What are the recommended first-line and second-line antispasmodic agents (e.g. dicyclomine, hyoscyamine, mebeverine) for treating smooth muscle spasms?

From the Guidelines

First-line antispasmodic agents for treating smooth muscle spasms include dicyclomine and hyoscyamine, while second-line options include mebeverine and peppermint oil, as recommended by the most recent guidelines 1. The choice of antispasmodic agent depends on the patient's specific symptoms, medical history, and tolerance to potential side effects.

• Dicyclomine (10-20 mg orally three to four times daily) and hyoscyamine (0.125-0.25 mg orally every 4 hours as needed) are anticholinergic medications that work by blocking muscarinic receptors, reducing acetylcholine's effect on smooth muscle and decreasing contractions.
• Mebeverine (135 mg three times daily or 200 mg twice daily of extended-release formulation) and peppermint oil (0.2-0.4 ml three times daily) are direct smooth muscle relaxants that can provide relief from abdominal pain and spasms. Antispasmodics are typically used for 4-6 weeks initially to assess efficacy, with treatment continued if beneficial, as suggested by the British Society of Gastroenterology guidelines 1. It is essential to individualize treatment based on symptom pattern, severity, and patient tolerance, with periodic reassessment to determine ongoing need, considering the potential side effects of anticholinergics, such as dry mouth, blurred vision, and constipation, while mebeverine has fewer side effects 1.

From the FDA Drug Label

12 CLINICAL PHARMACOLOGY

1. 1 Mechanism of Action 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.

The recommended first-line antispasmodic agent is dicyclomine, as it relieves smooth muscle spasm of the gastrointestinal tract through a dual mechanism of action.

• Dicyclomine has a specific anticholinergic effect and a direct effect on smooth muscle. However, the FDA drug label does not provide information on second-line antispasmodic agents, such as hyoscyamine or mebeverine 2.

From the Research

Antispasmodic Agents for Smooth Muscle Spasms

• The treatment of smooth muscle spasms often involves the use of antispasmodic agents, which can be classified into different therapeutic classes with various mechanisms of action 3.
• These classes include anticholinergic/antimuscarinic agents, calcium channel inhibitors, and direct smooth muscle relaxants, each with different effects on gastrointestinal smooth muscle contraction 3.
• Examples of antispasmodic agents used for treating smooth muscle spasms include dicyclomine, hyoscyamine, and mebeverine, among others 3, 4.

First-Line and Second-Line Antispasmodic Agents

• The choice of first-line and second-line antispasmodic agents may depend on the specific condition being treated, as well as the individual patient's response to different medications 3.
• Mebeverine, for example, has been shown to be an effective treatment option for irritable bowel syndrome (IBS), with a good safety profile and low frequency of adverse effects 5.
• Other antispasmodic agents, such as hyoscine and pinaverium, may also be used to treat smooth muscle spasms, although their efficacy and safety may vary depending on the specific context 3, 4.

Treatment of Specific Conditions

• The treatment of spasticity, a condition characterized by increased muscle tone, often involves the use of oral medications such as baclofen, diazepam, and tizanidine, although these may have limited efficacy and significant side effects 6.
• Intrathecal baclofen and botulinum toxin may be used to treat diffuse spasticity and localized spasticity, respectively, in patients who do not respond to oral medications 6.
• Muscle cramps and contractures, which can be caused by a variety of factors, may be treated with medications such as quinine, verapamil, and magnesium, although the optimal treatment approach may depend on the underlying cause and individual patient characteristics 7.