Ipratropium Bromide: Mechanism of action

Summary

This video explains the mechanism of action of hyoscine bromide, an anticholinergic bronchodilator. It works by inhibiting muscarinic type 3 receptors in bronchial smooth muscles, preventing acetylcholine from causing bronchoconstriction. This results in bronchodilation, making it easier to breathe. The video delves into the detailed intracellular cascade triggered by acetylcholine binding to muscarinic receptors, highlighting the role of second messengers and enzymes. Clinical applications of hyoscine bromide in treating asthma and chronic obstructive pulmonary disease (COPD) are also discussed, along with potential side effects like dry mouth and nausea.

Takeaways

• 😀 Hypertropium Bromide is an anticholinergic bronchodilator that inhibits acetylcholine binding to muscarinic receptors, leading to bronchodilation.
• 😀 Cholinergic receptors, which are activated by acetylcholine, are part of the parasympathetic nervous system and are found in various cells throughout the body.
• 😀 There are two main types of cholinergic receptors: nicotinic and muscarinic, with Hypertropium Bromide specifically targeting muscarinic type 3 receptors.
• 😀 Muscarinic type 3 receptors are located on bronchial smooth muscle cells and when activated, cause bronchoconstriction via an intracellular calcium increase.
• 😀 Hypertropium Bromide acts as a competitive inhibitor to acetylcholine, blocking the activation of muscarinic type 3 receptors and promoting muscle relaxation.
• 😀 The intracellular cascade triggered by acetylcholine binding to muscarinic type 3 receptors involves a series of reactions leading to calcium release and smooth muscle contraction.
• 😀 The binding of Hypertropium Bromide prevents the activation of G proteins and the subsequent cascade that causes smooth muscle contraction.
• 😀 Hypertropium Bromide is used clinically in respiratory medicine to treat conditions like asthma and chronic obstructive pulmonary disease (COPD).
• 😀 Adverse effects of Hypertropium Bromide include nausea, dry mouth, tachycardia, chest tightness, and coughing.
• 😀 Hypertropium Bromide should be used cautiously in patients with closed angle glaucoma due to the risk of increased intraocular pressure.

Q & A

What type of drug is hyoscyamine bromide and how does it work?

Hyoscyamine bromide is an anticholinergic bronchodilator. It works by binding to muscarinic receptors, specifically the muscarinic type 3 receptors located on bronchial smooth muscle, inhibiting acetylcholine binding and leading to bronchodilation.

What are cholinergic receptors, and why are they important in this context?

Cholinergic receptors are receptors activated by acetylcholine, a neurotransmitter. They are part of the parasympathetic nervous system and are crucial in regulating various physiological processes, including bronchoconstriction. Hyoscyamine bromide targets these receptors to prevent bronchoconstriction.

What are the two types of cholinergic receptors?

The two types of cholinergic receptors are nicotinic and muscarinic. Nicotinic receptors respond to both acetylcholine and nicotine, while muscarinic receptors respond to acetylcholine and muscarine.

Why does hyoscyamine bromide specifically target muscarinic type 3 receptors?

Hyoscyamine bromide targets muscarinic type 3 receptors because they are present in bronchial smooth muscle, which is involved in regulating airway constriction and dilation. By inhibiting these receptors, hyoscyamine bromide prevents bronchoconstriction.

What is the intracellular effect when acetylcholine binds to the muscarinic type 3 receptor?

When acetylcholine binds to the muscarinic type 3 receptor, it causes a conformational change in the receptor, leading to the activation of G proteins. This triggers a cascade that increases intracellular calcium, which in turn causes bronchoconstriction by facilitating actin and myosin cross-bridge formation.

How does hyoscyamine bromide affect the intracellular cascade triggered by acetylcholine?

Hyoscyamine bromide acts as a competitive inhibitor, binding to the muscarinic type 3 receptors and preventing acetylcholine from binding. This inhibition disrupts the intracellular cascade, leading to smooth muscle relaxation and bronchodilation.

What are the roles of IP3 and DAG in the intracellular cascade?

IP3 (inositol trisphosphate) and DAG (diacylglycerol) are second messengers produced from the breakdown of PIP2 by phospholipase C. IP3 triggers the release of calcium ions from the sarcoplasmic reticulum, while DAG activates protein kinase C, both of which contribute to smooth muscle contraction.

What clinical conditions is hyoscyamine bromide used to treat?

Hyoscyamine bromide is used to treat conditions involving reversible airway obstruction, such as asthma and chronic obstructive pulmonary disease (COPD) exacerbations. It is often used alongside other medications like salbutamol.

What are some potential side effects of hyoscyamine bromide?

Some potential side effects of hyoscyamine bromide include nausea, dry mouth, tachycardia, chest tightness, and a cough.

Why should hyoscyamine bromide be used cautiously in patients with closed-angle glaucoma?

Hyoscyamine bromide should be used cautiously in patients with closed-angle glaucoma because it can increase intraocular pressure, potentially exacerbating the condition.