Answered By: Cindy Schmidt
Last Updated: Sep 24, 2021     Views: 56133

It's often convenient to administer two different drugs through a single IV line or from a single syringe.  It's important that each of the drugs administered in this way be unchanged by the presence of the other drug and by the diluent.  Drug combinations are tested for compatibility in solution.  Incompatibility is present when visible or electronically-determined precipitates, particulates, haziness, turbidity, color, or gas evolution are detected.  A 10% or greater loss of intact drug within 24 hours is also considered evidence of incompatibility.


  • When testing for y-site compatibility,1:1 mixtures of solutions are tested (solution concentrations are provided). A y-site is an injection port on the side of an IV line. 
  • Tests for admixture compatibility involve combining test masses of the two drugs in various test diluents (normal saline(NS), ringers(R), lactated ringers (LR), 5% dextrose lactated ringers (D5LR), etc)
  • In tests for syringe compatibility, two already diluted drugs are combined in stated concentrations.


The McGoogan Library currently offers two electronic sources for custom IV compatibility reports:

LexiComp and Clinical Pharmacology both have custom IV compatibility report tools.  Both can produce reports from Trissel's, but the apprearance of the reports is different.  LexiComp can also produce reports from another data source, King's.


Students sometimes confuse drug incomatibility and drug interactionsIncompatibility typically occurs before the drugs even enter the body.  One or both drugs affect the stability of the other drug.  Precipitation, gas formation, cloudiness, a color change, or concentration change may be detectable. Interactions, on the other hand, occur in the body when one drug disrupts the absorption, metabolism, action or excretion of the other drug or when the pharmacologic effects of one drug increase or decrease the phrmacologic effects of the other drug.


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