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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.

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(a) Graph of heating an eicosane- SPION coated capsule in air demonstrating heating behaviour commensurate with the latent heat of melting of eicosane and (b) submerged in water. Melting was difficult to observe via an attached thermocouple as the thermocouple detached as the material melted, (c,d) are thermal images showing progression of melting with time, at 105 seconds in (c) and 285 seconds in (d) for the capsule heated in air.
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f3: (a) Graph of heating an eicosane- SPION coated capsule in air demonstrating heating behaviour commensurate with the latent heat of melting of eicosane and (b) submerged in water. Melting was difficult to observe via an attached thermocouple as the thermocouple detached as the material melted, (c,d) are thermal images showing progression of melting with time, at 105 seconds in (c) and 285 seconds in (d) for the capsule heated in air.

Mentions: Temperature versus time data extracted from the thermal imaging camera was used for the capsule in air (Fig. 3a). Although an attached fibreoptic thermocouple was used for the heating of the capsule in water in (Fig. 3b), the disintegrating nature of the melting coating made this exacting, so where appropriate, the thermal camera was used. As seen previously2223, the heating curve in air displayed initial heating to a plateau. This plateau is due to the energy required to supply the latent heat of melting, hence a plateau was observed as the material undergoes phase transition to a liquid. The incorporation of SPIONs tend to lower the melting temperature of the composite from the literature melting point of eicosane (35–37 °C), although incorporation of higher molecular mass alkanes again raises the melting point23. Rapid heating was observed as the solid eicosane matrix became liquid.


Magnetic hyperthermia controlled drug release in the GI tract: solving the problem of detection
(a) Graph of heating an eicosane- SPION coated capsule in air demonstrating heating behaviour commensurate with the latent heat of melting of eicosane and (b) submerged in water. Melting was difficult to observe via an attached thermocouple as the thermocouple detached as the material melted, (c,d) are thermal images showing progression of melting with time, at 105 seconds in (c) and 285 seconds in (d) for the capsule heated in air.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: (a) Graph of heating an eicosane- SPION coated capsule in air demonstrating heating behaviour commensurate with the latent heat of melting of eicosane and (b) submerged in water. Melting was difficult to observe via an attached thermocouple as the thermocouple detached as the material melted, (c,d) are thermal images showing progression of melting with time, at 105 seconds in (c) and 285 seconds in (d) for the capsule heated in air.
Mentions: Temperature versus time data extracted from the thermal imaging camera was used for the capsule in air (Fig. 3a). Although an attached fibreoptic thermocouple was used for the heating of the capsule in water in (Fig. 3b), the disintegrating nature of the melting coating made this exacting, so where appropriate, the thermal camera was used. As seen previously2223, the heating curve in air displayed initial heating to a plateau. This plateau is due to the energy required to supply the latent heat of melting, hence a plateau was observed as the material undergoes phase transition to a liquid. The incorporation of SPIONs tend to lower the melting temperature of the composite from the literature melting point of eicosane (35–37 °C), although incorporation of higher molecular mass alkanes again raises the melting point23. Rapid heating was observed as the solid eicosane matrix became liquid.

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.


Related in: MedlinePlus