Psychotropic drug-induced adverse drug reactions in 462,661 psychiatric inpatients in relation to age: results from a German drug surveillance program from 1993-2016.

Background: Clinical practice suggests that older adults (i.e., ≥ 65 years of age) experience adverse drug reactions (ADRs) more often than younger patients (i.e., < 65 years of age). ADRs such as falls, extrapyramidal symptoms (EPS), metabolic disorders, sedation, and delirium are particularly worrisome and often associated with psychotropic drugs.

Methods: This observational study investigated the risk for psychotropic drug-related ADRs in older (n = 99,099) and younger adults (n = 363,562) in psychiatric inpatients using data from the German pharmacovigilance program "Arzneimittelsicherheit in der Psychiatrie" (AMSP) from 1993-2016. The aim was to assess whether age influenced the risk of specific ADR types and if certain psychotropic drugs posed particular concerns.

Results: The risk for ADRs did not differ between older and younger patients (relative risk 0.98, 95% confidence interval 0.92-1.05). However, older patients had a higher risk for delirium (2.35, 1.85-2.99), hyponatremia (3.74, 2.85-4.90), and orthostatic syncope (2.37, 1.72-3.26), as well as certain types of EPS, e.g., parkinsonism (1.89, 1.45-2.48) and Pisa-/metronome syndrome (3.61, 2.51-5.18). The risk for other ADRs, such as acute dystonia (0.20, 0.10-0.37), akathisia (0.47, 0.29-0.76), liver dysfunction (0.63, 0.48-0.82), weight gain (0.07, 0.04-0.14), sexual dysfunction (0.03, CI 0.00-0.25), and hyperprolactinemia/galactorrhea (0.05, 0.02-0.17) was significantly lower for older patients. Older patients treated with any type of antidepressant drug (1.33, 1.26-1.40)-especially selective serotonin reuptake inhibitors (1.57, 1.26-1.40) and selective serotonin-norepinephrine reuptake inhibitors (2.03, 1.80-2.29)-and lithium (1.74, 1.52-2.00) had a higher ADR risk than younger patients. Second-generation antipsychotic drugs had a lower (0.74, 0.71-0.77) and low-potency first-generation antipsychotic drugs a higher (1.19, 1.07-1.33) ADR risk in older patients. The risk for ADRs involving multiple drugs was higher in older patients (1.28, 1.22-1.34). ADRs in older patients were 6.4 times more likely to result in death.

Conclusions: Clinicians and pharmacists should be aware of the types of ADRs and high-risk drugs across age groups and provide appropriate monitoring. Pharmacovigilance is crucial in psychiatric patients of all ages and should not be neglected, even for drugs generally considered "safe".