Nifedipine to Amlodipine Conversion
When converting from nifedipine extended-release 30 mg to amlodipine, start with amlodipine 5 mg once daily; when converting from nifedipine immediate-release 10 mg, also start with amlodipine 5 mg once daily, regardless of the nifedipine formulation or dose. 1, 2
Conversion Dosing Algorithm
From Nifedipine Extended-Release (30 mg)
- Discontinue nifedipine ER and initiate amlodipine 5 mg once daily 1, 2
- The FDA-approved starting dose for amlodipine is 5 mg once daily for most adults 1
- Clinical trial data demonstrates that amlodipine 5 mg once daily provides equivalent blood pressure control to nifedipine ER 30 mg once daily 3, 2
From Nifedipine Immediate-Release (10 mg)
- Start amlodipine 5 mg once daily 1, 4
- Nifedipine immediate-release 20 mg twice daily (40 mg total daily) was equivalent to amlodipine 5 mg once daily in controlled trials 4
- For lower nifedipine IR doses (10 mg), amlodipine 5 mg once daily remains the appropriate starting dose 1
Special Populations Requiring Lower Starting Dose
- Elderly, small, or fragile patients: Start amlodipine 2.5 mg once daily 1
- Hepatic insufficiency: Start amlodipine 2.5 mg once daily 1
Titration and Monitoring Plan
Initial Monitoring Period
- Monitor blood pressure weekly for the first 4-6 weeks after conversion 2
- Expect approximately 60% of patients to require dose titration after the initial conversion 2
- Check blood pressure at trough (24 hours after the last amlodipine dose) to ensure adequate 24-hour control 5
Dose Titration Strategy
- Wait 7-14 days between titration steps under normal circumstances 1
- If blood pressure remains above target (≥130/80 mmHg), increase amlodipine from 5 mg to 10 mg once daily 5, 6, 1
- Maximum dose is 10 mg once daily 1
- More rapid titration is acceptable if clinically warranted, provided frequent patient assessment occurs 1
Blood Pressure Targets
- Target blood pressure is <130/80 mmHg for most adults 6
- Confirm inadequate control with home blood pressure monitoring (≥135/85 mmHg) before escalating therapy 6
Key Pharmacologic Differences to Anticipate
Heart Rate Monitoring
- Monitor heart rate during the conversion period 7
- Nifedipine (especially immediate-release) may cause reflex tachycardia due to rapid vasodilation 5
- Amlodipine's gradual onset minimizes reflex tachycardia but may still cause mild increases 7
Duration of Action
- Amlodipine has a half-life of 30-50 hours, providing true 24-hour blood pressure control with once-daily dosing 8
- Nifedipine ER requires careful formulation selection, as tablets must be swallowed whole 9
- Nifedipine immediate-release has significant peak-trough variation, with blood pressure being significantly higher 12 hours post-dose compared to 2 hours post-dose 4
Common Pitfalls and How to Avoid Them
Adherence Assessment
- Check medication adherence before assuming treatment failure, as non-adherence is the most common cause of apparent inadequate control 6
- Amlodipine's once-daily dosing improves adherence compared to twice-daily nifedipine formulations 4, 10
Side Effect Profile Differences
- Peripheral edema is more common with amlodipine (10-30% at 10 mg dose) compared to nifedipine ER 6, 10
- Headache is more common with nifedipine retard formulations 10
- Edema is dose-dependent and more common in women 5
- If edema develops, consider adding an ACE inhibitor or ARB rather than discontinuing amlodipine, as combination therapy reduces edema incidence 5
Combination Therapy Consideration
- If blood pressure remains uncontrolled on amlodipine 5 mg after 4-6 weeks, consider adding a second agent rather than maximizing amlodipine to 10 mg 6
- Preferred combinations include amlodipine + ACE inhibitor/ARB or amlodipine + thiazide diuretic 5, 6
- Fixed-dose single-pill combinations improve adherence 6