Henderson,RK, J-G Concepcion, DJC Constable, SR Alston, GGA Inglis,G Fisher, J Sherwood, SP Binks and AD Curzons. 2011. Expanding GSK’s solvent selection guide – embedding sustainability into solvent selection starting at medicinal chemistry. Green Chemistry http://dx.doi.org/10.1039/c0gc00918k.
The large drug company GlaxoSmithKline (GSK) is reducing the use of problematic solvents in drug production in a unique way. They are changing the behavior of medicinal chemists – the researchers who develop new drugs.
An article in the journal Green Chemistry describes the company’s efforts to target the chemists by updating a popular green solvent guide and having the solvents easily available. The researchers’ choice of solvents is usually copied for industrial production of the drug. A change to a less harmful solvent has an enormous impact in creating a cleaner and safer pharmaceutical industry.
Organic chlorinated solvents are used in large quantities to produce pharmaceutical drugs. To produce 1 kilogram (kg) (2.2 pounds) of active drug, an average of 46 kg (100 pounds) of raw materials are used. Of these raw materials, an average 56 percent – or 26 kg (47 pounds) – are solvents.
Historically, medicinal chemists had a single focus: to develop new drug molecules in the shortest time possible. Solvent choice was purely based on familiarity with the chemical’s properties. Time to explore other, cleaner, solvents was not available as it slowed down new developments. The current focus on sustainability and safety is changing this single focus approach.
GSK’s approach is based on a solvent selection guide published in 1998. The guide ranks common solvents based on their environmental, health and safety issues. A 2003 update includes life cycle assessments – the environmental effects from production and disposal.
This latest edition extends the list of solvents to 110 from 47. It also provides more details in the assessments and presents a quick and comprehensive selection reference guide to steer scientists away from the most problematic solvents.
The complete solvent selection guide scores each solvent from 1 to 10 – one is bad, 10 is good – for eight categories. The categories include: waste treatment after use, environmental impact, human exposure and health effects, flammability, stability, life cycle impact from production, legislative limitations on its use and melting and boiling point.
Color coding makes it easier to understand. The combination of all data on one poster allows direct comparison. In addition, an electronic version includes links to documents with further information.
The guide alone was not enough to boost the use of greener solvents, so the company combined it with other methods to promote them. The greener solvents were readily available in the stockroom, the solvent selection guides were posted, and the benefits of less hazardous solvents were highlighted.
Chemists at GSK choose the greener solvent if they were aware of it. For example, the greener solvent 2-methyltetrahydrofuran is replacing other more problematic solvents. It was used in 16 percent of studies in 2007-2009 instead of 3.5 percent in 2005-2006.
The authors conclude that real changes can be made by improving availability of information, guidance and the actual solvents. The solvent selection guide described is a powerful tool. It is publically available, so it can be used by the whole scientific community and competing companies.
Even though reducing overall use of solvents should be the ultimate aim, this approach constitutes an important step in the right direction to a truly sustainable chemical and pharmaceutical industry, according to the study’s researchers.