Has anybody heard about the rat-tail burn technique? Eli Lilly used that term when they tested 450 (Four hundred fifty) different compounds – which later became the painkiller Darvon

Does anyone understand what they talk about in this four pages article that Eli Lilly send to FDA when Eli Lilly wants the painkilling substance Propoxyphene to be approved by the FDA

I myself just understand a few lines at page 4459; “Preliminary pharmacological evaluation. Using the rat-tail burn technique, has shown that a number of the esters are worthy of further study”

We can read about the rat-tail burn technique in the book “All in a century, The first 100 years of Eli Lilly and Company” by E-J-Kahn, Jr 1976. On page 116 we find:

-       -  Dr Albert Pohland who had joined the company in 1945 and was chiefly interested in analgesics, had been delving into the mysteries of methadone. Employing it as his root substance, Pohland synthesized some four hundred and fifty (450) compounds from 1948 on.

-         Lilly began testing the new compound´s analgesic effect upon rats´ tails, and the result was impressive. Rats that had been able to endure a certain amount of heat for only three to five seconds stood up under Darvon for fifteen. There was still a long way to go. 

    The discovery had to be demonstrated to be a nonnarcotic before it could be expected to be commercially worthwhile, and that took an interminable series of tests stretching over the better part of six years.

-         Not every drug is a medicine, but every medicine is a drug,