n :  a crystalline alkaloid C₂₀H₂₁NO₄ that constitutes about one percent of opium, that is made synthetically from vanillin, and that usu. in the form of its hydrochloride is used chiefly as an antispasmodic (as in spasm of blood vessels due to a blood clot) because of its ability to relax smooth muscle .
 
   
 
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