Prospective studies of PRN prescription and administration are needed to better understand the reasons underpinning its use and to gain objective data upon its effectiveness or otherwise in this vulnerable patient group.

We have investigated the use of 'as required' (PRN), sedative psychotropic medication in 242 forensic rehabilitation patients at a UK secure psychiatric hospital. In total, 176 (73%) patients were prescribed PRN medication and 90 (37%) received a total of 542 doses in the preceding two weeks. The principle indication for use was agitation. Oral benzodiazepines, particularly Lorazepam, were most commonly prescribed and administered followed by Haloperidol. Although high-dose antipsychotics and polypharmacy due to PRN prescribing were common (11 and 20%, respectively), on only 6% of the days studied did patients actually receive PRN antipsychotic medication. Using univariate analyses, PRN administration was associated with younger age, female gender, emotionally unstable personality disorder, shorter length of stay and detention in medium security. Case note documentation of PRN administration was often absent (44%) or vague. Further research, both quantitative and qualitative, is needed into the precise circumstances under which PRN is administered.

Relatively little research has been conducted into the use of pro re nata (PRN) medication in psychiatry. This article describes the frequency, nature and reasons for the administration of sedative PRN medication among inpatients at a secure psychiatric hospital and audits its documentation against good practice standards. Medication charts and case notes were scrutinised for doses of PRN medication administered in the previous 14 days. A total of 344 patients were studied. Thirty-four percent had received PRN medication in the previous fortnight. Most of the 618 doses (93%) were administered orally and none were described as rapid tranquillisation. There was no evidence of physical monitoring following PRN administration. Case note documentation was patchy, with no mention was made of side effects and in just 40% was the reason for using PRN recorded. In only 31% of instances was the outcome documented. PRN medication was commonly administered but poorly documented. Nursing staff need reminding that good case note documentation is important both clinically and for medicolegal reasons when administering sedative medication to patients.