Diarrhea may be controlled by Codeine 15 mg orally every 4 to 6 hours Tincture of opium 0.6 mL orally every 6 hours Loperamide 4 mg orally as a loading dose and 2 mg after each loose bowel to a maximum of 16 mg / day Diphenoxylate 5 mg orally 4 times a day Peripheral serotonin antagonists (eg, cyproheptadine 4 to 8 mg orally every 6 hours) Telotristat, a tryptophan hydroxylase inhibitor, 250 mg orally 3 times a day Niacin and adequate protein intake are needed to prevent pellagra because dietary tryptophan is diverted to serotonin by the tumor.