From Soakimi Pouhila, Auckland District Health Board, New Zealand: Hi George, any ideas on the stability of rivaroxaban in citrate samples?
Hello, Soakimi Pouhila, and thank you for your question, which sent me to PubMed to see if anything has been published on rivaroxaban stability. My search was fruitless, so I’m posting your question to attract comments from anyone with anecdotal experience. Let’s hope we get an answer soon.
Later on Thursday, October 24, 2013. Hello, again, Soakimi Pouhila, I’ve had unprecedented success in my search for an answer to your question. First, from Chris Ferrell, University of Washington. She writes, “We did a stability study and found the drug in citrated plasma to be stable at room temperature for 24 hours.”
Likewise from Ali Sadeghi-Khomami, PhD, Senior Chemist at Precision BioLogic Inc:
“Personally I have not seen any alarming sign for degradation of riva in citrated plasma. However I have to confess my judgment is based on good behaviour of the clotting time from incremental concentrations of riva spiked in citrated plasma during one shift, so it is not a solid conclusion but it is a good indication. I have checked on-line, surprisingly riva has good resistance to acid-hydrolysis too, only 2% loss in 1h at 0.1M HCl. Hope this helps, Ali.”
And third, Samama MM, Contant G, Spiro TE, et al. Evaluation of the prothrombin time for measuring rivaroxaban plasma concentrations using calibrators and controls: results of a multicenter field trial. Clin Appl Thrombos Hemostas 2012 18: 150–8. This group prepared and reconstituted rivaroxaban calibrators, then allowed the calibrators to stand at room temperature for 4 hours. They concluded, “The rivaroxaban calibrators prolonged the PT in a concentration-dependent manner and seemed stable at room temperature during the 4 hours after reconstitution. The change in clotting time was 0.1 to 0.2 seconds compared with baseline; the relative changes ranged from 0.4% to 0.8%. When the reproducibility within lot of the rivaroxaban calibrators was tested, the mean PT was 12.1, 14.4, 25.9, and 37.9 seconds, for calibrators with 0, 41, 219, and 430 ng/mL rivaroxaban, respectively, with the mean CV ranging from 0.3% to 1.0%.”
Next (added Saturday, October 26, 2013), Dr. Paul Riley of Diagnostica Stago sent package inserts for Stago’s lyophilized rivaroxaban calibrators and controls, designed for use with their liquid anti-Xa heparin assay. The inserts state that once reconstituted, the calibrators are stable for 8 hours when stored at room temperature. The controls are also stable for 8 hours at RT and 7 days when capped and refrigerated. I’ve attached both package inserts below: