Table 5.

Characteristics and challenges of stereolithography (SLA)

	Characteristics	Challenges
Method	The resin vat contains a build platform. A single point laser located inside the machine maps selectively a light solidifying the liquid material[10,16]. Usually, the products are post-cured by UV light to improve their mechanical properties[16]. Inverted SLA uses the light under transparent bottom of a resin tank[10]. SLA can print porous infill, such as QuickCast, from 3D systems. To modify the porosity of some tablets, it is necessary to change their geometry, because the objects that are printed with this method have a solid filling[10].	Post-processing with UV-curing could be unsuitable for the APIs[16]. The instruments are expensive[16]. The post-curing steps for render biocompatible material can result in a loss of drug loaded and subsequent imprecise dosing[12]. The residual resin can represent a toxicity risk[11].
Material	SLA uses photoreactive and photocurable materials[12]. The drugs can be loaded directly into the liquid pre-polymer solution depending on its solubility[12].	SLA has been limited by photopolymerizable materials that would be biocompatible and approved for human use[16]. SLA that works with multiples materials, such as polymer mixtures and drug loaded structures, is limited[16].
Quality	High accuracy and resolution that allows fabrication of personalized organic shapes for controlling drugs release kinetics[12,16]. An example is ProX/Project printer made by 3D Systems Company (US). This printer has a layer thickness of 20 – 150 mm and has a resolution of 50 µm[18].