The recent spell of unusually hot weather in the United Kingdom poses no significant risk to medicines stored at ambient temperatures, say pharmaceutics experts.
Most medicines are tested to meet the requirements of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use which demand stability in more challenging conditions than seen in the UK.
In general, products that meet the international requirements must remain within their specifications after storage for six months at 40C. Products which have to be stored in a refrigerator are expected to be stable for six months at 25C. More detailed stability testing is only needed if these conditions are not met. Products are also expected to tolerate “short term excursions outside the label storage conditions, such as might occur during shipping.”
One academic expert commented: “There’s nothing to worry about. Most medicines are tested up to 40C. Most dosage forms are formulated for a worldwide market and may sit on airport tarmacs for a few days at up to 50C.”
He added that short-term high temperatures were not a problem for solid dosage forms, provided they were not also exposed to high humidity. But semi-solids, such as ointments, could be expected to soften.
An Association of the British Pharmaceutical Industry spokeswoman said that manufacturers printed storage guidance on medicine labels and everyone should adhere to that guidance. Pharmacists who were concerned about individual products should contact their manufacturers for advice.
Boots The Chemists has hired air-conditioning units for some of its stores that are not air-conditioned. In addition, stores have been told to take appropriate action, including using cool boxes to protect more vulnerable lines.
A Royal Pharmaceutical Society spokesman said that the Society’s guidance to pharmacists was set out in the section on stock in the Code of Ethics and Standards. This says that pharmacists must exercise their knowledge of stability of materials to segregate for disposal any substances that are likely to have deteriorated.
The Royal Pharmaceutical Society issued a press release on 11 August warning members of the public that the summer heat could damage their medicines. People should keep medicines out of direct sunlight and away from heat, light and moisture, it said.
The Society’s science secretary, Dr John Clements, said: “Gelatin capsules can stick together and soften, ointments and creams can change in consistency and become runny, making them less easy to apply, and suppositories can melt.” The Society advised people who were unsure about the condition of their medicines to speak to their pharmacists.