What dose of Procardia XL (Nifedipine XL) should I start with when switching from Norvasc (Amlodipine) 10mg?

Switching from Norvasc 10mg to Procardia XL: Dosing Recommendations

When switching from Norvasc (amlodipine) 10mg to Procardia XL (nifedipine extended-release), start with Procardia XL 30mg once daily as the initial dose, with titration to 60mg if needed after 1-2 weeks based on blood pressure response.

Rationale for Dose Selection

The recommended starting dose of Procardia XL when switching from Norvasc 10mg is based on several key considerations:

1. According to the JNC 7 guidelines, Procardia XL (nifedipine long-acting) has a usual dosing range of 30-60mg once daily 1. This establishes the appropriate dosing parameters.

2. Clinical studies comparing amlodipine and nifedipine extended-release formulations have demonstrated that:

   • Amlodipine 5-10mg once daily is therapeutically equivalent to nifedipine extended-release 20-40mg twice daily 2
   • When converting from nifedipine extended-release to amlodipine, a 5-10mg daily dose of amlodipine was appropriate 3

3. Since you're switching from the maximum dose of amlodipine (10mg), starting with the middle of the Procardia XL dosing range (30mg) is appropriate to maintain blood pressure control while minimizing side effects.

Dosing Algorithm

1. Initial conversion:

   • Norvasc (amlodipine) 10mg daily → Procardia XL 30mg once daily

2. Monitoring:

   • Check blood pressure within 1 week of switching
   • Monitor for common side effects: headache, peripheral edema, dizziness

3. Dose titration:

   • If blood pressure remains elevated after 1-2 weeks: Increase to Procardia XL 60mg once daily
   • If blood pressure is well-controlled: Maintain Procardia XL 30mg once daily
   • If significant hypotension occurs: Consider reducing to Procardia XL 30mg every other day temporarily

Important Clinical Considerations

• Pharmacokinetic differences: Amlodipine has a longer half-life (30-50 hours) compared to nifedipine extended-release (approximately 7 hours with the extended-release formulation). This means blood pressure control may fluctuate more with Procardia XL 4, 5.

• Administration timing: Procardia XL should be taken on an empty stomach, as food can affect absorption. Avoid taking with grapefruit juice, which can increase drug levels.

• Monitoring parameters: Check blood pressure at trough (just before the next dose) to ensure 24-hour coverage.

Common Pitfalls to Avoid

1. Starting at too high a dose: Beginning with Procardia XL 60mg or higher may cause excessive vasodilation, leading to reflex tachycardia, headaches, or significant hypotension.

2. Inadequate monitoring: Failure to check blood pressure within the first week of switching may miss early signs of inadequate control or excessive effect.

3. Abrupt discontinuation: Never stop either medication abruptly as this can lead to rebound hypertension.

4. Overlooking formulation differences: Ensure you're using Procardia XL (extended-release) and not immediate-release nifedipine, which requires multiple daily dosing.

By following this approach, you can effectively transition from Norvasc 10mg to Procardia XL while maintaining blood pressure control and minimizing adverse effects.