178 
Digitalis  Leaves. 
Am.  Jour.  Pharm. 
March,  1919. 
activity  of  tinctures  from  digitalis  leaves  from  various  parts  of 
Germany. 
Biihrer,4  in  1900,  found  a  difference  of  400  per  cent,  in  the 
activity  of  some  fluidextracts.  Frankel5  found  variations  of  300  to 
400  per  cent,  in  tincture  and  infusions.  Edmunds,6  in  1907,  tested 
17  commercial  tinctures1  and  found  a  variation  of  400  per  cent. 
Many  other  similar  results  have  been  recorded,  in  some  cases  the 
reason  being  assigned  to  climate,  soil,  variety,  or  the  locality  from 
which  the  leaves  were  obtained. 
Focke7  observed  that  wild  digitalis  is  more  toxic  than  the  culti- 
vated and  the  second  year's  growth  than  the  first.  He  also  ob- 
served that  the  leaves  gathered  at  seeding  time  are  less  active  than 
when  collected  earlier.  He  was  the  first  to  record  his  observations 
as  to  the  causes  of  deterioration  and  the  effect  of  light  and  heat  in 
drying  the  leaves.  The  former  is  negligible,  but  he  considered  that 
when  dried  in  the  air  in  the  ordinary  way  without  special  care  in 
preserving  the  activity  is  soon  largely  lost.  This  is  considered  to 
be  due  to  the  moisture  content,  which  permitted  the  enzymes  and 
ferments  of  the  leaves  to  remain  in  an  active  state,  and  to  their 
action  in  breaking  down  the  sensitive  glucosides  to  less  active  sub- 
stances. His  remedy  is  to  heat  the  leaves  rapidly  to  a  temperature 
not  to  exceed  ioo°,  drying  to  a  moisture  content  of  about  ^2  per 
cent,  and  preserving  in  dark  air-tight  jars. 
Tordes,8  in  1867,  claimed  that  digitalis  from  the  vicinity  of 
Strassburg  was  better  than  that  from  other  localities  because  of  the 
careful  selection,  drying  and  preserving  of  the  leaves.  They  used 
leaves  of  the  second  year's  growth  only,  first  dried  in  the  shade, 
then  in  an  oven  at  a  temperature  not  over  40°.  They  were  then 
kept  in  tin  or  glass  containers  away  from  light  or  moisture. 
Sharp  and  Lancaster,9  in  a  series  of  careful  experiments,  showed 
that  digitalis  leaves,  not  specially  dried  but  kept  dry,  retained  their 
activity  for  11  years,  while  the  fluid  preparations  began  to  deteriorate 
between  the  thirteenth  and  fifteenth  months.  They  also  observed 
that  leaves  of  first-year  plants  were  intensely  bitter  and  probably 
very  active. 
4  Biihrer,  Inaug.  Diss.,  Basel,  1900. 
5  Frankel,  Therap.  Gegenw.,  43,  106,  1902. 
G  Edmund's,  /.  Am.  Med.  Assoc.,  48,  1744,  1907. 
7  Focke,  Arch.  Pharm.,  245,  646,  1907. 
8  Tordes,  Gas.  Med.  Strassburg,  27,  191,  1867. 
0  Sharp  and  Lancaster,  Pharm.  J.,  32,  102,  1911. 
