Polypharmacy continues to be a major concern in psychiatry. Besides the risk of unintended and untoward pharmacological interactions, it carries the potential to cause prescriber liability and increased healthcare costs. Although polypharmacy has been commonly reported in forensic units, there have been no studies examining potentially serious pharmacological interactions in secure settings.

To identify the prevalence of potential pharmacological interactions through a cross-sectional study of prescribing patterns in a medium secure unit in the UK.

Medications prescribed for all 43 patients on 3 male medium secure wards in London in September 2012 were analyzed for potential pharmacological interactions using the Medscape Drug Database/Interaction checker.

A total of 233 regular and 113 ‘as required (p.r.n)’ medications were prescribed. 98 medications were psychotropic and 248 were physical health related. 284 potential pharmacological interactions were present with an average of 6.6 interactions per patient (1-28), involving 31 of the 43 patients(72.09%). These interactions were categorized into four groups: 1.Contraindicated (4.65% of patients;2 interactions) 2.Serious-Use Alternative(30.23% patients;20 interactions) 3.Significant- Monitor Closely(69.6% patients; 232 interactions) and 4.Minor(39.53% patients;30 interactions). Interestingly, 65% of contraindicated/serious interactions involved non-psychotropic medication.

The findings highlight the high prevalence of potential pharmacological interactions in the forensic population. The challenging presentations in forensic psychiatry often necessitate ‘p.r.n. prescribing’ and medication augmentation to treat partial response. However, this can lead to unpredictable and dangerous interactions. Clinicians should be mindful of the pharmacodynamic and pharmacokinetic implications prior to prescribing psychotropic and non-psychotropic drugs.