Drug-drug interactions are common in older adults who have psychiatric disorders, according to a new study.
Investigators from Nanjing Medical University in China analyzed medical records for 308 older adults aged 60 years and older hospitalized in a geriatric and clinical psychiatry departments in July and August 2021. More than half (55%) had at least one potential drug-drug interaction (pDDI), they reported.
The researchers found 36 types of avoidable drug interactions. The most frequent undesirable drug combination was lorazepam, a benzodiazepine commonly used to address anxiety and sleep issues, with olanzapine (55.5%), used to treat psychiatric disorders. (Notably, olanzapine is not FDA-approved for use among dementia patients.)
They also found 26 adverse drug reactions linked to these pDDIs. The most common was constipation, experienced by 26% of patients. But the results also showed that four of the common pDDIs were not associated clinically significant, severe adverse reactions. These included coadministrations of olanzapine and lorazepam, quetiapine and potassium chloride, quetiapine and escitalopram, and olanzapine and clonazepam.
Polypharmacy side effects
The study also confirmed the potential for polypharmacy to increase the risk of side effects, the researchers reported. The use of a large number of drugs raised study participants’ odds of gastric distress, dizziness and fainting.
In addition, each additional medical diagnosis and additional drug prescribed was associated with a 9.4% and 10% increase in the number of adverse drug reaction types, respectively.
Mental illness is not uncommon in U.S. nursing homes. In a study using federal data, among more than 1.1 million new nursing home resident admissions in 2005, 2.7% indicated schizophrenia or bipolar disorder, and 27% indicated schizophrenia, bipolar disorder, depression or anxiety.
Polypharmacy also is a common problem among nursing home residents, and about 40% of U.S. adults report taking five or more medications daily. Multiple prescriptions can increase the possibility of potential drug-drug interactions, with results ranging from lowered drug efficacy, unexpected side effects and adverse reactions, according to the Food and Drug Administration.
Full findings were published in BMC Psychiatry.
