Timing of amlodipine administration
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Once-Daily vs. Divided Dosing of Amlodipine for Hypertension Control
Research comparing once-daily and twice-daily (divided) dosing of amlodipine shows that splitting the daily dose does not provide additional benefits in controlling blood pressure over a 24-hour period. Studies found no significant differences in trough plasma concentrations, arterial stiffness, or blood pressure control between once-daily and twice-daily administration in patients with essential hypertension . The long half-life of amlodipine allows for stable blood levels and effective blood pressure reduction with once-daily dosing 78.
Morning vs. Evening Administration: Chronopharmacology and Blood Pressure Effects
Several studies have examined whether the time of day amlodipine is taken affects its efficacy. A meta-analysis of 19 randomized controlled trials found that the timing of amlodipine administration (morning vs. evening) did not significantly affect office, daytime, or 24-hour mean blood pressure, nor heart rate. However, evening dosing was associated with a greater reduction in nighttime blood pressure and was more effective for patients with "non-dipper" hypertension, whose blood pressure does not decrease at night as it should . Another study confirmed that evening dosing led to a faster absorption and higher peak concentration, with greater reductions in systolic blood pressure and heart rate compared to morning dosing, suggesting that nighttime administration may be more effective for some patients . However, other research found no significant difference in blood pressure reduction between morning and evening dosing, indicating that both times are generally effective .
Pharmacokinetics and 24-Hour Blood Pressure Control
Amlodipine has a long elimination half-life (40–60 hours), high oral bioavailability, and accumulates to steady-state levels with once-daily dosing. This pharmacokinetic profile supports its use as a once-daily medication, providing consistent blood pressure control throughout the day and night with minimal fluctuations in plasma concentration 78. Studies confirm that once-daily dosing effectively lowers both daytime and nighttime blood pressure .
Implications for Patient Adherence and Chronotherapy
Strict adherence to the timing of amlodipine administration is important for optimal blood pressure control, but the drug’s long-acting nature provides flexibility. Chronotherapy—synchronizing medication timing with biological rhythms—may offer additional benefits for certain patients, such as those with non-dipper hypertension, by targeting nighttime blood pressure more effectively with evening dosing 236.
Conclusion
For most patients, amlodipine can be taken once daily, either in the morning or evening, with similar overall efficacy in blood pressure control. Evening dosing may offer added benefits for patients with non-dipper hypertension or those needing better nighttime blood pressure management. Dividing the daily dose does not provide additional advantages. The choice of timing should be individualized based on patient needs and lifestyle, with a focus on maintaining adherence to therapy.
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