6.10:
Adrenergic Agonists: Therapeutic Uses
Adrenergic agonists or sympathomimetics are vital during life-threatening reactions such as allergic reactions or hypovolemic shock.
Adrenaline administered parenterally relieves symptoms of severe anaphylaxis by suppressing mast cell mediator release. ꞵ2 -agonists like salbutamol also help relieve bronchial asthma.
Treating shock involves stabilizing blood flow and pressure using pressor agents. ꞵ1– agonists increase the heart rate and contractility, while α1 -agonists increase peripheral resistance. Dopamine is administered as a vasodilator and helps activate adrenoceptors.
Adrenaline or phenylephrine compresses help control excessive bleeding.
Catecholamine potentiators like amphetamine and methylphenidate are administered to patients with narcolepsy —to promote wakefulness, or ADHD —to control impulsiveness and improve attention span. Amphetamines also exert anorectic effects.
α -agonists help relieve congestion in colds, sinusitis, and rhinitis. Phenylephrine is also used in mydriatic eyedrops for ocular examinations.
Miscellaneously, the β2-agonist ritodrine is used as a uterine relaxant, while the β3-selective mirabegron helps treat urinary incontinence.
6.10:
Adrenergic Agonists: Therapeutic Uses
Adrenergic agonists have diverse therapeutic uses across various medical conditions and emergencies.
Emergency and Intensive Care Unit (ICU) applications: Pressor agents increase blood pressure, heart rate, and contractility in shock and organ failure situations. Dopamine can induce vasodilation and stimulate adrenoceptors. Endogenous catecholamines are effective in treating cardiogenic shock. α2-agonists like clonidine can reverse anesthesia-induced hypertension.
Allergies and anaphylaxis: Parenteral epinephrine is highly effective in treating allergic reactions and anaphylaxis, relieving symptoms such as itching, hives, edema, and airway narrowing. It suppresses the release of mediators like histamine.
Respiratory conditions: β-agonists are used to treat asthma. Isoproterenol, epinephrine, and selective β2-agonists like salmeterol are commonly used bronchodilators.
Central nervous system disorders: Indirect and mixed-acting agonists with good CNS penetration regulate brain dysfunction in conditions like narcolepsy and ADHD, producing mood-enhancing and stimulatory effects.
Nasal decongestion: Oxymetazoline and other nasal decongestants are employed to treat colds, rhinitis, sinusitis, and blocked noses in various forms.
Ophthalmology: Phenylephrine is utilized as a mydriatic in eyedrops for fundus examination.
Incontinence treatment: β3-agonists like mirabegron are employed to treat urinary incontinence.
Adrenergic agonists have many therapeutic applications. They provide valuable interventions in emergencies and help manage various medical conditions.