Magnetic Resonance Methods as a Prognostic Tool for the Biorelevant Behavior of Xanthan Tablets

Urša Mikac,Julijana Kristl

doi:10.3390/molecules25245871

Urša Mikac, Julijana Kristl

Open Access

https://doi.org/10.3390/molecules25245871

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Abstract

Hydrophilic matrix tablets with controlled drug release have been used extensively as one of the most successful oral drug delivery systems for optimizing therapeutic efficacy. In this work, magnetic resonance imaging (MRI) is used to study the influence of various pHs and mechanical stresses caused by medium flow (at rest, 80, or 150 mL/min) on swelling and on pentoxifylline release from xanthan (Xan) tablets. Moreover, a bimodal MRI system with simultaneous release testing enables measurements of hydrogel thickness and drug release, both under the same experimental conditions and at the same time. The results show that in water, the hydrogel structure is weaker and less resistant to erosion than the Xan structure in the acid medium. Different hydrogel structures affect drug release with erosion controlled release in water and diffusion controlled release in the acid medium. Mechanical stress simulating gastrointestinal contraction has no effect on the hard hydrogel in the acid medium where the release is independent of the tested stress, while it affects the release from the weak hydrogel in water with faster release under high stress. Our findings suggest that simultaneous MR imaging and drug release from matrix tablets together provide a valuable prognostic tool for prolonged drug delivery design.

Highlights

Matrix tablets are considered as a dosage form that may maximize the bioavailability of drugs and enable good adjustment of the doses, patient friendly administration, and relatively low manufacturing cost and are, attractive delivery systems, which are not fully understood yet
As the amount of water increased in the hydrogel layer, the signal intensity first increased and, at very high water content, decreased again due to the long T1 and short repetition time used in the magnetic resonance imaging (MRI) sequence
The MR signal intensity was uniform through the whole sample indicating that after 24 h, no hydrogel layer existed anymore, and disentangled polymer chains were uniformly distributed over the whole cell

Summary

Introduction

Matrix tablets are considered as a dosage form that may maximize the bioavailability of drugs and enable good adjustment of the doses, patient friendly administration, and relatively low manufacturing cost and are, attractive delivery systems, which are not fully understood yet. The principal objective of dosage form design is to achieve a predictable release and therapeutic response of a drug included in a formulation that is capable of large-scale manufacture with reproducible product quality. With conventional oral drug delivery systems, the drug level in the plasma rises after each administration of the tablet and decreases until the administration; frequent dosing is required. In order to avoid the “peaks and valleys” of standard dosage forms, innovative drug delivery systems have been formulated by testing a wide array of hydrophilic polymers and production strategies to prolong drug release and for safe and efficient use. Matrix tablets with prolonged release are well accepted by patients due to their reduced frequency of administration

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