Ganglion blockers
As of January 2022, when I last updated my understanding, there isn’t a particular class of medications known as “ganglion blockers.” I can, however, provide you details on ganglionic blockers and their background.
Drugs known as “ganglionic blockers” affect autonomic ganglia, which are collections of nerve cells that are not part of the central nervous system. The autonomic nervous system is in charge of controlling involuntary body processes including digestion, blood pressure, and heart rate. The communication between pre- and post-ganglionic neurons in the autonomic ganglia is disrupted by ganglionic blockers.
Ganglionic blockers have historically been used to treat hypertension, or high blood pressure. They function by obstructing the sympathetic nervous system’s ability to transmit signals to the parasympathetic nervous system, which can expand blood vessels and lower blood pressure. But once more focused and secure antihypertensive treatments were available, these ones frequently had serious side effects and lost popularity.
It’s important to remember that since my previous update, new medications or advancements may have been made, and medical knowledge may have changed. It is advised that you speak with a healthcare provider or reference more recent, reliable sources if you have questions concerning a particular medicine or class of medications.
Ganglion blockers classification
The mode of action and selectivity of ganglion blockers determine their classification. The autonomic ganglia, which are groups of nerve cells outside the central nervous system, are the primary target of these medications. The communication between pre- and post-ganglionic neurons in the autonomic ganglia is disrupted by ganglion blockers. Two major categories of ganglion blockers are as follows:
1.Nicotinic Receptor Antagonists:
Nicotinic receptor antagonists are drugs that block nicotinic acetylcholine receptors (nAChRs). These receptors are found in both the central nervous system (CNS) and the peripheral nervous system (PNS), and they play a crucial role in transmitting signals between nerve cells. Nicotinic receptors are classified as ionotropic receptors because their activation leads to the opening of ion channels.
In the context of ganglionic blockers, nicotinic receptor antagonists are primarily used to block autonomic ganglia, which are part of the peripheral nervous system. There are two main types of nicotinic receptors: neuronal nicotinic receptors (nAChRs) and muscle nicotinic receptors. Ganglionic blockers act on neuronal nicotinic receptors in autonomic ganglia.
Here are a couple of examples of drugs that act as nicotinic receptor antagonists in the context of ganglionic blockade:
Hexamethonium:
- Hexamethonium was historically used as a ganglionic blocker for the treatment of hypertension. It acts as a nicotinic receptor antagonist, blocking the transmission of signals in autonomic ganglia. However, its use has declined due to side effects and the availability of more selective antihypertensive medications.
Mecamylamine:
- Mecamylamine is another example of a ganglionic blocker that acts as a nicotinic receptor antagonist. Like hexamethonium, mecamylamine has been used in the past for the treatment of hypertension, but its use has decreased over time.
These drugs are non-selective and can block both sympathetic and parasympathetic ganglia, leading to a broad inhibition of autonomic function. Due to their non-specific actions and side effects, they are no longer commonly used in clinical practice for the treatment of hypertension. More targeted and selective medications have largely replaced them.
2.Non-Depolarizing Ganglionic Blockers:
Non-depolarizing ganglionic blockers are not a commonly recognized class of drugs. The term “non-depolarizing” is typically associated with neuromuscular blocking agents (NMBAs), not ganglionic blockers.
The correct classification for ganglionic blockers involves the distinction between ganglionic blockers and nicotinic receptor antagonists. Let me clarify:
Ganglionic Blockers:
- These drugs block nicotinic acetylcholine receptors in both sympathetic and parasympathetic ganglia, leading to a generalized block of autonomic function. Examples include hexamethonium and mecamylamine.
Nicotinic Receptor Antagonists:
- This category includes both depolarizing and non-depolarizing agents.
- Depolarizing Agents: Examples include nicotine, which causes persistent depolarization.
- Non-Depolarizing Agents: While non-depolarizing agents are more commonly associated with neuromuscular blockers (used to induce muscle paralysis in surgeries), they are not typically referred to as ganglionic blockers.
- This category includes both depolarizing and non-depolarizing agents.