Epinephrine

Drug Overview

Adrenaline is a steroid hormone secreted by the adrenal glands, widely used in medical emergency treatments after synthetic production. Its primary function is to stimulate the sympathetic nervous system, causing vasoconstriction and bronchodilation. It is commonly used to treat allergic shock, severe hypotension, and during cardiopulmonary resuscitation (CPR). This medication acts rapidly and is usually administered via injection or inhaler, requiring operation by healthcare professionals or self-administration by patients in emergency situations.

Brand Names and Scientific Name

The scientific name is Adrenaline (Epinephrine). Common brand names include:

• EpiPen (auto-injector)
• Adrenalin
• Primatene Mist (used in some regions)

Different formulations and packaging may vary by region; always check the medication leaflet before use.

Drug Classification

It belongs to α and β adrenergic receptor agonists, with sympathomimetic properties. This class of drugs is characterized by rapid regulation of blood pressure, bronchial tension, and metabolic responses, and is commonly found in emergency rooms and first aid kits.

Indications

Mainly used for:

• Type I allergic reactions (such as anaphylactic shock caused by food or insect bites)
• Post-cardiac arrest treatment during cardiopulmonary resuscitation (CPR)
• Vasoconstrictor during local anesthesia injections

It can also be used as a short-term relief medication during acute bronchial asthma attacks.

Special Applications

Occasionally used as a mydriatic agent in ophthalmic surgeries or to treat certain types of hypotension (such as distributive shock). Strict adherence to medical instructions is essential; self-medication is not advised.

Common Side Effects

Mild reactions:

• Palpitations and increased heart rate
• Dizziness or headache
• Tremors in hands and feet

This symptoms usually resolve spontaneously within a short period.

Serious side effects:

• Allergic reactions (such as rash, hives)
• Abnormal blood pressure elevation or arrhythmias
• Chest pain or difficulty breathing

If any of the above severe symptoms occur, seek medical attention immediately.

Warnings and Precautions

Contraindications:

• Patients with severe hypertension or arteriosclerosis
• Uncontrolled diabetes mellitus
• Obstructive arteriosclerosis

Patients should inform their doctor of all medical histories, including heart disease and thyroid disorders, before use.

Use during pregnancy and breastfeeding requires caution:

• Pregnancy category C; use only if necessary
• May be secreted into breast milk; breastfeeding should be temporarily discontinued during treatment

Black box warning: Includes risks of misuse in anaphylactic shock and cardiovascular complications.

Drug Interactions

Contraindicated interactions:

• Use with monoamine oxidase inhibitors (MAOIs) may trigger hypertensive crises
• Use with β-blockers (such as metoprolol) may antagonize the drug’s effects
• Use with certain antiarrhythmic drugs (such as procainamide) may increase cardiac toxicity

Foods and Supplements:

• High caffeine drinks may enhance palpitations
• Avoid use with foods containing tyramine (such as cheese, pickled foods)

Patients should inform their doctor of all medications and nutritional supplements they are taking before use.

Dosage and Administration

Administration depends on the symptoms:

• For allergic shock: usually 0.3-0.5 mg intramuscularly or subcutaneously
• For CPR: intravenous injection of 1:10,000 concentration
• For local anesthesia: mixed with local anesthetic at 1:100,000 concentration

Dosage should be adjusted according to body weight and severity of symptoms.

Proper use of self-injection pens (such as EpiPen):

1. Remove the safety cap and insert at a 45-degree angle into the outer thigh
2. Hold the injection for 10 seconds before removing the needle
3. Seek immediate medical attention for follow-up observation

Strictly prohibit subcutaneous injection into non-designated areas.

Handling Missed Doses

This medication is typically for emergency use. If a scheduled injection (such as a pre-filled auto-injector) is missed, administer the drug immediately and assess the risk. Non-regular medications do not require rescue measures but should be re-planned for future carrying.

If the auto-injector is mistakenly used on non-target areas (such as the hand), seek medical evaluation immediately, as overdose absorption may cause severe side effects.

Overdose Management

Overdose may lead to hypertensive crisis, arrhythmias, or central nervous system excitation. Immediate symptoms include:

• Severe headache and blurred vision
• Profuse tremors and confusion
• Chest pain or shortness of breath

Seek medical attention immediately and bring the medication leaflet for reference.

Emergency measures:

• Keep the patient lying flat with legs elevated
• Monitor vital signs until emergency services arrive
• Do not take other antihypertensive drugs without medical advice

 

Frequently Asked Questions

How to ensure the correct injection site when using an adrenaline auto-injector?

Choose the outer thigh muscle, avoiding blood vessels or the buttocks. Remove the safety cap and press the injector perpendicularly onto the skin, holding for 10-12 seconds to ensure full drug delivery. If the patient is wearing long pants, remove or pull up clothing to ensure accurate injection.

What should I do if I experience palpitations or dizziness after using adrenaline?

These may be side effects of the medication. If symptoms are mild, observe for 15 minutes. If the heart rate remains excessively high for over 20 minutes or severe dizziness with fainting occurs, seek medical evaluation immediately. It is recommended to carry a blood pressure monitor and regularly check vital signs.

Will using β-blockers affect the effectiveness of adrenaline?

β-blockers may reduce the bronchodilatory effect of adrenaline and could induce paradoxical blood pressure reactions. If combined use is necessary, the doctor may adjust the dose or suggest alternative medications excluding non-selective β-blockers. Always inform your healthcare provider of all medications being used.

What are the storage requirements for adrenaline auto-injectors?

Store in the original packaging away from light, at temperatures between 15-30°C, avoiding refrigeration or direct sunlight. Check the expiration date and clarity of the liquid every three months. If crystals or discoloration are observed, replace immediately. Regularly replenish stock at the pharmacy.

If a severe allergic reaction occurs, is it necessary to administer a second dose of adrenaline?

If symptoms do not improve or worsen, a second dose can be administered after 10-15 minutes, but no more than two doses in total. Immediate medical attention is required after injection, as some patients may need subsequent antihistamines, steroids, or vasopressor therapy. Do not rely solely on self-administration of additional doses.