A PHARMACOLOGICAL AND CLINICAL EXAMINATION OF BENZYL MANDELATE

A PHARMACOLOGICAL AND CLINICAL EXAMINATION OF BENZYL MANDELATE DAVID I. MACHT From the Pharmacological Laboratory, the John8 Hopkins University Received for publication July 13, 1923 In a study of the pharmacological properties of benzaldehyde (1) the author has shown that this compound exhibits the same antispasmodic properties for smooth muscle as were noted by him in the case of the benzyl esters, benzyl benzoate, benzyl acetate, benzyl succinate and benzyl nitrite (2); as also in the case of benzyl alcohol (3). Furthermore the author pointed out that mandelic acid, a simple derivative of benzaldehyde, also possesses to a certain degree these antispasmodic properties (4). These properties were exhibited mildly by the simple salt, sodium mandelate and very much more markedly by various esters of mandelic acid such as ethyl mandelate, etc. It occurred to the author that if a new ester, benzyl mandelate, were synthesized, it might possibly exhibit such antispasmodic properties to an even greater degree inasmuch as both the alkyl and the acid radicals of such a compound possess the same pharmacological characteristics. Accordingly at the suggestion of the author such an ester was synthesized for him by Dr. Daniel Base and its pharmacological properties were studied. CHEMICAL PROPERTIES Benzyl mandelate is a new ester of mandelic acid never having been synthesized before. This is a beautiful, colorless crystalline body. Its melting point is 93#{176}C. It is very little soluble in cold water and slightly soluble in boiling water but is freely soluble in alcohol, ether, benzene and chloroform. Solutions in alcohol are readily precipitated by the addition of water to make 40 or 443

w 444 DAVID I. MACHT 50 per cent alcohol. In boiling water less than 1 mgm. will dissolve in 10 cc. The method of preparation of this compound is described by Base elsewhere (5). TOXICITY In view of the low toxicity of such benzyl esters as the benzoate, succinate, etc., on the one hand and of the very low toxicity of mandelic acid, it was found as might be expected that benzyl mandelate is not very poisonous given by stomach tube to rabbits. Doses of 0.5 mgm. were certainly without deleterious immediate or late effects. The same was true for dogs. The exact lethal dose by mouth for these animals could not be determined for lack of sufficient material. Even when injected intravenously into dogs in the form of emulsions benzyl mandelate produced no alarming symptoms or after effects. Doses of 100 mgm. at a time were given repeatedly to dogs in this way. Intravenous injections in rabbits of emulsions of benzyl mandelate, containing 50 mgm. in 10 cc. were also not fatal. Injections of benzyl mandelate, 200 mgm. dissolved in oil and administered intraperitoneally in rabbits produced no dangerous symptoms. The author himself took by mouth capsules of benzyl mandelate containing as high as 250 mgm. without experiencing any discomfort or disagreeable symptoms. PHARMACOLOGY - A pharmacological examination of benzyl mandelate was made especially in regard to possible local anesthetic action and the characteristic antispasmodic effects on smooth muscle shown by other benzyl esters. Observations were also made on the - blood pressure and the effects on the heart and respiration. Owing to the very poor solubility of the ester in water considerable difficulty was encountered in experimenting with it especially on whole animals. The drug however, was found to be sufficiently soluble in warm water to produce definite pharmacological effects on isolated tissues and organs. For intravenous and intraperitoneal injections saturated solutions of benzyl mande-

EXAMINATION OF BENZYL MANDELATE 445 late in warm saline were used in some cases while in others when it was desired to introduce larger doses of the drug, it was necessary to resort to the use of emulsions. Anesthetii effect. Owing to the very poor sohibility of benzyl mandelate no effect on the sensory nerve endings could be demonstrated. Effect on smooth muscle. As was to be expected the effect of even very weak solutions on benzyl maidelate on isolated smooth muscle preparations was to produce a marked relaxation of the FIG. 1. UTERUS OF A GUINEA-PIG, STIMULATION WITH PITUITARY LIQUID AND RELAXATION WITH BENZYL MANDELATE same. Experiments were made on excised preparations from the uterus, intestine, urinary bladder, gall bladder and other organs. The results in every case being the same, as illustrated by the accompanying figures. Figure 1 shows the effect of an aqueous solution of benzyl mandelate on the uterus of a virgin guinea-pig. The uterus was first brought into a state of powerful contraction by two doses

446 DAVID I. MACHT of 0.1 cc. each of pituitrin. At the height of contraction a solution containing four milligrams of ethyl mandelate was introduced but was found ineffective in counteracting the powerful contractions produced by the pituitary extract. On addition of 5c c. of a saturated solution of benzyl mandelate, however, a complete relaxation of the uterus rapidly followed (fig. 1). Fiq. 2. SMALL INTESTINE OF RABBIT, STIMULATION WITH PILOCARPIN HYDRO- CHLORIDE, RELAXATION WITH BENZYL MANDELATE Figure 2 illustrates the effect of benzyl mandelate on an isolated preparation of a rabbit s jejunum. This was first stimulated to contraction by the introduction of 1 mgm. of pilocarpin hydrochloride in 50 of Locke s solution and then relaxed by the addition of 3 ee. of a saturated solution of benzyl mandelate (fig. 2).

EXAMINATION OF BENZYL MANDELATE 447 Figure 3 illustrates the effect of benzyl mandelate solution on the small intestine of a rat. In this case the piparation was brought into a tonic contraction with 2 mgm. of pilocarpin hydrochloride in 40 cc. of Locke s solution and relaxed with 5 cc. of a saturated solution of benzyl mandelate in water (fig. 3). FIG. 3. SMALL INTESTINE OF RAT, STIMULATION WITH PILOCARPIN HYDRO- CHLORIDE, RELAXATION WITH BENZYL MANDELATE The author was fortunate in securing several surviving preparations of human organs from various surgical operating rooms, and in this way he duplicated the results obtained in lower animals in the case of human beings. Figure 4 illustrates the effect of

448 DAVID I. MACHT benzyl mandelate on a bt of muscle obtained from a human uterus after a case of complete hysterectomy. The preparation was brought into a state of contraction by means of 2 mgm. of ergotoxin phosphate in 40 cc. of Locke s solution and was subsequently relaxed by the introduction of 5 cc. of a saturated solution of benzyl mandelate in water (fig. 4). Figure 5 shows FIG. 4. MUSCII iotoxin AND the effect ot. a human gall bladde ere introduced into and produced a slight contraction. This was followed by 1 mgm. of pilocarpin hydrochloride which produced a much greater contraction of the gall bladder muscle. The spasm was then relaxed by the introduction of 5 cc. of a saturated solution of benzyl mandelate (b.m.) (fig. 5).

EXAMINATION OF BENZYL MANDELATE 449 Blood pressure. Experiments on blood pressure were made on dogs, cats and rabbits. Great difficulty was encountered in the attempts to introduce benzyl mandelate intravenously. The use of saturated aq ueous solutions in dogs and cats was followed by very little effect. In rabbits however, such injections were followed by a marked fall in blood pressure. This agreed with Fia. 5. MUSCLE STRIP FROM HUMAN GALL BLADDER, STIMULATION BY MORPHINE, MARKED CONTRACTION BY PILOCARPIN, RELAXATION BY BENZYL MANDELATE the experiences of the authors with benzyl benzoate, published elsewhere, where the author called attention to the greater efficiency of the drug for herbivora. Figure 6 illustrates the effect of the injection of a saturated solution of benzyl mandelate into the vein of a rabbit. It will be noted that the injection of

450 DAVID I. MACHT 2 cc. was followed by a marked fall. It was found by the author that injections of emulsions of suspensions of benzyl mandelate intraperitoneally were also followed by a fall in blood pressure, which indeed was of a longer duration than after intravenous FIG. 6. BLOOD PRESSURE CURVE IN THE RABBIT UNDER PARALDEHYE ANESTHESIA, SHOWING THE EFFECT OF BENZYL MANDELATE INJECTED INTRAVENOUSLY injections. Again, the introduction of benzyl mandelate into the stomach through a stomach tube was also followed by a slow but prolonged fall in blood pressure as illustrated in figure 7.

EXAMINATION OF BENZYL MANDELATE 451 The results obtained by intraperitoneal and oral injections of the drug agree well with the experience of the author as well as other T 4 - /Wt(-. FIO. 7. RABBIT UNDER PARALDEHYDE ANESTHESIA. EFFECT ON RESPIRATION AND BLOOD PRESSURE OF BENZYL MANDELATE INTRODUCED INTO THE STOMACH writers (7) with various benzyl esters in which it was found that the pharmacological or therapeutic efficiency of these esters runs

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454 DAVID I. MACHT more or less parallel to the degree and rapidity of their hydrolysis or dissociation. Such a break up of the esters probably takes place just as rapidly or even more rapidly when given by mouth than when injected intravenously (figs. 6 and 7). Effects on the heart and respiration. Even after injections of large amounts of benzyl mandelate in emulsions by the intravenous route very little depression of the heart or respiration was noted. Inasmuch as 50 mgm. of the drug in the form of an emulsion were injected intravenously in rabbits without any very toxic effects, the author has found this compound to be certainly not more toxic in this respect than the other esters studied by him such as benzyl benzoate and benzyl succinate. CLINICAL EXPERIENCES In view of the low toxicity of benzyl mandelate and in view of the wide therapeutic employment of other benzyl esters in medical practice it was deemed quite safe to administer benzyl mandelate in small doses to a number of normal healthy individuals and subsequently also to a number of patients exhibiting hypertension or high blood pressure. The results were gratifying. The subjoined table gives the systolic and diastolic blood pressures of a number of cases studied by the author before and after administration of benzyl mandelate. The drug in each case was administered by mouth either in powdered form or in capsules and the blood pressure was measured one-half hour to an hour after the administration of the drug. The blood pressures were determined carefully by the ausculatory method with a sphygmomanometer of the Tycos type and whenever possible the readings were checked up by more than one observer. In a few cases graphic records of the blood pressure before and after the administration of the drugs were made with the Erlanger apparatus. It was found in every case that the administration of even small doses of benzyl mandelate (1 to 2 grains) was followed by a definite systolic and diastolic fall in blood pressure. In no case were there any untoward symptoms observed by the physician or complained of by the subject. On the other hand in a number of cases the patients stated that their symptoms were

EXAMINATION OF BENZYL MANDELATE 455 distinctly relieved. The author has also made a few observations on the effect of benzyl mandelate in other clinical cases, such as those of dysmenorrhea, asthma and diarrhea, but the data so far in hand are too few to warrant any definite statement on the subject. Inasmuch as the author has shown that mandelic acid itself is also a relaxant of smooth muscle a number of clinical observations were made with that drug. Administration of small quantities (2 to 5 grains), of mandelic acid in solution by mouth to patients were also followed by a distinct fall in blood pressure within thirty minutes. The effects of mandelic acid alone, however, were not as potent as those of the benzyl ester. SUMMARY A pharmacological and toxicological study of the new compound benzyl mandelate was made. It was found that this compound is of comparatively low toxicity on the one hand and is pharmacologically effective on the other hand. The most important pharmacological action of the drug is on smooth muscle. Benzyl mandelate produces a marked relaxation of all such preparations especially after they have been brought into a state of tonic or marked contraction. In view of the antispasmodic pharmacological properties of both the alkyl and acid components of the molecule a greater antispasmodic effect is produced by the compound than by other benzyl esters. This fact taken together with the lack of disagreeable taste of benzyl mandelate gives promise of its having considerable therapeutic interest. - REFERENCES (1) MACUT, D. I.: Archives Internat. d. Pharm. et de Therap., 1922, xxvii, 12. (2) MACLIT, D. I.: Proc. Soc. Exper. Biol. and Med., 1921, xviii, 177. (3) MACHT, D. I.: Jour. Pharm. and Exper. Therap., 1918, xi, 263. (4) MACHT, D. I.: Archives Internat. d. Pharm. et de Therap., 1922, xxvii, 175. (5) MACnT, D. I.: Jour. Pharm. and Exper. Therap., 1918, xi, 419. (6) BASE, D.: Jour. Amer. Pharm. Assoc., 1923, xii, 7. (7) NIELSEN, C., AND HIGGINS, J. A.: Jour. Lab. and Clin. Med., 1922, vii, 3.