What is the onset of action for amlodipine (calcium channel blocker)?

From the Guidelines

Amlodipine begins working within 6-12 hours after taking the first dose, but it typically takes 7-10 days of regular use to reach its full blood pressure-lowering effect. The onset of action for amlodipine, a calcium channel blocker, is an important consideration in its use for managing hypertension and angina.

• The medication's effects are dose-dependent, with a typical starting dose of 5 mg once daily, which may be adjusted based on patient response and tolerance 1.
• Amlodipine's pharmacokinetic properties, including its long duration of action, allow for once-daily dosing, which can improve patient adherence to treatment regimens 1.
• The gradual onset of action is beneficial in avoiding sudden drops in blood pressure that could cause dizziness or fainting, making it a suitable option for patients with hypertension or angina 1.
• It's essential to continue taking amlodipine exactly as prescribed, even if symptoms improve, as stopping suddenly can worsen the condition 1.
• Side effects, such as mild swelling in the ankles or feet, may appear within the first few weeks but often improve with continued use 1.
• Amlodipine's use in patients with unstable angina or non-ST-elevation myocardial infarction (UA/NSTEMI) has been studied, and it is generally well-tolerated, although its effects on mortality and morbidity in this population are still being researched 1.
• The choice of amlodipine as a calcium channel blocker may depend on various factors, including the patient's medical history, concomitant medications, and specific indications, such as hypertension or angina 1.

From the FDA Drug Label

Within the physiologic pH range, amlodipine is an ionized compound (pKa=8. 6), and its kinetic interaction with the calcium channel receptor is characterized by a gradual rate of association and dissociation with the receptor binding site, resulting in a gradual onset of effect. Because of the gradual onset of action, acute hypotension is unlikely.

The onset of action for amlodipine is gradual.

• The exact time to onset is not specified in the label.
• Gradual onset is mentioned in relation to the kinetic interaction with the calcium channel receptor and the likelihood of acute hypotension 2, 2, 2.

From the Research

Onset of Action for Amlodipine

• The onset of action for amlodipine is gradual after oral administration, which is due to an intermediate rate of drug absorption and physicochemical characteristics of the drug-cell membrane-receptor interaction 3.
• Peak plasma drug concentration occurs 6-8 hours after dosing, and the effect of the drug is consistent with its disposition 3.
• After single doses, blood pressure decreases gradually over 4-8 hours and may slowly return to baseline over 24-72 hours 3.
• The pharmacodynamic profile of amlodipine in hypertensive patients shows a smooth 24-hour blood pressure control without orthostatic hypotension 4.
• Amlodipine effectively reduces blood pressure throughout the whole 24-hour period without altering the normal circadian pattern, as shown in a study using continuous intra-arterial blood pressure monitoring 5.

Key Findings

• Amlodipine has a high oral bioavailability of 60-80% and accumulates to a steady-state with once-daily administration over a period of 1-1 1/2 weeks 3.
• The elimination half-life of amlodipine is 40-60 hours, which confers several pharmacokinetic characteristics that are not seen with other calcium-antagonist drugs 3.
• Amlodipine is effective for the treatment of hypertension and angina pectoris with once-daily dosing, and it is well tolerated as monotherapy and in combination with other antihypertensive drugs 3, 6, 4.