From Professor K. Sabra
SIR,—I would like to comment on the letter from Professor Allwood and Professor Sewell with regard to seeking independent expertise (PJ, August 21, p278).
I would like to stress my total support for the sentiment of the letter, although I would like to make a couple of comments.
It must be said that a limited number of companies in Europe are manufacturing intravenous solutions for a large number of marketing companies, ie, the same container, same sterilisation process, etc, and the only difference is the name of the company (scale of economy). Under these circumstances, extrapolation of stability data from one product to another can be assumed to be safe.
With regard to the use of different devices for delivery, especially for home care, I think in general the same rules should apply, ie, if the material used for the membrane is the same, then one can safely extrapolate the chemical stability of the drug in such devices. Obviously, microbiological stability cannot be extrapolated, and it should remain specific to each unit. Each unit must validate its own process microbiologically and this should be the criteria for shelf life. I think sometimes there is a mix up between chemical stability and microbiological stability, and both of those must be determined separately.
I agree with my learned colleagues that this issue needs a little more clarification. One of the problems facing different units is obtaining chemical stability from pharmaceutical companies with regard to their products. The companies are restricted by licensing authorities in different countries, and, accordingly, each unit is left to carry out its own stability work, which is neither practical nor economical.
However, I still stress that pharmacists must use their training and their scientific background to determine and clarify the information received from companies or published stability data. It is not practical to get independent evaluation for every product prepared within compounding facilities, especially when the containers are exactly the same and there is no change in the composition of the membranes used.
Obviously, there is a difference between filling such bags or devices for hospital use and filling them for outside hospitals or home health care. By law, in order to supply outside institutions or home patients with reconstituted drugs, units must have a manufacturing licence (specials licence in the UK) and a wholesale licence.
Both the manufacturing and wholesale licence applicants are routinely inspected by government authorities in order to grant both licences. Stability of products and matters to do with shelf life, etc, is one of the major areas that the inspector examines carefully.
Kamal Sabra
Chief Pharmacist, St James's Hospital, Dublin, Ireland