Paulson,1 being impressed by the accessibility, the thin mucous membrane and the abundant blood supply of the sublingual space, was one of the first to recommend the sublingual administration of drugs. His experience led him to believe that drugs were rapidly absorbed when administered in this manner. Other clinicians have held the same view, and recently Fantus2 has advocated the use of this method. But what evidence is there that drugs are readily absorbed from this space?
As far as we know, quantitative studies to determine the selective absorption capacity of this membrane have not been made. The claims found in the literature are, for the most part, based on clinical impressions. It is known that the effects of certain drugs are manifest soon
after their sublingual administration; at times, for example, the effects of nitroglycerine seem to appear within a few seconds after its introduction. Atropine and morphine, given
DAVIS D, AYMAN D. SUBLINGUAL ABSORPTION OF DRUGS: MORPHINE. Arch Intern Med (Chic). 1928;41(2):231-233. doi:10.1001/archinte.1928.00130140093005