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Preparations  of  Digitalis. 
Am.  Jour.  Pharm. 
Sept.,  1887. 
PREPAKATIONS  OF  DIGITALIS. 
Why  are  preparations  of  digitalis  frequently  inert? — Kobert,  of 
Dorpat,  answers  this  question  as  follows  in  an  article  reporting  a 
number  of  experiments  upon  digitalis  r1  "What  form  of  digitalis  shall 
be  employed?  Most  commonly  preferred  is  the  infusion.  This 
naturally  contains  only  those  substances  soluble  in  water.  Of  the 
three  important  active  principles  digitalein,  a  drug  which  produces 
dilatation  of  the  vessels  of  the  kidneys,  is  soluble  in  alcohol,  it  is  con- 
tained in  the  tincture  and  alcoholic  extract.  The  other  constituents, 
digitoxin  and  digitalin,  are  also  soluble  in  alcohol ;  in  alcoholic  pre- 
parations, as  well  as  in  the  leaves  themselves,  we  obtain  the  three 
important  active  principles.  In  fluid  extracts  digitoxin  is  precipitated 
as  an  insoluble  powder.  Acetum  digitalis  (vinegar  of  digitalis) 
approaches  the  infusion  most  closely  in  regard  to  its  contents.  It  is 
very  desirable  that  fresh,  well-dried  leaves  be  used.  When  the  leaves 
are  imperfectly  dried,  a  species  of  fermentation  may  occur  which  may 
decompose  the  three  essential  components  of  the  drug,  for  digitalin 
and  digitalein  are,  like  all  glucosides,  decomposable  through  foreign 
matter  and  fermentation.  Digitoxin  is,  however,  not  a  glucoside,  but 
decomposes  as  easily  and  under  the  same  circumstances  as  the  others. 
The  result  of  the  decomposition  of  digitalis  is  not  a  substance  pro- 
ducing the  desired  effects  upon  the  heart,  but  a  resin,  digitaliresin 
(from  digitalein  and  digitalin)  and  toxiresin  (from  digitoxin).  The 
effect  of  these  bodies  is  a  violent  irritation  of  the  convulsive  centres  of 
the  brain ;  severe  convulsions  may  also  occur,  as  in  poisoning  with 
picrotoxin  or  cicuta  virosa.  Whenever  the  usual  effects  of  digitalis 
are  wanting,  or  instead  cramps  occur,  we  are  safe  in  thinking  that  the 
preparation  used  was  a  poor  one.  The  decomposition  of  digitalis  may 
occur  not  only  in  the  leaves,  but  also  in  infusions  and  solutions  of 
digitalin  and  digitalein.  As  Tardieu  says,  i  The  pure  digitalein  when 
suspended  in  water  or  dissolved,  undergoes  decomposition  in  a  short 
time,  whereby  the  bitter  taste  is  altered,  and,  as  an  indication  of  a 
radical  change  in  the  constitution  of  the  drug,  gases  form/  Among 
my  patients  I  have  very  often  seen  decomposition  in  preparations  of 
digitalis  which  had  stood  two  days  in  a  room.  This  happens  from 
the  mixing  of  digitalis  tincture  with  syrup  or  watery  solution.  The 
practice  prevalent  in  America  of  not  preparing  the  drug  from  the 
leaves  when  desired,  but  of  using  a  concentrated  infusion,  explains 
the  frequent  disappointment  in  its  use." 
1  Therap.  Gazette,  June  15 ;  Med.  News,  July  23, 1887. 
