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.
After 1 day, patients exhibited significant improvement in day and night pain as well as clinician global evaluation when taking Donnatal® tablets and belladonna alkaloids, but the phenobarbital group also was statistically better for day and night pain, and the placebo group for day pain. Females taking Donnatal® tablets were 4 times more likely to experience weeks free of daytime pain compared to phenobarbital alone and twice as likely to experience weeks free of nighttime pain compared to belladonna alkaloids. Only the phenobarbital group demonstrated a significant change in pain type compared to belladonna alkaloids at the end of the study with an approximate 48% response rate. Patients on Donnatal® tablets, belladonna alkaloids, and placebo all had non-significant (p > 0.149) shifts to dull pain, 39.5%, 52.3%, and 40.4%, respectively compared to belladonna alkaloids eline. Males also showed a greater response for pain free-weeks on phenobarbital in comparison to Donnatal® tablets. All groups demonstrated an improvement in bowel movement frequency. FDA status
Donnatal® is considered part of the DESI drug category and currently is listed as one of 14 drugs still under evaluation by the FDA. In response to FDA questions about Donnatal® efficacy, A. H. Robins Co. filed abbreviated new drug applications for Donnatal® tablets (ANDA 86-676), capsules (ANDA 86-677), and Elixir (ANDA 86-661). These ANDAs, with the exception of the capsule formulation, are still in force today and the FDA has not changed the review status of Donnatal® as being conditionally approved for its indication.