330 
Notes  on  "Physiological  Testing! 
Am.  Jour.  Pharm. 
July,  1908. 
Our  Pharmacopoeia  demands  that  only  leaves  of  the  second  year's 
growth  be  used,  and  this  demand  is  supported  by  the  experiments  of 
Focke,  who  found  the  first  year's  leaves  weaker  toward  frogs  than 
those  of  the  second  year's  growth.  However,  Merck's  Report  (1907, 
p.  253)  quotes  Haynes  to  the  effect  that  the  leaves  of  the  first  year 
are  as  active  as  those  of  the  second  year,  provided  they  are  grown 
under  the  same  conditions. 
Fraenkel  has  noted  that  the  infusion  of  digitalis  varied  in  strength 
from  100  to  275  per  cent.,  while  tinctures  varied  from  200  to  400  per 
cent.  Tinctures  of  digitalis,  when  exposed  to  the  light,  lost  about 
one-half  of  their  original  strength  in  one  year.1  The  infusion  loses 
one-half  of  its  activity  in  twenty-four  hours  (Loewy).  The  addition 
of  a  small  amount  of  sodium  carbonate  is  claimed  to  preserve  the 
infusion  for  several  days.2 
Our  chemical  knowledge  of  these  drugs  is  extremely  deficient. 
There  have  been  a  number  of  bodies  isolated  from  digitalis  :  digi- 
talin,  digitalein,  digitophyllin,  digitoxin,  etc.,  and  as  decomposition 
products  of  these,  digitoxiresin  and  toxiresin.  Haynes3  and  Dixon 
have  reported  that  many  of  these  principles  are  inactive,  and  Haynes 
says:  " These  so-called  active  principles  require  standardization  even 
more  than  the  galenical  preparations.''  While  at  one  time  we 
thought  digitalin  was  the  active  principle,  now  it  is  thought  that 
digitoxin  is  the  real  principle,  and  attempts  are  made  to  standardize 
the  preparation  by  determination  of  the  digitoxin  present.4 
For  this  assay  the  method  of  Keller,  or  Keller's  method  modified 
by  Fromme,  is  usually  used.  Barger  and  Shaw  5  and  Ziegenbein6 
have  shown  by  experiments  on  frogs  that  the  toxicity  of  the  digi- 
1  Focke,  C.  Ueber  d.  prakt.  Wert  .unserer  Digitalistincturen.  Deutsch. 
Aerzt,  Zt%.,  Vol.  6,  p.  292.  1904. 
2  Focke,  C.  Wie  kann  man  em  Digitalisinfus  bis  zu  seinem  Verbrauch 
haltbar  machen  ?     Med.  Klinik,  Vol.  3,  p.  484.  1907. 
3  Haynes,  G.  S.  Pharmacological  Action  of  Digitalis,  Strophanthus  and 
Squill  on  the  Heart.    Bio- Chem.  Jour.,  Vol.  1,  p.  63.  1906. 
4  Reed,  E.  D. ,  and  Vanderkleed,  C.  E.  Standardization  of  Preparations 
of  Digitalis  by  Physiological  and  Chemical  Means.  Amer.  Jour.  Pharm., 
Vol.  80,  p.  no.  1908. 
6  Barger,  G.,  and  Shaw,  W.  V.  Chemical  and  Physiological  Assay  of  Di- 
gitalis Tinctures.    Yearbook  of  Pharmacy,  1904,  p.  541. 
6  Ziegenbein,  H.  Werthbestimmung  d.  Digitalisblatter.  Arch.  d.  Pharm., 
1902,  Vol.  240,  p.  454. 
