Abstract
Freeze-dried systems (L) comprising chitosan (CS) and caffeine (CAF) have been developed for oral administration. Different proportions of CS and CAF have been used in the preparation of the systems. Hot stage microscopy (HSM), differential scanning calorimetry (DSC) and X-ray diffraction powder have been used to characterize the systems prepared. X-ray diffraction patterns showed that there were no interactions between CAF and CS molecules within the freeze-dried systems and the crystallinity of CAF was decreased. Swelling and dissolution tests were carried out in two different media (demineralized water and pH progressive medium) in order to establish their influence over CAF/CS system behaviour. Characteristic swelling behaviour of freeze-dried CS systems (imbibition and dissolution processes) was influenced by the proportions of CS and CAF in the formulations, and by the nature of the medium due to the pH-dependent solubility of CS. Release of CAF from lyophilized systems was conditioned by the swelling process and it should be possible to obtain a CAF/CS binary system with a specific time for total drug release including concrete proportions of both components. Furthermore, the freeze-drying process allowed us to obtain feasible systems for controlled release of CAF until the total amount of drug was released.
Highlights
Time-controlled oral drug delivery systems offer several advantages over immediate-release dosage forms, including the minimization of fluctuations in drug concentrations in the plasma and at the site of action over prolonged periods of time, resulting in optimized therapeutic effectiveness and reduced side effects, a reduction of the total dose administered and a reduction of the administration frequency, leading to improved patient compliance [1]
Release of CAF from lyophilized systems was conditioned by the swelling process and it should be possible to obtain a CAF/CS binary system with a specific time for total drug release including concrete proportions of both components
Different CAF/CS systems, using acetate buffer for dissolving CAF and CS have been prepared by a freeze-drying process
Summary
Time-controlled oral drug delivery systems offer several advantages over immediate-release dosage forms, including the minimization of fluctuations in drug concentrations in the plasma and at the site of action over prolonged periods of time, resulting in optimized therapeutic effectiveness and reduced side effects, a reduction of the total dose administered (while providing similar therapeutic effects) and a reduction of the administration frequency, leading to improved patient compliance [1]. The choice of excipients in order to obtain controlled release drug delivery systems is of paramount importance. Chitosan (CS) is known as an excellent material for drug preparation It is a linear polycationic copolymer of β(1–4) linked 2-acetamide-2-deoxy-β-D-glucopyranose and 2-amino-2deoxy-β-D-glucopyranose obtained from deacetylation of chitin, the second most abundant natural polysaccharide [2]. CS has been gaining increasing importance in the pharmaceutical field owing to its good biocompatibility, low toxicity and biodegradability [5,6] This polymer has found wide applicability in conventional pharmaceutical devices as a potential formulation excipient, some of which include binding, disintegrating and tablet coating properties [7]. Thereby, when the pH of the medium used in the preparation of the complex was 4, a high controlled release of theophylline was obtained at pH 6.8 for 12 hours
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