Abstract
An increased interest in colonic drug delivery has led to a higher focus on the design of delivery devices targeting this part of the gastrointestinal tract. Microcontainers have previously facilitated an increase in oral bioavailability of drugs. The surface texture and shape of microcontainers have proven to influence the mucoadhesion ex vivo. In the present work, these findings were further investigated using an in situ closed-loop perfusion technique in the rat colon, which allowed for simultaneous evaluation of mucoadhesion of the microcontainers as well as drug absorption. Cylindrical, triangular and cubic microcontainers, with the same exterior surface area, were evaluated based on in vitro release, in situ mucoadhesion and in situ absorption of amoxicillin. Additionally, the mucoadhesion of empty cylindrical microcontainers with and without pillars on the top surface was investigated. From the microscopy analysis of the colon sections after the in situ study, it was evident that a significantly higher percentage of cubic microcontainers than cylindrical microcontainers adhered to the intestinal mucus. Furthermore, the absorption rate constants and blood samples indicated that amoxicillin in cubic microcontainers was absorbed more readily than when cylindrical or triangular microcontainers were dosed. This could be due to a higher degree of mucoadhesion for these particular microcontainers.
Highlights
Oral drug delivery remains the preferred administration route due to ease of use, flexibility and patient compliance [1]
scanning electron microscopy (SEM) showed uniform coatings covering the cavities of the drug-loaded microcontainers for all three shapes (Figure 2d–f)
We investigated the influence of microdevice shape on colonic mucoadhesion and drug absorption by applying an in situ closed-loop intestinal perfusion technique
Summary
Oral drug delivery remains the preferred administration route due to ease of use, flexibility and patient compliance [1]. Despite many advances in oral delivery systems [2,3,4], the design of ‘the ideal delivery device’ is still widely discussed and depends on the application. An increased interest in colon drug delivery has led to significant research with a focus on designing delivery devices that target this part of the gastrointestinal (GI) tract [5]. In addition to local delivery, the colon has been suggested as an interesting site for systemic drug delivery due to increased oral bioavailability for some drugs and longer transit time compared to the small intestine [6,7,8]. Mucoadhesion is an important factor in relation to targeted delivery to any part of the GI tract, since it can prolong the residence time and facilitate drug release in close proximity to the epithelium The prolonged transit time allows timing of the treatment to periods with maximal disease activity; for example, in diseases where symptoms are more pronounced in the morning (hypertension, asthma and arthritis) [7].
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