170 Proceedings of Royal Society of Edinburgh. [sess. 
In my hands the method of standardising preparations of 
adrenalin which has proved most serviceable is that of testing 
their antagonistic effect to a known dose of nitroglycerin, 0*6 mg. 
(iio g r -) which should require 0*0075 mg. of the adrenalin 
preparation to antagonise its dilator action. 
In one preparation of suprarenal submitted to the Laboratory 
for examination, the minimal effective dose was 0*5 c.c. of a 1 per 
cent, solution. The minimal effective dose of adrenalin is 0 , 00062 
mg. for a rabbit of about 2000 grams. Of the solution tested, 
*005 c.c. is then equal to *00062 mg. of adrenalin — that is, 1 c.c. 
= 0*12 mg. 
This result is corroborated when the nitroglycerin method of 
standardisation is used. The dilator effect of grain nitro- 
glycerin (*6 mg.) is opposed by *7 c.c. of 10 per cent. The same 
amount of nitroglycerin is neutralised in effect by *5 c.c. of 1*5 per 
cent, of adrenalin (*0075 mg.). Then 1 c.c. of the solution is equal 
to 0*107 mg. 
The solution is therefore rather more than —y as strong as the 
adrenalin chloride 1 in 1000 of Parke, Davis & Co. 
Summary. 
For the standardisation of adrenalin preparations. 
{a) The colorimetric method is not reliable with weak or im- 
pure solutions. 
(b) The effect on the pupil of the frog’s eye gives uncertain 
results. 
( c ) The determination of the minimum effective dose on the 
arterioles of the perfused frog is tedious and uncertain ; on an 
average 0*1 per million produces an effect. 
(i d ) The determination of the minimum effective dose in caus- 
ing a rise on the blood pressure of the atropinised rabbit yields 
fairly satisfactory results. 
(e) Adrenalin, suprarenalin, and hemisine all give a precisely 
similar result, 0*0003 mg. per kilo of body weight, or 0*006 per 
million, of the rabbit’s blood causing a distinct rise in the blood 
pressure in the rabbit, and 0*012 mg. per kilo of body weight, or 
0*24 per million, of the blood causing a rise in the cat. 
