Side Effects of Donnatal (belladonna/phenobarbital)

Donnatal (belladonna/phenobarbital) is a combination of naturally occurring belladonna alkaloids and a barbiturate used to treat abdominal pain, bloating and cramps in patients with irritable bowel syndrome.

Donnatal is also used in patients with acute inflammation of the stomach and intestines (gastroenteritis) to reduce pain and diarrhea.

It is used occasionally as additional therapy in patients with duodenal ulcer. Belladonna alkaloids block the action of acetylcholine, a chemical that nerves to use to communicate with other nerves and muscles.

Acetylcholine stimulates the muscles of the intestines that propels digesting food through the intestine. It also affects the secretion of fluids by salivary glands and the stomach.

By blocking acetylcholine, belladonna alkaloids relax intestinal muscles, slow passage of digesting food through the intestines, and reduce gastric secretion. Phenobarbital produces sedation. 

Common side effects of Donnatal include

• constipation,
• dry eyes,
• dry mouth,
• urinary hesitancy and retention (particularly in men),
• blurred vision,
• rapid heart rate,
• palpitations,
• headache,
• nervousness,
• drowsiness, and
• dizziness.

Serious side effects of Donnatal include

• worsening of certain medical conditions (glaucoma, myasthenia gravis, and urinary obstruction).

Patients with an unstable cardiac status, severe ulcerative colitis and acute intermittent porphyria should avoid Donnatal. Elderly patients may experience confusion, depression, and excitement even from small doses.

Drug interactions of Donnatal include voriconazole, bocepravir, ranolazine, and protease inhibitors, because phenobarbital reduces the blood levels of these drugs by increasing their breakdown in the body.

Donnatal should not be combined with potassium tablets because Donnatal slows the passage of potassium tablets through the gastrointestinal tract, leading to potassium-induced ulcers and high potassium levels in the blood.

Use of Donnatal during pregnancy has not been adequately evaluated. Pregnant women should use Donnatal only when the expected benefit outweighs the potential but unknown risks.

Donnatal is secreted in breast milk and may also reduce milk production. Consult your doctor before breastfeeding.

Adverse reactions include:

• constipation;
• dry eyes;
• dry mouth;
• urinary hesitancy and retention (difficulty urinating, particularly in men);
• blurred vision;
• rapid heart rate;
• palpitations;
• headache;
• nervousness;
• drowsiness; and
• dizziness

Caution is advised in patients with glaucoma, myasthenia gravis, and urinary obstruction since symptoms of these conditions may worsen with the use of belladonna/phenobarbital.

Patients with an unstable cardiac status, severe ulcerative colitis and acute intermittent porphyria should avoid belladonna/phenobarbital. Elderly patients may experience confusion, depression, and excitement even from small doses.

Adverse reactions may include

• xerostomia;
• urinary hesitancy and retention;
• blurred vision;
• tachycardia;
• palpitation;
• mydriasis;
• cycloplegia;
• increased ocular tension;
• loss of taste sense;
• headache;
• nervousness;
• drowsiness;
• weakness;
•  dizziness;
• insomnia;
• nausea;
• vomiting;
• impotence;
• suppression of lactation;
• constipation;
• bloated feeling;
• musculoskeletal pain;
• severe allergic reaction or drug idiosyncrasies, including
  • anaphylaxis,
  • urticaria and
  • other dermal manifestations; and
• decreased sweating.

Elderly patients may react with symptoms of excitement, agitation, drowsiness, and other untoward manifestations to even small doses of the drug.

Phenobarbital may produce excitement in some patients, rather than a sedative effect. In patients habituated to barbiturates, abrupt withdrawal may produce delirium or convulsions.

No information provided.