Pharmacology Study Notes on Sympathomimetics

Overview of the Study Notes

• This document contains detailed study notes on pharmacology, specifically focusing on sympathomimetic and sympatholytic drugs.
• It covers various aspects like receptors, mechanisms, and clinical uses of different drugs.
• It also includes the adverse effects and contraindications of each drug.

Sympathomimetic Drugs

• Direct-Acting Sympathomimetics:
  • Affect adrenergic receptors directly
  • Examples include epinephrine (adrenaline) and norepinephrine (noradrenaline), Phenylephrine, Isoprenaline
  • Ephinephrine/Epinephrine:
    • A catecholamine released from the adrenal medulla
    • Directly stimulates alpha and beta receptors
    • Cardio-effects: Increased contractility, heart rate, and AV nodal conduction速度, increased cardiac output
    • Vascular effects: Constricts blood vessels in skin, mucous membranes and visceral organs, dilates blood vessels in skeletal muscles
    • Other effects: Dilates the bronchioles , dilates pupil, increases blood clotting ability
    • Used therapeutically for acute asthma attacks, anaphylactic shock, cardiac arrest, terminating certain supraventricular tachycardias and local vasoconstriction
    • Adverse effects depend on dose and can include anxiety, fear, tension, headache, tremor and/or cardiac arrhythmias
    • Contraindications: conditions such as shock, hypertension, hyperthyroidism
  • Phenylephrine:
    • Direct alpha-1 agonist
    • Used for nasal decongestants, mydriasis
  • Isoprenaline:
    • Non-selective beta agonist
    • Used for bradycardia(slow heart rate), AV block, cardiac arrest
    • Adverse effects can include hypotension, angina
• Indirect-Acting Sympathomimetics:
  • Release norepinephrine from storage, increasing its effects on receptors
  • Examples include amphetamines
• Mixed-Acting Sympathomimetics:
  • Release norepinephrine and directly stimulate alpha and beta receptors
  • Examples include ephedrine
• Other sympathomimetics including: Dopamine, Dobutamine, Isoprenaline/Isoproterenol, Salbutamol, Terbutaline, Pirbuterol, Albuterol, Fenoterol, Soterenol, Isoxsuprin, Ritodrin, Etilefrin

Sympatholytic Drugs (Adrenergic Antagonists)

• Alpha-Blockers:
  • Non-selective alpha-blockers: Phenoxybenzamine, Phentolamine
    • Used in hypertension and pheochromocytoma
    • Adverse effects: orthostatic hypotension, dizziness, nasal congestion
  • Selective alpha-1 blockers: Prazosin, Terazosin, Doxazosin, Tamsulosin, Alfuzosin
    • Used in hypertension, benign prostatic hyperplasia (BPH), and Raynaud's phenomenon
    • Adverse effects: orthostatic hypotension, dizziness, headache
• Beta-Blockers:
  • Nonselective beta-blockers: Propranolol, Nadolol, Timolol, etc.
    • Impact beta 1,2 receptors
  • Cardioselective beta-blockers: Metoprolol, Atenolol, Bisoprolol, etc.
    • Primarily affect beta-1 receptors
  • Beta-blockers with intrinsic sympathomimetic activity: Pindolol, Acebutolol, etc.
    • Limited beta receptor blockade
• Uses, considerations, and adverse effects: ( vary based on specific med and receptor selectivity)
  • These drugs are used to counteract effects of SNS stimulation
  • Their uses include hypertension, cardiac arrhythmias, angina, migraine, tremor
• Important Considerations:
  • Selective vs. non-selective beta-blockers: This distinction is vital for tailoring treatment to specific needs. Non-selective blockers can have adverse effects on airways.
  • Beta-blockers' effects on other systems (e.g., respiratory): Beta-blockers can affect breathing, especially nonselective ones, and should be used cautiously, in patients with asthma or COPD.

Additional Drugs and Concepts

• Anticholinergics: These block muscarinic receptors, with diverse applications.
• Cholinesterase Inhibitors: These prevent the breakdown of acetylcholine, increasing its effects.
• Analgesics (Pain Relievers): Central and other types mentioned.
• Muscle Relaxants: These act on the central nervous system, not the neuromuscular junction, to reduce muscle spasms.
• NSAIDS: Nonsteroidal anti-inflammatory drugs, impacting COX enzymes.
• Other Drugs: Specific drugs and treatment contexts are highlighted. General principles of adverse effects, interactions, and contraindications are presented.
• Important Note: This is a summary and detailed information, including indications, dosages, adverse effects, and specific uses, should be reviewed in a medical textbook or consult with a medical professional before using this information to treat any medical condition.

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