Table 1.

Expandable devices for prolonged drug delivery.

Schematic of the device	Expansion mode	References
UROS infusor	Drug reservoir with a pressure responsive-valve. Expansion is achieved after filling with the drug solution	(Situs Co, 2000)
		(Matsuura et al., 2001)
Intravesical balloon	Intravesical balloon inflated with drug formulations and positioned within the bladder via magnetic control	(Innoventions Ltd, 2000)
		(Yachia and Hirszowicz, 2001
		(Yachia and Hirszowicz, 2002)
		(Yachia and Hirszowicz, 2006a, Yachia and Hirszowicz, 2006b)
Multiple spherical units device	Drug-containing polydimethylsiloxane microspheres embedded in biodegradable matrix units that are connected by flexible resorbable suture threads. The retentive configuration is achieved by pulling the threads	(Hopmann et al., 2015)
S-shaped 3D printed hollow device	Drug reservoir fabricated by SLA 3D printing based on an elastomer. The retentive configuration is achieved after catheter removal	(Xu et al., 2021)
LiRIS™ and GemRIS™	Silicon tube prefilled with the drug formulation. The retentive pretzel-like configuration is achieved thanks to the superelastic properties of a nitinol wire that regains its starting shape after catheter removal	(Lee et al., 2007) (Nickel et al., 2012)
		(Giesing et al., 2015)
		(Lee and Daniel, 2015)
		(Cima and Lee, 2020)
Osmotic device based on elastomeric materials	Biodegradable elastomer-based device having osmotic release mechanism	(Tobias et al., 2010)
PVA-based 4D printed intravesical device	U- and helix-shaped PVA matrices, fabricated by HME and 4D printing via FDM and deformed to an elongated temporary shape for insertion into the bladder via catheter. Retentive configurations achieved thanks to shape memory effect induced by exposure to urine at body temperature.	(Melocchi et al., 2019a)