Preparation, characterization, and in vitro release of oral drug delivery systems made from zein and pectin

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Preparation, characterization, and in vitro release of oral drug delivery systems made from zein and pectin


Author: Tang, Wai Wa
Title: Preparation, characterization, and in vitro release of oral drug delivery systems made from zein and pectin
Degree: M.Phil.
Year: 2016
Subject: Drug delivery systems.
Drugs -- Dosage forms.
Drugs -- Controlled release.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Applied Biology and Chemical Technology
Pages: xii, 117 pages : illustrations (some color)
Language: English
Abstract: Controlled drug delivery has been an extensively studied field in the past decades. The advanced drug delivery systems bring higher compliance and convenience to patients. And more importantly, they improve drug efficacy and reduce side effects. Modified-release or delayed-release drug delivery systems are two major designs of the controlled release dosage forms. The modified-release dosage forms provide slow and continuous drug delivery, while the delayed-release dosage forms control the drug delivery to specific sites. These dosage forms can be made by different strategies. This work presents the use of plant-derived materials taking advantages of their natural properties to make a controlled release capsule or dosage form. Corn zein is a hydrophobic protein having unique solubility and other properties which are favorable for developing a delayed-release capsule. Pure zein capsule can be very brittle and this hinders its use in pharmaceutical industry. In this project, the mechanical strength of the zein capsule was improved by plasticization. The effects of three types of plasticizers, i.e. oleic acid, polyethylene glycol (PEG) and glycerol, on the mechanical behavior, water vapor permeability (WVP), and structural morphology of the zein films were investigated. The supramolecular structures of the plasticized films were characterized using scanning electron microscopy (SEM). Changes in the secondary structure of the films were analyzed using Fourier transform infrared spectroscopy equipped with attenuated total reflectance (FTIR-ATR). Chemical interactions between the plasticizers and zein molecules were examined using differential scanning calorimetry (DSC). Water solubility and disintegration tests were also carried out for the zein capsules made. After characterization by the above tests, oleic acid-plasticized zein capsules were selected with satisfactory mechanical strength and good resistance to disintegration in liquid media. Dissolution studies of the capsules were performed showing that zein capsules have certain resistance to gastric digestion. Another plant-based material was also used in this project, which was pectin. Pectin is well-known for its indigestibility in the stomach and small intestine, and being degradable in the colon. However, its swelling property causes premature release making controlled delivery infeasible. Zein and pectin have very different behavior in their physical properties and digestibility. Combining zein and pectin has a potential in forming colon-specific delivery dosage forms. We proposed that zein and pectin formed complex by hydrogen bonding as observed from FTIR-ATR. Characteristic structures of the zein-pectin dosage forms were presented in the SEM images. From the swelling test, the swelling behavior of pectin was suppressed by zein in the zein-pectin interacted complex. Protection of zein against protease digestion by pectin was shown to be effective from the in vitro performance of drug release. These indicate that combination of zein and pectin may be a promising controlled drug delivery system.

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