Scalable 3D Screen Printing - High Degree of Freedom in Terms of Drug Choice

Additive manufacturing has the potential to revolutionize the pharmaceutical industry, enabling the production of customized drugs for the mass market. However, concerns over scalability, low mechanical resistance, low printing resolution, and limited material choices have hindered the practical application of current 3D printing (3DP) technologies. Although conceptually similar, each uses its method to deposit and cure the material. These limitations are highlighted by the fact that only a single 3D-printed medicine, Spritam® (an antiepileptic), is currently FDA-approved and marketed.

Scaling Production with 3D Screen Printing

We reported in Moldenhauer et al. the first proof of- concept study on 3D screen printing, termed SPID® (Screen Printing Innovational Drug Technology), in the fabrication of a drug delivery system (DDS). 3D screen printing uses a screen mesh to transfer a semi-solid, active pharmaceutical ingredient (API) containing paste onto a substrate, except in areas made impermeable by a blocking stencil. The deposited layer is then dried. The next layer is printed precisely on top of the previous one after lifting the screen by the dried layer thickness. This approach is based on the classic flatbed screen printing process widely used in industrial applications such as textile prints, electronic circuit boards, and precision materials. Critical advantages of screen printing versus other 3D printing technologies are the high freedom in the choice of materials and the number of tablets able to be produced at one time. 3D screen printing enables the build-up of thousands of units per screen. This is in stark contrast to other 3DP technologies that can only simultaneously produce one tablet per printing head. Using our current screen size, we can print between 12,000 and 40,000 tablets simultaneously, depending on the size of the tablets.

In Moldenhauer et al., SPID® was used to produce paracetamol (acetaminophen) tablets in five different geometries (disk, donut, cuboid, oval, and grid) in three different sizes (small, medium, large). We applied 100 printing cycles, each delivering layers of 20 μm in thickness. Produced tablets were highly uniform in their size, mass, breaking strength, fragility, the weight percentage of the API (paracetamol) per tablet, as well as their dissolution in artificial stomach acidic conditions (pH 1.2). Physical testing of the printed tablets demonstrated them to be on par with other established 3D printing techniques and, most importantly, with conventional tablet production, especially with regard to hardness. Furthermore, tablets were printed in accordance with relevant regulatory requirements outlined in the current European Pharmacopoeia supporting SPID®’s viability for manufacturing solid oral dosage forms.

3D printing, including screen printing, also has the potential to fabricate more complex DDS, including those with multiple APIs. We additionally showed the feasibility in our publication to print tablets with differently colored pastes to demonstrate this. Ongoing studies are currently addressing combinations of different APIs and excipients. Preliminary work indicates that the paste we developed for our proof-of-concept test is capable of accommodating other notable APIs, including, but not limited to, Dapsone (sulfone; antimicrobial and anti-inflammatory activity) and Levodopa (dopamine precursor) (Table 1). Interestingly, the developed paste can be used to print API-containing tablets in all four Biopharmaceutics Drug Disposition Classification System (BDDCS) classes.

API Name