What is the best course of action for a patient with elevated blood pressure (hypertension) who has missed their Amlodipine (calcium channel blocker) medication?

Immediate Management of Missed Amlodipine with Elevated Blood Pressure

Provide the patient with his Amlodipine 5mg and have him resume taking it immediately, then reassess his blood pressure within 2-4 weeks to determine if dose escalation or addition of a second agent is needed. 1

Immediate Actions

• Resume Amlodipine 5mg once daily immediately – the patient's BP of 151/99 mmHg represents Stage 2 hypertension that requires treatment, and restarting his prescribed medication is the first priority 1
• Counsel the patient to take the medication at the same time each day (with breakfast, dinner, or bedtime) to improve adherence 1
• If he missed only one dose and it's been less than 12 hours, take it now; if more than 12 hours have passed, skip the missed dose and resume at the regular time 1

Understanding Amlodipine's Pharmacokinetics

• Amlodipine has a long elimination half-life of 40-60 hours, meaning it takes 1-1.5 weeks to reach steady-state blood levels after starting or restarting therapy 2
• After resuming the medication, blood pressure will decrease gradually over 4-8 hours initially, with full therapeutic effect developing over several days to weeks 2, 3
• The long half-life provides consistent 24-hour blood pressure control with once-daily dosing, with only 20-25% fluctuation between doses 2

Follow-Up and Treatment Intensification Strategy

• Reassess blood pressure within 2-4 weeks after confirming medication adherence to evaluate response 4
• The target blood pressure is <140/90 mmHg minimum, ideally <130/80 mmHg for optimal cardiovascular risk reduction 4

If BP Remains Elevated After 2-4 Weeks on Amlodipine 5mg:

Option 1: Increase Amlodipine dose

• Increase to Amlodipine 10mg once daily if diastolic BP remains >90 mmHg after 6 weeks at 5mg 5
• Do not increase the dose before 6 weeks, as there is no advantage to early dose escalation 5

Option 2: Add a second agent (if BP remains ≥140/90 after optimizing Amlodipine)

• For non-Black patients: Add an ACE inhibitor (e.g., lisinopril 10mg daily) or ARB (e.g., losartan 50mg daily) as the preferred second agent 4
• For Black patients: Add a thiazide-like diuretic (e.g., chlorthalidone 12.5-25mg daily or hydrochlorothiazide 25mg daily) as the preferred second agent 4
• The combination of amlodipine with an ACE inhibitor/ARB provides complementary mechanisms and superior BP control compared to either agent alone 4, 6

Monitoring Parameters

• Check blood pressure at each visit until target is achieved 4
• Monitor for peripheral edema, the most common side effect of amlodipine, which may be attenuated by adding an ACE inhibitor or ARB 4, 1
• If adding an ACE inhibitor/ARB, monitor serum potassium and creatinine 2-4 weeks after initiation 4
• If adding a thiazide diuretic, monitor serum potassium and creatinine 2-4 weeks after initiation to detect hypokalemia 4

Critical Adherence Counseling

• Address the root cause of the missed medication – verify the patient understands the importance of daily dosing and has a system to prevent future lapses 4
• Emphasize that amlodipine must be taken continuously; stopping suddenly will cause blood pressure to gradually return to baseline over 7-10 days 2
• Non-adherence is the most common cause of apparent treatment-resistant hypertension 4
• Consider using pill organizers, smartphone reminders, or linking medication-taking to daily routines 7

Important Caveats

• Do not add a second antihypertensive agent before confirming adherence and allowing adequate time (6 weeks) for amlodipine 5mg to reach full effect 5
• If the patient has been off amlodipine for an extended period, it will take 1-1.5 weeks to re-establish steady-state levels 2
• Rare but serious: When first restarting amlodipine or increasing the dose, angina may worsen in susceptible patients – instruct the patient to seek immediate care if chest pain occurs 1