Administration of epinephrine by autoinjector depends on which factor?

• A. Knowledge of the patient on how to use it
• B. BP of the patient at the time of administration
• C. Type of allergen the patient was exposed to
• D. Device having a functional spring plunger

Answer: (D)

Autoinjectors deliver a fixed dose of epinephrine using a spring-driven mechanism. The crucial factor is that the device’s spring-loaded plunger functions properly; when activated, the spring drives the plunger to push the medication through the needle into the muscle. If the spring is defective or the device is damaged orexpired, the dose won’t be delivered, regardless of training, the patient’s blood pressure at administration, or the type of allergen. Training and recognizing anaphylaxis are important for timely use, but whether the drug actually goes into the body hinges on a working spring plunger in the device.