We thank Dr. Toda [1] for his interesting question. Dr. Toda asked, in response to our literature review [2], whether psychotropic drugs with longer half-lives are more likely to increase fall risk than psychotropic drugs with shorter half-lives. In our paper [2], we concluded that psychotropic fall-risk-increasing drugs (FRIDs) cause impairments in postural control, which is probably one of the mediating factors for the increased fall risk with which these FRIDs are associated. The effects of psychotropic FRIDs on postural control are more pronounced when people are of higher age, use psychotropics at higher daily dosages, for a longer period of time, and when the half-life of the drug is longer. By the latter, we mean that the effects on postural control of benzodiazepines with intermediate to long half-lives (>8 h) sustain for a longer period of time after taking the drug (the so-called hangover effect).

Regrettably, since we only examined the effects of FRIDs on postural control [2]—not on fall risk—we cannot conclude whether psychotropic drugs with a longer half-life are more likely to increase the risk of falling than psychotropics with a shorter elimination time. However, an interesting study by De Vries et al. [3] has recently been published, examining prospectively whether long-acting benzodiazepines are associated with a higher fall risk than short-acting benzodiazepines. The findings of De Vries et al. [3] are in line with the meta-analysis of Leipzig et al. [4], namely that the use of short-acting benzodiazepines is not associated with a lower fall risk compared with long-acting benzodiazepines. Remarkably, it must be noted that the cut-off defining short and long half-life differs in studies: for instance, we defined short half-life as ≤8 h [2], De Vries et al. [3] defined it as ≤10 h, and Leipzig et al. [4] as ≤24 h.

Thus, it can be stated that both short- and long-acting psychotropics increase the risk of falling in older people, the former not more than the latter. However, we can speculate about the moment and location of fall incidents caused by psychotropic FRIDs. For example, it can be hypothesized that short-acting benzodiazepines (mainly hypnotics) increase the risk of falling during the night, for instance when walking to the toilet because of nocturia (the nightly effects); while long-acting benzodiazepines (mainly anxiolytics) may increase the risk of falling both during the night and daytime because of residual daytime sleepiness (the hangover effect).

Nevertheless, the use of psychotropic FRIDs, both with short and long half-lives, should be discouraged in the older population, and when administered, only at the lowest effective dose and for a limited period of time.