Working towards greener manufacturing

Pharmaceutical Technology Europe spoke with Dr. Peter Dunn, Global Green Chemistry Lead at Pfizer, about the pharmaceutical industry's commitment to green manufacturing, some of the key changes that yield significant energy efficiencies and the strategy behind the company's green chemistry programme.
Jun 01, 2010
By Pharmaceutical Technology Editors
Volume 22, Issue 6

How committed is the pharmaceutical industry to green manufacturing?

The pharmaceutical industry has responded actively to the green chemistry challenge. For example, in 2005, the American Chemical Society Green Chemistry Institute (ACS GCI) established a pharmaceutical roundtable — a partnership between pharmaceutical corporations and the Institute dedicated to integrating green chemistry and green engineering into the global pharmaceutical industry. Today, nearly all major pharmaceutical research, development and manufacturing companies have joined this group. Furthermore, over the past 15 years, pharmaceutical companies have been awarded the US Environmental Protection Agency's (US EPA) Presidential Green Chemistry award multiple times. I think that shows a pretty good response to the green chemistry challenge by the industry.

What steps should industry be taking to be green?

There are seven key recommendations that I would make to pharmaceutical companies that seek to reduce the environmental impact of their manufacturing processes:

1. Select solvents carefully: within our industry, 80% of the waste generated is solvent; careful solvent selection and minimisation is vital.

2. Minimise materials used: it is also important to minimise the use of all other materials used in manufacturing wherever possible.

3. Reduce energy consumption: this goes without saying and will be a natural consequence of reducing the use of materials and waste, and improving the efficiency of manufacturing processes.

4. Avoid highly toxic reagents and solvents: significant costs are generally associated with the containment or disposal of highly toxic materials. This is an additional cost that can be avoided with a green solvent or reagent.

5. Select an efficient catalyst: use catalytic rather than stoichiometric reagents and, in particular, wherever possible I would recommend the use biocatalysis as the preferred mode of catalysis, i.e. using nature's own chemical catalysts.

6. Recycle: Companies should aim to design a process that enables a high percentage of solvent to be recycled. The process must of course be cost-effective.

Dr. Peter Dunn
7. Use key performance indicators: At Pfizer, we assess process efficiency by looking at the E-factor, i.e. the kilos of waste per kilo of product; it is a very quick way of getting a good indication of the effectiveness of a process. The E-factor was first proposed by Professor Roger Sheldon and is calculated by dividing the total waste (kg) by the amount of product (kg) produced. The metric is very simple to understand and to use and it highlights the waste produced in the process as opposed to the reaction, thus helping those who try to fulfil one of the twelve principles of green chemistry (see sidebar) to avoid waste production.

When will revalidation be required?

Whether a process change requires revalidation or not depends on the timing of the change; if you're making the process change during phase II or III of clinical testing, then no validation is required. If you're making a major change, such as a change in synthetic route after the product has been filed and approved — what we call a second-generation filing — then you will need to both re-file the chemistry and revalidate.

Going forward, one way that validation can be minimised is if we use design space or Quality by Design (QbD) filings. However, some of the biggest environmental savings come from radical changes, i.e. second-generation filings. These changes are so radical, they are outside of the QbD scope.

In which areas of manufacturing can the pharmaceutical industry make the most significant energy savings?

In small molecule chemistry one must understand that energy use actually has a much smaller CO2 impact than the amount of solvent used. In contrast, in the manufacture of large molecules, such as therapeutic proteins, energy use is much higher and much more critical. Therefore, I personally believe that the biggest opportunity to save energy going forward will be to improve large molecule synthesis. I think this is the single biggest area where energy savings can be made.

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