Swallowable smart pills for local drug delivery: present status and future perspectives

Abstract

Smart pills were originally developed for diagnosis; however, they are increasingly being applied to therapy – more specifically drug delivery. In addition to smart drug delivery systems, current research is also looking into localization systems for reaching the target areas, novel locomotion mechanisms and positioning systems. Focusing on the major application fields of such devices, this article reviews smart pills developed for local drug delivery. The review begins with the analysis of the medical needs and socio-economic benefits associated with the use of such devices and moves onto the discussion of the main implemented technological solutions with special attention given to locomotion systems, drug delivery systems and power supply. Finally, desired technical features of a fully autonomous robotic capsule for local drug delivery are defined and future research trends are highlighted.

Keywords:

• active locomotion
• gastrointestinal tract treatment
• local drug delivery
• smart pill
• swallowable robotic capsule

Financial & competing interests disclosure

This study was partially supported by the Policlinico Universitario Campus Bio-Medico di Roma. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Key issues

• Smart pills are swallowable autonomous capsules incorporating tools for diagnosis, monitoring, and localized treatment in the gastrointestinal tract.

• To reach the target areas and deliver specific topical treatments, positioning and locomotion systems are required. Moreover, therapeutic action is achieved with drug delivery systems.

• Personalized drug delivery consists of tailoring the dose for a specific patient and a targeted location in the GI tract according to data read by sensors on the smart capsule.

• Most of the capsules are currently remotely controlled: they require a constant bidirectional communication with external devices.

• Navigation of autonomous capsules can adopt passive or active locomotion strategies.

• Passive capsules are moved essentially by peristaltic forces. Active locomotion can be internal or external, a combination of them and active inhibition of the peristalsis have also been tested.

• Active locomotion systems should be able to stop and anchor the capsule. Active locomotion can be achieved through crawling systems, legged-locomotion, swimming robot or by modulating environmental forces.

• The ideal capsule should be completely autonomous: with reference to drug delivery, continuous sensing of physiological conditions should allow triggering the drug release according to tailored doses; as it concerns locomotion, active mechanisms capable of moving the capsule with the lowest possible energy consumption and exploiting environmental forces without damaging the tissue could make the capsule ‘smart’.

• In future, autonomous swallowable capsules should improve localization systems and overcome actual risks linked to retention of the capsule in some pathological conditions (diverticula, Crohn’s disease, etc.).

• Further miniaturization could bring capsules to approach other anatomical districts, such as the vascular circuit.

Notes