ADENOSINE INJECTION Injection/Solution for

What is ADENOSINE INJECTION

Adenosine Injection is a prescription medication used primarily to treat certain types of supraventricular tachycardia (SVT), a condition where the heart beats abnormally fast due to improper electrical signals. It is administered intravenously and acts rapidly to restore a normal heart rhythm. Adenosine is a naturally occurring nucleoside that plays a key role in biochemical processes such as energy transfer and signal transduction in the body.

Key points about Adenosine Injection:

• Therapeutic Use: Mainly used for acute management of paroxysmal supraventricular tachycardia (PSVT) and to help diagnose certain types of tachycardias by temporarily slowing the heart rate.
• Formulation: Provided as an injectable solution, typically in 2 ml glass vials containing a specific concentration of adenosine.
• Onset of Action: Adenosine works very quickly, usually within seconds, which makes it ideal for emergency cardiac situations.
• Pharmacological Class: It is classified as an antiarrhythmic agent, specifically a class V drug.
• Administration: Given intravenously under strict medical supervision due to its potent and immediate effects on heart rhythm.
• Additional Uses: Sometimes used in cardiac stress testing to simulate exercise-induced heart stress in patients unable to exercise.

How to use ADENOSINE INJECTION

Adenosine Injection must be administered by a healthcare professional in a controlled setting such as a hospital or emergency care unit. Proper technique and monitoring are essential to ensure safety and effectiveness.

• Preparation: Before administration, ensure the medication vial is intact, properly labeled, and stored at the correct temperature. Draw the required dose using aseptic technique.
• Route: Administered by rapid intravenous (IV) bolus injection, ideally through a large vein or a central venous catheter to ensure swift delivery.
• Dosing Procedure: The standard initial dose is typically 6 mg given rapidly over 1-2 seconds, followed immediately by a saline flush to push the drug into the circulation.
• Repeat Doses: If the first dose is ineffective, 12 mg doses may be administered up to two additional times at 1-2 minute intervals as needed.
• Monitoring: Continuous ECG monitoring is mandatory before, during, and after administration to observe the heart’s response and detect any adverse effects.
• Precautions: Patients should be monitored for transient side effects such as flushing, chest discomfort, or shortness of breath, which usually resolve quickly.
• Emergency Preparedness: Resuscitation equipment should be readily available in case of severe bradycardia or heart block.

Mode of Action ADENOSINE INJECTION

Adenosine acts by modifying the electrical conduction system of the heart to restore normal rhythm. Its pharmacodynamic effects are primarily exerted through activation of adenosine receptors in the heart.

• Receptor Binding: Adenosine binds to specific A1 adenosine receptors located on cardiac cells, especially within the atrioventricular (AV) node.
• AV Node Suppression: By activating these receptors, adenosine inhibits the transmission of electrical impulses through the AV node, temporarily blocking the pathway responsible for tachycardia.
• Hyperpolarization: It causes hyperpolarization of cardiac cells by increasing potassium efflux, making the cells less excitable and slowing conduction.
• Interrupting Re-entrant Circuits: This interruption breaks the re-entrant circuits that cause supraventricular tachycardia, allowing the heart to revert to a normal sinus rhythm.
• Rapid Onset and Short Duration: Adenosine’s effect occurs within seconds and lasts less than 10 seconds because it is rapidly taken up by red blood cells and metabolized.
• Additional Effects: It can also dilate coronary arteries by acting on A2 receptors, which may be useful during cardiac stress testing.

ADENOSINE INJECTION Interactions ADENOSINE INJECTION

Adenosine can interact with various medications and medical conditions that affect heart rhythm or conduction, which may alter its effectiveness or increase the risk of adverse events.

• Dipyridamole: This drug inhibits adenosine uptake and metabolism, significantly potentiating the effects of adenosine and increasing risk of side effects such as prolonged heart block.
• Theophylline and Caffeine: Both act as adenosine receptor antagonists and may reduce the effectiveness of adenosine by blocking its action.
• Beta-Blockers and Calcium Channel Blockers: Concurrent use can enhance the negative chronotropic effects of adenosine, increasing risk of bradycardia or AV block.
• Carbamazepine: May increase susceptibility to heart block when combined with adenosine.
• Other Antiarrhythmics: Drugs like digoxin may interact to increase the risk of arrhythmias or AV nodal conduction disturbances.
• Conditions Affecting Heart Rate: Patients on drugs affecting heart rate or with underlying conduction abnormalities should be carefully monitored during adenosine administration.

Dosage of ADENOSINE INJECTION

Dosage of Adenosine Injection must be individualized and carefully titrated to the patient’s condition and response. The general guidelines for adults are as follows:

• Initial Dose: 6 mg intravenous bolus given rapidly over 1-2 seconds, followed immediately by a 20 ml saline flush.
• If No Response: If the initial dose does not restore normal rhythm within 1-2 minutes, a second dose of 12 mg may be given.
• Maximum Doses: Up to two additional 12 mg doses can be administered at 1-2 minute intervals if necessary.
• Special Populations: Dose adjustment may be needed in pediatric patients or patients with impaired cardiac function; such administration must be guided by a cardiologist.
• Monitoring: Dosage should always be administered with continuous cardiac monitoring to observe therapeutic effect and adverse reactions.
• Overdose: Overdosage may cause prolonged heart block or severe bradycardia, which requires immediate medical intervention including supportive measures.

Possible side effects of ADENOSINE INJECTION

Although Adenosine Injection is generally safe when administered correctly, it can cause a range of transient side effects, mostly related to its cardiac and vascular actions.

• Common Side Effects: Flushing, chest discomfort or tightness, shortness of breath, headache, dizziness, and nausea. These effects are usually short-lived and resolve quickly.
• Cardiac Effects: Transient arrhythmias such as brief heart block, bradycardia, or premature atrial contractions may occur during or immediately after administration.
• Respiratory Effects: Bronchospasm or wheezing can occur, especially in patients with reactive airway disease or asthma.
• Hypotension: A brief drop in blood pressure may be observed.
• Rare but Serious: Prolonged heart block, severe bradycardia, or asystole requiring emergency intervention; hypersensitivity reactions like rash or anaphylaxis are rare.
• Monitoring and Management: Because of the risk of cardiac effects, close monitoring with ECG and readiness for resuscitation is essential.

ADENOSINE INJECTION Contraindications ADENOSINE INJECTION

Certain conditions or patient characteristics make Adenosine Injection inappropriate or unsafe due to the risk of serious adverse effects.

• Known Hypersensitivity: Allergy to adenosine or any component of the formulation.
• Second- or Third-Degree AV Block: Except in patients with a functioning pacemaker, due to risk of exacerbating heart block.
• Sinus Node Disease: Including sick sinus syndrome, unless a pacemaker is present.
• Atrial Fibrillation or Atrial Flutter with Accessory Pathway: Use caution as adenosine can increase conduction through accessory pathways and worsen arrhythmias.
• Bronchospastic Lung Disease: Such as severe asthma or chronic obstructive pulmonary disease (COPD), due to risk of bronchospasm.
• Unstable Cardiovascular Status: Patients with hypotension, shock, or unstable angina require extreme caution.

Storage of ADENOSINE INJECTION

Proper storage of Adenosine Injection is essential to maintain its potency and safety for use in emergency settings.

• Temperature: Store at controlled room temperature, typically between 20°C and 25°C (68°F and 77°F).
• Avoid Freezing: Protect from freezing; do not use if the solution has been frozen or crystallized.
• Light Protection: Keep vials in original packaging or protect from excessive light exposure to prevent degradation.
• Use Immediately: Once opened or drawn into a syringe, use immediately due to rapid degradation in solution.
• Expiration: Check expiry date before use; do not use after expiration.
• Storage Location: Keep out of reach of children and store in a secure area designated for emergency medications.