The therapeutic use of strophanthin1 is at present limited almost exclusively to its intramuscular or intravenous injection as an emergency cardiac stimulant. This is partly because of the well established fact that strophanthin is absorbed from the stomach and intestinal tract so inadequately as well as so irregularly that its oral administration is both unsafe and therapeutically unsatisfactory, although some continue to employ it or the tincture of strophanthus in this manner. Neither intramuscular nor intravenous injection is suitable for frequent repetition over the more or less prolonged periods generally required in the treatment of cardiac failure. Therefore the suggestions that strophanthin could be administered beneath the tongue, or in alcoholic solution applied to the dorsum of the tongue, with reasonable certainty of effective absorption and satisfactory therapeutic action were deemed of sufficient interest to warrant their further investigation.
The literature is very meager but is such
EGGLESTON C, WHITE TJ. THE ABSORPTION OF STROPHANTHIN FOLLOWING SUBLINGUAL AND PERLINGUAL ADMINISTRATION. JAMA. 1927;89(8):583-587. doi:10.1001/jama.1927.02690080015007