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. 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.
More water is added to make up the desired volume.
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. 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.