In the last decade, the top pharma players have ramped up their efforts to improve their environmental footprint. Sustainability enhancement efforts in the pharmaceutical industry have primarily been targeted at API synthesis, given its well-known high energy intensiveness 1 and far less attention has been given to the formulation steps that come after. As the demand for more sustainable medicines rises, more sustainable pharma manufacturing practices are being highly sought after.
Technical Challenge
High or low dose APIs are often challenged with flowability and processability issues. API(s) and excipients will therefore typically undergo a multistep process that begins with the dry mixing, followed by high shear or wet granulation (HSG or WG). The granules then undergo a milling or sieving step to improve their size distribution, after which the granules are sent to a drying unit to produce dry granules with good flowability and compactability. Following this, the dry granules undergo a second mixing step in which they are blended with extragranular excipients. Due to the high energy consumption of the multistep process, HSG is known to have a large environmental impact as demonstrated by a few LCA (life cycle assessment) studies.3,4
Efforts to reduce the environmental impact of tablet production have been pursued, with, for example, a batch to continuous transition in the WG step3, and meticulous selection of speciality pharmaceutical excipients.
The LCA result showed that the resource extraction and carbon emissions of API tablet production were reduced by roughly 25% and 16% respectively, upon transitioning to continuous WG.3,4
The environmental impact of API tablet production can also be lowered by using direct compression (DC) in place of HSG where the steps are even less and the drying step is omitted 4. Despite DC’s attractive environmental sustainability profile, less than 20% of APIs can be transformed into tablets by DC because most API particles typically do not possess sufficient flowability for successful tableting.5
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