Adenosine – Emergency Drug for Supraventricular Tachycardia (SVT)

Table of Contents:

1. Introduction  

2. Mechanism of Action  

3. Pharmacokinetics & Dynamics  

4. Indications & Drug of Choice  

5. Contraindications  

6. Side Effects  

7. Dosage  

8. Brand Names  

9. Price  

1. Introduction:

*Adenosine* is a *class V antiarrhythmic* drug used primarily in emergency settings to treat *paroxysmal supraventricular tachycardia (PSVT/SVT)*. Due to its *ultra-short half-life* and rapid onset, it's administered via *IV push* during episodes of tachyarrhythmias to restore normal sinus rhythm.

2. Mechanism of Action:

Adenosine activates *A1 receptors* in the *atrioventricular (AV) node*, leading to:

- *Temporary AV node conduction block*

- *Slowing of heart rate*

- *Restoration of sinus rhythm*

This makes it ideal for *interrupting re-entrant pathways* in SVT.

3. Pharmacokinetics & Dynamics:

| *Onset*         | Within *10–30 seconds* (IV)      |

| *Half-life*     | Less than *10 seconds*           |

| *Metabolism*    | Rapid uptake by *RBCs & vascular endothelium* |

| *Excretion*     | Not renally excreted (metabolized quickly) |

Because of its short action, *continuous monitoring* is required during administration.

4. Indications & Drug of Choice:

Indications:

- *Acute PSVT/SVT*

- Diagnostic aid for *wide complex tachycardias*

- Occasionally used during *cardiac stress testing*

Drug of Choice For:

- *Narrow complex SVT* (after vagal maneuvers fail)

- *AVNRT (AV nodal re-entrant tachycardia)*

5. Contraindications:

- ⁠- *Second or third-degree AV block* (without pacemaker)  

- *Sick sinus syndrome* (unless pacemaker present)  

- *Asthma or severe COPD* (risk of bronchospasm)  

- Known hypersensitivity to adenosine  

- *WPW with atrial fibrillation* (may enhance conduction via accessory pathway)

   6. Side Effects:

- *Common (transient):*

  - Flushing

  - Chest discomfort

  - Dyspnea

  - Lightheadedness

  - Palpitations

- *Rare:*

  - Asystole (brief, self-limiting)

  - Hypotension

  - Bronchospasm

  - Seizures (very rare)

*Most side effects resolve in seconds due to rapid metabolism.*

7. Dosage:

| *Adult*    | 6 mg rapid IV push      | 12 mg after 1–2 min (if needed) |

| *Pediatric*| 0.1 mg/kg IV (max 6 mg) | Then 0.2 mg/kg (max 12 mg)     |

- Always *flush with saline* immediately after administration.

- Use *central line* or *large bore IV* for best effect.

8. Brand Names:

- *Adenocard*

- *Adenoscan*

- *Adenosine AuroMedics*

- *Adenotab*

- *Adenocor*

9. Price:

- *Pakistan*: PKR 600–1500 per 6 mg vial  

- *India*: INR 250–600 per vial  

- *US*: 15–50 per vial (generic cheaper)