When a patient has a cholinergic overdose from excessive dosing of bethanechol (Urecholine), the nurse anticipates administration of which drug as the antidote?

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.

Beta-adrenergic blocking agents (beta blockers) are commonly used for hypertension, arrhythmias, and other cardiovascular disorders. However, non-selective beta blockers can block beta-2 receptors in the lungs, which may lead to bronchoconstriction, especially in patients with a history of asthma or COPD.

Rationale for correct answer:

3. Bronchoconstriction
Non-selective beta blockers can block beta-2 receptors in bronchial smooth muscle, leading to bronchoconstriction. This is particularly dangerous in individuals with underlying reactive airway disease.

Rationale for incorrect answer:

1. Pneumonia
Pneumonia may cause shortness of breath, but it is unrelated to beta-blocker therapy and would typically present with fever, cough, and crackles rather than sudden respiratory distress.

2. Pulmonary embolism
A pulmonary embolism is a possible cause of acute shortness of breath, but it is not a common adverse effect of beta blockers and requires other risk factors for thrombosis.

4. Bronchodilation
Bronchodilation is caused by beta-2 agonists, not beta blockers. Beta blockers would have the opposite effect on the airways.

Take-home points:

• Non-selective beta blockers may induce bronchoconstriction by blocking beta-2 receptors in the lungs.
• Patients with asthma or COPD should be prescribed cardio-selective beta blockers with caution.
• Shortness of breath following beta-blocker initiation requires immediate assessment for potential respiratory complications.