#60 - Adverse Effects and Interactions

For our first case, let's imagine a seventy-six-year-old woman who takes oxycodone for chronic pain and recently started taking clonazepam for anxiety.

Her daughter brings her in because she's been unusually sleepy and has fallen down twice recently while walking to the bathroom.

What interaction should you be concerned about here? That's right, the combination of an opioid and a benzodiazepine.

Very good.

Both medications depress the central nervous system, and so combining them can cause excessive sedation, impaired coordination, and potentially life-threatening respiratory depression, and this risk is especially concerning in older adults.

Gabapentin and pregabalin can also add to this risk, particularly when combined with opioids.

Benzodiazepines in particular need a careful discontinuation plan after regular use because abrupt withdrawal of benzodiazepines can cause anxiety, tremor, insomnia, and potentially seizures.

So when we identify a benzodiazepine as contributing to falls or sedation, we need to reduce it safely with an individualized taper.

Next up, let's imagine a seventy-nine-year-old man who takes oxybutynin for urinary urgency and recently started taking an over-the-counter sleep aid containing diphenhydramine.

He now has confusion, blurry vision, a dry mouth, constipation, and difficulty urinating.

What medication effects tie all of these symptoms together? That's right.

These are anticholinergic effects.

Very good.

Anticholinergic medications block muscarinic acetylcholine receptors, which affect several different organs at once.

In the brain, they can cause confusion and delirium.

In the eyes, they interfere with accommodation and can dilate the pupils.

In the GI tract, they slow motility, and in the bladder, they impair contraction and can cause urinary retention.

Common anticholinergic culprits include first-generation antihistamines like diphenhydramine, bladder medications like oxybutynin, and tricyclic antidepressants like amitriptyline.

In severe anticholinergic toxicity, you may also see tachycardia, hot, dry skin, urinary retention, and agitation, and the next step here is to manage symptoms supportively with benzodiazepines used as a first line to manage the acute agitation.

The anticholinesterase inhibitor, physostigmine, should only be used in anticholinergic toxicity for severe symptoms that are refractory to other treatments.

Next up, let's imagine a forty-two-year-old woman who takes sertraline for depression and was prescribed tramadol yesterday for back pain.

Today, she develops agitation, sweating, diarrhea, tremor, and a fever.

On physical exam, her reflexes are brisk, and you notice sustained ankle clonus.

What interaction do you think is responsible here? That's right.

Tramadol combined with an SSRI can cause serotonin syndrome.

For our first case, let's imagine a seventy-six-year-old woman who takes oxycodone for chronic pain and recently started taking clonazepam for anxiety.

Her daughter brings her in because she's been unusually sleepy and has fallen down twice recently while walking to the bathroom.

What interaction should you be concerned about here? That's right, the combination of an opioid and a benzodiazepine.

Very good.

Both medications depress the central nervous system, and so combining them can cause excessive sedation, impaired coordination, and potentially life-threatening respiratory depression, and this risk is especially concerning in older adults.

Gabapentin and pregabalin can also add to this risk, particularly when combined with opioids.

Benzodiazepines in particular need a careful discontinuation plan after regular use because abrupt withdrawal of benzodiazepines can cause anxiety, tremor, insomnia, and potentially seizures.

So when we identify a benzodiazepine as contributing to falls or sedation, we need to reduce it safely with an individualized taper.

Next up, let's imagine a seventy-nine-year-old man who takes oxybutynin for urinary urgency and recently started taking an over-the-counter sleep aid containing diphenhydramine.

He now has confusion, blurry vision, a dry mouth, constipation, and difficulty urinating.

What medication effects tie all of these symptoms together? That's right.

These are anticholinergic effects.

Very good.

Anticholinergic medications block muscarinic acetylcholine receptors, which affect several different organs at once.

In the brain, they can cause confusion and delirium.

In the eyes, they interfere with accommodation and can dilate the pupils.

In the GI tract, they slow motility, and in the bladder, they impair contraction and can cause urinary retention.

Common anticholinergic culprits include first-generation antihistamines like diphenhydramine, bladder medications like oxybutynin, and tricyclic antidepressants like amitriptyline.

In severe anticholinergic toxicity, you may also see tachycardia, hot, dry skin, urinary retention, and agitation, and the next step here is to manage symptoms supportively with benzodiazepines used as a first line to manage the acute agitation.

The anticholinesterase inhibitor, physostigmine, should only be used in anticholinergic toxicity for severe symptoms that are refractory to other treatments.

Next up, let's imagine a forty-two-year-old woman who takes sertraline for depression and was prescribed tramadol yesterday for back pain.

Today, she develops agitation, sweating, diarrhea, tremor, and a fever.

On physical exam, her reflexes are brisk, and you notice sustained ankle clonus.

What interaction do you think is responsible here? That's right.

Tramadol combined with an SSRI can cause serotonin syndrome.