Each of the prescribing errors is down to mistakes or misjudgements by hospital staff due to tiredness or complete ignorance of the drug and its correct dosage.

A research team from the University of London spent several months at a teaching hospital where pharmacists identified 88 prescribing errors that were potentially serious. One junior doctor alone was responsible for 50 of the errors. In all, 46 doctors - including senior and junior house officers, consultants, specialist registrars and a medical student - were responsible for one or more of the mistakes.

In interviews afterwards, the doctors admitted that the most common reason for the errors was because of a lapse in concentration, usually be-cause they were too busy or were interrupted while writing the prescription. Simple miscalculations of dosage were common, or occurred because the doctor was uncertain what the correct dose should be.

In 31 cases, a heavy workload was blamed for the mistake and, in 13 cases, the physical environment - such as noise - was cited; 15 cases were the result of low staffing levels.

Others confessed to an alarming ignorance of drug side-effects, and seemed to be totally unaware of what to do if something went wrong. In one case, a doctor admitted that he didn’t know that a drug was linked to kidney failure, or how to judge the level of kidney impairment in a patient, or even that he needed to reduce the dose of the drug if kidney failure happened.

The Department of Health is committed to reducing the level of prescribing errors by 40 per cent within three years. Judging things from this research, they have some way to go to meet this target (Lancet, 2002; 359: 1373-8).