Chemical and Physical Properties of the Admixture

Fortunately, each of the structural functional groups can undergo only a limited number of possible reactions. The most significant among them seems to be hydrolysis (as in the case of esters, amides, and lactams) and oxidation (of catechols, phenols, and unsaturated compounds) as well as precipitation of weak electrolytes or neutral, hydrophobic compounds. These reaction and their rates may be pH dependent.

A product may be stable or soluble only at a pH that is not physiologically safe. When added to an infusion, a change in pH could take place and the chance for precipitation or accelerated chemical degradation increases. For example, Potassium Penicillin G contains a citrate buffer, and the injection is buffered at pH 6.5 when reconstituted. The solution is stable for 24 hours at such pH; however, it loses activity much faster at a lower pH.

In general, the following intravenous fluids are NOT recommended for any drug admixture. These infusions are unstable by nature and drug admixtures could trigger adverse reactions such as coagulation, coalescence or gas evolution, therefore rendering the IV infusion potentially hazardous, if not fatal.

• Blood, plasma, and other blood products
• Plasma substitutes
• Protein hydrolysates
• Amino acid solutions
• Sodium bicarbonate
• Fat emulsion

You should recall that the solubility of a weak acid or base may depend on pH: amines (dobutamine, dopamine, epinephrine, morphine) are basic and are generally soluble in acid media, whereas carboxylic and other acids (penicillins, cephalosporins, 5-fluorouracil) are generally soluble in basic media. Making the former basic or the latter acidic could induce precipitation.

Common LVP and Their pHs

Different manufacturers may have slightly different pHs.