Calcium channel blockers: One size doesn’t fit all
Adalat CC vs. Procardia XL vs. amlodipine
Adalat CC or Procardia XL? Which long-acting nifedipine product to choose? While Adalat CC carries no AB rating — that is, it’s not considered bioequivalent to Procardia XL — it is sometimes substituted for Procardia XL to save money. Some Veteran’s Administration hospitals have even dumped Procardia XL in favor of the less-expensive Adalat CC.
The primary difference between the drugs is the manner in which they release nifedipine. Procardia XL leaches nifedipine through an osmotic pump delivery system. Adalat CC sloughs off the calcium channel blocking agent via successively dissolving layers.
But one Nebraska clinic found the differences go beyond mere delivery. Rich Wurdeman, PharmD, of Omaha’s Creighton University Cardiac Center, says Procardia XL may provide more long-lasting protection than Adalat CC. Wurdeman says a study involving patients using the two drugs found Adalat’s effectiveness fades earlier than Procardia XL’s; the patients wore 24-hour blood pressure monitors to catch normal daily blood pressure fluctuations.
"The data is suggesting the control is not as good with the Adalat," Wurdeman says, with early morning increases in blood pressure noted. Wurdeman isn’t ready to say whether these blood pressure changes are clinically significant.
Meanwhile, a few hundred miles away, W. Yamruedeewong, PharmD, clinical pharmacy coordinator at the Cheyenne, WY, Veterans Affairs Medical Center, decided to put a Pfizer pharmaceutical corporation claim to the test — namely, that patients taking Pfizer’s old calcium channel blocker, Procardia XL, can easily be switched to the company’s new product, Norvasc (amlodipine).
Yamruedeewong studied almost 30 patients stabilized on Procardia XL, who were then switched over to equipotent doses of amlodipine. She found that Pfizer’s data were pretty much on the mark. "In some patients, you have to go higher with the amlodipine than the company suggested," she says. "When we compare costs, Procardia XL is more expensive than an equivalent dose of amlodipine."
Amlodipine brings relief from side effects
Perhaps the only time you don’t save money between the two drugs, Yamruedeewong says, is when a patient is switched from 30 mg of Procardia XL to 5 mg of amlodipine. In that situation, the costs are about the same.
Patients reacted well to the amlodipine, Yamruedeewong says, with some experiencing relief from side effects such as leg swelling. "Nifedipine tends to dilate vessels more than amlodipine; it tends to cause blood to pool in the legs — but not in every patient." Her only complaint? Amlodipine seemed to take longer to kick in with an antihypertensive effect than nifedipine.
And finally, researchers in South Africa concluded that two long-acting diltiazem products, CardizemCD and DilacorXR, had differences in bioavailability, but this difference did ot ecessarily mean the products were bioinequivalent.
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