Lack of information

Last updated: Wednesday, November 12, 2025

You may be asked to give advice when there is simply no information, or very little information, on which to base your answer. Consider the following situation;

You are on a ward round at a local mental health unit and the consultant asks you about prescribing trihexyphenidyl. The patient is suffering with extrapyramidal side effects because of the antipsychotic medicines that they take. However, the patient has chronic renal failure and receives haemodialysis (HD) three times per week. Does the dose of trihexyphenidyl need to be adjusted?


Have a think about where you might look for the information before reading the next paragraph.



So, you begin to look for information. You check the manufacturer’s SmPC, the Renal Drug Database, Bazire’s Psychotropic Drug Directory, and the Maudsley Prescribing Guidelines in the first instance. But you find no relevant information. You then undertake a Medline, Embase and Google Scholar search for published experience of using trihexyphenidyl in patients on haemodialysis and don’t identify any useful papers.

What should you do now? Take time to think about this before clicking onto the next page to read our thoughts.