Product Details

ROCURONIUM

Rocuronium (rapid onset-curonium) is a desacetoxy analogue of vecuronium with a more rapid onset of action. It is an aminosteroid non-depolarizing neuromuscular blocker or muscle relaxant used in modern anaesthesia, to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation. Introduced in 1994, rocuronium has rapid onset, and intermediate duration of action. It is marketed under the trade name of Zemuron in the United States and Esmeron in most other countries. There is considered to be a risk of allergic reaction to the drug in some patients (particularly those with asthma), but a similar incidence of allergic reactions has been observed by using other members of the same drug class (non-depolarizing neuromuscular blocking drugs). The γ-cyclodextrin derivative sugammadex (trade name Bridion) has been recently introduced as a novel agent to reverse the action of rocuronium.

Indication

For inpatients and outpatients as an adjunct to general anesthesia to facilitate both rapid sequence and routine tracheal intubation, and to provide skeletal muscle relaxation during surgery or mechanical ventilation.

Associated Conditions

• Muscle fasciculation caused by succinylcholine

Associated Therapies

• Curarization therapy
• Neuromuscular blocking therapy therapy
• Facilitation of small bowel intubation therapy

Pharmacodynamics

Neuromuscular blocking agents are drugs that cause skeletal muscle relaxation primarily by causing a decreased response to the neurotransmitter acetylcholine (ACh) at the myoneural (neuromuscular) junction of skeletal muscle. At that site, ACh normally produces electrical depolarization of the postjunctional membrane of motor end-plate, which leads to conduction of muscle action potential and subsequently induces skeletal muscle contraction. Neuromuscular agents are classified as depolarizing or nondepolarizing. Rocuronium is a nondepolarizing neuromuscular blocking agent with a rapid to intermediate onset depending on dose and intermediate duration. Rocuronium, like vecuronium is longer acting in infants than in children. However, unlike vecuronium, rocuronium retains the characteristics of an intermediate-acting NMBD in infants.

Mechanism of action

Rocuronium acts by competing for cholinergic receptors at the motor end-plate. This action is antagonized by acetylcholinesterase inhibitors, such as neostigmine and edrophonium. Rocuronium acts by competitively binding to nicotinic cholinergic receptors. The binding of vecuronium decreases the opportunity for acetylcholine to bind to the nicotinic receptor at the postjunctional membrane of the myoneural junction. As a result, depolarization is prevented, calcium ions are not released and muscle contraction does not occur. Evidence also suggests that nondepolarizing agents can affect ACh release. It has been hypothesized that nondepolarzing agents bind to postjunctional ("curare") receptors and may therefore interfere with the sodium and potassium flux, which is responsible for depolarization and repolarization of the membranes involved in muscle contraction.

Absorption

Poorly absorbed from the GI tract.

Volume of distribution

• 0.3 L/kg [3 to <12 mos]
• 0.26 L/kg [1 to <3 yrs]
• 0.21 L/kg [3 to <8 yrs]

Protein binding

Approximately 30% bound to human plasma proteins.

Metabolism

Rocuronium is metabolized to a less active metabolite, 17-desacetyl-rocuronium, and is eliminated primarily by the liver.

• Rocuronium
   
  17-desacetyl-rocuronium

Route of elimination

Studies of distribution, metabolism, and excretion in cats and dogs indicate that rocuronium is eliminated primarily by the liver.

Half life

The rapid distribution half-life is 1-2 minutes and the slower distribution half-life is 14-18 minutes. Renal impairment has no net effect on half-life, however, half-life is almost doubled in patients with impaired liver function.

Toxicity

No cases of significant accidental or intentional overdose have been reported. Overdosage with neuromuscular blocking agents may result in neuromuscular block beyond the time needed for surgery and anesthesia.

SOURCE:DRUGBANK