Bioequivalence and Bioavailability Forum

Γεια σου Κωνσταντίνο

Agree with what ElMaestro and Ohlbe said above. It’s important to realize that only the analyst can tell the clinician how to treat samples. Some people simply ignore stability issues based on the weak excuse “we don’t have an analytical method for whole blood”. But it’s simple (use at least triplicates):

• spike whole blood at 37 ℃^* as you would do with plasma, homogenize
  
• centrifuge one set immediately
  
• keep the others at ambient temperature (let them cool down) and centrifuge sets after e.g., 5, 10, 15, 20, 30, 45 minutes
  
• same step as above, but vials on ice
  
• analyse as usual, assess for accuracy & precision

This should give you sufficient confidence about stability. Let’s say your drug is stable for 45’ on ice and 20’ without cooling. Then there is no reason for panic if you receive a sample description like ‘forgot to put on ice, but was centrifuged after 15 minutes’.

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• Everything in the lab is calibrated at 20 ℃. If you don’t want to fiddle around with the volumetric expansion of whole blood, set the concentration of the sample obtained immediately after spiking to 100%. If you compare results to the nominal concentration you might get values >100%.