 0 ) δ 6 . 8 - 7 . 7 ( m , 3h ), 4 . 4 ( s , 2h ), 2 . 5 ( s , 3h ) and 0 . 9 ( s , 18h ) ppm . anal . calcd for c 19 h 28 clno 5 : c , 59 . 13 ; h , 7 . 31 ; n , 3 . 63 ; cs , trace . found : c , 59 . 19 ; h , 7 . 22 ; n , 3 . 76 ; cs , 99 ppm . normal new zealand albino rabbits of either sex , weighing about 2 kg . were used in the studies . the animals were placed in wooden restraining boxes at least a half hour before the experiment and remained there throughout the test . the intraocular pressure was estimated using a standard tonometer , and the pupil diameter was measured with starrett micrometer held at constant distance from observer and animal eyes . prior to each pneuamtonometry the eye was given one drop of proparacaine hcl , ( alcaine ®), 0 . 5 % diluted 1 : 1 with normal saline , which was washed out a few seconds later with normal saline . the compound was dissolved in distilled water . dpa was freely soluble . the solutions were prepared freshly just before the experiment . a dose volume of 0 . 05 ml from an eppendorf pipet was used . the results of all intraocular pressure and mydriatic studies conducted are shown below in tables i and ii . table i__________________________________________________________________________the effect of dpa on intraocularpressure in normal albino rabbits__________________________________________________________________________concentration time ( hours ) __________________________________________________________________________ 0 1 2 4 6 8 10 23__________________________________________________________________________ intraocular pressure mmhg ( x ± s . e . ) __________________________________________________________________________0 % 24 . 8 25 . 2 24 . 2 24 . 8 24 . 7 24 . 8 25 . 2 26 . 2 ± 0 . 8 ± 1 . 0 ± 1 . 2 ± 1 . 0 ± 1 . 4 ± 1 . 2 ± 0 . 7 ± 0 . 70 . 01 % 26 . 2 22 . 8 17 . 7 20 . 5 20 . 7 22 . 7 22 . 2 27 . 2 ± 0 . 9 ± 2 . 1 ± 1 . 8 ± 2 . 1 ± 2 . 2 ± 1 . 8 ± 1 . 1 ± 0 . 40 . 1 % 25 . 2 24 . 7 18 . 7 16 . 5 15 . 2 16 . 8 19 . 3 25 . 5 ± 0 . 9 ± 1 . 3 ± 1 . 8 ± 1 . 0 ± 1 . 6 ± 0 . 7 ± 0 . 9 ± 0 . 80 . 5 % 25 . 2 22 . 7 22 . 5 17 . 8 13 . 5 13 . 0 15 . 7 25 . 2 ± 0 . 6 ± 1 . 1 ± 1 . 4 ± 2 . 3 ± 1 . 1 ± 0 . 9 ± 0 . 8 ± 0 . 81 % 24 . 3 21 . 8 23 . 8 18 . 3 14 . 5 14 . 8 13 . 2 22 . 2 ± 1 . 1 ± 1 . 1 ± 1 . 0 ± 1 . 7 ± 0 . 4 ± 1 . 0 ± 0 . 6 ± 1 . 3__________________________________________________________________________ table ii__________________________________________________________________________the effect of dpa on pupildiameter in normal albino rabbits__________________________________________________________________________concentration time ( hours ) __________________________________________________________________________ 0 0 . 5 1 . 5 3 5__________________________________________________________________________ pupil diameter mm ( x ± s . e . ) __________________________________________________________________________0 % 5 . 0 5 . 1 5 . 0 5 . 0 5 . 0 ± 0 . 1 ± 0 . 2 ± 0 . 1 ± 0 . 2 ± 0 . 10 . 01 % 4 . 7 5 . 6 5 . 2 4 . 7 4 . 7 ± 0 . 1 ± 0 . 3 ± 0 . 2 ± 0 . 1 ± 0 . 10 . 1 % 4 . 8 6 . 9 6 . 7 5 . 1 4 . 7 ± 0 . 1 ± 0 . 2 ± 0 . 2 ± 0 . 1 ± 0 . 10 . 5 % 5 . 0 7 . 2 6 . 9 5 . 2 5 . 0 ± 0 . 1 ± 0 . 5 ± 0 . 3 ± 0 . 2 ± 0 . 11 % 5 . 0 6 . 6 6 . 1 5 . 0 4 . 8 ± 0 . 1 ± 0 . 2 ± 0 . 1 ± 0 . 1 ± 0 . 1__________________________________________________________________________ when the preceding example is repeated , but this time , employing any one of the remaining compounds encompassed within formula i , substantially smilar results will be observed . pharameceutical compositions comprising any of the compounds of formula i in combination with a nontoxic pharmaceutically acceptable ophthalmological carrier therefor , suitable for ocular installation , is preferred for practicing the present invention . these include opthalmic solutions , ointments or any other equivalent ophthalmic vehicles . aqueous opthalmic solutions formulated in accordance with good pharmaceutical practices as set forth in chapter 83 of remington &# 39 ; s pharmaceutical sciences , fourteenth edition , mac publishing company , are preferred , although petrolatum based ointments may suffice . the ophthalmic solutions are naturally sterilized and preferably contain a bacteriological preservative to maintain sterility during storage and use . the quaternary ammonium bacteriostats such as benzalkonium chloride are satisfactory . antioxidants can also be employed if desirable , but in view of the fact that the compounds of formula i are highly stable toward degradation , antioxidants will seldom be necessary . by way of example , suitable antioxidants include sodium bisulfite , n - acetylcystene salts , sodium ascorbate and other water soluble opthalmologically acceptable antioxidants known in the pharmaceutical arts . ophthalmic solutions of any of the compounds of formula i may be adjusted with inert ingredients such as sodium chloride or boric acid to provide a solution which is comfortable for application to the eye . that is , adding ingredients to the basic opthalmological formulation for the purpose of achieving isotonicity with the eye are within the purview of the instant invention . ointments are prepared with conventional petralatum vehicles employing liquid petrolatum and white petrolatum in such proportions as to afford an ointment of desirable fluidity . the compounds of formula i and any opthalmological acceptable acid addition salt thereof may also be applied to the eye through the vehicle of a polymeric insert or soft contact lens . for the latter purpose , the polymeric hydrophilic hydrogels prepared from polymers of acrylic and methacrylic esters , modified collagens , cross - linked polyether gels , cross - linked polyvinyl alcohol , or cross - linked partially hydrolyzed polyvinylacetate as disclosed in u . s . pat . nos . 2 , 976 , 576 ; 3 , 220 , 960 and 3 , 419 , 006 may be employed . ocular inserts prepared from these or other polymeric materials which are insoluble in tear fluid but which may absorb tear fluid to form a swollen hydrogel as disclosed in u . s . pat . nos . 3 , 416 , 530 , 3 , 618 , 604 and 3 , 632 , 200 may also be employed . all such means of applying the compounds of formula i or any ophthalmologically pharmaceutically acceptable acid addition salt thereof are included within the present invention as are compositions adapted for such use . in practicing the process of the present invention for lowering intraocular pressure , an opthalmologically acceptable polymeric ocular insert placed and retained in contact with an eyeball is preferred wherein the compound of formula i diffuses from the insert at a rate sufficient to provide an effective intraocular pressure lowering dose over a period of 6 hours . ocular inserts , particularly preferred in the practice of the present invention , are conventionally prepared , for example , by soaking the polymeric insert or soft lens in an effective amount of a solution of the compound of formula i or an ophthalmologically acceptable acid addition salt thereof until equilibrium is established , which is generally within a period of one to five minutes . inserts prepared in this manner diffuse at a rate sufficient to provide a therapeutic dose to the eyeball over a period of six hours . from the foregoing description , one of ordinary skill in the art can easily ascertain the essential characteristics of this invention , and without departing from the spirit and scope thereof , can make verious changes and / or modifications to the invention for adapting it to various usages and contitions . accordingly , such changes and modifications are properly , equitably and intended to be , within the full range of equivalence of the following claims .
intraocular pressure in warm - blooded animals is reduced by topically applying to the eye thereof , an effective ophthalmologically acceptable amount of a compound of the formula : ## str1 ## wherein r represents a member selected from the group consisting of hydrogen or a c 1 - c 5 straight or branched alkyl group ; and wherein r 1 and r 2 , which may be the same or different , represents an acyl member selected from the group consisting of alkanoyl having 1 - 22 carbon atoms , alkenoyl having one or two double bonds and having 4 - 22 carbon atoms , ## str2 ## having a total of 4 - 10 carbon atoms of which 3 - 7 are ring carbon atoms in cycloalkyl and wherein n is zero , one , or two , phenoxyacetyl , naphthalenecarbonyl , pyridinecarbonyl , ## str3 ## wherein n is zero , one or two and phenyl is unsubstituted or is substituted by 1 - 3 alkyl having 1 - 4 carbon atoms , alkoxy having 1 - 4 carbon atoms , halo , trifluoromethyl , dialkylamino having 2 - 8 carbon atoms , and alkanoylamino having 1 - 6 carbon atoms ; or an ophthalmologically acceptable acid addition salt thereof .