Pills from the 3D printer

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Pills come in many shapes and sizes as well as names. They deliver medicine at different rates and for different reasons, depending on the patient's age, illness, or disposition towards swallowing. With 3D printing technology, scientists are finding ways to create pills in complex shapes that will allow drugs to be released more efficiently. How and why is this being considered?

A complex pill shape proposed for study 

What are the many types of pills? Tablets are compressed powders into a disk, sphere, or oblong shape. Caplets are smaller and usually have a smooth coating. Capsules are powder, miniature pellets, or liquid contained inside a hard or soft shell. Chewable tablets are meant to be ground by the teeth and taste good. Some tablets are meant to be broken down on or under the tongue, or by dissolving in water. Some meds are small packets of powder meant to be poured into the mouth, followed by washing down with a liquid. 

Image from fotostock.com

Researchers at the Max Planck Institute for Informatics in Germany are using mathematical modelling to figure out what shape of pill would dissolve the best in the body. Since it optimizes that process and deals with the topology (shape) of pills, the design is called topology optimization.

If you think about it, the idea is very simple. The more surface area that something has to come into contact with water or body fluids, the easier it will be to dissolve. Crystalline shapes like those below give a lot of surface area to the weight of the drug.

Some designs for 3D pills (Max Planck Institut)

Researchers determine what kind of timeline the drug needs in order to be spread throughout the body, how much should be in the blood or tissues, for example, and how long it can remain active, and then they work out mathematical models of the proper shape a pill would have to be in order to dissolve, release, and maintain that amount of active ingredient.

Dr. Vahid Babaei and his colleagues from Max Planck took the mathematical data and programmed a standard 3D printer to build the desired shape. The material they use is a polymer called AquaSys 12O, which dissolves rapidly in tap water. It is sold as an amber-colored filament wrapped around a spool.

AquaSys 12O (Amazon.com)

The AquaSys 12O absorbs light when it is dissolved in water. That means scientists can measure how much of it is in the water by the amount of light that they measure with special devices. They keep the water in the beaker agitating to mix uniformly with a spinning  magnet on the bottom, while a camera records how much light is measured as the pill dissolves. Eventually, the undissolved pill fragment settles on the bottom, and the amount of light stops changing. 

Experimental setup to measure light from dissolving pill shapes (ACM Transactions on Graphics journal, 2022)

How long it takes, and what kind of time pattern is seen are both used to improve on pill shapes. The graphs below show how different shapes release the AquaSys 12O more and more until it finally levels off after some point. The pattern of that release depends on the shape of this fake pill.

Experimental data of dissolving shapes of AquaSys 12O over time 

Now, the body doesn't have a spinning magnet, and the liquids inside the stomach and intestines don't mix as vigorously as in a beaker. If the AquaSys 12O shape is left to dissolve without any turbulent water action, the shape breaks down differently, but it still provides data that researchers can use. Later, when this research reaches the lab animal stage, blood samples can be taken over time to confirm how much of the drug is in the body.

Heart-shaped AquaSys 12O dissolving in undisturbed water (ACM Transactions on Graphics journal, 2022)

All of this is just around the corner. In 2015, the first (and so far only) 3D-printed drug was approved by the US FDA. Spritam is made by Aprecia Pharmaceuticals for epilepsy. Others are undoubtedly on the way. The UK company FabRx was created in 2014 to make such specially designed pills, and it estimated this will be quite common in 5-10 years' time. As of July 2022, three other companies have gotten into the commercialization, so it looks like FabRx was not wrong.

If you're interested in learning more about new technologies to deliver medicine to the human body, here's a cool website with animated images showing 7 new potential methods.

Here are some short videos on the 3D pill printing process, too.

How to 3D print the 'wonder pill'  (6:50)

Developing 3D Printed Drugs for Personalized Medicine with FabRx (1:34)

Customising 3D printed pills as a treatment for patients (2:49)