Choline esters like carbachol are most likely to cause which of the following adverse effects
**Core Concept**
Choline esters, such as carbachol, are a class of drugs that act as cholinergic agonists. They mimic the action of the neurotransmitter acetylcholine by activating muscarinic and nicotinic receptors in the central and peripheral nervous system. This leads to various physiological effects, including increased parasympathetic tone.
**Why the Correct Answer is Right**
Carbachol and other choline esters stimulate both muscarinic and nicotinic receptors, resulting in increased parasympathetic activity. This leads to a variety of adverse effects, including bradycardia, hypotension, increased salivation, and bronchospasm. The muscarinic receptors are primarily responsible for these effects, as they are found in the heart, smooth muscle, and exocrine glands. The activation of muscarinic receptors in the heart leads to a decrease in heart rate and contractility, resulting in bradycardia and hypotension.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe a common adverse effect of choline esters.
* **Option B:** This option is incorrect because it is not a typical adverse effect of choline esters. While choline esters can cause increased salivation, it is not the most likely adverse effect.
* **Option D:** This option is incorrect because it is not a direct effect of choline esters on the body.
**Clinical Pearl / High-Yield Fact**
Choline esters can cause a condition known as "holinergic crisis," which is characterized by excessive muscarinic receptor activation leading to severe bradycardia, hypotension, and respiratory failure. This is a life-threatening condition that requires immediate medical attention.
**Correct Answer: C. Bradycardia**