Indomethacin is a cyclooxygenase (COX) inhibitor that prevents ex-vivo Thromboxane B2 formation and other prostaglandins 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. For measuring some prostaglandins, it may be useful to block the ex-vivo formation of prostaglandin. The tubes are graduated, with a silicone washer sealed and external threads. They can be stored at temperatures as low as -80 degrees. Thus, indomethacin sampling tubes may be useful for any COX metabolites studies.