Is Reglan (metoclopramide) used to treat constipation?

Metoclopramide (Reglan) for Constipation

Metoclopramide is not recommended as a primary treatment for constipation, but may be considered only in specific cases where gastroparesis is suspected as the underlying cause of constipation. 1

Mechanism and Indications

• Metoclopramide is a dopamine receptor antagonist that stimulates gastric emptying and small intestinal transit, enhancing gastrointestinal motility 1
• It is FDA-approved for diabetic gastroparesis and to facilitate small intestinal intubation, not for constipation 2
• Metoclopramide acts by antagonizing dopamine receptors both peripherally (improving gastric emptying) and centrally (providing anti-emetic effects) 3

Role in Constipation Management

• Guidelines do not recommend metoclopramide as a primary treatment for constipation 1, 4
• It may only be considered when gastroparesis is suspected as the underlying cause of constipation symptoms 1
• In a small study of diabetic gastroparesis patients, metoclopramide did improve bowel habits in those who were previously constipated, but this was not its primary indication 5

Safety Concerns and Limitations

• Metoclopramide carries significant risks including extrapyramidal side effects and potentially irreversible tardive dyskinesia, especially with prolonged use 1
• The European Medicines Agency's Committee recommends against long-term use of metoclopramide due to these safety concerns 1
• The FDA has issued a black box warning against using metoclopramide for longer than 12 weeks due to the risk of tardive dyskinesia 3
• Side effects include drowsiness, restlessness, hyperprolactinemia, and movement disorders 3, 6

Recommended Treatments for Constipation

• First-line treatments for constipation include:

  • Bulk-forming laxatives such as unprocessed wheat bran, methylcellulose, ispaghula, and sterculia 1
  • Osmotic laxatives including polyethylene glycol (macrogols), lactulose, or magnesium salts 1
  • Stimulant laxatives such as senna (with or without docusate) and bisacodyl 1

• For opioid-induced constipation:

  • Prophylactic bowel regimens should be started when initiating opioid therapy 1
  • Peripherally acting μ-opioid receptor antagonists (PAMORAs) such as methylnaltrexone, naldemedine, and naloxegol are effective when constipation is opioid-related 1

Clinical Decision Making

• For general constipation:

  1. Start with lifestyle modifications (adequate fluid intake and fiber) 1
  2. Use bulk-forming or osmotic laxatives as first-line pharmacological treatment 1
  3. Add stimulant laxatives if needed 1

• For suspected gastroparesis-related constipation:

  1. Confirm gastroparesis diagnosis (delayed gastric emptying without mechanical obstruction) 3
  2. Consider short-term metoclopramide only if gastroparesis is confirmed 1
  3. Limit treatment duration to less than 12 weeks due to safety concerns 3

• For opioid-induced constipation:

  1. Use prophylactic stimulant laxatives (senna with or without docusate) 1
  2. Add osmotic laxatives if needed 1
  3. Consider PAMORAs for refractory cases 1

Metoclopramide should be reserved for cases where gastroparesis is the underlying cause of constipation, and even then, used with caution due to its significant side effect profile and limited duration of use.