Assay pilocarpine

Analog (130), having the same substitution pattern as pilocarpine,was equipotent to pilocarpine in a guinea pig ileum assay. In vitro base-catalyzed epimerization of pilocarpine at the C-ethyl group position forms the diaste-reomer isopilocarpine in which pharmacologic activity is lost (171). 

For further evaluation, selected compounds are submitted to a dog assay (117,118) in which the prostaglandin is administered by aerosol to an anesthetized pilocarpine bronchoconstricted dog (n=3 to 6) and the decrease in airway resistance is recorded at the same time effects on the cardiovascular system (femoral pressure, pulmonary pressure, heart rate) are noted. This experiment is allowed to proceed for one hour, which also permits an assessment of the compound s ability to produce a prolonged bronchodilation. In this assay salbutamol maintains its effect for the entire hour, whereas isoproterenol and 1-PGEi lose theirs within the first twenty minutes. At the conclusion of the study a standard dose of isoproterenol is administered to determine the animal s maximum capacity to respond. 

Cyclopentyl-17,20-tetranor-PGEi (XX) also is of interest, since in the pilocarpine assay it is perhaps the most potent prostaglandin we have yet seen (Fig. 3) however, in contrast to the 16,16-trimethylene series, it is a short-acting compound. 

In our Konzett assay, ll-deoxy-16-methyl derivatives showed exceptionally high potency (48), an observation also made by a Wyeth group (113). However, Turther examination of 11-deoxy-16(R/S)-methyl-PGEi (XXIV) in the pilocarpine dog assay indicated this compound to be relatively ineffective and of no interest. Another member of this series, 16(S)-methyl-20-methoxy-PGE2 (XXV, YPG-209), has been reported to be 230 times as potent as PGE2 in the guinea pig vs. histamine-induced spasms. It also is claimed to be orally effective in this model without concommitant hypotension or diarrhea (169). This is the first claim, that we are aware of, for oral activity for any prostaglandin bronchodilator and we await the results of further studies with this compound. 

Introduction of alkyl substitutuents at C15 or C e of the 15-hydroxy series and at Cje or C17 of the 16-hydroxy series has provided compounds of high potency. However, bronchoconstrictive effects often have been noted and high activity has not been demonstrable for the 15-hydroxy series in our pilocarpine dog assay. 

Subnanogram Assay for Pilocarpine in Biological Fluids J. Pharm. Sci. 65(12) 1724-1728 (1976) CA 86 65253e... 

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