There are two more definitions that are important particularly when considering reporting a suspected ADR: serious and severe.

- Serious ADRs are defined as those that prove fatal; are life-threatening; are disabling or incapacitating; result in or prolong hospitalisation; produce congenital abnormalities or are considered medically significant.

- Severe ADR may not be life-threatening or disabling but for the individual patient may be extreme. An example could be a headache, which would not normally be considered serious but may be very severe.

As a prescriber, you must report ALL potential ADRs for new drugs which are being monitored by the MHRA. These are indicated by an inverted black triangle next to the drug's name in the BNF. For example, in the BNF 61 varenicline has an inverted black triangle for the brand Champix ® . Note that these will change depending on the edition of the BNF as they remain only while the MHRA are monitoring the particular drug.

Looking at ADR Reports

To see if a drug you use has had ADRs reported you can use the MHRA website www.medicines.org.uk. The reports are called Download Drug Analysis Prints or DAPs. Following up the varenicline activity example, varenicline shows the following DAP. The earliest report for varenicline was December 2006. From that date to the end of November 2011, there were over 7,000 individual reports containing over 18,000 potential ADRs with 81 deaths. The report does not prove causality and there may have been more than one drug being taken at the time and we do not know the patient’s medical condition.

Which patient groups are most at risk of suffering an adverse drug reaction?

If you can identify which groups of patients are more likely to suffer an ADR then you can begin to prevent them. Age, gender, racial groups and metabolic disorders have all been cited as being important factors in identifying susceptible individuals. Similarly those on more than one medicine or who have co-morbidities are also considered as being at a higher risk of ADRs. Dealing with specific medical groups goes into more detail but briefly the main points are:

• Monitor renal function in the very old and very young, particularly neonates
• Women appear to be more susceptible to adverse drug reactions but the exact reason is not fully understood.
• Pregnancy, conception and breast feeding needs careful consideration.
• Some ethnic groups may be more susceptible to ADRs than others. (McDowell et al, 2006)
• Anyone with existing renal or hepatic dysfunction will handle drugs differently.
• The incidence of drug interactions and ADRs increases with the number of drugs taken.

Which drugs potentially cause more adverse drug reactions?

There are over 900 million prescription items issues in England alone each year. With such a large number of prescription medicines being taken by patients the potential for ADRs is high. Most prescriptions are issued in the community and NSAIDs are the most common drug group for the reporting of ADRs. Red flag drugs are indicated in the student formulary with an inverted red triangle.