Adrenomimetics
Adrenomimetics, also known as adrenergic agonists, are drugs that stimulate adrenergic receptors in the sympathetic nervous system. They can act directly on adrenergic receptors or indirectly by increasing the availability of endogenous catecholamines.
Classification
- 1. Direct-Acting Adrenomimetics (Bind to receptors and activate them):
- Alpha-Selective:
- Alpha-1: Oxymetazoline, Xylometazoline, Phenylephrine – Primarily used for vasoconstriction (e.g., nasal decongestants).
- Alpha-2: Clonidine – Reduces norepinephrine release, decreasing blood pressure.
- Beta-Selective:
- Beta-1: Dobutamine – Increases heart rate and myocardial contractility.
- Beta-2: Salbutamol, Fenoterol, Salmeterol – Promote bronchodilation for asthma and COPD.
- Non-Selective:
- Epinephrine – Activates both alpha and beta receptors, increasing heart rate, vasoconstriction, and bronchodilation.
- 2. Indirect-Acting Adrenomimetics (Enhance norepinephrine release or inhibit reuptake):
- Amphetamine, Cocaine, Tyramine – Promote norepinephrine release or prevent reuptake, leading to prolonged adrenergic effects.
- MAO inhibitors – Block norepinephrine degradation, increasing its availability.
- 3. Mixed-Acting Adrenomimetics (Both direct and indirect effects):
- Ephedrine – Binds to adrenergic receptors while also promoting norepinephrine release.