Am.  Jour.  Pharm.l 
June,  1899.  / 
Pharmacological  Notes. 
287 
a  greater  fall  of  blood-pressure,  and  a  blocking  of  auricular  impulses 
to  the  ventricle  producing  a  rhythm,  which  is  largely  reversed  to 
that  of  aconitine.  Digitalin  is  said  to  be  "  the  most  effective  antag- 
onist towards  benzaconine."  Aconine,  compared  with  the  three 
compounds  considered,  is  relatively  harmless  to  the  heart ;  it  even 
shows  an  antagonistic  effect  towards  aconitine  and  diacetyl-aconitine. 
As  regards  the  respiration,  "  aconitine  at  first  stimulates  the  re- 
spiratory centre  and  the  sensory  vagal  fibres  in  the  lung.  Depress- 
ion rapidly  follows,  death  in  mammals  being  due  to  cerebral  respira- 
tory failure."  Diacetyl-aconitine  produces  less  initial  stimulation, 
and  benzaconine  depresses  both  the  respiratory  centre  and  pulmon- 
ary vagus  from  the  first.  Aconine  slows  the  respiration  from  its 
action  on  the  centre,  and  produces  a  curare-like  action  on  the  motor 
nerve  endings  in  the  respiratory  muscles. 
The  cerebro-spinal  centres  and  sensory  nerves  seem  to  be  stimu- 
lated by  aconitine  at  first,  and  afterwards  depressed.  After  large 
doses  loss  of  consciousness  sometimes  occurs.  Diacetyl-aconitine 
produces  a  similar,  though  less  marked  effect.  The  motor  nerve- 
terminations  also  seem  to  be  depressed  by  this  drug.  Benzaconine 
depresses  the  cerebro-spinal  centres,  but  it  exerts  no  effect  on  sen- 
sory nerves,  except  in  deep  poisoning.  Aconine  has  comparatively 
little  effect ;  its  chief  action  is  a  curare-like  effect  on  motor  nerve- 
endings. 
The  effect  on  the  temperature  was  almost  parallel  with  their  effect 
on  the  heart  and  respiration  ;  aconitine  is  the  most  active  (half- 
lethal  dose  causes  a  fall  of  about  2°  C);  aconine  the  least. 
It  would  therefore  appear  that  the  addition  of  two  acetyl  groups 
to  an  aconitine  molecule  merely  exerts  a  weakening  effect,  but 
that  the  withdrawal  of  the  acetyl  radicle  forming  part  of  the  aconi- 
tine molecule  results  in  a  complete  change  in  physiological  action. 
Similarly,  the  loss  of  a  benzoyl  radicle  from  benzaconine  produces 
a  transformation  in  its  physiological  effect.  Instead  of,  for  example, 
depressing  the  heart,  aconine  acts  as  a  slight  tonic  to  it.  Both 
benzaconine  and  aconine  are  to  some  extent  antagonistic  to  aconi- 
tine, the  latter  possessing  the  most  marked  effect  in  this  direction. 
This  is  of  interest  in  connection  with  the  fact  that  both  of  these 
substances  occur  in  the  plant  from  which  our  medicinal  preparations 
are  made. 
J.  L.  D.  M. 
