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Basic Pharmacology

Basic Pharmacology. What is a drug? any chemical agent which effects any biological process. What is pharmacology ? the study of how drugs effect biological systems. Lange Katzung. Pharmacology

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Basic Pharmacology

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  1. Basic Pharmacology

  2. What is a drug? • any chemical agent which • effects any biological process • What is pharmacology ? • the study of how drugs • effect biological systems

  3. Lange Katzung

  4. Pharmacology - Study of substances that interact with living systems through chemical processes

  5. Pharmacology - Especially by binding to regulatory molecules and activating (turning on) or inhibiting (turning off) normal body processes

  6. Pharmacology - Pharmcology is NOT the memorizing of long lists of medications or drug companies’ latest products

  7. Pharmacology • This course intends to teach you about how medications are used to treat and prevent illness • It also reveals the complexity of living regulatory systems

  8. Medical Pharmacology - Medical Pharmacology is the science of substances used to prevent, diagnose and treat diseases.

  9. Toxicology - Toxicology is the branch of pharmacology that studies the harmful effects of chemicals on living systems

  10. Drug - A drug is ANY substance that interacts with a molecule or protein that plays a regulatory role in living systems

  11. What is pharmacology ? - the study of substances that interact with living systems through chemical processes especially by binding to regulatory molecules and activating or inhibiting normal body processes.

  12. What is a drug? - may be defined as any substances that brings about a change in biologic function through its chemical actions

  13. The drug molecule interacts as an agonist (activator) or antagonist (inhibitor) with a specific molecule in the biologic system that plays a regulatory role. This target molecule is called a receptor.

  14. Drug (D) + receptor-effector (R) = drug-receptor-effector complex – effect D + R = drug-receptor complex = effector molecule = effect D + R = drug-receptor complex – activation of coupling molecule = effector molecule = effect Inhibition of metabolism of endogenous activator = increased activator action on an effector molecule = increased effect

  15. Drug affinity – the tendency of two substances to form strong or weak chemical bonds forming molecules or complexes

  16. A. Physical Nature of Drugs Solid drugs -> oral route aspirin or atropine Liquid drugs -> oral route, IM, SC nicotine or ethanol Gaseous drugs -> inhalation nitrous oxide, halothane, amylnitrite Many drugs are weak acids or bases pH differences in the body may alter the degree of ionization of drug

  17. What is Pharmacology ? Pharmacokinetics Pharmacodynamics What the body does to drug What the drug does to body Pharmacology Pharmacotherapeutics Pharmacocognosy The study of the use of drugs Identifying crude materials as drugs Toxicology

  18. Pharmacokinetics What the body does to the drug - Absorption - Distribution - Metabolism (Biotransformation) - Excretion Half-life (t1/2) - the time required for the plasma concentration of a drug to be reduced by 50 %

  19. Pharmacodynamics What the drug does to the body - Drug receptors - Effects of drug - Responses to drugs - Toxicity and adverse effects of drugs

  20. Sources of DrugsPharmacocognosy Animals Plants Minerals Synthetic Microbes

  21. Many of these old sources are still in use today Foxglove plant Meadow flower Colchicum autumnale Beef or pork pancreas Digitalis comes from the foxglove plant and is used in the treatment of CHF Colchicine is the drug of choice for treatment of gout Insulin is used today to treat diabetes and is derived from the pancreas of beef or pork or may be synthetically produced as well.

  22. Drugs Derived from Plants Ephedrine is present in the leaves of a bushy shrub (species name Ephedra), which, when burned were used by the ancient Chinese to treat respiratory ailments. Today, it is a bronchodilator. Many estrogen hormone replacement therapy drugs are derived from yams. The belladonna plant – source of atropine, which is still used to dilate the pupils.

  23. Endogenous • Exogenous • Hormones • Xenobiotics • Toxins • Receptor

  24. Agonist • Competitive antagonist • Noncompetitive antagonist • Chemical antagonist • Physiologic antagonist – any drug or chemical that has an opposite effect but through completely different physiologic pathways • Specificity – whether agonist or antagonist, drugs must be a specific size and shape to interact with a given receptor

  25. Agonist – is any drug that binds to a receptor and activates the receptor • Competitive antagonist – is any pharmacologic antagonist that “competes” with the binding of agonist at the binding site • Noncompetitive antagonist – is any pharmacologic antagonist that binds to a site on the receptor other than the agonist binding site • Chemical antagonist – any drug that binds directly to an agonist and deactivates the agonist

  26. Histamine and Epinephrine • Anaphylaxis is a severe systemic allergy reaction. Excess histamine released by the body is part of the problem. • Epinephrine is given to counteract the effects of histamine

  27. Drug-Receptor Interactions Agonists activates or enhances cellular activity. triggers a series of biochemical events alteration in function second messengers: biochemicals that initiate these changes Antagonists do not initiate a change in cellular function. prevent the binding and the action of agonists “blockers”

  28. Drug-Receptor Interactions Factors Governing Drug Action 1. Affinity: measure of the tightness that a drug binds to the receptor 2. Intrinsic activity: measure of the ability of a drug to generate an effect, producing a change in cellular activity

  29. Binding of a drug drug must interact with complementary surfaces on the receptor.

  30. Antagonist exhibit affinity for the receptor do not have intrinsic activity at the receptor competitive antagonist: binds to the receptor in a reversible mass-action manner -agonists given in high concentrations  can displace the antagonist from the receptor -agonist can then produce its effect

  31. Drugs must have specificity • - Whether agonist or antagonist, drugs must be of a specific size, charge, and shape to interact with a given receptor

  32. Drugs must be absorbed • - A drug must be able to be absorbed by the body. • A drug must have delivery • - a drug must be able to be delivered to site of action

  33. Drugs must have elimination • drugs must be eliminated at a reasonable rate

  34. Most drugs are weak acids or bases • Weak vs strong • NaCl example • pH • pKa – is the pH at which the molecule or drug is completely balanced between the uncharged (lipid soluble) and the charged (water soluble) form

  35. Stronger means more complete dissociation not how much it burns • NaCl Na+ Cl- • NaCl is not a strong acid or a strong base this is just a concept for explanation

  36. HCl H+ Cl- • NaOH Na+ OH-

  37. Neutralize • H+ plus OH- results in H2O • Adding base to acid neutralizes them

  38. Weak means incomplete dissociation in water • Weak acid like aspirin = C8H7O2COOH = white powder • If you placed it in water (H2O) • R-COOH R-COO-H+ • (uncharged aspirin) (ionic aspirin) • (lipophilic/fat soluble) (hydrophilic/water soluble)

  39. Saturated • Instead of dissolving… • Mass Action pushes the equation to the left • NaCl Na+ Cl- • In Mass Action: • NaCl Na+ Cl-

  40. pH • pH is a measure of acidity (<7) • pH is a measure of alkalinty (>7)

  41. Acidity pH < 7 • Acidity means the solution has excess H+ • This “mass action” of H+ can push the equation toward the protonated form of the drug

  42. If you placed it in acid • R-COOH R-COO-H+ • (uncharged aspirin) (ionic aspirin) • (lipophilic/fat soluble) (hydrophilic/water-soluble) • Because of mass action (too much H+) • Shifts to the fat-soluble part of the drug

  43. Alkalinity pH >7 • Alkalinity means the solution is able to remove any H+ from the solution • This “mass action” of H+ can pull the equation toward the unprotonated form of the drug

  44. If you placed it in a basic solution • R-COOH R-COO- • (uncharged aspirin) (ionic aspirin) • (lipophilic/fat soluble) (hydrophilic/water-soluble) • Basic solution has OH-

  45. Most drugs are weak acids or weak bases because only small changes in pH are required to shift between: • Lipid soluble (easily passes cell membranes) • Water soluble (does not pass without transport)

  46. In cases of Tricyclic Antidepressant overdose, we “alkalinize” the blood with sodium bicarbonate to change the drugs effect on the body

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