Can amlodipine cause constipation?

Amlodipine and Constipation

Yes, amlodipine can cause constipation, though it occurs less frequently than with other calcium channel blockers like verapamil. 1

Mechanism and Risk

Amlodipine, a dihydropyridine calcium channel blocker, works by blocking L-type calcium channels in vascular smooth muscle. While it has high selectivity for vascular tissue rather than cardiac tissue, it can also affect smooth muscle in the gastrointestinal tract:

• Amlodipine can inhibit spontaneous intestinal activity in a dose-dependent manner 2
• The relative risk of developing constipation is 4 times higher in patients taking amlodipine alone compared to those taking amlodipine with atenolol 2
• Constipation is less common with dihydropyridines like amlodipine than with non-dihydropyridine calcium channel blockers like verapamil 3

Comparison with Other Calcium Channel Blockers

Different calcium channel blockers have varying propensities for causing constipation:

• Verapamil is known to decrease intestinal motility, making constipation a common side effect, especially in elderly patients 1
• Dihydropyridines like amlodipine have higher selectivity for vascular L-type channels and generally cause fewer gastrointestinal effects 1
• The most common side effects of dihydropyridines are flushing, headache, and edema rather than constipation 3

Management of Amlodipine-Induced Constipation

If constipation develops while taking amlodipine:

1. Assess for other causes - Rule out other medications, dehydration, or underlying conditions 1
2. Lifestyle modifications:
   • Increase fluid intake
   • Increase physical activity when appropriate
   • Consider added dietary fiber for patients with adequate fluid intake 1
3. Laxative therapy if needed:
   • Start with stimulant laxatives like bisacodyl 10-15 mg, 2-3 times daily 1
   • Goal: one non-forced bowel movement every 1-2 days 1
   • For persistent constipation, consider adding osmotic laxatives like polyethylene glycol, lactulose, or magnesium-based products 1

Clinical Considerations

• When prescribing amlodipine, be aware of the potential for constipation, especially in elderly patients or those with pre-existing bowel motility issues
• Consider alternative antihypertensive medications if constipation becomes problematic
• For patients with 22q11.2 deletion syndrome who may already have gastrointestinal issues, monitor bowel habits closely when starting amlodipine 1
• In patients with swallowing difficulties, amlodipine tablets can be crushed and mixed with food or liquid without affecting efficacy 4

Monitoring Recommendations

• Ask about bowel habits at follow-up visits for patients on amlodipine
• Be particularly vigilant in elderly patients and those with risk factors for constipation
• If constipation persists despite management, consider switching to another antihypertensive agent

While constipation is not the most common side effect of amlodipine, clinicians should be aware of this potential adverse effect and manage it appropriately to maintain medication adherence and quality of life.