SN2 SHORT NOTE 5M ★ High-yield

Write a short note on Dantrolene.

General Surgery · Final Professional

Definition & Use

Dantrolene is the specific drug treatment for malignant hyperthermia (MH). It is a skeletal muscle relaxant that acts directly on muscle by reducing calcium release from the sarcoplasmic reticulum (via the ryanodine receptor), thereby switching off the sustained muscle contraction and hypermetabolism that drive the MH crisis.

Administration & Points

In an MH crisis, dantrolene is given intravenously in repeated doses until the hypermetabolic signs (rising CO₂, tachycardia, rigidity, temperature) settle, alongside stopping the trigger, cooling, and correcting acidosis and hyperkalaemia. Because a crisis needs many vials rapidly, dantrolene must be immediately available wherever triggering agents are used, and staff must know where it is and how to reconstitute it.

CLINICAL PEARL

Dantrolene treats MH by reducing calcium release from the sarcoplasmic reticulum (ryanodine receptor), stopping the hypermetabolism. It must be immediately available wherever volatiles/suxamethonium are used, and given in repeated IV doses.

Availability & Storage

A practical point that examinations often test is that dantrolene must be stocked and immediately accessible in every location where triggering anaesthetic agents are used, because a malignant hyperthermia crisis requires a large number of vials to be given quickly and the drug is slow to reconstitute. Departments therefore keep a dedicated supply, ensure staff know its location and how to prepare it, and rehearse the emergency, since any delay in giving dantrolene worsens the outcome; alongside the drug itself, the response depends on immediately stopping the trigger, calling for help and beginning cooling and the correction of the metabolic disturbances.

CLINICAL PEARL

Dantrolene works by shutting off the runaway calcium release from the sarcoplasmic reticulum that drives malignant hyperthermia, and the two things examiners want are its mechanism and the fact that it must be immediately available and given in repeated IV doses in a crisis.

In Brief

In short, know its mechanism and that a department must be able to lay hands on it — and enough of it — within moments.

Specific treatment for malignant hyperthermia — must be immediately available.

KEY POINT

Key points TO remember

Dantrolene: specific treatment for malignant hyperthermia.
Acts directly on muscle — reduces sarcoplasmic-reticulum calcium release (ryanodine receptor).
Given IV in repeated doses until hypermetabolic signs settle (with stop trigger, cool, correct K⁺/acidosis).
Must be immediately available where triggering agents are used.

EXAM TIP

Sources: Morgan & Mikhail’s Clinical Anesthesiology; Miller’s Anesthesia; Ajay Yadav’s Short Textbook of Anaesthesia.

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