Australia. Amnesia or memory impairment in association with drug therapy is a rare occurrence. The Adverse Drug Reactions Advisory Committee has received only 210 reports of this adverse reaction in the past 10 years.

There are some drugs such as the benzodiazepines which are established as a cause of amnesia and would not normally be the subject of a report because the association is well known. The drugs most commonly reported to the ADRAC in the past 10 years are listed in the table below.

*The drug with the highest proportion of reports (7:3.4%), dexfenfluramine, has recently been withdrawn.

Of the 219 reports of drug-induced amnesia analysed, there was a single drug suspected in the majority (84%) of the reports. Ages of the patients ranged from 5 to 98 years (median 48) and the onset of the reaction varied from the day drug therapy was commenced (over 25%) to many years afterwards, with most occurring during the first week of therapy. The reaction occurred on rechallenge in 16 of the patients and most of the patients had recovered at the time the report was submitted.

Reference: Australian Adverse Drug Reactions Bulletin 17(3): 11 (1998).