Adenosine
Indications
Adenosine injection is used in hospital to quickly restore a normal heart rhythm in certain types of fast, regular heartbeat that start in the upper part of the heart (paroxysmal supraventricular tachycardia). It is also used during some heart scans (stress tests) when a person cannot exercise, and to help doctors identify the type of a fast heart rhythm.
How It Works
Adenosine briefly slows the electrical signal passing through the heart's natural pacemaker area (the AV node). This can break the short circuit causing the fast rhythm. It also widens the blood vessels of the heart, which is useful in heart scans. Its effect lasts only seconds.
Dosage and Administration
Adenosine is given only by a doctor or nurse in hospital as a rapid injection into a vein, with continuous heart monitoring and resuscitation equipment ready. The dose is as prescribed and depends on the purpose and, in children, on body weight.
Interactions
Dipyridamole strongly increases its effect, so a much lower dose is needed. Caffeine, Theophylline and Aminophylline reduce its effect; caffeine-containing drinks are usually avoided before a stress test. Carbamazepine may increase the risk of heart block.
Contraindications
- Allergy to adenosine.
- Second or third degree heart block or sick sinus syndrome, unless a working pacemaker is fitted.
- Asthma or severe chronic obstructive lung disease with wheezing.
- Long QT syndrome, very low blood pressure or severe heart failure.
Side Effects
Many people feel a brief, strong sense of chest tightness, flushing, shortness of breath, headache, dizziness or a feeling of doom. These usually pass within a minute. Slow heartbeat or a short pause of the heart can occur. Rarely it can cause wheezing, a serious rhythm problem or seizures.
Because it is given under monitoring, staff will act straight away. Tell the nurse or doctor at once if you have breathing difficulty, chest pain that does not settle, or feel faint after the injection.
Pregnancy and Lactation
It may be used in pregnancy when the doctor decides it is needed. Because it acts for only seconds, it is not expected to affect breastfeeding.
Precautions and Warnings
Used with caution in people with heart failure, recent heart attack, heart valve narrowing, certain conduction problems, epilepsy or lung disease. Tell the doctor about asthma and all medicines you take, and avoid tea, coffee, cola and chocolate before a stress test if told to.
Overdose
The effect wears off within seconds because the body clears it very fast. Any problems are managed by the hospital team.
Therapeutic Class
Anti-arrhythmic medicine.
Storage
Store below 30°C. Do not refrigerate, as crystals may form. Keep out of the reach of children. Hospital stock is handled by the healthcare team.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.
All brands of Adenosine