Therapeutically relevant blood pressure differences with two nifedipine (60 mg) osmotic delivery systems of differing...

During the introduction of a new once-daily nifedipine 60 mg osmotic delivery tablet to Canada in 2009, several patients previously maintained at target blood pressure on regimens that included nifedipine 60 mg daily were observed to have > 10 mmHg rises in their systolic pressure during follow-up. The only difference noted in their medication and clinical status was a substitution with the new 60 mg nifedipine formulation by their pharmacists. Three patients agreed to report home blood pressure for N of 1 studies in which all clinical parameters remained the same, but their nifedipine was repeatedly switched between the original and alternate formulations each week. Of 14 recorded switches, systolic pressure was higher on the alternate formulation 13 times. In at least some patients, the alternate pump technology appears less effective. This highlights the need for better bioequivalence criteria for comparing differing delivery technologies that artificially retard absorption of the drug.