Medication and pharmacological aspects: effects of high temperatures

Mitigation and take home messages

Review the patient’s medicines:

Ø During hot weather, it is even more important to apply the general principles of using the lowest effective dose for the shortest possible time.

Ø People prescribed a psychotropic medicine are at a particularly high risk because of both the effect of their illness on behaviour and the medicines they take.

It is especially important for people on psychotropics to have the dose reviewed and for them to have an awareness of the risks of heat-related illness and knowledge of the protective measures they can take.

Ø If practical, delay initiating or increasing the dose of a psychotropic medicine until the hot weather is over.

Ø If prescribed a diuretic, consider dose reduction during hot weather if appropriate. An individualized plan for the patient to adjust their diuretic medicine themselves on hot days can be useful.

Ø If on fluid restrictions, consider whether relaxing the restrictions during periods of hot weather is appropriate.

Ø When combinations of medicines, such as a diuretic and ACE inhibitor or ARB, are initiated during hot weather, they may increase the risk of hypovolaemia and dehydration. Consider initiation of the diuretic at a lower dose, if possible.

Ø A review of an older person’s medicines by an accredited pharmacist either in their home, if living independently, or in an aged care facility, if a resident there, may be prudent. Provide counselling about how to stay well and store medicines safely during hot weather.

Take home messages:

1. Medications and hot weather can create risks.

2. Healthcare professionals should be aware of the increasing prevalence of hyperthermia and the possible involvement of drugs.

3. Some classes of medications commonly used by older patients with chronic conditions may predispose these individuals to heat-related complications.

4. These medications can sensitize a patient to heat by disrupting thermoregulatory responses that maintain core body temperature, either by interfering with cognitive processes or by directly disrupting autonomic mechanisms.

5. Thermoregulation may be affected by numerous centrally-acting medications for neuropsychological disorders including antipsychotics, beta blockers, stimulants, and a broad array of medications with anticholinergic properties.

6. Dehydration with or without concurrent electrolyte disturbance may also contribute to thermoregulatory failure, and medications that suppress thirst and disrupt fluid balance such as angiotensin converting enzyme (ACE) inhibitors and diuretics, are commonly used by older patients with chronic conditions.