Amlodipine Dosing: Can 5 mg Be Taken Twice Daily?
No, amlodipine 5 mg should not be taken twice daily. The FDA-approved dosing for amlodipine is once daily administration, with a maximum recommended dose of 10 mg once daily for adults. 1
Standard Dosing Recommendations
- The usual initial antihypertensive oral dose of amlodipine is 5 mg once daily, with a maximum dose of 10 mg once daily 1
- Amlodipine has a long half-life of 36-45 hours, which allows for effective 24-hour blood pressure control with once-daily dosing 2
- For patients requiring dose adjustment, the recommended approach is to increase from 5 mg to 10 mg once daily, not to split the dose into twice-daily administration 1
Pharmacological Properties Supporting Once-Daily Dosing
- Amlodipine belongs to the dihydropyridine class of calcium channel blockers with unique pharmacokinetic properties 2
- The long plasma half-life of amlodipine permits steady-state blood levels with once-daily dosing 3
- Clinical studies have demonstrated that amlodipine maintains effective blood pressure control throughout a 24-hour period when administered once daily 3, 4
Dose Titration Guidelines
- When dose adjustment is needed, wait 7 to 14 days between titration steps to allow for full effect assessment 1
- Studies show that early dose increases (before 6 weeks) provide no advantage in antihypertensive effect compared to maintaining the 5 mg once-daily dose 5
- If 5 mg once daily is insufficient after an adequate trial period (6 weeks), the appropriate next step is to increase to 10 mg once daily, not to divide the dose 5
Special Populations
- For elderly, fragile patients, or those with hepatic insufficiency, a lower starting dose of 2.5 mg once daily is recommended 1
- For pediatric patients ages 6-17 years, the effective antihypertensive dose range is 2.5 mg to 5 mg once daily 1
- In pregnancy, amlodipine is considered safe for breastfeeding with a relative infant dose of 1.7%-4.3% 6
Potential Adverse Effects
- The most common side effect of amlodipine is peripheral edema 2
- Other potential side effects include headache, flushing, and dizziness 6
- Twice-daily dosing could potentially increase the risk of adverse effects without providing additional therapeutic benefit 2
Comparison with Other Calcium Channel Blockers
- Unlike some other calcium channel blockers (like diltiazem) that may require multiple daily doses, amlodipine is specifically designed and approved for once-daily administration 6
- When converting from other calcium channel blockers like nifedipine extended-release to amlodipine, the appropriate approach is to use amlodipine 5 or 10 mg once daily, not divided doses 7
Remember that deviating from approved dosing regimens may lead to unnecessary side effects without additional therapeutic benefit. If blood pressure control is inadequate with amlodipine 10 mg once daily, adding a different class of antihypertensive medication would be more appropriate than splitting the amlodipine dose.