Shape changeable drug delivery vehicle for controlling residence time of capsule in specific parts of the body

Though advances in drug delivery has engender the ability to tune the concentration of drugs at specific parts of the body, there remains few technological solutions for localizing the drug delivery vehicle or capsule at particular organs for concentrating drugs to diseased sites. This situation comes forth due to reliance of most drug delivery capsules on the systemic circulation for transporting drugs to specific body sites. By accumulating at diseased sites, the drug delivery vehicles would be able to provide damaged tissue and cellular structure with drugs targeted at ameliorating cell damage and enabling cellular repair.


Nevertheless, new research described in MIT News (Link) utilized an innovative approach of shape changeable drug delivery vehicle to enable the localization of the capsule (loaded with drugs) in the stomach for a defined period of time to aid drug delivery. In studies conducted in pigs, the capsule does not cause noticeable harm such as clogging during the period of stomach localization.


Specifically, by designing different shape changeable segments to the drug delivery vehicle, the researchers managed to use stomach acid to prompt a shape change where polymeric arms folded into the capsule open up into a star shape, which, by increasing the size of the vehicle, prevents the capsule from leaving the stomach through peristaltic motion. Although “trapped” in the stomach, the star shaped capsule did not cause physiological upsets in animal studies such as those that may manifest due to a blockage.


Given the biodegradable nature of the polymeric arms, progressive surface erosion of the polymer trim the length of the arms; thereby, reducing the length of the arms and size of the capsule, which facilitated the eventual removal of the capsule from the stomach at the end of the drug delivery period of two weeks. Thus, by understanding the time progression of surface erosion of the polymer used in developing the drug delivery vehicle, the duration of its stay in the stomach could be designed through increasing or decreasing the amount of polymer used in the foldable arms of the capsule.


Overall, the research is an innovative solution for maintaining a drug delivery vehicle at a specific locale in the body such as the stomach; however, it is not generally applicable to most drug delivery scenarios where the delivery vehicle requires the help of the blood circulation to reach a specific body site. Hence, localization of the drug delivery vehicle at specific body sites would need the accumulation of the capsules at the cell and tissue level. However, application of similar ideas of shape changeable capsules for delivering drugs to cells that borders small capillaries or veins is not feasible, given problems of blood clogging and subsequent thrombosis (i.e. formation of blood clogs that could lead to downstream problems such as strokes or major organ failure).


Category: drug delivery, biotechnology,

Tags: drug delivery, polymeric capsule, shape changeable, stomach, clogging, localization, surface erosion, drug delivery duration,




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