Keeping the bugs out of drugs

The worst contaminants in a sterile environment are the workers. In fact, according to Fluor Daniel's Ian Dacey, speaking at a recent conference on Sterile Manufacturing of Active Pharmaceutical Ingredients organised by the international society for pharmaceutical engineering (ISPE) and the Institution of Chemical Engineers (IChemE) – pharma subject group, 'Humans are less of a person, more of a habitat!'

There are, on average, 10¹⁴ bugs on a person, while only 10¹³ cells make them up. Bugs exist in every possible environment, he said, are able to adapt to high and low temperatures, acid or alkaline conditions and can multiply at a great rate.

Sterilisation is the process used to control these bugs – sterile being defined as 'free from viable micro-organisms' – and the main industrial sterilisation methodologies were highlighted by John Woolston, from Isotron. Irradiation, heat and ethylene oxide-based methods can be used, but 'while moist and dry heat are frequently employed within the pharmaceutical industry, gamma and electron beam irradiation and ethylene oxide are less well understood and hence less used', he said. He also outlined the range of standards that will shortly be introduced to provide requirements for the validation and routine control of sterilising technologies.

'The processing of sterile APIs brings with it some unique manufacturing challenges', AstraZeneca's Phillip Richardson said. 'The manufacture of APIs sits on the boundary between bulk and secondary production. The ISPE guidelines for sterile manufacturing facilities are geared towards secondary manufacture, but a number of the principles can be justifiably applied to sterile API manufacture.' Richardson spoke about designing a sterile system according to the process needed and the final product, and came to the conclusion: 'Don't do it unless you really have to! And, if you really have to, determine exactly what's being transferred, where to and how, and integrate the materials flow and area cleanliness using classification diagrams.'

The design of a facility as a whole, rather than just the sterilising unit, was discussed by Richard Linnell, a consultant architect for Kvaerner. He said that the issues involved in developing a viable concept design included the expansion of the client brief and had to ensure GMP compliance. The aim is to gather data, agree the principles by understanding the process – 'the basis of design' – define all the inputs and outputs, and identify gaps and 'difficult' areas. It is then necessary to find the solutions – or options. He said: 'A solid concept design with good communications leads to a cost-effective facility which meets clients expectations with minimum change required and completion on time.'