Histidine-tryptophan-ketoglutarate, or Custodiol HTK solution is a high-flow, low-potassium preservation solution used for organ transplantation. Custodiol HTK is the registered trademark of Dr. Franz Köhler Chemie GmbH, Bensheim, Germany.
HTK solution is intended for perfusion and flushing of donor liver kidney, heart, lung and pancreas prior to removal from the donor and for preserving these organs during hypothermic storage and transport to the recipient. HTK solution is based on the principle of inactivating organ function by withdrawal of extracellular sodium and calcium, together with intensive buffering of the extracellular space by means of histidine/histidine hydrochloride, so as to prolong the period during which the organs will tolerate interruption of oxygenated blood. The composition of HTK is similar to that of extracellular fluid. All of the components of HTK occur naturally in the body. The osmolarity of HTK is 310 mOsm/L.