Buscopan labeled with carbon‐14 and deuterium

Hyosine butyl bromide, the active ingredient in Buscopan, is an anticholinergic and antimuscarinic drug used to treat pain and discomfort caused by abdominal cramps. A straightforward synthesis of carbon-14– and deuterium-labeled Buscopan was developed using scopolamine, n-butyl-1-14C bromide, and n-butyl-2H9 bromide, respectively. In a second carbon-14 synthesis, the radioactive carbon was incorporated in the tropic acid moiety to follow its metabolism. Herein, we describe the detailed preparations of carbon-14– and deuterium-labeled Buscopan.