Anticholinergic and psychotropic medications are well known for their potential to cause or worsen delirium, especially in older adults or those with pre-existing cognitive impairments. The anticholinergic effect is due to the blockade of acetylcholine, a neurotransmitter important for memory and cognition, while psychotropic drugs can affect various neurotransmitter systems in the brain.
- Common Anticholinergic Drugs Known to Cause Delirium:
- Antihistamines: Especially older, first-generation antihistamines like diphenhydramine (Benadryl) and promethazine (Phenergan).
- Tricyclic Antidepressants: Such as amitriptyline, nortriptyline, imipramine, and doxepin.
- Antipsychotics: Older antipsychotics (like chlorpromazine, thioridazine) and some newer ones have anticholinergic properties.
- Antimuscarinics for Overactive Bladder: Such as oxybutynin and tolterodine.
- Antiparkinsonian Drugs: Including drugs like benztropine and trihexyphenidyl.
- GI Antispasmodics: Such as hyoscine
- Common Psychotropic Drugs Known to Cause Delirium:
- Benzodiazepines: Especially those with longer half-lives, like diazepam (Valium), can cause or exacerbate delirium.
- Non-benzodiazepine Hypnotics: Such as zolpidem (Ambien), which is used for sleep but can contribute to delirium.
- Antipsychotics: Besides their anticholinergic effects, drugs like haloperidol, risperidone, and quetiapine can cause delirium, particularly in high doses or rapid escalation.
- Mood Stabilizers: Like lithium, which requires careful monitoring of blood levels to avoid toxicity.
- Opioids: Especially in high doses or in individuals with sensitivity to these medications. Examples include morphine, hydrocodone, and oxycodone.
- Selective Serotonin Reuptake Inhibitors (SSRIs): While generally safer, they can still contribute to delirium in certain cases, particularly in the elderly or those with other risk factors.
- Important Considerations:
- Polypharmacy: The use of multiple medications increases the risk of delirium, especially when combinations include drugs with anticholinergic and sedative properties.
- Individual Susceptibility: Elderly patients and those with prior cognitive impairment or kidney or liver dysfunction are at higher risk.
- Dose and Duration: Higher doses and longer durations of use increase the risk.
It’s crucial for healthcare providers to regularly review the medication lists of their patients, especially older adults, to identify drugs that might contribute to delirium. In many cases, safer alternatives can be used, or dosages can be adjusted to minimize risk. Additionally, non-pharmacological approaches should always be considered first for managing conditions like insomnia, anxiety, and mild agitation, particularly in the elderly.