Medicines risk

Medicines risk

The characteristics of medicines expose people taking those medicines to the risk of adverse drug reactions. There are a number of terms which are used to describe adverse drug reactions and these have been defined by the World Health Organization:

An adverse drug reaction (ADR) is a response to a medicine which is noxious and unintended, and which occurs at doses normally used in man.

Adverse drug reactions are associated with the way the individual patient responds to the medicine. The patient may exhibit an unexpected or exagger-ated response to the medicine which is unpleasant for the patient. Adverse drug reactions may be side-effects. A side-effect is ‘any unintended effect of a pharmaceutical product occurring at doses normally used by a patient which is related to the pharmacological properties of the drug’. For example, a patient might experience an unexpectedly large reduction in blood pressure following administration of a licensed dose of an antihypertensive medicine. Such a reaction is related to the pharmacology of the drug.

Sometimes adverse drug reactions are not related to the pharmacology of the drug and are unpredictable. These unexpected adverse reactions are less common than side-effects but have the potential to be more serious. An unexpected adverse reaction is ‘an adverse reaction, the nature or severity of which is not consistent with domestic labelling or market authorisation, or expected from characteristics of the drug’. Serious adverse events are those events with the potential for permanent patient harm, including death. A serious adverse event is any event that falls into one of the following categories:

·      is fatal

·      is life-threatening

·      is permanently/significantly disabling

·      requires or prolongs hospitalisation

·      causes a congenital anomaly

·      requires intervention to prevent permanent impairment or damage.