The InterSol additive is an isotonic solution designed to replace a portion of the plasma used in the storage of leuko-reduced apheresis platelets, under standard blood banking conditions. The platelets can be stored in a mixture of up to 65% InterSol solution and 35% human plasma, which can then be used for other therapeutic purposes. There is no direct therapeutic effect to be expected from the formulation, and the solution should never be infused directly into a patient. The InterSol solution is provided as a 500 ml sterile and nonpyrogenic solution in a non-PVC plastic container, with a sterile fluid path. Platelets prepared with the solution may be stored for up to 5 days at 20 °C to 24 °C, with continuous agitation.

The solution contains constituents that are naturally occurring components present in many cellular systems: sodium acetate as a nutrient, sodium citrate to prevent platelet clumping and activation, sodium phosphate for buffering, and sodium chloride for osmolarity. The InterSol solution does not have a pharmacological effect in vivo, but rather acts to provide the appropriate environment and nutrients in lieu of a portion of the plasma normally used for the storage of platelets. The InterSol solution is a product of Fenwal Blood Technologies (Lake Zurich, IL, USA), and has been approved for use by the U.S. Food and Drug Administration exclusively with platelets collected using the Fenwal Amicus separator, a medical device that collects platelets and other blood components from eligible donors.

"FDA approval for the InterSol solution is an exciting milestone for Fenwal and represents our collaboration with customers, industry, and scientific leaders to introduce new ways to collect, process, and store blood for transfusion,” said William H. Cork, Fenwal senior vice president and chief technology officer (CTO).

Refrigerated platelets have better in vitro function than those stored at room temperature, but once transfused, they are rapidly cleared from the circulation. In 1981, platelet storage at room temperature was extended from 3 days to 5 days due to improved platelet storage bags that allowed more efficient gas exchange. However, with the extended storage at room temperature, bacterial proliferation became a significant problem and an increased number of platelet transfusion-associated sepsis reactions occur.

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