Abstract
After patent protection of original brand is over, there are a lot of generic products occurring on the pharmaceutical market. It may be the way to reduce the price, but on the other hand, one should expect the same quality and almost identity with original brand, because the development of generic drugs is based on pharmacological properties of the original brand. The aim of this study was to compare the similarity of two products with controlled release of felodipine--generic product Presid and original brand Plendil--which are commercially available in Czech Republic, based on in vitro dissolution testing. The dissolution test in three dissolution media of increasing pH (1.2, 4.5, and 6.5) for the simulation of physiological pH within the gastrointestinal tract confirmed controlled release of felodipine from the original product Plendil ER 5 mg and Plendil ER 10 mg during the period of 24 hours. The release of felodipine from generic products Presid 5 mg and Presid 10 mg was not controlled for 24 hours as it is indicated in the information leaflet. In the generic products, felodipine release was controlled just for 12 or 18 hours and in this respect did not show similarity with the original brand. Since patients take the drug just once a day in the morning, the controlled release of felodipine, which lasts only 12 to 18 hours, can cause insufficient blood pressure control especially in the most critical morning hours and higher cardiovascular risk.
Highlights
Felodipine is a calcium antagonist that selectively reduces smooth muscle contractile activity in resistance vessels
The present study revealed no discrepancies between the real and declared contents of felodipine in a tablet
The nominal content of original brand Plendil® ER was slightly higher in some dissolution media as original Modip® in Petersen dissolution study [9]
Summary
Felodipine is a calcium antagonist that selectively reduces smooth muscle contractile activity in resistance vessels. Hypertension is the most important ( reversible when treated) risk factor for most cardiovascular diseases It is strongly associated with ischemic stroke, myocardial infarction, end-stage renal disease, and heart failure. Myocardial infarction, sudden cardiac death, ischemic stroke, unstable angina pectoris show a clear circadian variation, exhibiting a peak in the morning hours. This pattern results from the stress arising from tasks and duties of the forthcoming day. Blood viscosity rises in the morning hours, and the tissue plasminogen activator does not show sufficient increase to compensate for the above-mentioned risks This imbalance might result in relative attenuation of fibrinolysis that would promote a hypercoagulable state. It seems to be necessary to manage smooth blood pressure control within all 24 hours, especially in the morning hours [6, 7]
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