CHAPTER 16 



Techniques of ColchlcLne 

 Treatment 



A. In Animals 



16A.1: Solutions 



It has been explained in Chapter 5 that the substance which has 

 been repeatedly called colchicine in this book may have differed from 

 author to author. One reason tor this discrepancy is the factor of 

 crystallization. Whereas pure, amorphous colchicine is very soluble 

 in water, crystallization from aqueous or chloroformic solutions yields 

 complex crytals which are less soluble and may have other biological 

 properties. ^'"^ Colchicine may crystallize Avith i/C molecide of water, 

 A\ith i/o niolecule or 1 molecide of chloroform. This last form of 

 crystalline colchicine is only soluble in water in the proportion of 4 

 per cent.^'^ It has often been used in experimental research. In 

 botanical work, results may be modified by the presence of chloro- 

 form, which is itself a mitotic poison. ^-^ In experiments on animals, 

 where the amounts of colchicine used are far smaller and the solu- 

 tions much more dilute, the presence of chloroform does not appear 

 to have any importance. But, for any quantitative estimation of the 

 activity of the drug, it must not be forgotten that crystalline colchi- 

 cine with 1 molecule of chloroform contains 25 per cent by weight of 

 the solvent.55 On the other hand, chemical work has demonstrated 

 that the plant Colchicum contains many alkaloids closely related to 

 colchicine, but with different pharmacological properties.^i- °~ One 

 of these, desmethylcolchicine, is found in the colchicine preparations 

 of the U.S. Pharmacopeia. •^'5 In the most recent work on colchicine, 

 care has been taken to purify the alkaloid before testing it.-^- ^ This 

 applies only to a very small number of the papers, and some results 

 may differ because the injected drug differed in its mode of prepara- 

 tion froiii the plant.! ^Vhile the above-mentioned differences are only 



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