What muscle relaxers do hospitals use?

October 7, 2025 •

5 min read

Hospitals employ different types of muscle relaxers, categorized broadly as neuromuscular blocking agents (NMBAs) for procedures and centrally acting agents for spasms. These powerful medications are essential for a range of interventions, from facilitating emergency intubation to ensuring patient immobility during complex surgical operations.

Quick Summary

Hospitals administer potent muscle relaxers, primarily neuromuscular blocking agents (NMBAs), for surgical procedures and critical care. These are divided into depolarizing (like succinylcholine) and nondepolarizing (like rocuronium) types, chosen based on onset, duration, and patient factors. Less powerful agents, such as baclofen, are used for managing muscle spasms.

Key Points

Two Primary Classes: Hospitals use two main classes of injectable muscle relaxers: depolarizing (succinylcholine) for rapid paralysis and nondepolarizing (rocuronium, vecuronium, cisatracurium) for longer procedures.
Emergency Intubation: Succinylcholine is the fastest-acting agent, making it critical for emergency situations requiring quick airway management.
Surgical Procedures: Rocuronium, vecuronium, and cisatracurium are commonly used during surgery for controlled, intermediate-duration muscle relaxation.
Safety First: All powerful hospital muscle relaxers require the patient to be under deep sedation and on a mechanical ventilator, as they cause complete respiratory paralysis.
Tailored Choice: The specific muscle relaxer is chosen based on the procedure's needs, the patient's medical history (e.g., liver/kidney function), and the required duration of muscle paralysis.
Reversal Options: While some agents like rocuronium can be reversed quickly with drugs like sugammadex, others are allowed to wear off naturally.

In a hospital setting, the muscle relaxers used are far more potent and have a different mechanism of action than the oral tablets commonly prescribed for back pain. These powerful medications, known as neuromuscular blocking agents (NMBAs), are administered intravenously to induce complete muscle paralysis for specific clinical purposes. The selection of the agent depends on the clinical context, including the procedure's urgency and duration, and specific patient factors.

The Different Types of Hospital Muscle Relaxers

Hospital muscle relaxants can be broadly divided into two major classes, each with a distinct mechanism of action and clinical role:

Depolarizing Neuromuscular Blockers: These agents, most notably succinylcholine, work by mimicking the neurotransmitter acetylcholine, causing a persistent depolarization of the muscle's endplate. This leads to an initial brief period of muscle contraction (fasciculations) followed by rapid and complete paralysis.
Nondepolarizing Neuromuscular Blockers: This class, which includes rocuronium, vecuronium, and cisatracurium, acts as a competitive antagonist by blocking acetylcholine receptors without causing depolarization. They prevent muscle contraction and are used for maintaining paralysis during longer procedures.

Depolarizing Neuromuscular Blockers: Succinylcholine

Succinylcholine (brand names: Anectine, Quelicin) is the only depolarizing NMBA currently in use. It is prized for its extremely rapid onset of action, typically under 60 seconds, and very short duration, lasting only a few minutes. These properties make it the ideal agent for emergency situations requiring rapid sequence intubation (RSI), where a breathing tube must be placed quickly to secure the airway.

However, succinylcholine is not without significant risks. It can cause a temporary but potentially dangerous increase in potassium levels (hyperkalemia), posing a threat to heart function, especially in pediatric patients or those with pre-existing conditions like burns or major trauma. It is also one of the triggers for malignant hyperthermia in susceptible individuals. For these reasons, its use is carefully restricted to specific emergency situations where its benefits outweigh the risks.

Nondepolarizing Neuromuscular Blockers: Rocuronium, Vecuronium, and Cisatracurium

Nondepolarizing NMBAs are the workhorses of surgical and critical care settings. Rocuronium (Zemuron), vecuronium (Norcuron), and cisatracurium (Nimbex) all have an intermediate duration of action, offering a longer and more controlled period of muscle relaxation. They are commonly used during complex surgeries and to facilitate mechanical ventilation in the Intensive Care Unit (ICU).

Rocuronium: A very fast-acting nondepolarizing NMBA that is often used as an alternative to succinylcholine, particularly when succinylcholine is contraindicated. Its effects can be rapidly reversed with the agent sugammadex, which is a significant advantage in managing the airway.
Vecuronium: A moderately long-acting NMBA with minimal cardiovascular side effects, making it a good choice for patients with heart conditions.
Cisatracurium: Known for its organ-independent elimination via a process called Hofmann elimination, making it particularly safe for patients with kidney or liver disease.

Comparison of Common Hospital Muscle Relaxers


Feature	Succinylcholine (Anectine)	Rocuronium (Zemuron)	Vecuronium (Norcuron)	Cisatracurium (Nimbex)
Classification	Depolarizing NMBA	Nondepolarizing NMBA	Nondepolarizing NMBA	Nondepolarizing NMBA
Onset	Very rapid (~60 seconds)	Rapid (1-2 minutes)	Intermediate (3-5 minutes)	Intermediate (2-4 minutes)
Duration	Very short (5-10 minutes)	Intermediate (30-40 minutes)	Intermediate (25-40 minutes)	Intermediate (45-70 minutes)
Typical Use	Emergency intubation	Emergency/routine intubation, surgery	Surgery, mechanical ventilation	Surgery, mechanical ventilation
Key Risks	Hyperkalemia, malignant hyperthermia	Anaphylaxis	Prolonged paralysis with long-term use	Seizures (rare)
Reversal	Spontaneous breakdown	Sugammadex, neostigmine	Neostigmine	Spontaneous breakdown

How Hospitals Choose the Right Muscle Relaxer

Choosing the correct muscle relaxant is a nuanced process undertaken by anesthesiologists and critical care specialists. Several factors are considered to ensure patient safety and optimize outcomes:

Type of Procedure: For emergency intubation, succinylcholine's rapid onset is critical. For a planned, longer surgical procedure, an intermediate-acting nondepolarizing agent like rocuronium or vecuronium is preferred.
Patient's Health: A patient's liver and kidney function heavily influence the choice. Cisatracurium's unique elimination pathway makes it a top choice for patients with organ dysfunction. For patients at risk for hyperkalemia or malignant hyperthermia, succinylcholine is avoided.
Duration and Control: For continuous paralysis, such as during prolonged mechanical ventilation, a continuous infusion of an NMBA is used, often vecuronium or cisatracurium.
Reversal Agents: The availability and suitability of reversal agents play a role. For instance, rocuronium can be rapidly reversed with sugammadex, offering an additional safety measure.

Side Effects and Safety Considerations

Muscle relaxers used in hospitals are powerful drugs that must be administered and monitored by trained professionals. The most critical safety consideration is the complete paralysis of the respiratory muscles, which requires mechanical ventilation. Common side effects of NMBAs include a potential for allergic reactions, changes in heart rate, and prolonged weakness, especially after long-term use. All NMBAs have a boxed warning concerning respiratory paralysis, and they must never be administered without ensuring the patient is adequately sedated first.

Conclusion

Hospitals rely on a specific class of drugs called neuromuscular blocking agents (NMBAs) to induce muscle paralysis for surgical procedures and critical care. The choice between depolarizing agents like succinylcholine and nondepolarizing agents like rocuronium, vecuronium, or cisatracurium is made carefully based on the clinical needs of the situation, the required duration of effect, and the patient's underlying health. The administration of these potent medications is always accompanied by mechanical ventilation and careful monitoring to ensure patient safety and recovery. For managing non-procedural muscle spasms, hospitals also use centrally acting muscle relaxants like baclofen. The expertise of the medical team is crucial for safe and effective use. For additional information on specific drugs, authoritative resources like the National Institutes of Health provide detailed information. [https://www.ncbi.nlm.nih.gov/books/NBK499984/]

Potential Complications with Hospital Muscle Relaxers

Respiratory Arrest: All NMBAs paralyze the diaphragm and other respiratory muscles, requiring mechanical ventilation for the patient to breathe.
Prolonged Weakness: Long-term use of NMBAs in the ICU can sometimes lead to prolonged muscle weakness, requiring extended recovery and rehabilitation.
Allergic Reactions: Severe, life-threatening allergic reactions (anaphylaxis) are a risk with all neuromuscular blockers.
Malignant Hyperthermia: Succinylcholine is a known trigger for this rare but severe reaction in susceptible individuals.
Cardiovascular Effects: While some NMBAs are designed to be minimally cardioactive, others like succinylcholine can affect heart rate and potassium levels.
Inadequate Sedation: Administering an NMBA without sufficient sedation can lead to a patient being awake and paralyzed, a highly distressing and unethical situation.

Specific Use Cases of Hospital Muscle Relaxers

Surgical Anesthesia: To relax the skeletal muscles of the chest and abdomen to allow for surgical access and manipulation without resistance.
Emergency Intubation: To rapidly paralyze the muscles of the larynx and vocal cords to allow for the quick insertion of a breathing tube.
Critical Care: To facilitate mechanical ventilation and prevent patient-ventilator asynchrony or shivering during therapeutic hypothermia.
Managing Spasticity: For chronic conditions like multiple sclerosis, hospitals may administer centrally acting agents like baclofen orally or intrathecally to manage spasticity.
Elective Procedures: To provide optimal conditions for non-emergency procedures that require muscle relaxation, like certain endoscopic or orthopedic surgeries.

Frequently Asked Questions

Hospital muscle relaxers, known as neuromuscular blocking agents (NMBAs), are powerful, injectable drugs that cause full paralysis for surgical or critical care purposes. In contrast, oral muscle relaxers for back pain or spasms, such as cyclobenzaprine or methocarbamol, act centrally to reduce muscle tone but do not cause full paralysis.

A patient might need a hospital-grade muscle relaxer for several reasons, including to facilitate surgical procedures that require complete muscle stillness, to assist with emergency or routine intubation for a breathing tube, or to aid mechanical ventilation in the Intensive Care Unit (ICU).

Common side effects include prolonged muscle weakness, changes in heart rate and blood pressure, and potential allergic reactions. Since these medications cause respiratory paralysis, the most significant risk is a breathing emergency, which is managed with mechanical ventilation and constant monitoring.

Yes, succinylcholine is still used in hospitals, particularly for emergency intubation, due to its very rapid onset and short duration. However, because of significant risks like hyperkalemia, its use is restricted, and alternatives like rocuronium are often preferred in non-emergency settings.

Sedatives are administered with hospital muscle relaxers to ensure the patient is unconscious. The muscle relaxer causes paralysis but does not affect consciousness or pain perception. Without sedation, the patient would be awake and aware but unable to move or breathe, a deeply traumatic experience that must be avoided.

The choice is based on several factors, including the procedure type, the desired duration of effect, patient age, and any pre-existing health conditions, especially those affecting the kidneys, liver, or heart. The availability of reversal agents also plays a role in the decision-making process.

Yes, nondepolarizing muscle relaxers like rocuronium and vecuronium can be reversed by administering other medications, such as neostigmine or sugammadex. Sugammadex is particularly effective and fast-acting for reversing rocuronium, providing an important safety measure.