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Magnetic hyperthermia controlled drug release in the GI tract: solving the problem of detection

View Article: PubMed Central - PubMed

ABSTRACT

Drug delivery to the gastrointestinal (GI) tract is highly challenging due to the harsh environments any drug- delivery vehicle must experience before it releases it’s drug payload. Effective targeted drug delivery systems often rely on external stimuli to effect release, therefore knowing the exact location of the capsule and when to apply an external stimulus is paramount. We present a drug delivery system for the GI tract based on coating standard gelatin drug capsules with a model eicosane- superparamagnetic iron oxide nanoparticle composite coating, which is activated using magnetic hyperthermia as an on-demand release mechanism to heat and melt the coating. We also show that the capsules can be readily detected via rapid X-ray computed tomography (CT) and magnetic resonance imaging (MRI), vital for progressing such a system towards clinical applications. This also offers the opportunity to image the dispersion of the drug payload post release. These imaging techniques also influenced capsule content and design and the delivered dosage form. The ability to easily change design demonstrates the versatility of this system, a vital advantage for modern, patient-specific medicine.

No MeSH data available.


Magnetic resonance images showing signal hypointensity produced by iron oxide wax-coated capsules compared to capsules coated in the wax only.Axial (a,e,h,k), and coronal slices (b,f,I,l) through the capsules are shown, as well as a volume rendering of the agar phantom containing the capsules.
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f4: Magnetic resonance images showing signal hypointensity produced by iron oxide wax-coated capsules compared to capsules coated in the wax only.Axial (a,e,h,k), and coronal slices (b,f,I,l) through the capsules are shown, as well as a volume rendering of the agar phantom containing the capsules.

Mentions: Multi-slice images were taken across the capsule and agar phantom, and reconstructed into 3D volumes, Fig. 4. In the capsules coated in wax only, the cavity and coating of the capsule can be seen as a hypo-intense region against the background signal provided by the agar (Fig. 4a_c). In the capsules coated in the wax-iron oxide composite, however, the hypo-intense region was enlarged, resulting in a drop out of signal from all but the top edges of the agar phantom (4d to f). Coatings on only one half of the capsule, or as dots on the capsule, produced intermediate volumes of hypo-intensity between those of the capsules with wax only, and a full coating of iron oxide-wax (4 h to m). The large amount of iron in the coatings required for hyperthermia-mediated drug release precluded the possibility of obtaining accurate T2 maps, due to the extreme T2 shortening.


Magnetic hyperthermia controlled drug release in the GI tract: solving the problem of detection
Magnetic resonance images showing signal hypointensity produced by iron oxide wax-coated capsules compared to capsules coated in the wax only.Axial (a,e,h,k), and coronal slices (b,f,I,l) through the capsules are shown, as well as a volume rendering of the agar phantom containing the capsules.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037467&req=5

f4: Magnetic resonance images showing signal hypointensity produced by iron oxide wax-coated capsules compared to capsules coated in the wax only.Axial (a,e,h,k), and coronal slices (b,f,I,l) through the capsules are shown, as well as a volume rendering of the agar phantom containing the capsules.
Mentions: Multi-slice images were taken across the capsule and agar phantom, and reconstructed into 3D volumes, Fig. 4. In the capsules coated in wax only, the cavity and coating of the capsule can be seen as a hypo-intense region against the background signal provided by the agar (Fig. 4a_c). In the capsules coated in the wax-iron oxide composite, however, the hypo-intense region was enlarged, resulting in a drop out of signal from all but the top edges of the agar phantom (4d to f). Coatings on only one half of the capsule, or as dots on the capsule, produced intermediate volumes of hypo-intensity between those of the capsules with wax only, and a full coating of iron oxide-wax (4 h to m). The large amount of iron in the coatings required for hyperthermia-mediated drug release precluded the possibility of obtaining accurate T2 maps, due to the extreme T2 shortening.

View Article: PubMed Central - PubMed

ABSTRACT

Drug delivery to the gastrointestinal (GI) tract is highly challenging due to the harsh environments any drug- delivery vehicle must experience before it releases it’s drug payload. Effective targeted drug delivery systems often rely on external stimuli to effect release, therefore knowing the exact location of the capsule and when to apply an external stimulus is paramount. We present a drug delivery system for the GI tract based on coating standard gelatin drug capsules with a model eicosane- superparamagnetic iron oxide nanoparticle composite coating, which is activated using magnetic hyperthermia as an on-demand release mechanism to heat and melt the coating. We also show that the capsules can be readily detected via rapid X-ray computed tomography (CT) and magnetic resonance imaging (MRI), vital for progressing such a system towards clinical applications. This also offers the opportunity to image the dispersion of the drug payload post release. These imaging techniques also influenced capsule content and design and the delivered dosage form. The ability to easily change design demonstrates the versatility of this system, a vital advantage for modern, patient-specific medicine.

No MeSH data available.