Am "iprii"  ^9i7m'  }  Milk  Sugar  in  Headache  Powders. 
153 
These  experiments  show  the  typical  action  of  the  drug  in  slowing 
and  strengthening  the  heart  beat  to  be  identical  with  that  of  the  U. 
S.  P.  digitalis.  The  powerful  ventricular  contractions  were  espe- 
cially noticeable. 
The  other  typical  heart-tonic  action  of  digitalis,  namely,  its 
pressor  effect  on  the  circulatory  system,  is  observed  best  on  an  an- 
esthetized dog.  The  dog  is  anesthetized  with  chloreton2  which  af- 
fects the  system  only  slightly.  These  experiments  failed  to  discover 
this  typical  effect  when  thapsi  drug  was  administered  while  the  trac- 
ings obtained  after  injection  of  the  official  drug  almost  invariably 
show  a  distinct  rise  in  blood  pressure  followed,  unless  the  dose  be 
too  large,  by  a  return  approximately  to  normal. 
The  two  drugs  were  injected  one  following  the  other  into  two  dogs. 
The  first  dog  received  first  0.2  Cc.  of  the  tincture  (freed  from 
alcohol)  of  the  thapsi  drug.  The  rate  was  lowered,  but  no  increase 
of  blood  pressure  could  be  detected.  After  the  action  of  the  drug 
was  apparently  over,  about  one  hour  after  first  injection,  0.5  Cc.  tr. 
digitalis,  U.S. P.  was  administered  followed  shortly  by  the  charac- 
teristic effects  of  the  drug,  including  a  distinct  increase  in  blood 
pressure.    The  heart-beats  soon  became  irregular  and  the  dog  died. 
In  another  dog  the  order  of  dosing  was  reversed,  the  official 
tincture  being  administered  first  followed  by  an  equivalent  dose  of 
the  thapsi  tincture.  The  effects  observed  from  the  first  experiment 
were  duplicated  in  the  second,  but  reversed.  The  official  tincture 
raised  the  blood  pressure  while  the  thapsi  tincture  had  no  effect  on 
the  blood  pressure,  but  slowed  the  heart  and  the  experiment  ended  by 
the  irregular  heart  beats  and  final  death  of  the  animal. 
While  the  experiments  detailed  above  are  more  or  less  prelim- 
inary to  a  more  exhaustive  examination  of  the  pharmacologic  prop- 
erties of  this  variety  of  digitalis,  they  are  sufficient  to  show  that  it 
possesses  at  least  two  of  the  valuable  properties  of  Digitalis  pur- 
purea, namely,  the  effects  on  the  rate  and  amplitude  of  the  heart 
beat.  They  show  also  that  it  more  nearly  resembles  strophanthus 
in  having  no  effect  or  at  least  very  slight  action  on  the  blood  pres- 
sure3— a  property  which  in  many  cases  is  a  distinct  advantage. 
The  observed  activity  of  the  drug — a  toxicity  three  times  as  great 
as  that  of  the  average  official  variety — is  not  to  be  taken  as  repre- 
2  Rowe,  Journal  of  Pharmacology  and  Experimental  Therapeutics,  vol. 
9,  1916. 
3  Cushney,  "  Pharmacology  and  Therapeutics." 
