354 
Pharmacy  of  Tethelin. 
Am.  Jour.  Pharm. 
June,  1919. 
circumstances,  the  residue  left  after  partial  use  of  the  contents  of  a 
tube  be  used,  if  it  has  been  exposed  to  the  air  for  some  time  and  has 
become  moist  and  dark  in  color. 
Because  of  hygroscopicity  and  proneness  to  oxidation,  tethelin 
should  not  be  dispensed  in  capsules  or  tablet  form,  without  special 
means  being  taken  to  protect  the  products  from  air  and  moisture, 
except  for  the  most  extemporaneous  use. 
The  Manufacture  of  Sterile  Preparations  of  Tethelin. 
Dry  tethelin  withstands  a  temperature  of  8o°  C.  without  appar- 
ent change  in  physical  appearance,  but  begins  to  darken  between 
100  and  no°  C.  It  will  thus  be  evident  that  this  substance  is  quite 
sensitive  to  the  degree  of  heat  commonly  employed  in  sterilization. 
Dry  tethelin  can  be  prepared  in  a  final  sterile  condition  only  by  the 
exercise  of  the  utmost  care  in  maintaining  sterile  conditions  through- 
out the  process  of  manufacture  and  placing  the  finished  product 
through  a  thorough  sterilizing  process  under  carefully  regulated 
temperature  which  is  not  allowed  to  rise  above  8o°  C.  Sterility 
tests  on  the  final  product  are  absolutely  essential  in  order  to  obtain 
positive  assurance  of  its  safety  for  hypodermic  use. 
Sterilization  of  tethelin  in  the  dry  form  should  never  be  at- 
tempted at  a  temperature  above  8o°  C.  As  supplied  in  tubes,  tethe- 
lin is  sterile  as  proven  by  actual  bacteriological  tests.  If  extra 
sterilization  is  desired,  the  most  safe  and  satisfactory  method  is  to 
place  the  tube  in  boiling  alcohol,  the  alcohol  being  boiled  by  means 
of  a  steam  bath  or  an  electric  stove,  and  not  over  a  naked  flame. 
Heated  water  as  a  bath  should  not  be  employed  for  the  sterili- 
zation of  tethelin  unless  convenient  means  are  available  to  regulate 
the  temperature  of  8o°  C,  since  if  the  temperature  is  permitted  to 
mount  near  to  the  boiling  point  of  water,  the  substance  will  soften 
and  darken  and  become  decomposed,  to  some  extent. 
Heat  is  particularly  active  in  bringing  about  decomposition  of 
tethelin,  particularly  in  access  of  air  and  moisture.  For  this  rea- 
son, no  attempt  must  be  made  to  sterilize  solutions  of  tethelin  by 
heating  them  in  contact  with  air.  The  proper  method  of  preparing 
sterile  solutions  of  this  substance  is  to  add  the  sterile  powdered 
tethelin  directly  from  its  tube  to  recently  sterilized  and  cooled  water 
contained  in  a  sterile  glass  vessel.  The  tethelin  dissolves  imme- 
diately upon  slight  agitation  of  the  mixture  and  is  then  ready  to  be 
drawn  directly  into  a  sterile  hypodermic  syringe. 
