- Regular use of any drug or dietary supplement known to cause constipation (e.g. iron, opioids, sucralfate, misoprostol, 5-HT#-antagonists, antacids with magnesium, calcium or aluminum, antidiarrheal medication, anticholinergic agents, calcium supplements, calcium channel blockers, tricyclic antidepressants or NSAIDs), within 1 month before screening.