Evaluation of zero-order controlled release preparations of nifedipine tablet on dissolution test, together with cost benefit point of view.

ABSTRACT

Many generic drugs have been released to decrease medical expenses, but some problems have been reported with regard to bioavailability and safety. In this study, we compared three once-a-day controlled-release preparations of nifedipine by the dissolution test (one branded and two generic preparations). Although the two generic drugs were equivalent to the branded drug according to the criteria listed in the Japanese "Guideline for Bioequivalence Studies of Generic Products", there was still a possibility of problems arising. For example, side effects could be caused by a rapid increase in the blood level of nifedipine with one generic drug, while bioavailability might be inadequate with the other due to its small area under the concentration vs. time curve. When each drug was prescribed at a dosage of 20 mg once daily for two weeks, the difference in the copayment for the patient was only 10 yen. Accordingly, it is important for doctors and pharmacists to carefully consider whether such a slight difference in price is really a benefit for the patient.