Mr. Johnson suffers from urinary retention and a hypoactive urinary bladder. Bethanechol, a drug that mimics acetylcholine's autonomic effects, is prescribed to manage his problem. First explain the rationale for prescribing bethanechol, and then predict which of the following adverse effects Mr. Johnson might experience while taking this drug (select all that apply): dizziness, low blood pressure, deficient tear formation, wheezing, increased mucus production in bronchi, deficient salivation, diarrhea, cramping, excessive sweating, undesirable erection of penis.

Verified step by step guidance

1. Bethanechol is a cholinergic agonist, meaning it mimics the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system.
2. The parasympathetic nervous system is responsible for 'rest and digest' functions, including stimulating bladder contraction to promote urination.
3. By activating muscarinic receptors in the bladder, bethanechol helps alleviate urinary retention by enhancing bladder muscle tone and promoting urination.
4. Common adverse effects of cholinergic agonists like bethanechol include increased secretions and smooth muscle contractions, due to enhanced parasympathetic activity.
5. Potential adverse effects Mr. Johnson might experience include dizziness, low blood pressure, wheezing, increased mucus production in bronchi, diarrhea, cramping, excessive sweating, and undesirable erection of the penis.

Key Concepts

Bethanechol and its Mechanism of Action

Bethanechol is a cholinergic agonist that mimics the action of acetylcholine, particularly on muscarinic receptors. It stimulates bladder contraction, which helps alleviate urinary retention by promoting urination. Understanding its mechanism is crucial for recognizing how it addresses Mr. Johnson's hypoactive bladder.

Cholinergic Side Effects

Cholinergic drugs like bethanechol can lead to a range of side effects due to overstimulation of the parasympathetic nervous system. Common adverse effects include increased salivation, sweating, gastrointestinal motility, and bronchial secretions. Recognizing these effects is essential for predicting potential reactions in patients.

Autonomic Nervous System Balance

The autonomic nervous system (ANS) regulates involuntary bodily functions and consists of the sympathetic and parasympathetic divisions. An imbalance, such as excessive parasympathetic activity from cholinergic drugs, can lead to symptoms like low blood pressure and dizziness. Understanding this balance helps in anticipating adverse effects when using drugs like bethanechol.