Dose Conversion to Felodipine from Other Dihydropyridine Calcium Channel Blockers

Brittani Parks, PharmD Candidate

            One challenge of a preferred drug list is safely and effectively converting patients to the preferred agent.  Limited data exists to guide the dose conversion between calcium channel blockers. 

Nifedipine to Felodipine

            One study1 has examined a conversion from immediate-release nifedipine to felodipine.   The method of conversion is described in Table 1 below.

Table 1.  Dose conversion between nifedipine and felodipine.Adapted from 1

Nifedipine dose (mg/day)

Equivalent felodipine dose (mg/day)

30

5

60

5-10

80-120

10

 

This conversion illustrates that clinical judgment is still important when converting from one agent to another.  For example, patients taking 60 mg/day of nifedipine can be converted to either 5 or 10 mg/day.  The focus of this study was not the safety and efficacy during the transition.

Amlodipine to Felodipine

            More studies have looked at the conversion of amlodipine to felodipine with differing results.  In all studies, the initial transition was made using an identical dose of felodipine to that of amlodipine.2-5  However, at the conclusion of three of the trials, the average felodipine dose was statistically higher after titration for efficacy.2-4   After conversion to felodipine, two studies showed an inferior control of hypertension based on blood pressure2 or a statistical increase in additional cardiovascular medications.3  Regardless, converting between equal doses of these agents appears to be a reasonable starting place.

Conclusion

            The conversions to felodipine discussed are guidelines for the initial transition.  Although these agents are in the dihydropyridine structural class of calcium channel blockers, pharmacologic and pharmacokinetic differences in the agents exist, so an individual may not necessarily respond identically to the agents.  Because the published results of conversion to felodipine vary, the conversion should be approached on a patient-by-patient basis.

References

 

1.       Kaplan RC, Psaty BM, Kriesel D, Heckbert SR, Smith NL, Gillett C, Golston AG.  Replacing short-acting nifedipine with alternative medications at a large health maintenance organization.  Am J Hypertens 1998;11:471-477.

 

2.       Blivin SJ, Pippins J, Annis LG, Lyons F.  A comparative analysis of amlodipine and felodipine in a military outpatient population:  efficacy, outcomes, and cost considerations.  Mil Med 2003;168:530-535.

 

3.      Oatis GM, Stowers AD.  Conversion from amlodipine to felodipine ER:  did the change fulfill expectations?  Formulary 2000;35:435-442.

 

4.       Manzo BA, Matalka MS, Ravnan SL.  Evaluation of a therapeutic conversion from amlodipine to felodipine.  Pharmacotherapy 2003;23(11):1508-1512.

 

5.      Walters J, Noel H, Folstad J, Kapadia V, White CM.  Prospective evaluation of the therapeutic interchange of felodipine ER for amlodipine in patients with hypertension.  Hosp Pharm 2000;35:48-51.