How does Bentyl (dicyclomine) work?

From the Guidelines

Bentyl (dicyclomine) works by relaxing the smooth muscles in the digestive tract to relieve symptoms of irritable bowel syndrome (IBS) and other digestive disorders. It is an anticholinergic medication that blocks the action of acetylcholine, a neurotransmitter that stimulates muscle contractions in the intestines 1. By reducing these contractions, Bentyl helps decrease abdominal pain, cramping, and irregular bowel movements associated with IBS. Some key points to consider when using Bentyl include:

• The medication's anticholinergic properties can cause side effects such as dry mouth, blurred vision, dizziness, and constipation 1
• Bentyl should be used cautiously in elderly patients and those with certain medical conditions like glaucoma or urinary retention
• The typical adult dose is 20-40 mg taken 3-4 times daily, with treatment duration determined by symptom response
• Patients should take Bentyl 30-60 minutes before meals for optimal effect
• The medication typically begins working within 1-2 hours after taking it, though full therapeutic effects may take several days of consistent use to develop According to the British Society of Gastroenterology guidelines 1, antispasmodics like Bentyl have been shown to provide significant additional benefit over placebo in reducing abdominal pain, with an average improvement of 64% compared to 45% on placebo.

From the FDA Drug Label

Dicyclomine relieves smooth muscle spasm of the gastrointestinal tract Animal studies indicate that this action is achieved via a dual mechanism: a specific anticholinergic effect (antimuscarinic) at the acetylcholine-receptor sites with approximately 1/8 the milligram potency of atropine ( in vitro, guinea pig ileum); and a direct effect upon smooth muscle (musculotropic) as evidenced by dicyclomine’s antagonism of bradykinin- and histamine-induced spasms of the isolated guinea pig ileum.

Bentyl (dicyclomine) works by relieving smooth muscle spasm of the gastrointestinal tract through a dual mechanism:

• Anticholinergic effect: blocking acetylcholine-receptor sites
• Direct effect on smooth muscle: antagonizing bradykinin- and histamine-induced spasms 2

From the Research

Mechanism of Action of Bentyl

Bentyl, also known as dicyclomine, is an antispasmodic agent used to treat chronic abdominal pain and other gastrointestinal disorders. The mechanism of action of Bentyl can be understood by looking at its classification as an anticholinergic/antimuscarinic agent, which works by inhibiting the contraction of gastrointestinal smooth muscle 3.

Key Points about Bentyl's Mechanism of Action

• Bentyl belongs to a class of therapeutic agents that inhibit GI smooth muscle contraction, thereby relieving symptoms of abdominal pain and other gastrointestinal disorders 3.
• As an anticholinergic/antimuscarinic agent, Bentyl works by blocking the action of acetylcholine, a neurotransmitter that stimulates muscle contractions in the gastrointestinal tract 4.
• The antispasmodic effects of Bentyl are similar to those of other tropane alkaloids, such as hyoscyamine, which are found in plants like Atropa belladonna 5.
• Bentyl's mechanism of action is distinct from other antispasmodic agents, such as calcium channel inhibitors and direct smooth muscle relaxants, which work through different pathways to relieve gastrointestinal symptoms 3.

Efficacy and Safety of Bentyl

The efficacy and safety of Bentyl have been evaluated in various studies, including a review of antispasmodics available in North America 3. While the results of these studies are inconsistent due to differences in treatment dosing and duration, patient profiles, and diagnostic criteria, Bentyl has been found to be effective in relieving symptoms of chronic abdominal pain and other gastrointestinal disorders 3, 5. However, its use is associated with potential risks, including toxicity and adverse effects on the nervous system, particularly at high doses 4.