The recommended maximum storage and transit temperatures for most medications is 25°C and are set by the pharmaceutical manufacturers.
Are healthcare providers following these guidelines? In the July issue of the Journal of the Royal Society of Medicine, Dr Brian Crichton, of Hobs Moat Medical Centre in Solihull, investigates how Britain’s local pharmacies are storing medications during hot weather spells.
Typical storage of medicines
Doctors who run family practices in the UK store medicines either on practice premises or in ‘bags for emergency use on home visits.’ Most drugs are licensed for storage at a temperature up to 25°C because, at higher temperatures, there is a ‘risk that their efficacy will be adversely affected,’ the author says. He argues, ‘The quality of drugs carried by family doctors for emergency use needs to be above suspicion.’ This study investigated the storage conditions of medicines in a suburban primary care setting in England during a heatwave.
Temperatures are ‘too high’
Thermometers were placed on the shelf in the drugs cupboard at the practice location and in typical doctors’ bags. The bags were then placed in the boots of two different coloured cars - one silver and the other dark blue - parked in similar places in the car park. The medicines ‘at every storage site exceeded 25°C’ throughout the entire study, Dr Crichton writes. Medicines on the drug cupboard shelf reached a high temperature of 37°C; in the silver and blue cars, temperatures reached 43°C and 49.5°C respectively.
Storage conditions and efficacy
The author believes these conditions are consistent across the UK. A telephone survey of the ten closest dispensing pharmacies found that not one used air conditioning or temperature logs for drug storage. ‘Do these deviations from the recommended storage temperatures matter in practice?’ Dr Crichton asks. A previous study revealed that some drugs show ‘no significant alterations’ by exposure to high ambient temperatures. Others, however, ‘do seem temperature sensitive.’ Many drugs, including cefalexin, ampicillin and erythromycin have shown a reduction in efficacy when exposed to high temperatures. Aspirin, for example, degrades under increased temperature conditions.
‘A need for more work’
Although this study does not investigate the responses of specific drugs to high temperatures, the author stresses the need for this issue to be further investigated. ‘We must react to the implications of this study to ensure the safety of the medications patients receive in the primary care setting,’ he says. ‘The issue of drug efficacy and stability needs to be studied more closely, before a problem occurs. If pharmacies are air conditioned in other parts of the world, why don’t we set the same standard in the UK?’