Methods of Preparation must  be  in  a  fine  degree  of  subdivision.  Label suspensions  with  a  “Shake   Well”   label. USES:  Suspensions  are  used  for  the  ad- ministration  of  oral  medicaments,  which  have  low volubility  in  water  or  aqueous  vehicles.  Also, suspensions  are  used  for  parenteral  drugs  and ophthalmic   solutions. OINTMENTS Ointments   are   semisolid, fatty,  or  oily preparations of medicinal substances of such con- sistency  as  to  be  easily  applied  to  the  skin  and gradually  liquefy  or  melt  at  body  temperature. Ointments vary in color according to their ingre- dients.  The  base  of  an  ointment  is  generally  of a greasy character, and the medicinal substances combined with it are always intended to be in very fine  particles,  uniformly  distributed. Methods  of  Preparation Incorporation:  The  medicinal  substances  are finely powdered, if necessary, and then they are levigated into the fatty base, either in the mortar or  on  the  ointment  tile. Fusion:  The  fatty  base  is  melted,  then  the finely powdered ingredients are added and mixed thoroughly.  The  solution  is  cooled  so  that  the base,  now  containing  the  medicinal  substances, returns to its natural state. USES: Ointments have long been a preferred form  for  the  external  application  of  medicinal substances.  In  addition  to  the  action  of  the medicinal  substances  combined  with  them,  the fatty  bases  are  emollient  and  protective  in  nature. Example:  Zinc  Oxide  Ointment SUPPOSITORIES They  are  solid  bodies  intended  to  introduce medicinal substances into the various orifices of the  body.  The  ingredients  are  incorporated  in  a base that melts at body temperature. They are of the  following  types: .  Rectal l  Vaginal .   Urethral 8-17 Fusion method: The ingredients are added to melted theobroma oil (cocoa butter), and the mix- ture poured into the suppository mold. The mix- ture is allowed to cool, and the suppositories are removed  from  the  mold. Hand  Method:  The  medicinal  ingredient  is combined  with  theobroma  oil,  and  the  mixture is triturated into a pliable mass. The mass is rolled by hand into the shape of a cylinder and divided into  the  required  number  of  equal  parts,  which are  then  formed  into  the  desired  shape. USES:  Suppositories  are  commonly  used  for the local application of medicinal substances, as in  the  treatment  of  hemorrhoids.  Occasionally suppositories  are  used  in  administering  medicinal substances when administration by mouth is not practical. CAPSULES Capsules  are  gelatin  shells  containing  solid  or liquid medicinal substances to be taken orally. The most common type of capsule is that in which the medicine, in the form of a dry powder, is enclosed in transparent cases made of gelatin. They are in sized universally designated by numbers: 5, 4, 3, 2,  1,  0,  00,  000.  The  number  5  has  the  capacity of  about  65  mg  of  aspirin  powder  and  the  00 about  975  mg  of  the  same  substance.  It  should be noted that only sizes 3 through 00 are available through  the  Federal  Stock  System. INCOMPATIBILITIES An  understanding  of  incompatibilities  can  save the  pharmacy  technician  valuable  time  in  com- pounding as well as ensure the therapeutic effi- ciency  of  the  products.  Incompatibilities  are divided into three classes: therapeutic, physical, and  chemical. THERAPEUTIC This  type  of  incompatibility  occurs  when agents antagonistic to one another are prescribed together.  Such  circumstances  seldom  occur,  but when they do it does not necessarily indicate a mo- ment  of  forgetfulness  on  the  part  of  the  physi- cian. Such agents may have been used together in  order  for  one  agent  to  modify  the  activity  of