Should I administer 5 mg of Amlodipine (generic name) twice daily, once at night and once in the morning?

No, Do Not Give Amlodipine Twice Daily

Amlodipine should be administered once daily only, not twice daily. The FDA-approved dosing is 5-10 mg once daily for adults, and administering it both at night and in the morning (totaling 10 mg split into two doses) is not the correct approach 1.

Correct Dosing Strategy

Standard Once-Daily Administration

• Start with 5 mg once daily as the initial dose for most adults with hypertension 1
• The medication can be taken at any time of day that is most convenient for the patient to improve adherence 2
• Amlodipine's long half-life of 30-50 hours supports true once-daily dosing and provides sustained 24-hour blood pressure control 3, 4

When to Increase the Dose

• Wait 7-14 days between dose adjustments to assess response 1
• If blood pressure remains above target (≥130/80 mmHg) after 2-6 weeks at 5 mg, increase to 10 mg once daily (not split doses) 2
• The maximum approved dose is 10 mg once daily 1
• Studies show no advantage to early dose escalation; wait at least 6 weeks at 5 mg before considering an increase to 10 mg 5

Why Not Twice Daily?

Pharmacokinetic Evidence

• Amlodipine has an elimination half-life of 36-60 hours, which is much longer than the 24-hour dosing interval 6, 7
• Plasma concentration fluctuation between doses is only 20-25% with once-daily dosing, indicating stable drug levels throughout the day 7
• The drug accumulates to steady-state over 1-1.5 weeks with once-daily administration 7

Clinical Guidelines Are Clear

• The American College of Cardiology, American Heart Association, and European Society of Cardiology all recommend amlodipine as a once-daily medication 3
• Unlike shorter-acting calcium channel blockers (nicardipine, isradipine) that require 2-3 times daily dosing, amlodipine is specifically designed for once-daily use 8, 3

Timing Considerations

Morning vs. Evening Dosing

• Either morning or evening dosing is acceptable and equally effective for blood pressure control 9
• One study showed that nighttime dosing may provide slightly better control of the morning blood pressure surge, but both timings effectively lower 24-hour blood pressure 9
• Choose the time that best fits the patient's routine to maximize adherence 2

Alternative Strategies If 5 mg Is Insufficient

Before Increasing to 10 mg

• Verify medication adherence first, as non-adherence is a common cause of apparent treatment failure 2
• Confirm inadequate control with home blood pressure monitoring (≥135/85 mmHg) or 24-hour ambulatory monitoring (≥130/80 mmHg) 2

Consider Combination Therapy

• Add a second agent rather than maximizing amlodipine if blood pressure remains uncontrolled after 4-6 weeks at 5 mg 2
• Preferred combinations include amlodipine + ACE inhibitor/ARB or amlodipine + thiazide-type diuretic 2
• Most adults with hypertension require two or more medications to achieve target blood pressure <130/80 mmHg 2

Common Pitfall to Avoid

Do not split the daily dose into twice-daily administration. This is pharmacologically unnecessary given amlodipine's long half-life and is not supported by FDA labeling or clinical guidelines 1, 3. If 5 mg once daily is insufficient, the correct approach is to increase to 10 mg once daily after an appropriate trial period, not to give 5 mg twice daily 1, 5.