Selective agonist binding to the alpha-1 receptor can lead to hypertension. The most common side effects are changes in heart rate and blood pressure. The adverse effects seen with adrenergic drugs are broad. Caution should be used when prescribing the medication to patients with renal failure as and it is recommended to begin with a low dose and increase as needed. Clonidine can also be prescribed via an immediate-release tablet at 0.1 mg/day to 0.3 mg/day and an extended-release tablet with a dosage of 0.1 mg/day.
While other medications such as clonidine (alpha-2 agonists) may be prescribed as transdermal patches with dosages of 0.1 mg/day to 0.3 mg/day while changing the patch every week. While doses at the higher end can be prescribed at 5 mcg/kg/min to 20 mcg/kg/min. The doses at the lower end can also be prescribed at 2.5 mcg/kg/min to 5 mcg/kg/min. Dosages for Beta-1 agonists such as dobutamine can begin with 0.5 to 1 mcg/kg/min and go up to 40 mcg/kg/min on the maximum end. Common methods of administration are oral, intravenous, intranasal, and topical. Given adrenergic drugs are a broad class of medications, they are collectively available in almost every drug dosage form. Gi protein-coupled receptors are also activated, and this will decrease intracellular cAMP. The adenylate cycle becomes activated through the Gs-protein-coupled receptors, and there is an increase in intracellular cAMP. As a result, intracellular calcium rises.Īdenylate cyclase is inactivated, which leads to a decrease in intracellular cyclic adenosine monophosphate (cAMP).Īdenylate cyclase is activated, and intracellular cAMP increases. Phospholipase C is activated, which leads to the formation of inositol triphosphate (IP3) and diacylglycerol (DAG). All beta receptors are also Gs coupled-receptors.Īgonist binding to the adrenergic receptors induces the following cellular mechanisms: Beta-2 and beta-3 are also Gi coupled-receptors. These receptors are all G-protein-coupled receptors.Īlpha-1 receptors are Gq coupled-receptors, whereas alpha-2 receptors are Gi coupled-receptors. Alpha-1 and alpha-2 receptors both have three subtypes. Those two classes further subdivide into alpha-1, alpha-2, beta-1, beta-2, and beta-3. Adrenergic receptors, otherwise known as adreno-receptors, are classified as either alpha or beta receptors.