The patient in the scenario who has recently been prescribed a beta-adrenergic blocking agent now presents to the emergency department with shortness of breath. Which adverse effect from the medications is the patient likely exhibiting?

Tacrine (Cognex) is a cholinesterase inhibitor used in the treatment of Alzheimer’s disease. It increases acetylcholine levels in the brain to enhance memory and cognition. However, excessive cholinergic stimulation from overdose can lead to signs of cholinergic toxicity, which nurses and caregivers must closely monitor.

Rationale for correct answer:

1. Excessive sweating, salivation, and drooling
These are hallmark signs of cholinergic toxicity. Tacrine increases parasympathetic activity, and an overdose may lead to excessive secretions, bradycardia, muscle weakness, and in severe cases, respiratory compromise.

Rationale for incorrect answer:

2. Extreme constipation
Constipation is more typical of anticholinergic toxicity, not cholinergic excess. Tacrine enhances cholinergic activity, which usually increases GI motility rather than slowing it down.

3. Hypertension and tachycardia
These are signs more often associated with sympathetic nervous system overactivity, not with cholinergic overstimulation caused by drugs like tacrine.

4. Excessively dry eyes and reddened sclera
Dry eyes are an anticholinergic effect. Tacrine, being a cholinergic agent, would more likely cause increased lacrimation (tear production), not dryness.

Take-home points:

• Tacrine overdose manifests with signs of cholinergic excess, including sweating, salivation, drooling, and bradycardia.
• Cholinergic drugs increase parasympathetic activity; caregivers should know the early signs of overdose to act promptly.
• Differentiating between cholinergic and anticholinergic effects is essential for safe medication management in Alzheimer’s care.

Anticholinergic effects of certain medications, including some antihistamines, can impact the parasympathetic nervous system. This can lead to reduced smooth muscle activity, especially in organs like the bladder. Nurses must be able to explain these effects clearly to help clients understand and manage their symptoms.

Rationale for correct answer:

4. “Your medication is causing your bladder to relax because it is inhibiting the cholinergic receptors, therefore the bladder is slower to contract to expel the urine.”
This explanation is accurate and appropriate. Anticholinergic activity reduces detrusor muscle contraction, which delays urine expulsion and may lead to urinary retention.

Rationale for incorrect answer:

1. “Antihistamines are used to treat allergy symptoms, and do not affect the bladder.”
This response is inaccurate. Many antihistamines with anticholinergic effects can impair bladder contraction, especially in older adults or males with prostatic hypertrophy.

2. “This medication you are taking has the effect of causing dry mouth and sedation, but I never heard of it causing urinary retention.”
Minimizing or being unaware of a known side effect such as urinary retention reflects a lack of pharmacologic understanding and could delay proper client education or treatment.

3. “I am sure your symptoms will get better if you wait a few weeks and let your body adjust to the medication.”
Telling the client to wait without addressing a potentially serious side effect may risk complications like urinary retention and bladder distention.

Take-home points:

• Anticholinergic drugs can cause urinary retention by reducing bladder muscle contractility.
• Nurses should assess for and educate clients about common anticholinergic side effects such as dry mouth, constipation, and urinary retention.
• Client concerns about side effects should be addressed with clear explanations based on the drug’s mechanism of action.