4-(hydroxymercuri)Benzoic Acid(PHMB) is used to inhibit cysteine-protease and acts as a reversible thiol-specific blocker. While blocking the acylated ghrelin degradation, it allows the AcetylCholine Esterase AChE™ used in SPI-Bio EIA kits to work normally, in contrast to serine-protease inhibitors.

BHT is a phenolic antioxidant and free radical scavenger. It has been shown to inhibit lipid peroxidation.

Indomethacin is a COX inhibitor that prevents ex vivo TXB2 formation and other PGs that can not be prevented using anticoagulant alone. The samples have to be transferred in indomethacin sampling tubes as soon as possible after blood collection.