A Future of Printing Powders?

In a recent review of FDA drug approvals for 2015, I noted an upswing in the number of ‘never-before-sold’ therapeutic ingredients – a total of 45; a 19-year high that highlights the shift towards ‘speciality medicines’ (1). With many ‘blockbusters’ now commoditized within the generic sector, there seems to be greater focus on innovating medicines that, although only relevant for a small percentage of the population, would have a major impact on hard-to-treat diseases. Within this context, 3D printing (also known as additive manufacturing) is a technique with much commercial potential in the drug development industry, as clearly demonstrated by the first FDA approval of a 3D printed drug in 2015 (Aprecia’s SPRITAM).

The hardware for 3D printing has advanced at an impressive rate in recent years and is now delivering commercial benefits across a number of industries. Printing prototypes to advance the design of a new product has become commonplace and 3D printers are already producing spare parts for everything from pumps to people (2). These applications showcase a key strength of the technology; its suitability for producing one-offs or small runs with unique properties. It can also be used to create very unique oral solid dosage forms.

Aprecia’s new drug similarly exploits these capabilities and was discussed in a recent issue of The Medicine Maker (3). SPRITAM is based on the company’s Zipdose Technology platform, which uses 3D printing to produce a rapidly disintegrating, highly porous oral solid dosage form capable of delivering high drug loadings. The new product is for the treatment of epilepsy and enables seizure sufferers to access drugs without using conventional, hard-to-swallow tablets. Its introduction demonstrates how 3D printing may establish a place alongside other techniques for advanced, precisely controlled drug delivery that is closely tailored to the treatment requirements for a specific disease or of a particular patient group.

Although conventional tableting processes have been refined for more than a century now, some would argue that there is still room for improvement, with continuous manufacturing representing some of the current focus. Learning how best to characterize a tablet blend supports manufacturers’ efforts to access new levels of production performance, and those exploiting 3D printing are experiencing an analogous need. The processing environment in a 3D printer is, of course, quite different from that of the tablet press, so expecting interchangeability in the associated formulations is unrealistic. Those wanting to work at the forefront of 3D printing will need to pay close attention to characterization – they will need to delve deep into their powders to identify the properties that are predictive of printed tablet critical quality attributes. In this regard, flowability has already been established as a crucial parameter because the efficiency of 3D printing is so dependent on continuous, highly-controlled powder flow and dispersion across the printing platform. In my view, dynamic test methods are the best way forward because they allow measurement of aspects such as a powder’s resistance to flow whilst it is in motion and can be used to better predict a powder’s behavior when subjected to processing (4).

The establishment of 3D printing as a pharmaceutical processing technique will call on characterization techniques that not only predict the success or otherwise of a feed, but also quantify the impact of variability on both manufacture and the end product. Understanding how a change in raw materials will affect the printing process and the properties of the finished drug is vital for the application of Quality by Design for the development of a robust submission and, more crucially, for safe manufacture.

It’s clear that formulating optimized blends for 3D printing is a skill that is very much in its infancy. Advancing understanding in this area is essential if we are to fully exploit its potential in future manufacturing practice.