Pcol

• PHARMACOLOGY – study of drugs
• DRUG


  Any article/agent used in the mitigation, diagnosis, prevention, treatment, and cure of diseases in man and in animals
• Main divisions of pharmacology


  • Pharmacodynamics
  • Pharmacokinetics
  • Pharmacotherapeutics
• Pharmacodynamics


  Deals with the study of biochemical and physiologic effects of drugs in biological systems and the mechanisms by which these effects were produced
• Pharmacokinetics


  Study of fate and disposition of drugs in the body
• Pharmacotherapeutics


  Study of rational drug use in the management of certain diseases
• General mechanisms by which drugs alter normal functions of cells


  • Interaction with receptors
  • Alteration of enzyme activity
  • Antimetabolite action
  • Non-specific chemical or physical interactions
• Receptors


  Naturally occurring target macromolecules which mediate actions of endogenous physiologic substances
• Types of drug-receptor interactions


  • Type I
  • Type II
  • Type III
  • Type IV
• Affinity


  Ability of a ligand to bind to the receptors
• Intrinsic activity


  Ability of a ligand once bound to activate the receptor
• Ligand classes


  • Agonists
  • Antagonists
• Agonists


  Capable of binding to, and activating, a receptor
• Types of agonists


  • Full agonists
  • Partial agonists
  • Inverse agonists
• Antagonists


  Bind to the receptor but do not initiate a response; block the action of an agonist or endogenous substance that works through the receptor
• Types of antagonists


  • Competitive antagonists
  • Non-competitive antagonists
• Graded-dose response curve


  Expresses an individual's response to increasing doses of a drug

  
• Efficacy


  Measure of the ability of a drug to elicit the MAXIMUM pharmacologic response
• Potency


  Relative measure of the ability of a drug to produce half of the maximum response

  
• Ceiling dose


  The smallest dose which produces the maximum response
• Slope


  Indicates changes in response; Steep curve implies a small change in dose produces a large change in response
• Quantal-dose response curve


  Relates the dosage of a drug to the frequency with which a designated response will occur within a population

  
• Autonomic nervous system (ANS)


  Subdivision of the peripheral efferent nervous system; controls involuntary activity
• Divisions of the ANS


  • Parasympathetic nervous system
  • Sympathetic nervous system
  • Enteric nervous system
• Synaptic transmission


  Mechanism of impulse across the synapse
• Differences between sympathetic and parasympathetic nervous systems


  • Anatomical differences
  • Neurotransmitters
  • Effects on target organs
• Catecholamines


  Possess a catechol nucleus and an ethylamine side chain; include norepinephrine, epinephrine, dopamine
• Biosynthesis of catecholamines


  Tyrosine -> DOPA -> Dopamine -> Norepinephrine -> Epinephrine
• Storage and release of catecholamines


  Stored in vesicles, released through calcium-dependent exocytosis from nerve terminals and adrenal medullary chromaffin cells
• Factors affecting catecholamine release

  • Reserpine (blocks storage)
  • Tyramine, ephedrine, amphetamine (enhance release)
  • Guanethidine, guanadrel, bretylium (inhibit release)
• Mechanisms of catecholamine termination

  • Reuptake
  • Diffusion
  • Metabolism via COMT and MAO
• Sympathetic receptors

  • Alpha-1
  • Alpha-2
  • Beta-1
  • Beta-2
• Classifications of sympathomimetic agents

  • Direct-acting
  • Indirect-acting
  • Mixed-acting
• Sympathomimetics


  Mimic the effects of endogenous catecholamines (norepinephrine, epinephrine)
• Pharmacologic effects of sympathomimetics


  • Cardiovascular
  • Respiratory
  • Metabolic
  • Other effects
• Specific sympathomimetic agents


  • Non-selective direct-acting (epinephrine, norepinephrine, dopamine)
  • Selective beta-1 agonists (dobutamine)
  • Selective beta-2 agonists (terbutaline, albuterol)
  • Selective alpha-1 agonists (phenylephrine, methoxamine)
  • Selective alpha-2 agonists (clonidine, methyldopa)
  • Indirect-acting releasers (ephedrine, pseudoephedrine)
  • Mixed-acting (amphetamine, methylphenidate)
• Therapeutic uses of sympathomimetics


  • Cardiovascular
  • Respiratory
  • Eye
  • Central nervous system
  • Other uses
• Adverse effects and toxicity of sympathomimetics


  • Hypertension, cardiac arrhythmias, digital necrosis
  • Rebound hypertension with clonidine
  • Addiction/drug abuse with amphetamines
• Drug interactions of sympathomimetics


  • Potentiation with tricyclic antidepressants
• Classifications of sympatholytics


  • Direct-acting (alpha and beta blockers)
  • Peripherally-acting (adrenergic neuronal blockers)