Production Of Medicines Using Selective Laser Sintering (SLS)

August 10, 2017 | News

The use of 3-dimensional printing (3DP) in the healthcare industry is becoming an increasingly popular trend. 3DP allows the manufacturing of personalized-dose medicines to be tailored to the individual combining different drugs. The replacement of conventional drug manufacture and distribution could provide patients with personalized polypills fabricated at the point of care, thus reducing cost and enhancing therapy adherence. The FDA approval, in August 2015, of the first 3D printed medicine (Spritam®) proved that 3DP technology works and the race is now on to push forward its development in the pharmaceutical field.

3D printing technologies

In recent years different 3DP technologies have been used to produce these new medicines e.g. stereolithography (SLA) or fused deposition modeling (FDM), which has been the most employed 3DP technology to date, due to it being inexpensive and easy to use.

Printlets, 3D printed tablets

Researchers from FabRx Ltd. and UCL – School of Pharmacy have recently reported in the International Journal of Pharmaceutics the use, for the first time, of selective laser sintering (SLS) to produce personalised 3D printed tablets (Printlets™).

What about selective laser sintering (SLS)?

Selective laser sintering is currently used for industrial manufacturing of plastic, metallic and ceramic objects but, to date, there have been no reports on the use of SLS to fabricate oral drug loaded products.

Schematic representation of the SLS printer (Fabrizio Fina)

SLS uses a laser to bind together the powder particles from a powder bed. During the printing process, the laser is directed to draw a specific pattern onto the surface of the powder bed. Once the first layer is completed, a roller distributes a new layer of powder on top of the previous one. The object is built layer-by-layer, which is then recovered from underneath the powder bed. Advantages of SLS technology include the fact that it is a solvent-free process and offers faster production and resolution compared to other methods.

Is it an industrial process?

In this first study paracetamol (acetaminophen) was selected as a model drug, mixed with pharmaceutical excipients and incorporated in the powder bed of a commercial desktop SLS 3D printer, Sintratec kit. Sintratec printer is the first desktop printer in the market which makes SLS accessible to consumer customers.

Image of a Sintratec kit desktop SLS 3Dprinter

Sintratec SLS technology has enabled printing of personalized-dose printlets of different shapes, with high resolution and no drug degradation. The SLS technology offers a platform technology to formulate and manufacture 3D printed medicines with almost any drug compound in a range of shapes, sizes, colours, textures and flavours to make them more attractive to various patient groups, particularly the young or the elderly, facilitating compliance of the treatment. The manufacturing process allows precision of dose strength and is suitable for both low and high drug concentrations.

Images of printlets containing paracetamol (acetaminophen) prepared by SLS printing

How is the drug release?

Drug release tests from the printlets were performed in a Dynamic Dissolution Model that modulates pH over time, precisely simulating gastro intestinal conditions during transit of the medicines. Proper selection of excipients allows FabRx to design printlets possessing any desired drug release profile, ranging from immediate release to sustained and delayed release.

Drug dissolution profiles from printlets. Red line shows the pH values of the media

The Potential of SLS printing in Pharmacy

The new technology provides the means for producing personalized medicines that can be adapted to individual patients’ requirements. The technology offers a simple, fast method to fabricate personalized drug-loaded, high resolution printlets with any drug compound. SLS appears to be a versatile and practical 3D printing technology which can be applied to the pharmaceutical field, thus widening the armamentarium of 3D printing technologies available for the manufacture of modern medicines.

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