Clinical Pharmacology: Adrenergic Drugs

Course Information

• Course Name: Clinical Pharmacology
• Course Code: BSRITCP, BSMUTCP
• Course Credit Hours: 02
• Instructor: MYEDA SAEED

Adrenergic Agonists and Antagonists

• Learning Outcomes: Classification, location, and actions of adrenergic receptors, mechanism of action of classified drugs, pharmacokinetics, therapeutic uses, adverse effects, and contraindications
• Adrenergic Agonists: Drugs of Sympathetic Nervous System that stimulate α and β receptors
• List of Adrenergic Agonists: Albuterol (Ventolin), Epinephrine (Epipen), Norepinephrine (Levophed), Isoproterenol (Isuprel), Dobutamine (Dobutrex), Formoterol (Foradil), Salmeterol (Serevent diskus), Cocaine

Epinephrine

• Synthesis: Synthesized in the adrenal medulla and released into the bloodstream along with norepinephrine
• Receptors: Interacts with both α and β receptors
• Actions: Major actions on the cardiovascular system, strengthens myocardial contractility, causes powerful bronchodilation by acting directly on bronchial smooth muscle
• Medical Uses: Narrowing blood vessels, opening airways; used in emergency treatment of respiratory tract conditions (e.g., asthma, anaphylactic shock), cardiac arrest
• Pharmacokinetics: Rapid onset and brief duration of action due to rapid degradation
• Adverse Effects: CNS disturbances (anxiety, fear, tension, headache, tremor), cardiac arrhythmias, and pulmonary edema

Norepinephrine

• Pharmacokinetics: Administered IV for rapid onset; duration of action is 1 to 2 minutes; potent vasoconstrictor
• Therapeutic Uses: Used to treat shock due to increase in blood pressure
• Adverse Effects: CNS disturbances (anxiety, fear, tension, headache, tremor), cardiac arrhythmias, and pulmonary edema

Isoproterenol

• Receptors: Stimulates both β1- and β2-adrenergic receptors
• Increases Cardiac Output
• Therapeutic Uses: Stimulate heart in emergency situations.
• Adverse Effects: CNS disturbances (anxiety, fear, tension, headache, tremor), cardiac arrhythmias, and pulmonary edema

Dobutamine

• Actions: Increases cardiac rate and output
• Therapeutic Uses: Used to increase cardiac output in acute congestive heart failure
• Adverse Effects: Tachyarrhythmia

Albuterol

• Classification: Short-acting β2 agonist
• Therapeutic Use: Primarily as a bronchodilator administered by a metered-dose inhaler
• Adverse Effects: Tremors and restlessness

Salmeterol and Formoterol

• Classification: Long-acting β2-adrenergic agonists
• Bronchodilators: Provide sustained bronchodilation over 12 hours
• Therapeutic Use: Agents of choice for treating nocturnal asthma in symptomatic patients taking other asthma medications

Cocaine

• Classification: Highly addictive drug
• Therapeutic Uses: Applied topically as a local anesthetic during eye, ear, nose, and throat surgery
• Adverse Effects: Depression

Adrenergic Antagonists

• α Blockers: Phenoxybenzamine (Dibenzyline), Phentolamine (Regitine), Prazosin (Minipress), Terazosin (Hytrin)
• β Blockers: Esmolol (Brevibloc), Nadolol (Corgard), Propranolol (Inderal LA), Timolol (Betimol)

Phenoxybenzamine

• Duration of Action: 24 hours after a single administration
• Therapeutic Uses: Used in the treatment of pheochromocytoma
• Adverse Effects: Postural hypotension, Nausea, Vomiting

Phentolamine

• Mechanism of Action: Competitive block of α1 and α2 receptors
• Duration of Action: Approximately 4 hours after a single administration
• Therapeutic Use: Short-term management of pheochromocytoma
• Adverse Effects: Postural hypotension

Propranolol

• Mechanism of Action: Blocks both β1 and β2 receptors
• Actions: Vasoconstriction and bronchoconstriction
• Pharmacokinetics: Is subjected to first-pass effect; only about 25 percent of the administered dose reaches the circulation. Useful in calculating proper dosage.
• Therapeutic Effects: Useful in treating various conditions and used to calculate dosages
• Adverse Effects: Bronchoconstriction, arrhythmias, and depression

Timolol and Nadolol

• Potency: More potent than propranolol
• Duration of Action: Nadolol has a very long duration of action; used topically in treating chronic glaucoma; less commonly used for hypertension
• Therapeutic Uses: Chronic glaucoma, occasionally for hypertension
• Adverse Effects: Bronchoconstriction and arrhythmias

Pulmonary Edema

• Description: illustrated as clear alveoli in contrast to fluid buildup in the alveoli