Measurement of anticholinergic effects of psychotropic drugs in humans

Psychotropic drugs are often liable to unwanted anticholinergic effects that reduce tolerance and compliance. Especially, in certain patient groups, such as elderly patients, anticholinergic adverse effects may be hazardous. There are also occasions in therapy when antimuscarinic activity is desired, e. g. in the treatment of neuroleptic-induced extrapyramidal symptoms with biperiden and other potent anticholinergic drugs. In this review, we describe various techniques to evaluate the anticholinergic influences of psychotropic drugs in vivo and also provide examples of previous human studies where these methods have been applied. By combining subjective ratings of anticholinergic effects to in vitro measurements of antimuscarinic activity in blood, as well as the functional state of salivary glands, sweat glands, heart and eye, a researcher can obtain a detailed anticholinergic profile of the drug in question, or a clinician can estimate the anticholinergic burden of his/her psychiatric patient who often uses multiple medications.