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Assay  of  Heart  Tonics. 
f  Am.  Jour.  Phanu. 
\     October,  1909. 
The  method  as  presented  to  the  American  Medical  Association 
June  9,  1898,  for  the  assay  of  strophanthus  preparations,  has  been 
employed  continuously  since,  with  very  slight  modification,  and  may 
be  described  briefly  as  follows : 
1.  The  pharmacological  assay  of  drugs  depends  upon  the  bio- 
logical fact  that  the  functioning  of  the  cellular  protoplasm  of  animal 
tissue  may  be  altered  in  degree  but  not  in  kind  through  the  use  of 
drugs  which  unite  with  one  or  more  constituents  of  the  protoplasm, 
such  union  probably  being  chemical. 
2.  Certain  drugs  have  an  elective  affinity  for  special  animal  tissue, 
which  affinity  can  be  utilized  for  measuring  the  value  of  such  drugs. 
The  reaction  between  strychnine  and  nerve  tissue  is  a  noteworthy 
example. 
3.  The  reaction  chosen  as  a  measure  for  determining  the  activity 
of  a  given  drug  should  be  the  most  constant  and  characteristic  ob- 
servable for  such.  The  heart  tonics  possess  a  special  affinity  for  the 
heart  muscle,  particularly  observable  when  these  drugs  are  adminis- 
tered to  frogs,  turtles,  etc. 
4.  The  kind  of  animal  chosen  for  making  the  observation  should 
be  the  one  in  which  the  reaction  is  most  nearly  uniform  and  clearly 
discernible.  In  the  writers'  experience,  frogs  weighing  about  15 
grammes  each  have  been  chosen  on  account  of  their  uniformity 
and  the  ease  with  which  they  can  be  obtained.  (During  the  breed- 
ing season  only  male  frogs  should  be  employed,  as  at  this  time  the 
weight  of  the  females  is  greatly  altered  by  the  contained  spawn.) 
5.  The  animals  employed  for  making  an  assay  of  the  heart  tonics 
should  be  of  the  same  species,  differing  as  little  as  possible  from  one 
another  in  weight  and  other  characteristics,  such  as  length  of  time 
kept  in  captivity,  sex,  etc.,  in  order  that  the  resistance  of  the  several 
animals  employed  for  making  a  test  shall  be  as  uniform  as  possible. 
6.  The  animals  employed  should  be  kept  under  identically  the 
same  conditions  prior  to  and  during  the  time  they  are  used  for  test 
purposes.  Food,  ventilation,  moisture,  temperature,  etc.,  are  im- 
portant factors  in  maintaining  uniform  conditions  of  experiment. 
7.  In  making  a  quantitative  assay,  the  strength  of  the  unknown 
should  be  compared  with  the  strength  of  a  standard  preparation  of 
the  same  drug,  the  assay  of  both  being  made  at  the  same  time  and 
the  conditions  of  the  experiment  being  precisely  the  same  in  both 
cases. 
8.  The  standard  adopted  should  possess  the  characteristic  action 
