From the Guidelines
Amlodipine should be administered once daily, not twice daily, as its long half-life of approximately 30-50 hours allows it to maintain therapeutic blood levels throughout a 24-hour period with just a single dose 1. The standard dosing regimen for amlodipine is 2.5 to 10 mg once daily, which is sufficient for most patients.
Key Points to Consider
- The pharmacokinetic profile of amlodipine enables steady-state plasma concentrations with once-daily dosing, providing consistent blood pressure control throughout the day and night.
- Splitting the dose to twice daily administration is generally unnecessary and not supported by standard clinical guidelines.
- In rare cases where patients experience breakthrough symptoms or edge-of-dose effects, a clinician might consider divided dosing, but this would be an exception rather than standard practice.
- Patients should take amlodipine at the same time each day to maintain consistent blood levels and maximize therapeutic effect.
Evidence-Based Recommendation
The most recent and highest quality study, published in 2018, recommends the use of long-acting once-daily medications, such as amlodipine, to reduce complexity of the regimen and promote adherence 1. This study supports the use of once-daily dosing of amlodipine, rather than twice daily, to achieve optimal blood pressure control and minimize potential side effects.
Clinical Implications
In clinical practice, administering amlodipine once daily can help improve patient adherence to medication regimens, reduce the risk of adverse effects, and optimize blood pressure control. Clinicians should consider the individual patient's needs and response to treatment when determining the optimal dosing regimen for amlodipine.
From the FDA Drug Label
The usual initial antihypertensive oral dose of Amlodipine besylate tablets is 5 mg once daily, and the maximum dose is 10 mg once daily. The recommended dose for chronic stable or vasospastic angina is 5 to 10 mg, with the lower dose suggested in the elderly and in patients with hepatic insufficiency. The recommended dose range for patients with coronary artery disease is 5 to 10 mg once daily.
The FDA-approved dosing regimen for amlodipine is once daily. There is no indication to give amlodipine twice daily in the provided drug label 2.
From the Research
Amlodipine Administration Frequency
- The standard administration frequency of amlodipine is once daily, due to its pharmacokinetic properties, which allow for effective blood levels to be maintained throughout the dosing interval 3, 4, 5.
- Studies have shown that amlodipine has a long plasma half-life, permitting steady-state blood levels to be achieved with a once-daily dose regimen 4, 6, 5.
- The slow rate of elimination and high oral bioavailability of amlodipine contribute to its suitability for once-daily administration 4, 5.
- There is no indication in the available evidence to suggest that amlodipine should be administered twice daily 3, 4, 7, 6, 5.
Pharmacokinetic Properties
- Amlodipine has a terminal elimination half-life of 40-60 hours, which allows for once-daily dosing 4, 5.
- The drug has a high degree of protein binding (98%) and a large volume of distribution (21 L/kg) 5.
- Amlodipine is extensively metabolized in the liver, but there is no significant presystemic or first-pass metabolism 5.
Clinical Efficacy
- Amlodipine has been shown to be effective in reducing blood pressure in patients with mild to moderate hypertension, with a dose-related reduction in blood pressures 7.
- The drug produces a gradual onset of effect, with a decrease in blood pressure over 4-8 hours, and a slow return to baseline over 24-72 hours 4.
- Amlodipine has been found to be well tolerated, with a low incidence of side effects, and no clinically significant effects on pulse rate, electrocardiogram, or body weight 3, 7.