May 10, 2015 | By Simon

Usually when we think about the medicine, vitamins and supplements that we take in pill and tablet form, one or two common shapes come to mind: in most cases it’s either an elongated oval/spherical form or a simple extruded circle.  

While there are a number of reasons why we’ve come to expect our pills and tablets to come in similar shapes and sizes - particularly due to the manufacturing methods and nature of the drug release - advancements in additive manufacturing have made it possible for scientists to further explore what could possibly be done in this territory.

Using a combination of hot melt extrusion and 3D printing, a group of researchers from the University College London’s School of Pharmacy recently explored the effects of geometry on drug release on tablets that have been 3D printed - with the goal of producing a variety of different shaped tablets which would be difficult to produce using the traditional powder compaction manufacturing method.   

“The future of medicine design and manufacture is likely to move away from mass production of tablets/capsules of limited dose range towards extemporaneous fabrication of unit dosage forms of any dose, personalised to the patient,” wrote the researchers in their report for the International Journal of Pharmaceutics.  

“To face this challenge, the pharmaceutical industry needs to evaluate and embrace novel manufacturing technologies. One technology with such potential is 3D printing (3DP).”

Due to the low cost and relative accessibility of fused deposition modeling (FDM) 3D printers, the team chose to focus their efforts on combining this particular additive manufacturing technology with a manufacturing technique that is commonly used in the pharmaceutical industry - hot melt extrusion (HME).  HME is a commonly used manufacturing technique in the pharmaceutical industry and consists of rotating a screw to pump raw materials at high temperatures through a die to generate a uniformly-shaped product.

To conduct the experiments, a single-screw filament extruder, FilaBot hot melt extruder was used to obtain approximately 4% paracetamol-loaded filaments of polyvinyl alcohol with characteristics that were suitable for use in fused deposition modeling 3D printers.  For their study, the team used a MakerBot Replicator 2 to conduct the experiments with the newly-created filament.  

To create the physical shapes of the new tablet designs, the team used Autodesk’s AutodCAD 2014 and exported the stereolithography (.stl) file into MakerWare v. 2.4.1.  In total, a cube, a pyramid, a cylinder, a sphere and a torus were created.  

"The .stl format encodes only the surface data of the object to be printed and requires the thickness of the surface to be defined in order to print the desired object." wrote the researchers. "The printer settings were as follows: standard resolution with the raft option deactivated and an extrusion temperature of 180C, speed while extruding (90 mm/s), speed while travelling (150 mm/s), number of shells (2) and layer height (0.20 mm). The infill percentage was 100% in order to produce tablets of high density. The selected 3D geometries were cube, pyramid, cylinder, sphere and torus. The sizes of the shapes were varied using the scale function of the software to fabricate tablets of constant surface area (275 mm2), surface area/volume ratio (1:1) or weight (500 mg). In all cases, however, the ratio of the length, width and height of each shape was kept constant."

“Manufacture of such complex and intricate shapes by powder compaction would be extremely challenging and so the study immediately suggests that 3D printing offers a route of manufacture of dosage forms of novel geometries not previously possible,” added the researchers.

After all of the shapes had been printed using the same filament, a series of tests were conducted to determine how quickly the drug was released in relation to the shape of the tablet.  In total, the 3D printed pyramid tablet dissolved the fastest and the cylinder dissolved the slowest.

In their findings, the team determined that the printing process did not affect the stability of the drug and that the drug release from the tablets was not dependent on the surface area of the shape but rather the surface area to volume ratio - which ultimately indicates that the geometric shape does in fact influence the rate of drug release in a 3D printed tablet.  

Aside from potentially changing what the near future of our medicine, vitamins and supplements may look like, the researchers have also proven that these oral doses can be customized per the needs of a patient and be printed in literally any size based on the patient’s needs, too.

Adds the team:

“Fabrication of different shaped objects with 3D printing may modulate drug dissolution profiles and can aid in the rational design of new dosage forms with specific pharmaco- kinetics characteristic or targeted to different sites of the gut.”

 

Posted in 3D Printing Applications

 

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Wendy Yoder (windyonder@me.com) wrote at 2/10/2016 12:43:34 PM:

Hi - I am including a citation for this article & would like to include the authors full name. Is it possible to get it from you? I.e. SImon ??????? Thx windyonder@me.com

Terry wrote at 5/11/2015 12:25:24 AM:

I can't believe this needs to be said but I am not swallowing any pills with pointy corners. It's just ridiculous.



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