Pharmacology: Sympathomimetic Drugs

Sympathomimetic Drugs

Sympathomimetic drugs, also known as adrenergic drugs, are a class of medications that mimic the effects of the sympathetic nervous system.

Mechanism of Action

• Bind to alpha and beta adrenergic receptors, stimulating the sympathetic nervous system
• Increase the levels of norepinephrine, a neurotransmitter involved in the "fight or flight" response

Effects

• Increase heart rate and blood pressure
• Increase cardiac output and contractility
• Vasoconstriction (narrowing of blood vessels)
• Increase glucose release from energy stores
• Increase energy and alertness
• Bronchodilation (relaxation of airway muscles)

Types of Sympathomimetic Drugs

• Alpha-1 agonists: Increase blood pressure, vasoconstriction, and pupil dilation
  • Examples: phenylephrine, midodrine
• Alpha-2 agonists: Decrease blood pressure, decrease sympathetic outflow
  • Examples: clonidine, methyldopa
• Beta-1 agonists: Increase heart rate and contractility
  • Examples: dobutamine, isoproterenol
• Beta-2 agonists: Bronchodilation, relaxation of airway muscles
  • Examples: salmeterol, formoterol
• Mixed agonists: Combination of alpha and beta effects
  • Examples: epinephrine, norepinephrine

Clinical Uses

• Cardiovascular: Increase blood pressure in hypotensive patients, treat heart failure
• Respiratory: Treat bronchospasm and asthma
• Anesthesia: Increase blood pressure during anesthesia
• Ophthalmic: Treat glaucoma and pupil dilation

Adverse Effects

• Cardiovascular: Increased heart rate, blood pressure, and cardiac workload
• Central nervous system: Anxiety, tremors, and insomnia
• Respiratory: Tachypnea (rapid breathing) and bronchospasm

Contraindications

• Hypertension: Avoid using sympathomimetic drugs in patients with uncontrolled hypertension
• Cardiac disease: Avoid using sympathomimetic drugs in patients with cardiac disease or arrhythmias
• Pregnancy: Use with caution in pregnant patients due to potential effects on fetal heart rate and blood pressure

Sympathomimetic Drugs

Mechanism of Action

• Bind to alpha and beta adrenergic receptors, stimulating the sympathetic nervous system
• Increase levels of norepinephrine, a neurotransmitter involved in the "fight or flight" response

Effects

• Increase heart rate and blood pressure
• Increase cardiac output and contractility
• Cause vasoconstriction (narrowing of blood vessels)
• Increase glucose release from energy stores
• Increase energy and alertness
• Cause bronchodilation (relaxation of airway muscles)

Types of Sympathomimetic Drugs

Alpha-1 Agonists

• Increase blood pressure, vasoconstriction, and pupil dilation
• Examples: phenylephrine, midodrine

Alpha-2 Agonists

• Decrease blood pressure, decrease sympathetic outflow
• Examples: clonidine, methyldopa

Beta-1 Agonists

• Increase heart rate and contractility
• Examples: dobutamine, isoproterenol

Beta-2 Agonists

• Cause bronchodilation, relaxation of airway muscles
• Examples: salmeterol, formoterol

Mixed Agonists

• Combination of alpha and beta effects
• Examples: epinephrine, norepinephrine

Clinical Uses

• Cardiovascular: increase blood pressure in hypotensive patients, treat heart failure
• Respiratory: treat bronchospasm and asthma
• Anesthesia: increase blood pressure during anesthesia
• Ophthalmic: treat glaucoma and pupil dilation

Adverse Effects

• Cardiovascular: increased heart rate, blood pressure, and cardiac workload
• Central nervous system: anxiety, tremors, and insomnia
• Respiratory: tachypnea (rapid breathing) and bronchospasm

Contraindications

• Hypertension: avoid using sympathomimetic drugs in patients with uncontrolled hypertension
• Cardiac disease: avoid using sympathomimetic drugs in patients with cardiac disease or arrhythmias
• Pregnancy: use with caution in pregnant patients due to potential effects on fetal heart rate and blood pressure