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How to recycle lightly used drugs

Scientists develop a green process to recover valuable pharmaceuticals during drug development so they don’t go to waste

by Stephen K. Ritter
July 31, 2017 | A version of this story appeared in Volume 95, Issue 31

A schematic diagram with photos of solution vials at each step depicts a process for extracting pure active pharmaceutical ingredients from formulated tablets with steps including dissolution, centrifugation, ultrafiltration, reversse osmosis, crystallization.
Credit: Org. Process Res. Dev.
Bristol-Myers Squibb’s engineered process is designed to recover pure active pharmaceutical ingredients from formulated tablets.

When drugmakers design and test dosage formulations of new medications, they mix hundreds of kilograms of the active pharmaceutical ingredient (API) with excipients such as polymer binders and inorganic salt lubricants to produce tablets. At this point in the drug development pipeline, time is short and supply of the API, which can cost thousands of dollars per kilogram, can become tight.

To avoid losing time and money by synthesizing more drug, a Bristol-Myers Squibb development team has engineered a process to recover kilograms of pristine APIs from unused or off-spec tablets generated during formulation testing (Org. Process Res. Dev. 2017, DOI: 10.1021/acs.oprd.7b00146).

Daniel S. Hsieh and coworkers first crush tablets containing the API, cellulose-based binders, magnesium stearate and silicon dioxide lubricants, and PVA-PEGpolymeric tablet coatings. After dissolving the material in warm water, the researchers separate out polymer and other solids by centrifuge, remove soluble polymers by ultrafiltration, and then remove water by reverse osmosis to concentrate the API. In the final step, they add acetone to precipitate out and recrystallize the API.

This process, guided by theoretical modeling, is adjustable depending on the solubility, density, and other physical properties of the drug and the excipients. Overall, the Bristol-Myers Squibb approach recovers 90% of the API with better than 99% purity, which is sufficient for formulating new tablets and carrying out other studies. Hsieh and his colleagues consider the approach green engineering because it’s economical and minimizes waste generation: No chemical steps are required, water is the separation medium, and mechanical energy rather than heat is the driving force for liquid separations using membranes.


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