Amlodipine dosage twice a day
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Amlodipine Dosage Twice a Day: Efficacy and Compliance
Introduction to Amlodipine and Dosage Frequency
Amlodipine, a long-acting calcium channel blocker, is commonly prescribed for the management of hypertension and angina pectoris. The standard dosing regimen is typically once daily due to its long half-life, which ensures sustained blood pressure control over a 24-hour period. However, there is ongoing research into the potential benefits and drawbacks of dividing the daily dose into two administrations.
Compliance with Once vs. Twice Daily Dosing
Studies have shown that patient compliance tends to be higher with once-daily dosing compared to twice-daily regimens. A clinical trial comparing once-daily amlodipine to twice-daily diltiazem found that while overall compliance was high for both regimens, the patterns of pill-taking were more erratic with twice-daily dosing, particularly among men. This suggests that once-daily dosing may be more convenient and lead to better adherence.
Blood Pressure Control and Circadian Rhythm
Research on the effects of amlodipine on circadian blood pressure profiles in hypertensive rats indicated that both once-daily and twice-daily dosing effectively reduced blood pressure and ventricular hypertrophy. However, twice-daily dosing resulted in a bimodal blood pressure pattern, whereas once-daily dosing primarily affected the resting period. This suggests that while both regimens are effective, the timing of doses can influence blood pressure patterns.
Trough Concentrations and 24-Hour Blood Pressure Control
A study investigating the impact of dividing a 10 mg daily dose of amlodipine into two doses found no significant differences in 24-hour blood pressure control, trough plasma concentrations, or arterial stiffness between once-daily and twice-daily administration. This indicates that splitting the dose does not provide additional benefits in terms of maintaining consistent blood pressure levels throughout the day.
Persistence of Antihypertensive Effect
The persistence of the antihypertensive effect after missed doses is an important consideration. A study comparing amlodipine and diltiazem found that amlodipine, with its longer half-life, maintained blood pressure control better during short periods of noncompliance. This highlights the advantage of once-daily amlodipine in ensuring sustained blood pressure control even if a dose is missed.
Clinical Implications and Patient Outcomes
Clinical trials have consistently shown that once-daily amlodipine is effective in reducing blood pressure and is well-tolerated by patients. For instance, a study on patients with mild to moderate hypertension demonstrated significant blood pressure reductions with once-daily amlodipine, with minimal side effects. Another study confirmed the 24-hour efficacy of once-daily amlodipine in maintaining blood pressure control.
Conclusion
While both once-daily and twice-daily dosing of amlodipine are effective in managing hypertension, once-daily dosing offers advantages in terms of patient compliance and sustained blood pressure control. The convenience of a once-daily regimen, combined with the drug's long half-life, makes it a preferable option for many patients. Dividing the dose into two administrations does not appear to provide additional benefits and may complicate adherence. Therefore, once-daily amlodipine remains the recommended dosing regimen for optimal patient outcomes.
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