**Question:** All of the following side effects are seen with Ipratropium bromide except -

A. Dry mouth
B. Dizziness
C. Sedation
D. Increased heart rate

**Correct Answer:** D. Increased heart rate

**Core Concept:** Ipratropium bromide is a muscarinic acetylcholine receptor antagonist commonly used in the treatment of chronic obstructive pulmonary disease (COPD). It works by blocking the action of acetylcholine at muscarinic receptors, leading to relaxation of bronchial smooth muscles and improvement in airflow.

**Why the Correct Answer is Right:** Ipratropium bromide primarily targets and acts on parasympathetic muscarinic receptors (M3 subtype) in the bronchial smooth muscles, leading to bronchodilation. However, it does not affect the sympathetic stimulation of the heart, which results in a relatively selective effect on the airways without the significant impact on the heart rate.

**Why Each Wrong Option is Incorrect:**

A. Dry mouth: Ipratropium bromide does not selectively affect the salivary glands, which are primarily controlled by parasympathetic cholinergic stimulation. Thus, dry mouth is a side effect but typically less severe than others.

B. Dizziness: Dizziness is a side effect due to indirect effects on the cardiovascular system and autonomic nervous system. Ipratropium bromide does not specifically target these systems, so dizziness is a side effect.

C. Sedation: Ipratropium bromide does not cause sedation directly due to its action on the respiratory system. However, sedation can occur as a result of respiratory depression or hypoxia, leading to fatigue or tiredness.

**Clinical Pearl:**

Avoiding sedation and increased heart rate is crucial when prescribing Ipratropium bromide, especially in patients with pre-existing cardiovascular disorders or those on concomitant medications affecting the cardiovascular system. Regular monitoring of vital signs and patient response is advised to minimize the risk of these side effects.