Am.  Jour.  Pharm. 
April,  1887. 
Absorption  through  the  Skin. 
197 
ABSORPTION  THROUGH  THE  SKIH. 
Ritter  and  Pfeiffer  have  repeated  the  experiments  which  have  been 
made  on  this  much-disputed  topic,  and  their  results  serve  to  strengthen 
the  doubts  which  others  have  before  expressed  as  to  the  capability  of 
the  skin  to  absorb  the  substances  which  have  been  long  used,  probably 
following  up  a  false  analogy  with  the  effects  of  mercurial  inunctions, 
with  the  intention  of  producing  their  constitutional  effects  by  their 
transmission  through  the  skin  into  the  general  blood-current.  The 
method  which  they  employed  consisted  in  rubbing  well  into  the  ex- 
tensor surface  of  a  perfectly  healthy  arm  or  leg  about  half  an  ounce  of 
a  salve  containing  the  substance  under  investigation,  and  then  keeping 
the  skin  firmly  covered  for  24  hours  with  a  protective  bandage,  so  as 
to  prevent  any  possible  absorption  by  the  lungs.  The  urine  was  col- 
lected for  24  hours  and  examined,  both  with  and  without  previous 
concentration,  for  the  presence  of  the  drug.  By  these  means  it  was 
found,  that  a  10  per  cent,  iodide  of  potassium  salve  transmitted  the 
salt  through  the  skin  only  once  in  five  different  cases,  and  then. only 
after  being  used  for  four  days ;  that  is,  in  other  words,  only  after  the 
skin  had  been  irritated  and  its  continuity  destroyed  by  the  prolonged 
action  of  the  fatty  acids  derived  from  the  decomposition  of  the  lard. 
Salicylate  of  soda  applied  in  the  same  way  never  showed  the  slight- 
est trace  of  its  presence  in  the  urine. 
Salicylic  acid,  on  the  contrary,  invariably  gave  its  characteristic 
color  test  with  ferric  chloride  within  a  few  hours  after  its  application. 
This  is  easily  explained  by  its  well-known  action  in  softening  the 
epidermis  and  rendering  it  permeable.  If  iodide  of  potassium  be 
applied  to  a  spot  which  has  been  previously  treated  with  salicylic  acid, 
it  quickly  passes  into  the  organism  and  becomes  detectable  in  the  urine. 
In  a  series  of  parallel  experiments  made  with  the  view  of  testing 
the  reputed  power  of  Liebreich's  lanolin  in  assisting  bodies  incor- 
porated with  it  to  penetrate  the  skin,  the  authors  were  unable  (in 
common  with  the  majority  of  other  experimenters)  to  perceive  that  it 
possessed  such  power  in  the  slightest  degree.  [Its  physical  proper- 
ties are,  however,  undoubtedly  useful  as  a  salve  base.] 
Ritter  repeated  also  the  experiments  which  he  had  previously  carried 
out  in  order  to  test  the  capability  of  the  skin  to  absorb  substances 
which  were  sprayed  on  to  it  in  watery  solution.  Rohrig,  and  later 
Juh],  had  asserted  this  apparently  paradoxical  action  really  occurred. 
