Keep in a cool place: exposure of medicines to high temperatures in general practice during a british heatwave

Keep in a cool place: exposure of medicines to high temperatures in general practice during a British heatwave Exposure of medicines to high temperatures in storage or in transit could reduce their efficacy, and most licences specify storage at 258C or less. To assess whether this criterion was being met, maximum temperatures in a generalpractice drug cupboard and in drug bags placed in car boots were recorded for two weeks during a British heatwave (average peak daily ambient temperature 268C). Also, ten neighbouring dispensing pharmacies werequestioned about their temperature-control policies.
On every day of the study, maximum temperatures in the drug cupboard and in the car boots exceeded 258C.
Mean daily maxima (range) were: drug cupboard 30.7 (27.5–37.0); silver car 37.5 (32.0–43.5); dark blue car 41.8 (35.0–49.5). None of the local dispensaries had air conditioning or kept a temperature log.
In the course of a British summer, medicines were exposed to temperatures that might in theory have reduced their efficacy. This aspect of quality control deserves more attention.
Box 1 Agents commonly carried in doctors’ bags Family doctors in the UK store medicines either on practice premises or in bags for emergency use on home visits.
Manufactured drugs, in general, are licensed for storage at temperatures up to 258C.1 At higher temperatures there is the risk that their efficacy will be adversely affected, and the quality of drugs carried by family doctors for emergency use—for example, benzylpenicillin for suspected bacterial meningitis—needs to be above suspicion. Box 1 lists some of the agents commonly carried in this way. The temperature conditions of medicines were in- vestigated in a suburban primary care setting during an was recorded at 1900 h each day from 4 to 15 August 2003, inclusive—a time of warm weather. Over the same period,the maximum ambient air temperature at the ColeshillWeather Station, 8 km from the practice, was obtained from the national UK meteorological website.
Three mercury maximum/minimum thermometers were On 13 August the ten geographically closest dispensing purchased and checked by comparison of maximum pharmacies were contacted by telephone and were asked: temperatures recorded after 24 hours on the same shelf Does your dispensary have air conditioning? Do you of the practice drugs cupboard. They agreed within 0.58C.
Two of the thermometers were then put in doctors’ bags(Gladstone, burgundy coloured), which in turn were placed in the boots of two cars (A, silver coloured; B, dark blue),which occupied similar positions in the car park. The third Table 1 shows the maximum temperatures for the drugs thermometer was installed on the top shelf (41 cm below cupboard and the boots of the two cars, together with ceiling height) of a locked metal drugs cupboard in the maximum ambient air temperatures during the days of the practice treatment room. The day’s maximum temperature study. On every day, at every drug storage site,temperatures exceeded 258C. The telephone survey Hobs Moat Medical Centre, Ulleries Road, Solihull B92 8ED, UK indicated that none of the ten local pharmacies had air conditioning or monitored dispensary temperatures.
significant reductions in activity at one year.6 Aspirin The journey of a medicine begins at the site of manufacture follows first-order kinetics with regard to temperature and passes through warehouses, pharmacies, and sometimes degradation, and a similar finding was recorded for other environments before reaching the end user.
diclofenac tablets exposed to high ambient temperatures Temperature conditions in the earlier stages have received (dissolution rate was reduced significantly in as little as attention, but little work has been done in primary care three months, with resultant reduction in maximum plasma settings and community pharmacy settings in the UK. A previous study, by Rudland and Jacobs,2 did draw attention There is a duty to ensure that medicines are kept in an to high temperatures in the boots of doctors’ cars. The environment that maintains their efficacy. The manufacturer findings of the present study suggest that temperature will be responsible for shortcomings only if storage has quality control in primary care and community pharmacies occurred as stipulated in the Summary of Product (if ours are typical) leaves much to be desired. Where air Characteristics.8 In almost all cases the specified tempera- conditioning is not standard practice, medicines are at the ture is 258C or less. The effect of temperature is seen in the mercy of the ambient temperature; and conditions in car rate of oxidation or hydrolysis: for every 108C increase in boots are particularly disturbing. The difference between temperature there is generally an exponential increase in the cars was of interest: although the vehicles were not the rate of reaction.9 (Drug stability can also be affected by identical models, the paint colour was probably the relevant low temperatures, especially liquid preparations liable to feature: car B was dark blue, and more likely to absorb heat This research highlights some important areas in In all three environments, drugs were exposed to medicines management. Manufacturers need to offer more temperatures exceeding 258C. Do these deviations from the drug stability data in relation to temperature. Even if the recommended storage temperatures matter in practice? immediate stability of stored medicines is not seriously Looking at one of the drugs commonly carried, adrenaline, affected there may well be an effect on shelf life or expiry Rudland and co-workers found no significant alterations in date. To rectify this, practices and pharmacies may have to activity by high ambient temperatures.3,4 However, some consider arrangements for cooling. As to the carriage of other products do seem temperature sensitive. For medicines by healthcare professionals in their cars, simple example, the capsules of certain brands of cefalexin precautions are to avoid leaving drug bags in the boot or to degraded more rapidly in hot conditions and this caused ‘serious fluctuations’ in absorption.5 The present observations, though made in exceptional Ampicillin, erythromycin, furosemide for injection and weather conditions for the English Midlands, highlight the benzylpenicillin stored in a tropical climate showed need for further work on storage conditions for medicinesin primary care and in community pharmacies.
1 US Pharmacopeia, Vol 26. Rockville, MD: USP, 2000 2 Rudland SV, Jacobs AG. Visiting bags: a labile thermal environment.
3 Rudland SV, Annus T. Adrenaline activity is not significantly altered by high ambient temperatures. Emerg Med 1997;9:109–11 4 Rudland SV, Annus T, Dickinson J, Langdon S. Adrenaline degradation in general practice. Br J Gen Pract 1997;47:827–8 5 Molokhia AM. Effect of storage on the bioavailability of cephalexin from its capsules. Res Commun Chem Pathol Pharmacol 1984;45:219–24 6 Ballereau F, Prazuck T, Schrive I, et al. Stability of essential drugs in the field: results of a study conducted over a two-year period in BurkinaFaso. Am J Trop Med Hyg 1997;57:31–6 7 Risha PG, Vervaet C, Vergote G, Bortel LV, Remon JP. Drug formulations intended for the global market should be tested for stability under tropical climatic conditions. Eur J Clin Pharmacol 8 [http://emc.medicines.org.uk] accessed 21 April 20049 US Pharmacopeia, Vol 28. Rockville, MD: USP, 2002:2232–3

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