Standard preparation— Prepare as directed in the Assayunder Digitalis.

Assay preparation— Empty the contents of not less than 20Capsules into a hard-glass,glass-stoppered container of not less than 50-mLcapacity.Add a menstruum consisting of 4volumes of alcohol and 1volume of water so that the total volume of menstruum corresponds to 1mLfor each expected USP Digitalis Unit.Insert the stopper,the upper third of which is greased lightly with petrolatum.Shake the mixture at 25±5for 24±2hours by mechanical means,which continuously brings the solid material into fresh contact with the liquid phase.Immediately thereafter transfer to a centrifuge tube,centrifuge,and decant the supernatant tincture into a dry,hard-glass bottle having a tight closure.Preserve under refrigeration,and use within 30days.

Pigeons,Preparation of test dilutions,Injection of test dilutions,and Calculation of potency— Proceed as directed in the Assayunder Digitalis.