Adenosine
| Net effect | -ve chronotropy. For SVT*. |
|---|---|
| Mechanism of action | - temporary AV node block - acts on A1 receptors to inhibit Ca channel opening - antagonises cAMP-mediated catecholamine stimulation of ventricular muscle - ↑ K efflux |
| Presentation | 3mg/ml solution |
| Pharmacokinetics | Absorption IV Distribution Metabolism Elimination rapid onset, t½ 10s (due to endogenous salvage system!) |
| Adverse effects | Bronchospasm |
| Contraindications | Accessory pathway (i.e. WPW) 2nd/3rd degree AV block caution in COPD/asthma |
| Drug interactions | Dipyramidole potentiates effects of adenosine |
- well, the regular narrow complex arrthythmia with P waves.
endogenous adenosine
- released from heart, skeletal muscle, brain
- hyperpolarising presynaptic terminals
- mediates metabolic hyperaemia
- effect:
- vasodilation
- shortens refractory periods of ventricular myocytes
- positive inotrope and chronotrope
- t½ 5h
- antagonised by caffeine
also mediates degradation of cAMP -> platelet aggregation