Chemical Structure:
C6H15ClN2O2
Mechanism of Action:
Carbachol is a cholinomimetic drug that binds to and activates both muscarinic and nicotinic acetylcholine receptors.
Structure-Activity Relationship (SAR) of Carbachol:
1.Choline Structure:
Carbachol closely resembles the structure of acetylcholine.
It has a choline structure with an ester linkage to a carbamic acid, instead of acetic acid as in acetylcholine.
2.Ester Linkage:
The ester linkage in carbachol is more resistant to hydrolysis by acetylcholinesterase, making it longer acting than acetylcholine.
3.Nitrogen Atom:
The quaternary ammonium group is essential for activity.
It mimics the positively charged nitrogen found in acetylcholine, which is crucial for binding to the cholinergic receptors.
4.Substituents:
The lack of bulky substituents allows carbachol to interact with both muscarinic and nicotinic receptors, similar to acetylcholine.
Synthesis of Carbachol:
The synthesis of carbachol typically involves the following steps:
1.Formation of Carbamic Acid Ester:
Ethanolamine + Methyl Carbamoyl Chloride → Carbamate Intermediate
2.Quaternization:
Carbamate Intermediate + Methyl Iodide → Carbachol
In the first step, ethanolamine reacts with methyl carbamoyl chloride to form a carbamate intermediate. Then, this intermediate is quaternized with methyl iodide to form Carbachol. This process involves the formation of the carbamic acid ester and the introduction of the quaternary ammonium group, which are critical for the biological activity of Carbachol.
Uses:
It's used in glaucoma (eye drops) to decrease intraocular pressure and in gastrointestinal and urinary tract to stimulate smooth muscle activity.
Side Effects:
Side effects may include blurred vision, eye irritation, sweating, flushing, and abdominal cramps.