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Substituted amylose matrices for oral drug delivery
S H Moghadam1, H W Wang, E Saddar El-Leithy
1Faculty of Pharmacy, University of Montreal, Montreal, Quebec, Canada.
Biomedical Materials (Bristol, England)
|May 7, 2008
Summary
Substituted amylose (SA) polymers from corn starch form drug-controlled release tablets. These tablets exhibit a unique release profile due to an unusual melting process during tabletting.
Area of Science:
- Polymer Chemistry
- Pharmaceutical Sciences
- Materials Science
Background:
- High amylose corn starch is a potential material for drug delivery systems.
- Chemical modification of starch can yield polymers with tailored properties.
- Understanding polymer behavior during tabletting is crucial for controlled release formulations.
Purpose of the Study:
- To synthesize substituted amylose (SA) polymers.
- To prepare and characterize SA hydrophilic matrix tablets for drug-controlled release.
- To investigate the influence of formulation parameters and tabletting process on SA tablet properties.
Main Methods:
- Etherification of high amylose corn starch using 1,2-epoxypropanol to obtain SA polymers.
- Preparation of drug-controlled release tablets by direct compression.
- In vitro dissolution testing (USP XXIII no 2) to assess drug release.
- Gravimetric analysis for polymer swelling and water uptake.
- Scanning electron microscopy (SEM) and mercury intrusion porosimetry for tablet characterization.
Main Results:
- SA hydrophilic matrix tablets demonstrated a sequential release profile: an initial burst effect followed by near-constant release.
- Surface pores disappeared post-burst effect due to amylose chain association, forming a diffusion barrier.
- High crushing strength in SA tablets was attributed to an unusual melting process during tabletting, unlike HPMC tablets.
- Formulation parameters like compression force, drug loading, and diluent concentration were investigated for their impact.
Conclusions:
- SA polymers can form effective hydrophilic matrix tablets for controlled drug release.
- The unique release behavior is linked to the polymer's ability to form a diffusion barrier.
- An unusual melting phenomenon during tabletting contributes to the high mechanical strength of SA tablets.
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