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Improving the dissolution and bioavailability of nifedipine using solid dispersions and solubilizers
L H Emara1, R M Badr, A Abd Elbary
1Industrial Pharmacy Laboratory, Department of Pharmaceutical Sciences, National Research Centre, El-Tahrir Street, Dokki, Giza 12622, Egypt. lhemara@hotmail.com
Drug Development and Industrial Pharmacy
|September 19, 2002
Summary
This study enhanced nifedipine (NF) bioavailability using solid dispersions with polyethylene glycol (PEG) and beta-cyclodextrin (beta-CyD). The solvent method yielded the best dissolution, while fusion surprisingly gave the highest rabbit absorption.
Area of Science:
- Pharmaceutical Sciences
- Drug Delivery Systems
- Materials Science
Background:
- Nifedipine (NF) exhibits poor water solubility and low oral bioavailability.
- Existing methods like solid dispersions and solubilizers show limited in vivo data.
- Improving NF's therapeutic efficacy requires enhanced dissolution and absorption.
Purpose of the Study:
- To enhance nifedipine's (NF) therapeutic efficacy by incorporating it into various carriers.
- To investigate the in vitro dissolution and in vivo bioavailability of NF formulations in rabbits.
- To compare the performance of different preparation methods and carriers for NF solid dispersions.
Main Methods:
- Nifedipine solid dispersions were prepared using fusion, solvent, and freeze-drying methods with polyethylene glycol (PEG) 6000 and PEG monomethylether 5000 (PEG MME 5000).
- Complexation with beta-cyclodextrin (beta-CyD) and solubilization with sodium lauryl sulfate (SLS) were also evaluated.
- In vitro dissolution was assessed using a flow-through cell under perfect sink conditions; in vivo bioavailability was studied in rabbits.
Main Results:
- Solid dispersions significantly increased NF dissolution rates compared to the pure drug.
- The highest in vitro dissolution rate was observed with 95% PEG 6000 prepared by the solvent method.
- Unexpectedly, the highest in vivo absorption in rabbits was achieved with 95% PEG 6000 prepared by the fusion method.
- Beta-cyclodextrin (beta-CyD) demonstrated superior in vitro and in vivo performance compared to sodium lauryl sulfate (SLS).
- Characterization techniques (DSC, XRD) confirmed homogeneous drug distribution and absence of crystallization in solid dispersions, suggesting potential new solid forms.
Conclusions:
- Solid dispersions, particularly with PEG 6000, effectively enhance nifedipine (NF) dissolution.
- The preparation method significantly impacts NF's in vitro and in vivo performance.
- Beta-cyclodextrin (beta-CyD) shows promise as a carrier for improving NF bioavailability.
- Further investigation into the fusion method's enhanced in vivo absorption is warranted.