Dihydropyridine derivatives, also known as calcium channel
blockers, are slightly water-soluble drugs, and poorly absorbed in the
digestive tract. In order to improve absorption, addition of an
absorbefacient (agents that improve absorption), improvement of dosage form
designs etc. are necessary. The general means to overcome poor absorption
are: pulverization of crystals, addition of surfactants, emulsification,
cyclodextrin inclusion, dissolution in polyethylene glycol, vegetable oil
etc. However, these approaches may not guarantee sufficient absorption from
digestive tract. Dihydropyridine derivatives are also unstable to light
exposure and are prepared into light resistant preparations or stored in
light-resistant containers. |
Formulation summary |
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Bioavailability (BA) of the pharmaceutical composition was
conducted as follows. A composition from examples was administered to beagle
dogs weighing about 10 kg after fasting for 20 hours before administration at
a dose of 3 mg/0.1 ml/kg. Blood samples were drawn at given time intervals up
to 24 hours after the administration. The plasma of the blood sample was
centrifuged, deproteinized with acetonitrile and determined by high
performance liquid chromatography (HPLC). The BA% was estimated on the basis of
blood concentration.
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Stability tests |
The dihydropyridine preparations with Neusilin® were subjected to stability tests at 60°C for 4 weeks. The content of analogous substance and appearance was recorded.
*Dihydropyridine degradation products |
Conclusions |
Dihydropyridine derivatives prepared by adding a fatty acid monoglyceride and/or polyoxyethylenesorbitan fatty acid ester and absorbing on to Neusilin® markedly improved the bioavailability and stability of these pharmaceutical compositions. In addition, this preparation facilitated the production of hard capsules. |
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