CA1117528A - Glaucine phosphate salts - Google Patents

Abstract

ABSTRACT
Novel glaucine phosphates selected from l-glaucine phosphate, d, l-glaucine phosphate and mixtures thereof are prepared by reacting 1- or d, l-glaucine or a mixture thereof with phosphoric acid. The salts possess antitussive and analgesic activity.

Description

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PHOSP~L~TE SALTS OF l-AND d ,1--GLAUCINE

This invention ls directed to the phosphate salts of l-glaucin~, d,l~gLaucine and mi~tures of l-and d,l-glaucine, to pharmaceu-tical compositions containing said salts and to methods for using them as an-titussive and analgesic agents.
Glaucine which has the following structure: -H3CO ~

possesses an asymmetric center indicated in the -above formula with a star. Thus two optical isomers are possible. Only one of them, the dextrorotatory form (d-glau-cine) occurs naturally and can be isolated from the yellow poppy. The racemate, d,l-glaucine, can be synthesized ~rom papaverine! following the procedure of Frank and Tietze, Angewandte Chemie (1967) pp. 815-6, or according to a vari-ety of other preparative methods such as those described by Chan and Maitland in J. Chem. Soc. (C) 1966, 753 or by Cava et al., in J. Org.Chem. 35j 175 (1970). Separation of the two enantiomers can be carried out by conventional procedu-res such as using an optically active acid, for instance d- or l-tartaric acid, to form the diastereoisomeric-salts which can be separated by fractional crystallization.

d-Glaucine hydrobromide and d-glaucine hydro-chloride are k~n to have antitussive activity (Donev, Farma-` ~

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tsia (Soia) 1962, 12, t4), p. 17, and Aleshinskaya, Khim. Farm. Zh. 10, (1), pp. 144~147 (1~76) and Cheml-cal Abstracts 84 : 159725 ~)~
In addition, Aleshinskaya, supra, stated tha-t glaucine derived fxom the yellow horned poppy (d-glaucine), pro longes hexenal and chloral hydrate sleep time in mice, and has analgesic activity at doses of 50-100 mg/Kg, as well as adrenolytic activity.
More recent investigations proved that levorotatory and recemic isomers o glaucine hydrobromide have superior antitussive properties over the prior-art dextrorotatory form (Belgian patent No. 866.079).

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As it can be ascertained by the above formula, ~laucine is structurally related to other plant alkaloids :
such as co~eine. Codeine and related compounds, such as hydrocodone, are well known as antitussive and narco*ic analgesic agents. Merck Index, Ninth Ed., Merck & Co., Rahway, N.J. (1976) monographs Nos. 2420-24 and 4672.
Although these compounds are also well known to have a high potential for habituation or addiction, they remain the most potent and widely used antitussive agents. Anti-tussive agents are usually administered orally, most ty-pically in the form of a liquid formulation such as an elixix, suspension or syrup, or in a solid lozenge or cough drop which is held in the mouth until it dissolves. In both cases the unpleasant bitter flavor o~ the alkaloid is known disadvantage o~ such agents. Various formulations have been developed to mask the unpleasant taste and after taste of j2~

codeine ~it~ varying degrees of success. None of these technlques ho~ever have ~een completely successful.
Glaucine, like codeine, has an unpleasant ~itter taste.
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It has no~ surprisingly been found that l-and - d,l-glaucine phosphate salts, besides having antitussive properties that are superior to the d-ylaucine, have analgesic activity unexpectedly superior to that of d-glau-cine coupled with a very low addictive potential, parti-cularly desirable solubility and stabiiity properties, and unexpected flavour and palatability properties which make them particularly useful orally.

The novel glaucine phosphate salts include the phosphates of the l-glaucine mixed with up to an equi-molar amount of d-glaucine. Since a mixture of e~uimolar amounts of the levo~ and dextro-rotatoryisomers is a rà-cemic d,l-mixture, the mixed enantiomers of the inven-tlon can be referred to as the racemate or a mixture of the racemate with the l-enantiomer, i.e., as d,l-glaucine or a mixture of l-and d,l-glaucine.

The novel phosphate salts of the invention are crystalline solids which are prepared by reacting l-glaucine or d,l-glaucine (or mixtures thereo~ in t~e form of the base, with phosphoric acid under conditions adapted to the formation of phosphate salts of organic bases. - -~75~3 ..
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~ ; The -crys~alline solld salts include from about 0.3 or 0.4 to about ~.6 or 0.7 molar proportion of excess phosphoric acid, typically one mole of glaucine base to about 1.4 to 1.6 moles of phosphoric acid. The predominant crystalline phosphate salt, readily obtained using excess phosphoric acid, includes about 1.4 to 1.6 and usually about 1.5 molecular proportions of phosphoric acid per molecular proportion of 1-or d,1-glaucine. The molecular proportions of glaucine and phosphoric acid can be determined by conven- -tional procedures such as elemental analysis, or by X-ray crystallography and crystal density measurements.
This salt can be referred to as glaucine phosphate (2:3), or (glaucine)2 3~3PO4, or glaucine-1l,~3PO~, for example.

The 1- and d,1-glaucine phosphate salts melt in the range from about 240-to a~-out 254C and have 20 useful solubility in water, and are less soluble -in organic solvents such as methylene chloride, acetone and diethyl ether. They are acidic in solution and generally have a pH in water solution (O.5 grams~100 ml) of about 2.4-2.6. The exact melting point of ~articular preparations can vary depending on the preparative and purification pro-cedures used, indicating that factors such as water of hydration or crystalline solvate formation with the reactio~ medium or with recrystallization sol-vents may be involved~

Depending on the amounts of reactantsemployed, the glaucine phosphate salt can contain a minor amount of a second glaucine phosphate, .

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believed to be diglaucine phosphate, detectable by a differential scanning calorimetry peak at about 219-221C, although the elemental analysis confirms the (2:3) structure. This peak can be removed by treating the product with additional phosphoric acid, to obtain the glaucine phosphate ~:3) salt free of the lower melting impurity.
The salts can also be obtained in association with unreacted phosphoxic acid, when large excesses of phosphoric acid are employed. Excess associated phosphoric acid can be removed by conventional techniques such as filtration, or partial neu-tralization. When excess 1- or d,l~glaucine is employed, the salts can also be obtained in association with unreacted glaucine, depending on ~he reaction conditions and solvent employed.
Unreacted glaucine can be removed by conventional purification techniques such as recrystallization and washing, or converted to the phosphate salt with ad~itional phosphoric acid.

The compounds can be readily prepared by reacting the free glaucine base with phosphoric acid. The reaction proceeds readily in the pres-ence of an inert organic solvent, such as acetone, ethanol, chloroform, methylene chloride, methanol, diethyl e~her, or ethyl acetate. The phosphate salt typically forms a5 a precipitate, which can be recovered by conventional techni~ues such as filtration or decantation and purified by conven-tional steps such as recrystallization and washing.
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The reaction is typically carried out bydissolving the free base glaucine in the inert organic solvent at a temperature from ambient ~7 5~

temperature to the boiling point of the mixture, and mixing the solution with an excess of phos-phoric acid. Phosphoric acid is employed in from about 0.5 to about 1 to 2 to 3 fold molar excess S or more. Use of eguimolar amounts or excess glau- -cine reactant can result in obtention of a mix-ture of the glaucine phosphate (2:3) salt with impurities such as unreacted or partially reac-ted glaucine base. Such products can be reacted with additional phosphoric acid to con~ert the impurities to glaucine phosphate (2:3).

When using excess phosphoric acid, so as to obtain the glaucine phosphate (2:3) salt in relatively pure form or a solid phosphate associated with excess phosphoric acid, any excess phosphoric acid content can be reduced by partial neutralization followed by recrystallization. In such procedure, the solid salt is first titrated to determine the molar amount of phosphate in excess over the molar amount of glaucine. The solid salt can then be - mixed with alcoholic alkali metal hydroxide base, such as sodium or potassium hydroxide in methanol or ethanol, using an amount of a alkali metal hy-droxide suf~icient to neutralize the excess phos-phoric acid. The glaucine phosphate (2:3) saltcan then be:purified by conventional recrystal-lization, for example, with ethanol. Partial neutralization is generally unnecessary to obtain a useful salt in crystalline form. Preferably, the product is digested by heating under reflux in ethanol for four to eight hours, before recrys- -talli~ation and drying.

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When the salts are in solution, the ratio - of gl~ucine to phosphoric acid can be increased by conventional proceduxes such as partial titration to reduce the level of phosphoric acid. Such pro-cedures can pxoduce mixtures of the glaucine baseand the glaucine phosphate salt, and can lead to precipitation of the free base. Addition of excess phosphoric acid substantially beyond the (2:3) molar ratio in the salt generally results in precipitation of the glaucine phosphate salt.

Mixtures of the d,1- and 1-glaucine phosphate salts and the salts, whether or not associated or complexed with additional phos-phoric acid or containing minor amounts of 15 unreacted or partially reacted glaucine are all - -useful as antitussive agents ~nd analgesic agents, with similar desirable properties. For convenience it is generally preferred to use a single phosphate salt, such as the d,1-glaucine phosphate or 1-glau-cine phosphate. The preferred salt is the salt having 1.5 molar proportions of phosphoric acid per molar proportion of d,l-glaucine.

The glaucine phosphate salts are highly --effective, orally active antitussive agents and also have analgesic activity when administered orally, combined with surprising palatability and desirable stability and solubility, and a useful freedom from undesired side effects, such as addictive properties. They can be administered at dosages of from about 0.1 to about 40 milli-grams or more per kilograms (mg/kg) for anti-tussive effect, and from about 0.1 to about 60 -75~

mg/Kg for analyesic use, prefera~ly by oral admini-stration. They are also acti~e parenterally as anti-tussive and analgesic~, b~ .Lntraper~toneal injection, for example.
In practicing the method of the invention, an antitussive amount of one or more of the glaucine phospha-tes, is administered internally to an animal, typically a mammal in need'~hereof. Administration can be carried out either by a parenteral route, such. as by intravenous, intra-peritoneal, or intramuscular injection; or by introduction _-into the gastrointeskinal tract via oral or.rectal admini-stration, for example, or by oral ad~inistration of a glau-cine phosphate solutlon in th.e form of a throat spray; for example.
' The antitussive amount of the compound, that is, the amount of the glaucine phosphate sufficient to inhibit or all'eviate coughing depends on various factors such as the size, type and age of th animal to be treated,.the parti-cular salt or mixture of salts employed, the route and fre-quency o~ administration, the severity of cough (if any) and the causative agent involved, and the time o administration.
Similar considerations appiy to selection of the analgesic amount of glaucine phosphate,.i.e., the amount of the glaucine phosphate :su~fi~ient:to~alleviate pain symptoms~when 'admi-~' nistered to animals.~The 'glaucine~phosphate s'alts are general-ly effective at lo~ dosages when administered orally as com-pared to parenteral dosages. For example, in antitussive eva~
luations in whi.ch codeine p~osphate has an ED50 of 10.9 mg/Kg by intraperitoneal injection and an oral ED50 of 86.6 mg/Kg, the oral and intraperitoneal ED50's obtained with (d,l-glau-cinex2~3H3po~ are quite simllar, 17~8 and 17.3 mg/Kg.

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In particular ca~e the dosage to be administered can be ascertained by conventional range finding technlques for e~ample, ~y observing the antitugsive act1vi-ty produced ~ _ .., at dlffereilt dosage rates.
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Good antitussive results can be obtained when the salts are administered orally at dosage rates from about 0.1 to about 0.2, to about 0.5 to about 1 to about 10 to about 20 to 25 to 30 to 40 to about 80 milligrams of glaucine salt compound per kilogram o~ animal body weiyht and at rates of 0.1 to 40 mg/kg by intraperitoneal injection. It =
is generally desirable to administer individual dosages at the lowest amount which provides the -desired cough suppression consonant with a -~
convenient dosing schedule. Oral administration - is the route generally preferred for administration of antitussi~e agents. The glaucine phosphates of the invention thus combine high oral antitussive potency with palatability.

Dosage units adaptable to oral administration -:-such as tablets, capsules, lozenges, elixirs, syrups and the like are preferred and the active glaucine phosphate compound can be formulated in conventional timed release capsule or tablet formulations.

In using the compounds of the invention, the active glaucine phosphate ingredient is pre-ferably incorporated in a composition comprising a pharmaceutical carrier and from about 0.001 to about --~
95 percent by weight of the glaucine phosphate salt compound or a pharmacologically-acceptable salt thereof. The term "pharmaceutical carrier" refers ~ :-~7S;2~

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. to known pharmaceutical excipients useful in form-ul~ting pharmacologically-active compounds for internal administration to animals, and which are substantially non-toxic and non-sensitizing under conditions of use. The compositions can be pre-pared by known techniques for the preparation of tablets, capsules, cough drops, lozenges, troches, suppositories, solutions, elixirs, syrups, emulsions, dispersions, wettable and effervescent powders, 10 sterile injectable compositions, and can contain . _.
suitable excipients known to be useful in the - -. pre~aration of the particular type of cornposition desired. As with phosphates generally, liquid compositions should generally be substantially free of cations which form highly.insoluble phos-- phate salts, to avoid undesired salt precipitation.

The compounds may be administered in conjunction with other active ingredients or other .antitussive or analgesi~ agents. Other active .
ingredients can include, for example, antihista-mines, decongestants, expectorants, mucolytic agents, bro~chodilators and antibacterial agents or local anesthetics. Combinations of this type are generally useful for treating coughing or pain in combination with other sym~tomsO

Particularly desirable compositions are those prepared in the form of dosage units, such as solid forms, including troches, lozenges, tablets, capsules, or measured volumes of liquid compvsitions, containing from about 0.1 milligram to about 20 to30 to 40 milligrams of the glaucine salt per unit, for antitussive use and from about 0.1 milligram to about 30 to about 60 milligrams for analgesic use.

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Example 1 - Preparation of d,l-Glaucine Phos~hate A. 43.5 Grams (0.1 mole) of glaucine hydrobromide was suspended in 200 millilitexs o~
deionized water in a separation funnel. 50 Milli- -liters o~ aqueous 10 percent sodium hydroxide was added, and the resulting mixture was extracted twice with chloroform using 100 milliliters of chloroform for each extraction. The combined -chloroform extracts were dried over anhydrous sodium sulfate, filter~d and concentrated ~o dryness under reduced pressure~ The resulting white solid d,1-glaucine base was obtained as a residue, melting at 13~C. (Yield 96%). When desired it can be purified further by recrystal-lization from ethyl acetate.

B. 3.6 Grams (0.01 mole) of d,l-glaucine base was dissolved in 150 milliliters of Alcohol USP
(95 percent ethanol, 5 percent water), with warming to a temperature of 60C. A solution of 2.0 grams (0.022 mole) of phosphoric acid (85 percent phos-phoric acid in water) dispersed in 100 milliliters of Alcohol USP (95 percent ethanol, 5 percent water) was added slowly, with stirring, over a period of about twenty minutes. The d,l-glaucine phosphate -~
product began to appear as a precipitate during the phosphoric acid addition. The product was separated by filtration, and found to melt at 240C with decomposition. The white crystalline solid product ~as recrystallized by mixing with 80 percent ethanol in water; heating under reflux and cooling to ambient temperature. The recrystal-lized product was then taken up and stirred in a mixture of diethyl ethe~ (3 parts) to one part ethanol, separated by filtration, dried and found 7~ii2~3 to melt at 247C with decomposition. (Yield 94.3%~
C, ~, N (calculated) for C~lH25N04~ ~3P0~: 50.2, 5.gl, 2.79; (found): 50.29, ~.03, 2.93.

The elemental analysis is thus consistent with the structure (d,l-glaucine)2-3H3PO4. (The theoretical C, H, ~ contents calculated for a 1:1 glaucine phosphate (C2lH~5N04 ~3P04) 6.22, and 3.09.) ~

By differential scanning calorimetry the _-product appears to be at least 95 percent pure, with a sin~le large peak at 247C, and with about 5 per- -cent or less as a single small peak believed to be di-d,l-glaucine phosphate at 221C. The ~d,1-glau-cine)2 3H3P04 crystals are discrete, well-formed white crystals of rod-like to needle-like shape.

C. In a similar procedure 2 grams of l-glaucine hydrobromide was suspended in water, 5 milli-liters of a~ueous lO percent sodium hydroxide was added, and the mixture was extracted with two 50 milliliter 20 portions of chloroform. The extracts were dried, --filtered and evaporated to dryness. The resulting l-glaucine base was reacted with 0.25 mole phosphoric ----acid in a procedure similar to that in Example lB.
The crystalline product was separated, dissolved in 5 milliliters of 95 percent ethanol and reprecipitat~d by addition of diethyl ether, and rècrystallized a -- second time from ethanolO The white crystalline (l-glaucine)2 3H3P04 tl glaucine phosphate (2:3)]
product was found to melt at 242.9C, with decompo-sition. In a similar procedure with an additional recrystallization from ethanol the product was found to melt at 253C. -~75~

D. In a similar procedure 56.8 grams of d, l-glaucine in 250 milliliters Alcohol USP was reacted with 32 grams of 85 percent phosphoric acid in 500 milliliters Alcohol USP, by adding the glau-cine base solution to the phosphoric acid solution.
The product showed two peaks by differential scanning calorimetry, one at about 245C and a smaller peak at about 219C (believed-to be di-d,l-glaucine phosphate).
The (d,l-glaucine)2 3H3PO4 product was dried overnight at 120C and found by elemental analysis to have C, H, N, O contents of 50.66, 6.06, 3.23 and 30.09 percent and a phosphorus content (P) o~ 10.07.
Theoretical C, ~, N, o and P calculated for C21H25NO4~ H3P04: ~0.20, 5.91, 2.79, 31.85 and 9.25.
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E. In ~ similar procedure, a d,l- --glaucine phosphate was prepared. C, H, N, P: calculated for C21~25NO4 1.4 H3 4 5.97, 2.84, 8.8; C, ~, N found: 50.80, 6.00,

2.95 (average of four replications~ and P 8.22.

F. A sample of the d,l-glaucine phosphate (2:3) salt of Example l.D, melting at 245.2C, was washed thoroughly with a mixture of 3 parts diethyl-ether and one part ethanol, dried and found to melt at 250.7C. A mixture of the washed and unwashed crystals was found to melt at 242.2C, indicating the presence of different crystalline solvates in the two glaucine phosphate preparations.

G. 1 Gram (O.0028 mole) of d,1-glaucine was dissolved in 30 milliliters of distilled acetone.
0.3 Gram (0.003 mole) of 85 percent phosphoric acid was added. The resulting white precipitate was ~7~

removed by filtration, washed with 20 ml of dry acetone, dried in air then dried at 50-55C under vacuum overnight. The glaucine phosphate product (1.0 gram yield) was found to melt at 240-243C.
C, H, N: found: 51.2~ 6.07, 2.96; calculated for C21H25N04 13~3P04 50.2, 5.91, 2.79. In a similar --operation using 0.6 gram d,l-glaucine in 20 ml of acetone and 0.4 gram phosphoric acid, the washed, air dried product was dried under vacuum at 60 for about 2~i days. The glaucine phosphate was found to melt at 240-2~2C.- C, H, N: found: 49.3, 5.91, 2.7~; C, H, N calculated for C21H25N04 1.6-P04: ~9.24, 5.86, 2.73.

H. 2.5971 Kilograms (5.95 mole) of d,l-lS -glaucine hydrobromide, 10.0 liters of deionized water, and 3.5 liters of methylene chloride were mixed.
The mixture was stirred rapidly, and 500 milliliters of 50 percent sodium hydroxide were slowly added. The sodium hydroxide was washed in with 100 milliliters of deionized water. After the addition was complete, the mixture was stirred for 15 minutes. The stirrer :
was then stopped and the mixture allowed to stand for 10 minutes to permit the layers to separate. The methylene chloride layer was drained off and stored. -The aqueous layer was mixed with 3.5 liters of meth-ylene chloride, and the mixture stirred rapidly for 15 minutes. The mixture was allowed to stand for 10 minutes to permit the layers to separate. The methylene chloride layer was drained off. An addi-tional 200 milliliters of methylene chloride wasadded to the agueous layer. The methylene chloride layer was drained off. The methylene chloride layers were combined and mixed with 3 liters of deionized water.

Ihe resultillg mixture was s~irre(l rapiclly f~or lS minutcs then allowcd to stall~l Eor 15 tnlnutes to perm;t the layers to scparate. '~he metllylellc chloricle laycr was drlined off ancl stored. This methylene chlor-ide solution of cl,l-g~lucille base was then added to a well stirred solution of 1.4235 kilograms 112.35 mole) of 85 percent phosphoric acid in 9.8 liters of toluene-denaturecl, absolute ethanol. A heavy, white slurry formed. The slurry was stirred for 15 minutes, and then allowed to stand, under nitrogen, for about 1~-16 hours. The stirrer was then started, and the slurry was slowly drained into 3 liter, sintered glass funnels. The solid which resulted was placed in large glass drying dishes and air dried, then vacuum dried at 50-65C to give 2.902 kilograms ~97.1 percent yield) of d,l-glaucine phosphate.
A 22 liter flask was charged with 1.500 kilograms of the d,l-glaucine phosphate and 15 liters of 80 percent toluene-denatured, absolute ethanol (20 percent water). The mixture was stirred and heated to reflux ~78C) under nitrogen. The slurry was held at reflux for 5-6 hours, then allowed to cool to 22-25C. The slurry was then slowly drained into 3 liter sintered glass funnels. The resulting solid was then air-dried.
The solid was thoroughly washed with 3 liters of toluene-denatured, abso-lute ethanol and air-dried again. The solid was then vacuum dried at 50-65C to give 1.375 kilogram (91.7 percent recovery~ of d,l-glaucine phosphate having a chunky prismatic crystallin0 form.
By differential scanning calorimetry, the product showed a single peak, with a melting . . .

~7~ 8 point of 253~. C, H, N, found. 50.2, 5.97, 2-67, C, H, N calculated for C21H25NO~-l.SH3PO
50.2, 5.91, 2.79.

I. L-Glaucine phosphate, prepaxed as described above, was recrystallized three times from ethanol to obtain the purified salt in fine, po~der-like crystals. C, H, N, Found: 50.~0, 5.91, 2.73; C, ~, N, Calculated for C21~25N0*- -o ~1.5~3P04: 50.2, 5.91, 2.79.

J. Crystal density of d,l-glaucine phosphate was measured by suspending at least four crystals of d,l-glaucine~1.5H3P04 in a solution mixture of benzene and carbon tetra-chloride; adjusting the ratio of benzene andcarbon tetrachloride to e~ual density with the suspended crystals; and measuring density of the solution mixture which produced an equal-density suspension using a pycnometer. The crystal density thus obsexved was 1.460 grams per cubic centimeter.
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Unit cell constants for the d,1-glaucine-1.SH3P04 crystals were measured by single crystal X-ray crystallography. The cell dimensions were -found to be a = 89.854 Angstrom units; b = 8.565 Angstrom units and c - 23.830 ~ngstrom units, the crys~als being monoclinic with a ~ angle of 93.7.
Theoretical densities were calculated using as the smallest apparent cell volume V = 1/8 abc si~ ~ = 2.286 cubic Angstrom units (2.286 x 10-cubic centimeters) and Z equal to four molecules per small cell ~olume. For a (1:1) glaucine :
phosphate the calculated theoretical density .

~75;~3 Gram Mo~ecular_Weiqht Z
Avogadro Number x V

was 1.319 gram~/cm3. For a (1:2) sait, glaucine ~ diphosphate, the theoretical density was 1.602 grams/cm3. For a (2:1) salt, diglaucine mono phosphate, the theoretical density is greater than 2.3 srams/cm3. For d,l-glaucine 1.5H3PO4 the theoretical calculated crystal density was - 1.460 grams/cm3, which corresponds to the observed crystal der.sity.

Examp-le 2 Separate groups of guinea pigs were orally administered various doses of a test compound, or distilled water for a control group. One hour after oral dosing,-the guinea pigs were exposed to a 5 per-cent aerosol of citric acid for a 10 minute test period. The number of cough responses produced during the last five minutes o~ exposure to the citric acid aerosol was recorded and the dosage effect to suppress coughing in 50 percent of the guinea pigs (ED50~ was calculated. An antitussive e~fect was recorded for a quinea pig when its total number of coughs during the 5 minute test period were at least two standard deviation units below the mean number of coughs per guinea pig in the control group. In these operations, codeine phos phate was found to have an oral ED50 of g6.6;
d-glaucine hydrobromide an ED50 of as . o; d-glau-cine phosphate an ED50 of 170.1; d,l-glaucine phosphate ~d,l-gluacine)2 3(H3PO4)] an ED50 f 17.8; and 1-glaucine phosphate [(1-glaucine)2-

3(H3PO4)] an ED50 of 1~.9 milligrams perkilogram.

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The g5 percent confidence limits of the ED50's determined for codeine phosphate, the d,l-glaucine phosphate and the 1-glaucine phosphate were 52.3-232.6; 6.0-53.1; and 0.4-33.8, respectively.
The data indicate that the glaucine phosphates are approximately 4 to 8 times as potent as codeine in this test.
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Example 3 In an operation similar to that of Example 2, test compounds were administered to guinea pigs by intraperitoneal injection, with one group of guinea pigs receiving distilled water as a control.
ED50's were calculated for antitussive activity in the citric acid aerosol test ~s described in Example 2. Codeine phosphate was found to have an ED50 of 10.9 mg/kg; d-glaucine hydrobromide an ED50 f lO.Q mg/kg; and d,l-glaucine phosphate t(d,l-glau-)2 3(H3P04)] an ED50 of 17.3 mg/kg.
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Example 4 A cough syrup vehicle formulation was -prepared containing the following pharmaceutically- ---acceptable excipients:

Exci~ient Amount Sugar (cane) 1600 grams ~ Sorbitol solution USP 600 grams E~hanol (Alcohol USP~ 21 grams Water g.s. to 4 liters total The solubility of d,1-glaucine hydrobro- -mide in ~his cough syrup vehicle was found to be 30; 0.3 percent, or about 15 milligrams in a 5 milliliter 52i3 dosage unit. The solubility of d,1-glaucine phos-phate was ound to be 1 percent, or about 50 milli-grams per ~ milliliter dosage unit.

Example 5 Stability of d,1 glaucine phosphate was examined in the syrup vehicle of Example 4~ After -one month at ambient temperature, 40C and 55~C, :~
respectively, syrup formulated to contain 0.6 per-cent d,l-glaucine phosphate was ~ound ~o retain 101.3, 100.0 and 98.4 percent, respectively, of the original glaucine concentration.
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Syrups containing codeine phosphate, 0.2 percent contained 97.5, 104.5 or 100 percent, - :
respectively, after one month at ambient temper-ature, 40C or 55C. Syrups containing d,l--glaucine hydrobromide, 0.2 percent, resulted in assays of 99, 96 and 89.5 percent, respec-tively, after one month at ambient temperature, 40C and 55C. After three months, the percen-tage amount of antitussive agent remaining was as shown below. -Percentage Remaining after 3 months at Compound ~mbient 40C 5~C
d,1-Glaucine Phosphate (2:3) 101.6 101.1 98.7 Codeine Phosphate 101.3 101.1 88.4 d,1-Glaucine HBr 100.8 93.3 91.4 . .
After 12 months at 55aC the phosphate salt had an assay of 101.8 percent and the hydro-bromide an assay result of 87.3 percent.

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Example 6 In a procedure similar to that of Example 5, syrup formulations were prepared, plac~d in amber glass bottles and transparent (flint) glass bottles, and held under condikions of ambient temperature with continuous exposure to light.
(About 2000 Foot~candles of combined fluorescent and incandescent light, for 24 hours/day.) - After one month, the-d,l-glaucine hydro-10 bromide assay of amber bottles was 84 percent, - -that of flint glass was 74.5 percent. D,1-glau-cine phosphate in amber glass had an assay of 97.7 percent, in flint glass 90 percent. Codeine phos-phate appeared stable in both types of container, with assays of 100 percent.
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In similar operations, the crystalline glaucine phosphate (2:3) salt was found to retain over 98 percent of the original glaucine content after two months at 40C.

20 Example 7 :
The abuse potential of d,1-glaucine phosphate was studied in two monkeys in a pro-cedure similar to ~hat described by Deneau, et al., Psychopharmacologia 16(1) 30-48, 1969.

In this procedure, the test monkeys are restrained and a catheter inserted into the external jugular vein for injection of test substances in -response to pressing a bax lever by the monkey. The test monkeys are first habituated to self-administer codeine at a rate of 100 micrograms/kilogram per injection. The self-administration rate of the ~7~

two monkeys so trained and habituated was about 100 to 150 lever pushes per two hour session at the 100 microgram codeine level. When d,1-glau- -cine phosphate (2:3) was subs~ituted for codeine, the monkey response rate was found to decline, from 100-150 responses/two hour session for codeine to 10-20 responses/two hour session after substitution - of d,l-glaucine phosphate, at rates of 50, 100, 200 and 400 micrograms per kilogram injection.

Example 8 Physical dependency liability was eval-uated in mice by the procedure of Saelens, et al., Arch. Int. Pharmacodynam, 190:213-218, 1971. In this procedure, mice are administered increasing doses of a test compound at intervals on two con-sective days. The last dosage on the s~cond day is followed by intraperitoneal injection of the morphine antagonist, naloxone, at a dosage of 100 mg/kg, and the mice are observed ~or charac- -teristic jumping behaviour indicative of opiate withdrawals or morphine antagonism. In these operations, morphine sulfate produced stimulation -and Straub tail in mice, followed by jumping in 5 of 9 mice (g6 jumps total) after naloxone treatment. Codeine phosphate produced Straub tail and stimulation, and naloxone induced jumping in 2 of 6 mice (23 jumps total). d,l--Glaucine phosphate (2:3~ produced no Straub tail at the highest dose (100 mg/kg) and no jumping behaviour in any of the eight mice tested.

Example 9 --Several d,1-glaucine salts were prepared as 0.2 percent (weight ~y volume) solutions in 7~

.

distilled water. The various salt solutions were evaluated for palatability by touching a few drops to the tongue. In these operations, which included blind sampling by a trained flavor formulator exper- --5 ienced in flavoring of formulations containing agents -such as codeine and dextromethorphan, the hydro- --bromide was characterized as objectionable with a bitter, sharp and metallic initial taste which --increased with time. The sulfate, maleate, citrate, acetate and p-toluenesulfonate salts were similar to the hydrobromide and similarly objectionable. ~ -:
The salicylate and succinate salts were ranked as more objectionable than the hydrobromide. d,l- =
. -Glaucine phosphate (2:3) was found to lack the --sharp, metallic flavor and to be unobjectiona~le.

Example 10 A. A flavored cough syrup formulation is prepared to contain the following:
. .
Ingredient Amount 20 Sucrose (100% Invert Sugar- -:
-Dry Basis) 26.4 Grams - --Sorbitol Syrup USP10 Milliliters (Ml) -Glycerine 5 Ml -Alcohol USP 5.4 Ml 25 Piperonal 10.0 Milligrams (Mg) Vanillin 7.5 Mg Ethyl Vanillin 10.0 Mg Ethyl Mhltol 7.5 Mg l-Menthol 7.5 Mg d,l-Glaucine Phosphate (2:3)600 Mg Purified Water USP g.s. to 100 Ml Total .

- ., . -~ .~ - .

~75~

The syrup contains 0.6 percent (weight by volu~e) d,l-glaucine phosphate and a 5 ml dosage unit (1 teaspoon) contains 30 mg of active phosphate salt. The syrup can be sealed into 5 ml plastic lined foil pouches, or filled into conventional glass bottles. Dosage units of 15 mg and 20 mg per 5 ml dose can be made by using 300 or 400 mg of d,l-glaucine phosphate (2:3) or l-glaucine phosphate (2:3~ or mixtures thereof in the above formula.

B. Tablets are prepared as follows:
40 gr~ams l-glaucine phosphate; 150 grams of modified starch (Sta-Rex 1500) are mixed and granulated with sufficient aqueous alcohol (75 percent water, 25 percent ethanol~ to prepare a granulation. The granulation is dried and mixed --with-15 grams starch USP; 1.5 grams stearic acid (40 mesh); 0.5 grams hydrogenated vegetable oil (40 mesh3 3 grams colloidal silicon dioxide and microcrystalline cellulose q.s. to 300 grams.
The ingredients are mixed and compressed into 300 milligram tablets using 11/32 inch tablet dies. The tablets contain 40 milligrams of l-glaucine phosphate each.

C. Capsules are prepared by blending 5 grams d,1-glaucine phosphate, and 5 grams 1-~laucine phosphate; 3 grams colloidal silica; 2 grams stearic acid and 285 grams lactose; and filling the blend into No. 2 gelatin capsules, 300 milligrams per capsule. --This provides 10 milligrams of glaucine phosphate per capsule. Larger unit dosages, such as 15, 20 or 25 mg, can be prepared by using 15, 20 or 25 grams glaucine phosphate and lactose q.s. to 300 grams.
Smaller dosages are similarly prepared.

~'i'5~8 -24~

, .

D. Troches are prepared by mixing 30 grams d,l-glaucine phosphate (2:3), 435 grams powder~d sugar and 35 grams powdered acacia; adding sufficient water to form a pliable mass; rolling the mass into a cylin- ~
drical shape and dividing the mass into 0.5 gr~m segments.

Example 11 In other operations, various dosages of d,l-glaucine phosphate (2:3) were administered to 10 groupsofmioe bythe oral route or by intraperitoneal - _ injection, and the dosage which is lethal to 50 per- - -cent of the mice (LD50) was calculated from the mortality observations wit~in 72 hours after admin-istration. The LD50 for intraperitoneal injection was found to be 178 mg/kg. The oral LD50 in these operations was found to be egual to or greater than 681 mg/kg.
.
These data, together with the ED50's determined in Examples 2 and 3, indicate that the phosphate salt has a therapeutic ratio (LD50/ED~o) of 38 for oral antitussive activity and 10 for intraperitoneal activity.
,'`:' In other operations, 1- and d~glaucine phosphate (2:3) were orally administered to sep-arate guinea pigs and plasma concentrations o~l- or d-glaucine were measured at intervals after dosing. These data showed that the l-glaucine phosphate produced high plasma levels of glaucine within 15 minutes after dosing, and that plasma levels remained high, generally 3 to 6 or more times as great as the plasma levels of d-glaucine, over a two hour test period. -.

L75~Z5 -2~-Example 12 Text compounds were evaluated for analgesic activity in the phenyl-p-guinone mouse wri~ing test of Hendershot & Forsaith, J. Pharrnacol. Exptl. Therap.
125(3) 237 (1959). The test cornpounds were admin-istered orally 30 minutes prior to the phenyl-p- --quinone c~allenge. In these operations, the oral ED~o's for d-glaucine-~Br, codeine phosphate and d,l-glaucine phosphate (2:3) were found to be 34.0, 21.1 and ~300 mg/kg respectively.
.

.

Claims (21)

1. THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
   PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
   
   l. A process for preparing a glaucine phosphate salt selected from 1-glaucine phosphate, d, 1-glaucine phosphate and mixtures thereof, which comprises reacting 1-glaucine, d, 1-glaucine or a mixture thereof with phosphoric acid.
2. 2. A process according to Claim 1, wherein 1-glaucine is reacted with phosphoric acid.
3. 3. A process according to Claim 2, wherein from about 1 to about 2 moles of phosphoric acid are employed per mole of 1-glaucine.
4. 4. A process according to Claim 3, wherein between 1.4 and 1.6 moles of phosphoric acid are employed per mole of 1-glaucine where by to obtain the 1-glaucine phosphate (2:3) salt.
5. 5. A process according to Claim 1, wherein d, 1-glaucine is reacted with phosphoric acid.
6. 6. A process according to Claim 5, wherein an excess of about 0.3 to 0.7 moles of phosphoric acid is employed.
7. 7. A process according to Claim 5, wherein between 1.4 and 1.6 moles of phosphoric acid are employed per mole of d, 1-glaucine, whereby to obtain the d, 1-glaucine phosphate (2:3) salt.
8. 8. A process of preparing a glaucine phosphate salt, which comprises reacting a compound selected from 1-glaucine, d, 1-glaucine and mixtures thereof with at least about a 1.4 molar excess of phosphoric acid, to pro-duce a salt having a melting point of about 240° - 254°C with decomposition, and a pH in water solution (0.5 grams/100 milliliters) of about 2.4-2.6.
9. 9. A phosphate salt of a member of the group consisting of l-glaucine d,l-glaucine and mixtures thereof, whenever prepared by the process of Claim 1, or by an obvious chemical equivalent thereof.
10. 10. l-Glaucine phosphate, whenever prepared by the process of Claim 2, or by an obvious chemical equivalent thereof.
11. 11. l-Glaucine phosphate having from about 1 to about 2 molar pro-portions of phosphoric acid per molar proportion of l-glaucine, whenever prepared by the process of Claim 3, or by an obvious chemical equivalent thereof.
12. 12. l-Glaucine phosphate (2:3), whenever prepared by the process of Claim 4, or by an obvious chemical equivalent thereof.
13. 13. d,l-Glaucine phosphate, whenever prepared by the process of Claim 5, or by an obvious chemical equivalent thereof.
14. 14. d,l-Glaucine phosphate having from about 0.3 to about 0.7 molar proportions of excess phosphoric acid per molar proportion of glaucine, whenever prepared by the process of Claim 6, or by an obvious chemical equivalent thereof.
15. 15. d,l-Glaucine phosphate (2:3), whenever prepared by the process of Claim 7, or by an obvious chemical equivalent thereof.
16. 16. A glaucine phosphate salt selected from l-glaucine phosphate and d,l-glaucine phosphate and having a melting point of about 240-254°C and a pH in water solution of from about 2.2 to about 2.6, whenever prepared by the process of Claim 8, or by an obvious chemical equivalent thereof.
17. 17. A process according to claim 5, 6 or 7 wherein the d,l-glaucine phosphate obtained from the reaction is purified by recrystallization from ethanol.
18. 18. A process of preparing a glaucine phosphate salt, which comprises reacting d,l-glaucine with at least about a 1.4 molar excess of phosphoric acid, to produce a salt having a melting point of about 240° - 254°C with decomposition, and a pH in water solution (0.5 grams/100 milliliters) of about 2.4-2.6, digesting this salt by heating in ethanol under reflex for 4 to 8 hours, allowing the mixture to cool to effect recrystallization of the d,l-glaucine phosphate, and recovering and drying the crystalline product.
19. 19. A process of preparing a glaucine phosphate salt, which comprises reacting d,l-glaucine with at least about a 1.4 molar excess of phosphoric acid, to produce a salt having a melting point of about 240° - 254°C with decomposition, and a pH in water solution (0.5 grams/100 milliliters) of about 2.4-2.6, digesting this salt by heating in aqueous ethanol (20:80) under reflux for 5 to 6 hours, allowing the mixture to cool to effect recrystalliza-tion of the d,l-glaucine phosphate, and recovering and drying the crystalline product.
20. 20. A process of preparing a crystalline d,l-glaucine phosphate which comprises reacting d,l-glaueine with about 2 moles of phosphoric acid per mole of d,l-glaueine, recovering the d,l-glaucine phosphate salt so formed, heating this salt under reflux in aqueous ethanol (20:80) for 5 to 6 hours, allowing the mixture to cool to effect recrystallization of the salt, and recovering and drying the crystalline product.
21. 21. d,l-Glaucine phosphate in chunky crystalline form, having a melting point of about 253°C and exhibiting a single peak under differential scanning calorimetry, when prepared by the process of claim 20 or by an obvious chemical equivalent thereof.