Dimethyltubocurarine chloride

A neuromuscular-blocking drug

Dimethyltubocurarine chloride is a neuromuscular-blocking drug that is used in anesthesia to induce muscle relaxation and facilitate endotracheal intubation. It is a derivative of tubocurarine, a naturally occurring alkaloid found in the bark of certain South American plants. Dimethyltubocurarine chloride is classified as a non-depolarizing neuromuscular blocker, meaning it competes with acetylcholine at the neuromuscular junction to prevent muscle contraction.

Chemical Structure

Chemical structure of Dimethyltubocurarine

Dimethyltubocurarine chloride is a quaternary ammonium compound, which contributes to its inability to cross the blood-brain barrier. This property limits its effects to the peripheral nervous system, making it useful in surgical settings where muscle relaxation is required without central nervous system involvement.

Mechanism of Action

Dimethyltubocurarine chloride acts by binding to the nicotinic acetylcholine receptor at the neuromuscular junction. By occupying these receptors, it prevents acetylcholine from binding and triggering muscle contraction. This competitive antagonism results in muscle paralysis, which is reversible with the administration of acetylcholinesterase inhibitors such as neostigmine.

Clinical Use

In clinical practice, dimethyltubocurarine chloride is used primarily during surgical procedures to provide muscle relaxation. It is particularly useful in abdominal surgery, orthopedic surgery, and any procedure requiring mechanical ventilation. The drug is administered intravenously and has a relatively slow onset and long duration of action compared to other neuromuscular blockers.

Side Effects

The use of dimethyltubocurarine chloride can lead to several side effects, including hypotension, bronchospasm, and histamine release. These effects are due to its action on autonomic ganglia and the release of histamine from mast cells. Careful monitoring and management of these side effects are essential during its use.

Pharmacokinetics

Dimethyltubocurarine chloride is not absorbed orally and must be administered parenterally. It is distributed throughout the extracellular fluid and is metabolized in the liver. The drug is excreted primarily through the kidneys, and its elimination can be prolonged in patients with renal impairment.

History

The development of dimethyltubocurarine chloride was inspired by the traditional use of curare as a poison for hunting by indigenous peoples of the Amazon. The isolation and modification of tubocurarine led to the synthesis of dimethyltubocurarine, which was introduced into clinical practice as a safer and more controllable alternative to natural curare.

Related Pages

• Neuromuscular-blocking drug
• Tubocurarine
• Acetylcholine
• Anesthesia
• Endotracheal intubation