Some remarks on the problem of cannabis

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Some remarks on the problem of cannabis

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RECAPITULATION

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Author: Prof. G. Joachimoglu
Pages: 5 to 6
Creation Date: 1959/01/01

Some remarks on the problem of cannabis

Biological evaluation of cannabis preparations.

Prof. G. Joachimoglu Athens

The chemistry of cannabis is described in document E/CN.7/ 297. 1 Despite the great advances made in this field, we have so far no chemical method of determining the physiological effects of a cannabis preparation. That being so, pharmacological mehods must be used. I gather from such literature as I am acquainted with that S. Frankel 2 was the first to carry out pharmacological experiments with cannabis on animals. He extracted 2.2 kg of resin from 10 kg of hashish with petroleum ether. The resin was subjected to fractional distillation at 0.5 mm/Hg. By repeated distillation at 215°C a light yellow liquid was obtained, which Frankel called "cannabinol ". This should not be confused with crystalline cannabinol, 3 which is pharmacologically inactive, whereas Frankel's cannabinol is active. Frankel observed a characteristic intoxication pattern in dogs even after small doses. The cannabinol was given to the dogs orally either wrapped in meat or dissolved in oil. The animals became surprisingly quiet after one to two hours: "They immediately stop running around the cage and seem, to begin with, to lapse into a dreamy condition. A dog intoxicated with cannabinol is never heard to bark; only a few whimper after large doses. When moderate doses are given, the animals stand about the cage struggling, in a dreamy state, to fight off sleep. Now and then they will lift a front paw and try to grab an apparition in the air. In this condition the head is bent backwards and the eyes are directed towards imaginary objects hovering in the air. The intoxication develops slowly and, particularly after somewhat bigger doses, the animals freely adopt the most remarkably distorted postures. They will maintain for a long time any pose, no matter how uncomfortable, in which the experimenter puts them. At the hypnotic stage the animals stand about the cage fighting against sleep, their heads sinking lower and lower until their muzzles touch the ground. Then they start up, lift their heads again and let them drop once more as far as they can go, starting up again, and this goes on over and over again, often for an hour at a time, rather like a waking dream such as people experience on long railway journeys when they fall into a doze out of which they start at the slightest irregularity in the joltings - e.g., when the train passes over points - only to sink back immediately into their doze. Other animals stagger about the cage, generally falling head over heels. The animals react feebly to external stimuli and, as soon as they are left alone again, they relapse into their apparently very pleasant dream condition. After large doses

1

United Nations document E/CN.7/297, entitled "The possibility of replacing hemp fibre and hemp seed by other crops of similar industrial value or of developing narcotic-free strains of the Cannabis plant ", 24 March 1955.

2

S. Frankel, Arch. u. experimentelle Pathologie u. Pharmakologie, 1903, 49, 283, quoted after Joachimoglu in A. Heffter's " Handbuch der experimentellen Pharmakologie", vol. II, part 2, pp. 1114-1119.

3

Document E/CN.7/297, p. 13.

they lie down and can hardly be got on their feet again." (S. Frankel) So far as I know, it is only in dogs that cannabis provokes such a characteristic intoxication pattern.

K. D. Sargin & V. V. Vasilyeva 4 have made use of the absence of corneal reflex observed by Straub & Gayer in rabbits to assay cannabis preparations pharmacologically. After an injection of cannabis extracts the animals show a negative corneal reflex - i.e., when the cornea is touched, the eyelids do not close.

Difficulties arise in preparing an injectable extract. Sargin & Vasilyeva used cannabis resin dissolved in alcohol for injecting rabbits, while other authors prefer acetone solutions. The cannabis preparation (Extractum Cannabis Indicae spissum) is dissolved in slightly heated alcohol to produce a 1% solution. The volume injected intravenously is always 0.25 cc per kg of the animal's weight. Only the concentration of the preparation varies. A corneal unit is the smallest quantity of the preparation per kg of body weight that intermits the corneal reflex. It should be noted that the dose of alcohol injected does not of itself reduce the sensitivity of the cornea, and also that this method gives only approximate results.

The results of Sargin & Vasilyeva's experiments with rats and mice are interesting. With these animals, the intravenous injection of a 1% solution of cannabis resin in doses of 0.2 cc (or up to 0.5 cc for rats) produces no visible symptoms. Sensitivity to pain is not reduced. After injection of the aforementioned doses many of the animals, particularly rats, die.

G. N. Pershin 5 and E. A. Kechatov 6 have prepared emulsions from cannabis extracts and gave rabbits intravenous injections of them. Pershin's method is as follows: The weighed quantity of extract is dissolved in 10 parts of alcohol, 5 parts of powdered gum arabic being added to the solution. The sticky mass is then carefully mixed with water in a mortar until it becomes "runny ". More water is added to make up the desired volume. The dark-field microscope shows the emulsion to consist of small round particles, mostly less than 1 micron in diameter, with few larger-size particles 1-6 microns in diameter. It should be noted that the emulsion is very liqueous and passes through a Seitz filter without leaving any perceptible deposit.

Ketchatov used apricot gum in preparing the emulsion. A concentrated extract was obtained by macerating with alcohol (90%). This was dissolved in alcohol (1: 1) and prepared with apricot-gum emulsions at varying concen- trations - viz., 2%, 5% and 10%. This author mentions that the cornea dose in Pershin's tests for extracts of Cannabis Indica was only 0.001 g per kg of body weight, whereas in his own tests it was: with a 2% emulsion (0.25 cc = 0.005 g resin) 5 times higher, with a 5% emulsion (0.25 cc = 0.012 g resin) 12 times higher, and with a 10% emulsion (0.25 cc = 0.025 g resin) 25 times higher. His conclusion is that" resinous substances contained in cultivated and wild growing plants showed that these substances do not have the same physiological effects as do the resinous substances derived from cannabis plants from India ". Why the cornea dose was so different depending on the strength of the apricot-gum emulsion applied is a difficult matter to explain. It should be noted that the resorption of the active constituents of an emulsion and its transmission into the central nervous system cannot be uniform. It is not customary in pharmacology to give intravenous injections of emulsions. Corpora non agunt nisi soluta. I am not aware of such differences being observed when using drugs dissolved in water or oil, as Kechatov found with cannabis.

4

K. D. Sargin & V. V. Vasilyeva: "The Biological Assay of Cannabis Preparations", Pharmakologiya i Toxikologiya, 1939, vol. 2, No. 4, pp. 63-66.

5

G. N. Pershin: "The Pharmacology of Cannabis ", Pharmakologiya i Toxikologiya, 1949, vol. 12, No. 4, p. 37.

6

E. A. Kechatov: "Cannabinol reactions and pharmacological analyses of the resinous secretions from Cannabis cultivated or grown wild in the northern Caucasus ", United Nations Document E/CN.7/352, 3 April 1958.

It may be possible to dissolve the active constituents of cannabis in a neutral oil and to inject the solution intraperitoneally. With oily solutions of camphor, the full effects of the camphor can be observed quickly. 7

When making pharmacological tests to determine the effective dose for animals, it is absolutely necessary to use a standard preparation. This enables an accurate estimate to be made of the animal's sensitivity. Among those used are the digitalis preparations (leaves, tinctures, etc.). Without a standard preparation, no such estimates can be made.

With cannabis it is also important to test the corneal reflex quantitatively -- i.e., to determine the strength of the stimulus

7

G. Joachimoglu: Archiv f. experimentelle Pathologie & Pharmakologie, vol. 80, 1, 1916.

applied to the cornea. For this purpose, von Frey's method can be applied. He used hairs of different thicknesses (0.05 - 0.1 nun). The weight required to produce the pressure that must be exerted to bend the hair is determined by means of a balance. If, for instance, this weight is 0.525 g and the hair is 0.07 mm thick, the pressure value of the hair tested is

stronger the stimulus applied to the cornea. A series of hairs of increasing pressure value is used in order to find which produces a positive corneal reflex. In the case of a narcotic effect a hair with a fairly high pressure value will obviously produce such a reflex. Therefore, the sensitivity on the cornea will be tested with the hairs before the cannabis is given, and then compared with the sensitivity after various doses and intervals of time.

RECAPITULATION

  1. The activity of cannabis preparations cannot so far be determined by chemical methods; pharmacological methods must be used.

  2. Cannabis produces a characteristic intoxication pattern in dogs. As any quantitative estimate of the active constituents of cannabis demands the use of many animals, a method in which dogs are used will encounter serious difficulties.

  3. The method using rabbits would appear to be more promising.

  4. In testing the corneal reflex in rabbits with the irritant hairs used in the von Frey method, the sensitivity of the cornea can be determined quantitatively.

  5. In any pharmacological method used for quantitatively determining the active constituents of a drug, comparison with a standard preparation is indispensable.