Introduction

Succinylcholine chloride remains a cornerstone of anesthetic practice, especially for rapid-sequence induction and emergent airway control. Its ultrashort duration and depolarizing mechanism make it uniquely suited to these scenarios, but safe, reliable clinical performance depends on appropriate storage. Understanding the chemical and physical stability of succinylcholine, the hazards of improper storage, and the rationale behind manufacturer recommendations is essential for anesthesiology trainees and practitioners. This article provides a concise, clinically oriented synthesis of optimal storage and stability considerations for succinylcholine in both undiluted and diluted forms.

The science of succinylcholine stability

Succinylcholine is a diquaternary ammonium compound that undergoes spontaneous hydrolysis in aqueous solution. Hydrolysis and other degradation pathways are accelerated by elevated temperature, alkaline pH, and light exposure. Degraded succinylcholine has reduced potency and may produce inconsistent neuromuscular blockade, compromising intubation conditions and patient safety.

Key degradation factors

• Temperature: Higher temperatures markedly accelerate hydrolysis.
• pH: Stability is best in slightly acidic conditions; the commonly cited stability range is pH 3.75–4.50.
• Light: Exposure to light promotes oxidative or photo-initiated degradation.

Storage of undiluted succinylcholine

Primary storage recommendations

• Temperature: Refrigerate at 2–8°C (36–46°F).
• Light protection: Store protected from light for prolonged shelf life.
• Shelf life: Follow manufacturer-specified expiration dates; under proper refrigeration most commercial preparations retain labeled potency for their marketed shelf life (commonly up to 24 months depending on product).

Room-temperature allowance

• Short-term: Many hospital policies accept storage at room temperature (approximately 15–30°C) for short periods when the product will be used promptly, such as in anesthesia carts or emergency kits.
• Typical operational window: Up to 14 days at room temperature is commonly cited in practice guidelines when vials are protected from light and monitored for integrity.

Representative stability observations from the literature

• Small, gradual potency loss (~7–9%) has been observed at 25°C over 4–6 weeks in some experimental settings.
• Studies report approximately 10% loss at 20–26°C over several months and rapid loss under extreme heat (for example, marked degradation after exposure to 70°C).
• Refrigeration at 4–6°C minimizes hydrolysis and preserves potency for long periods consistent with manufacturer shelf-life data.

Storage of diluted succinylcholine

Common dilution practice

• Typical diluted concentrations: 1–2 mg/mL in either 0.9% sodium chloride or 5% dextrose for infusion or small-volume boluses, and higher concentrations (for intermittent dosing) such as 10–20 mg/mL for convenience.

Recommended storage for diluted solutions

• Temperature: Strict refrigeration at 2–8°C is recommended for diluted preparations.
• Duration: Use diluted solutions within 24 hours of preparation in clinical practice, even though some experimental data suggest longer chemical stability in certain concentrations and containers.
• Light protection: Store protected from light when feasible.
• Labeling and infection control: Label syringes and infusion bags clearly with time and date of preparation and designate “single-patient use” to avoid cross-contamination.

Avoid freezing

• Freezing risk: Accidental freezing (for example, by direct contact with ice packs or in excessively cold storage compartments) can crystallize the solution, damage container integrity, or otherwise alter drug availability.
• Clinical consequence: Freezing events may produce unpredictable drug potency and administration delays; frozen or thawed syringes/solutions should be discarded.

Practical clinical recommendations and pearls

• Emergency trolley stock: Maintain undiluted succinylcholine in emergency kits; if stored at room temperature, monitor cumulative exposure time and replace within institutional time limits (commonly ≤14 days) while protecting from light.
• Operating room and ICU infusion use: Prepare diluted succinylcholine immediately before use and store refrigerated; discard diluted solutions after 24 hours.
• Transport: When succinylcholine must be carried (for example, on a transport trolley or ambulance), monitor ambient conditions and prefer temperature-controlled carriers rather than direct contact with cold packs.
• Handling uncertainty: If storage history is unknown or the product has been exposed to extreme temperatures, do not use the vial or syringe; replace it.
• Institutional policies: Align local practice with manufacturer's labeling, pharmacy guidelines, and hospital medication-management policies; document any deviations and implement routine checks of emergency drug kits.

Summary

• Undiluted succinylcholine vials should be stored refrigerated at 2–8°C and protected from light for long-term potency; short-term room-temperature storage (commonly up to 14 days) is accepted in many clinical workflows provided the vial is protected from light and monitored.
• Diluted succinylcholine solutions must be refrigerated and are best used within 24 hours of preparation in clinical practice; despite some experimental evidence of longer chemical stability, bedside safety dictates conservative use limits.
• Always avoid freezing and prevent direct contact with cold packs. When in doubt about storage history or physical integrity, discard and replace the product.
• Adherence to these storage principles preserves predictable pharmacodynamics and supports safe airway management in time-critical situations.