Antiarrhythmic agents include-

Group I -  Moricizine, Qunidine, Procainamide, Disopyramide, Lidocaine, Phenytoin,

                Tocainide,   Mexiletine, Flecanide, Encainide, Propafenone
Group II- Propranolol, Esmolol, Acebutol
Group III- Bretylium, Amiodarone, Solatol
Group IV- Verapramil, Digoxin, Adenosine

Interacting drugs- summary
      
+ Adenosine-
 

Carbamazepine  

 Carbamazepine increases the degree of heart block produced by other agents.  As the primary effect of adenosine is to   decrease conduction through AV node, higher degrees of heart block may be produced in the presence of carbamazepine

Dipyridamole 

Effects of adenosine are potentiated. Thus smaller doses of adenosine may be effective in the presence of dipyridamole

Methylxanthines/caffeine/theophylline 

Effects of adenosine are antagonised. In the presence of  methylxanthines, larger doses of adenosine may be required or adenosine may be ineffective

Digitalis

Use adenosine with digitalis may rarely be associated with ventricular fibrillation         

 

Antiarrhythmic agents include-

Group I -  Moricizine, Qunidine, Procainamide, Disopyramide, Lidocaine, Phenytoin,

                Tocainide,   Mexiletine, Flecanide, , Propafenone
Group II- Propranolol, Esmolol, Acebutol
Group III- Bretylium, Amiodarone, Solatol
Group IV- Verapramil, Digoxin, Adenosine

Cardiovascular-

Facial flushing,  ( 18% )headache,  ( 2% )
sweating, palpitations, chest pain, hypotension, ( < 1% )
 prolonged  asystole,  ventricular fibrillation, ventricular tachycardia, transcient increase in
 blood pressure. ( post market)

CNS-

Light headedness, dizziness, tingling in arms, numbness, ( 1% )
apprehension, blurred vision, burning sensation, heaviness in arms, neck/back pain( < 1% )

GI-

Nausea,  ( 3% )  metallic taste, tightness in throat, pressure in groin. ( < 1% )

Respiratory-

Shortness of breath/dyspnea,  ( 12% )  chest pressure,  ( 7% )
 hyperventilation, head pressure. ( < 1% )

Second or third degree AV block or sick sinus syndrome, atrial flutter, atrial fibrillation and ventricular tachycardia (the drug is not effective in converting these arrhythmias to normal sinus rhythm, hypersensitivity to adenosine

Special precautions- Asthma- be alert to the possibility of adenosine- induced bronchoconstriction in patients with asthma.

Warnings-

Heart block- patients who develop high-level block on one dose of adenosine should not be given additional doses. Because of the very short half-life these effects are generally self-limiting.

Arrhythmias- at the time of conversion to normal sinus rhythm, a variety of new rhythms may appear on the ECG. They last only for a few seconds without intervention and may take the form of premature ventricular contractions, atrial premature contractons, sinus bradycardia, sinus tachycardia, skipped beats and varying degrees of AV nodal block.

Treatment of other arrhythmias- adenosine is not effective in converting rhythm other than PSVT , such as atrial fluter, artial fibrillation or ventricular tachycardia to normal sinus rhythm.

Ventricular response- in the presence of artial flutter or atrial fibrillation, a transcient modest slowing of ventricular response may occur immediately following use.

Hepatic and renal failure- since the drug has a direct action, hepatic and renal function are not required for the activation or metabolism of bolus injection.

Pregnancy- use during pregnancy only if clearly needed

Indications:

Conversion to sinus rhythm of PSVT, including that associated with accessory bypass tracts (W-P-W) syndrome

Dosage:

For rapid bolus IV use only- initial dose - 6mg as a rapid IV bolus (administered over a 1 to 2 second period) . If the first dose does does not result in elimination of the supraventricular tachycardia within 1 to 2 minutes, give a 12mg dose as a rapid bolus. Repeat 12mg dose a second time if required. Doses more than 12mg are not recommended.

Overdosage- Symptoms

Treatment

Adverse effects are generally rapidly self-limiting

1. Individualize treatment of prolonged adverse effects and direct toward the specific effect.

2. Methlxyanthines are compettive antagonists of adenosine

Missed dose

• If you miss a dose of this medicine, and remember within 6 hours of take it as soon as possible unless the dose is less than 4 hours.
• However, if you do not remember until later, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

To be administered only with the prescription and care of a Doctor

Refer Contraindication regarding general precautions and usage 

Pharmacology:

Adenosine is an endogenous nucleoside occuring in all cells of the body. Adenosine slows the conduction time through the AV node, can interrupt the re-entry pathways through the AV node and can restore normal sinus rhythm in patients with paraoxymal supraventricular tachycardia(PSVT).

Pharmacokinetics:

IV adenosine is removed from the circulation very rapidly. Half-life is estimated to be less than 10 seconds.

Pregnancy:

As adenosine is a naturally occuring material, widely dispersed throughout the body, no fetal effects would be anticipated. However, because of the unknown factor, use during pregnancy, only if clearly needed.