COMPATIBILITY SYMBOLS USED IN THE GRID  
  The special grid included on monograph pages allows for quick reporting of compatibility (C), incompatibility (X), or conflicting data (Ø). In some instances conflicting results have been reported in the literature for a particular admixture. These contradictory reports are noted with a Ø, and are described in the written entries. NOTE: Absence of a notation in the grid does not imply that the combination is compatible. Rather, it means that no information has been reported for that particular combination. The presence of other symbols in the grid, such as # and *, are included to help the reader locate the specific written entry about the drug combination, and the reference that pertains to that entry.  
           
 
X
     Evidence of incompatibility has been reported  
 
C
     Evidence of compatibility has been reported  
 
Ø
     Conflicting reports of compatibility have been reported  
 
#,*
     Symbols refer the reader to the written comments adjacent to the grid within the monograph  
 
blank
     Absence of a notation in the grid does not imply compatibility.  
           
  TYPES OF INCOMPATIBILITY  
  Many studies on the compatibility of parenteral admixtures have used precipitation, effervescence, color change, and related visual methods as the criteria for deciding if a combination is compatible. These changes that are detected by the unaided eye are termed physical or visual incompatibilities. Physically incompatible combinations of parenterals should not be administered.Some studies on the compatibility of parenteral admixtures have investigated the change in potency or stability of the admixed drugs. These changes that are not visible with the unaided eye are termed nonvisual or chemical incompatibility. Stability, per se, has been defined as a product or combination of drugs that retain at least 90% of its original potency during the life of the product. Therefore a mixture is rated chemically incompatible(or unstable) if it loses more than 10% of its original concentration. Chemically incompatible combinations of parenterals should not be administered.  
     
  CONFLICTING REPORTS  
  Contradictory results have been reported over the years in research studies on parenteral drug admixture compatibility. Some of these conflicting reports may be attributed to the concentrations used in a particular study, the order of mixing, adjuvants included in the formulations, materials from which contained may be fabricated, and unavoidable differences in various lots of the same drug product. Variations in permissible pH ranges of some infusion fluids may also contribute to the problem of conflicting reports. In addition some combinations may be physically (i.e., visually) compatible yet be chemically (i.e., nonvisually) incompatible. The symbol in the grid for conflicting data is Ø. The reader should use caution when deciding on the appropriateness of a given admixture if conflicting data has been reported.