Risperidone (RIS) is an atypical antipsychotic drug. It is commonly prescribed for patients with delirium. The active metabolites of RIS are mainly excreted by the kidneys; so, in patients with impaired renal function, sedation, which is one of the drug side-effects, may be delayed. Falls are an important problem that not only significantly impair patients’ activities of daily living and quality of life, but also prolong hospital stay. Previous studies have demonstrated the effects of sleep and antihypertensive medications on falls. However, few studies have investigated the effect of antipsychotic medications on falls. In this study, we aimed to assess the risk factors of falls in patients who regularly used RIS to improve delirium symptoms.

We compared the backgrounds, diseases, and concomitant medications that increased the risk of falls between the fall and non-fall groups. The risk factors for falls were extracted using logistic regression analysis.

A total of 197 patients were included in the study. There were 21 and 176 patients in the fall and non-fall groups, respectively. The fall group had a significantly lower estimated glomerular filtration rate (eGFR) (p=0.007) and creatinine clearance (p=0.00294) than the non-fall group. The non-fall group had a significantly higher daily RIS dose than the fall group (p=0.0206). However, there were no significant differences in age, sex, height, weight, body mass index, disease, or concomitant medications that increased the risk of falls. eGFR (odds ratio [OR], 0.974; 95% confidence interval [CI]: 0.954–0.994, p=0.0125) and daily dose of RIS (OR, 0.192; 95% CI: 0.0382–0.964, p=0.045) were significant risk factors for falls.

These results suggest that impaired renal function is a risk factor of falls in patients receiving RIS. In addition, low-dose RIS administration may be associated with an increased risk of falls owing to inadequate improvement in delirium symptoms.

Recently, drug-induced kidney injury (DKI) has been increasing with society’s aging. Therefore, the early detection and severity prevention of DKI by pharmacists is expected. We experienced a case of DKI develop after oral vancomycin (VCM) treatment. The renal function of the 80-year-old man rapidly declined after receiving VCM and intravenous teicoplanin (TEIC) treatment for pneumonia and colitis caused by methicillin-resistant Staphylococcus aureus. VCM-induced acute interstitial nephritis was suspected because the patient’s renal function further declined in spite of the discontinuation of TEIC. The patient’s renal function was improved by steroid therapy and discontinuation of VCM. Regarding the pharmaceutical intervention against DKI suspecting acute interstitial nephritis, it is essential to discontinue the suspected drugs and collaborate with a doctor, such as considering the early introduction of steroid therapy.