Is hyoscine (scopolamine) suitable for treating constipation?

Hyoscine Is Not Recommended for Treating Constipation

Hyoscine (scopolamine) is not recommended for treating constipation as it has anticholinergic effects that can actually worsen constipation. 1, 2

Mechanism of Action and Effects on Constipation

• Hyoscine butylbromide is an antimuscarinic drug that inhibits acetylcholine actions on structures innervated by postganglionic cholinergic nerves and smooth muscles 2
• It specifically inhibits gastrointestinal propulsive motility, which would worsen rather than improve constipation 2
• Hyoscine and other anticholinergic drugs are actually known to cause constipation as a side effect 1

Appropriate Medications for Constipation

For constipation management, the following medications are recommended instead:

First-line options:

• Stimulant laxatives (e.g., senna, bisacodyl) to increase bowel motility 1
• Osmotic laxatives such as polyethylene glycol 1
• Stool softeners may be considered, though evidence suggests they may not add significant benefit when used with stimulant laxatives 1

Second-line options:

• Secretagogues such as linaclotide or plecanatide for constipation-predominant IBS or chronic idiopathic constipation 1
• For opioid-induced constipation, peripherally acting μ-opioid receptor antagonists like methylnaltrexone 1

Appropriate Uses for Hyoscine

While not indicated for constipation, hyoscine does have legitimate therapeutic uses:

• Treatment of abdominal pain and cramping associated with gastrointestinal spasms 3
• Management of smooth muscle spasm in irritable bowel syndrome 1, 4
• First-line treatment for abdominal pain in IBS along with other antispasmodics 1

Potential Adverse Effects of Hyoscine

• Common anticholinergic side effects include dry mouth, dizziness, blurred vision 4, 3
• Can cause constipation as a side effect 1, 2
• Rare but serious adverse effects may include hypotension and myocardial ischemia 5
• Anticholinergic syndrome can occur with overdose, characterized by CNS depression 6

Clinical Decision Making

When treating constipation:

1. Identify and address underlying causes (e.g., medications, metabolic disorders) 1
2. Begin with stimulant laxatives with or without stool softeners 1
3. If inadequate response, add or switch to osmotic laxatives 1
4. For refractory cases, consider secretagogues or peripherally acting μ-opioid receptor antagonists 1
5. Avoid medications with anticholinergic properties like hyoscine, as they can worsen constipation 1

In summary, hyoscine should be avoided in patients with constipation due to its inhibitory effect on gastrointestinal motility, which would exacerbate rather than relieve constipation symptoms.