When improvement was clinically assessed, 69% of belladonna alkaloids/phenobarbital patients were reported to improve compared to 24% of placebo patients. For the 12 patients who were switched therapies, it was found that they originally were given placebo and switched to treatment therapy. While on placebo, 11.1% of patients reported a mean improvement, whereas 55.5% reported mean improvement on treatment therapy. The authors noted that the response for patients on placebo was rather quick with immediate effects. Further, they noted that among patients with diarrhea, 100% reported an improvement while 53.2% of those with constipation reported an improvement. In several patients with constipation, fiber and laxatives also were provided. In patients where constipation was the chief complaint, the authors noted that they failed to respond. Several office-belladonna alkaloids ed case series also presented positive outcomes for almost 1,000 patients on the effect of belladonna alkaloids and phenobarbital formulations in irritable colon, other functional disorders, and gastric/duodenal. Donnatal clinical research
A. H. Robins developed and began marketing Donnatal® in the 1940s. Two studies have been performed over the years specifically with the Donnatal® formulation. Steigmann and Kaminski  examined the antisecretory effect of 0.1296 mg belladonna alkaloids + 16.2 mg phenobarbital (Donnatal®) in peptic ulcer patients, motility in a subgroup of patients and clinical effects in all patients (N =176). Of the IBS patients (n =66), a reported good response with complete relief was found in 53% of male patients and 58% of female patients.
Metirosine (INN and BAN; α-Methyltyrosine, Metyrosine USAN, AMPT) is an antihypertensive drug. It inhibits the enzyme tyrosine hydroxylase and, therefore, catecholamine synthesis, which, as a consequence, depletes the levels of the catecholamines dopamine, adrenaline and noradrenaline in the body. It is available as a generic medication. Clinical use
Metirosine has been shown to suppress catecholamine synthesis and alleviate symptoms related to catecholamine excess, including hypertension, headache, tachycardia, constipation, and tremor. Metirosine is primarily used to reduce these symptoms in patients with pheochromocytoma. It is contraindicated for the treatment of essential hypertension. Metirosine is used as an off-label treatment for DiGeorge syndrome.Metirosine is used in scientific research to investigate the effects of catecholamine depletion on behavior. There is evidence that catecholamine depletion causes an increase in sleepiness that is more pronounced than sleep deprivation, and that the fatigue lingers after the drug is discontinued. Negative mood is also a reported side effect of catecholamine depletion, although this is reported less consistently than sleepiness. See also
p-Chlorophenylalanine

References
External links
"Metyrosine". Drug Information Portal. U.S. National Library of Medicine.