[Thiophene as a structural element of physiologically active compounds. 19. The synthesis of substituted (6H-thieno[2,3-b]pyrrol-4-yl)phenylmethanones]. / Thiophen als Strukturelement physiologisch aktiver Substanzen, 19. Mitt. Die Synthese von substituierten (6H-Thieno[2,3-b]pyrrol-4-yl)-phenylmethanonen.

The synthesis of 4-Methoxyphenyl-[5-methyl-6-(2-(4-morpholinyl)-ethyl)-6H-thieno[2,3- b]pyrrol-4-yl)phenylmethanone (1), a thiophene analogue of the analgesic Pravadoline B, is described. Starting with the acetylprotected thienylhydrazine 2b compound 7 was obtained in a Fischer-analogue cyclication in two steps. Use of the BOC-protected thienylhydrazine 2a yielded the pyrazol 5. Alkylation of 7 with N-(2-Chloroethyl)morpholine gave the target compound 1. In the acetylcholine-writhing-test in mice as well as in the acetic acid-writhing-test in rats 1 showed a significant lower antinociceptive activity than Pravadolin (B).

Pharmacodynamic actions of midodrine, a new alpha-adrenergic stimulating agent, and its main metabolite, ST 1059.

Pharmacodynamic actions of alpha-(2,5-dimethoxyphenyl)-beta-glycinamido-ethanol-hydrochloride (midodrine, Gutron) and alpha-(2,5-dimethoxy-phenyl)-beta-aminoethanol (ST 1059), the main metabolite of midodrine, were investigated in various experimental procedures. Midodrine raises arterial blood pressure both after parenteral and enteral administration in animal experiments. Midodrine increases peripheral vascular tone when given in doses still ineffective in raising blood pressure. The d(+)-isomer of midodrine is by far less effective than the racemic mixture. Pretreatment with atropine, reserpine, guanethidine or hexamethonium has no influence on midodrine activity. Midodrine effects are greatly reduced by phentolamine but rather enhanced by propranolol pretreatment. Midodrine raises blood pressure in pithed rats, too; in the experiments performed the drug is devoid of central effects even when high doses are given. Chronic pretreatment with midodrine over a longer period reduces the effect of a subsequent single injection of this substance. Because of the results cited above midodrine may be classified as a direct peripheral alpha-adrenergic stimulating agent. alpha-Adrenergic receptor stimulation induced by midodrine can be demonstrated in various smooth muscle organs (blood vessels, nictitating membrane, intestine, pupil, urinary bladder, bronchi). In contrast to other pressor sympathomimetic agents, midodrine is of long duration of action and good efficacy after enteral administration. ST 1059, the main metabolite of midodrine, is an active alpha-adrenergic stimulating agent with a shorter duration of action than midodrine. It is suggested that midodrine is the well-absorbed "transport form", from which ST 1059, the actural pressor agent, is formed enzymatically in organism.