338 
Kemtlh- coated  Fills. 
f  Am.  Jour.  Pharm. 
\       July,  1885. 
KERATIN-COATED  PILLS. 
By  Dr  Unna. 
Dr.  Unna,  of  Hanibnrg,  has  discovered  a  coating  for  pills,  which  is 
likely  to  prove  even  more  nsefnl  than  it  is  ingenious.  The  task  which 
he  set  himself  was  to  find  a  coating  which  would  resist  the  solvent 
action  of  the  gastric  juice,  but  would  dissolve  in  the  small  intestine. 
This  he  has  succeeded  in  doing  by  the  use  of  keratin,  a  substance 
extracted  from  the  shavings  of  ox  or  buffalo  horn.  The  shavings  are 
first  digested  by  artificial  gastric  juice  (pepsin  solution  with  1  percent, 
hydrochloric  acid),  and  are  then  macerated  for  weeks  in  ammonia. 
When  the  ammonia  is  driven  off,  a  gummy  solution  of  keratin  is  left, 
from  which,  by  drying,  keratin  is  obtained  in  the  form  of  shining, 
bright,  yellow  flakes. 
A  pill  which  is  to  be  covered  with  keratin  requires  to  be  prepared 
in  a  special  manner.  The  medicine  employed  is  first  rubbed  well  up 
with  cacoa  butter  or  tallow,  with  the  addition  of  some  indifferent 
powder,  if  necessary,  and  pills  are  made.  The  pills  are  then  covered 
with  cacoa  butter,  so  as  to  prevent  any  of  the  medicine  from  being  on 
the  surface  of  the  pill.  When  the  pill  is  hard  it  receives  one,  or, 
better,  two  or  three  coatings  of  solution  of  keratin.  If  the  substance 
of  which  the  pill  is  made  renders  solution  in  ammonia  inconvenient,  a 
solution  in  glacial  acetic  acid  may  be  used.  Keratin-coated  pills  are 
insoluble  in  the  gastric  juice,  but  dissolve  as  soc»n  as  they  enter  the 
.small  intestine,  and  have,  therefore,  a  special  value  in  cases  in  which 
medicines  which  have  an  irritating  effect  on  the  mucous  membrane  of 
the  stomach  are  to  be  administered  for  any  length  of  time  ;  for  example, 
when  arsenic,  salicylic  acid,  kreosote,  copaiva,  cubebs,  tartar-emetic, 
and  vermifuge  medicines  are  prescribed. 
The  method  is  further  useful  when  medicines  are  given  which  are 
affected  by  digestion  in  the  stomach,  forming  insoluble  precipitates 
with  pepsin  and  peptones  ;  for  examj^le,  tannin,  alum,  acetate  of  lead, 
subnitrate  of  bismuth,  nitrate  of  silver,  bichloride  of  mercury,  etc. ; 
and,  further,  in  the  case  of  medicines  which  it  is  desired  should  enter 
the  intestine  in  as  concentrated  a  form  as  possible,  and  medicines  which 
are  given  with  the  view  of  affecting  favorably  diseased  conditions  of 
the  mucous  membrane  of  the  stomach  without  exercising  an  irritating 
local  action ;  for  example,  iron,  quinine,  arsenic  in  catarrh  of  the 
stomach  arising  from  ammonia. — British  Medical  Journal ;  Jour.  Am. 
Med.  Assoc.,  April  4,  1885. 
