Aminosteroid

Class of neuromuscular blocking agents

Aminosteroids are a class of neuromuscular-blocking drugs that are used primarily in anesthesia to induce muscle relaxation during surgery. These compounds are characterized by their steroidal structure and the presence of an amino group, which contributes to their pharmacological activity.

Structure and Chemistry

Aminosteroids are derived from the steroid nucleus, which consists of four fused carbon rings. The presence of an amino group in their structure is crucial for their interaction with the nicotinic acetylcholine receptor at the neuromuscular junction. This interaction blocks the action of acetylcholine, leading to muscle relaxation.

Pancuronium, a typical aminosteroid neuromuscular blocker

Mechanism of Action

Aminosteroids act as competitive antagonists at the nicotinic acetylcholine receptors located on the motor end plate of the neuromuscular junction. By binding to these receptors, they prevent acetylcholine from attaching and triggering muscle contraction. This results in a reversible paralysis of the affected muscles, which is useful during surgical procedures to facilitate intubation and ensure muscle relaxation.

Clinical Use

Aminosteroids are commonly used in general anesthesia to provide muscle relaxation. They are particularly useful in procedures that require endotracheal intubation or when muscle relaxation is necessary for surgical exposure. Some of the widely used aminosteroid neuromuscular blockers include pancuronium, vecuronium, and rocuronium.

Pancuronium

Pancuronium is a long-acting aminosteroid neuromuscular blocker. It is often used in surgeries that require prolonged muscle relaxation. Pancuronium is known for its cardiovascular effects, including an increase in heart rate and blood pressure, which can be beneficial in certain clinical situations.

Vecuronium

Vecuronium is an intermediate-acting aminosteroid that is commonly used due to its minimal cardiovascular side effects. It is often chosen for procedures where rapid recovery of muscle function is desired.

Rocuronium

Rocuronium is a rapid-onset aminosteroid that is frequently used for rapid sequence induction of anesthesia. Its quick onset makes it ideal for emergency situations where rapid intubation is necessary.

Pharmacokinetics

Aminosteroids are typically administered intravenously. They are metabolized in the liver and excreted primarily through the kidneys. The duration of action can vary depending on the specific agent used, with some providing short-term effects and others offering prolonged muscle relaxation.

Side Effects

Common side effects of aminosteroids include prolonged muscle weakness and respiratory depression. These effects are generally reversible with the administration of acetylcholinesterase inhibitors such as neostigmine, which increase the concentration of acetylcholine at the neuromuscular junction, overcoming the blockade.

Related Pages

• Neuromuscular-blocking drug
• Anesthesia
• Acetylcholine
• Nicotinic acetylcholine receptor