I. General principles of Pharmacology

1. I. General principles of Pharmacology

2. A. Pharmacology and its major areas • Pharmacology is the study of drugs. It takes into account their composition, uses, characteristics/properties, and effects.

3. The subdivisions in pharmacology include: • 1. pharmacy: the science of preparing and dispensing medication

4. 2. toxicology: the study of the harmful effects of medications on living tissue

5. 3. neuropharmacology: the study of the effects of medication on nervous system and behavior functioning

6. 4. pharmacotherapeutics: the study of the use of drugs in treating disease

7. 5. pharmacokinetics: the study of the processes involving the absorption, distribution, metabolism and excretion of medications.

8. It is the study of what the body doesto a drug.

9. 6. pharmacodynamics: the study of the actions of medications on livingtissues.

10. It is the study of the biochemical and physiological effects of drugs, the mechanisms of drug action, and the relationship between drug concentration and effect.

11. Pharmacodynamics is the study of what a drug does to the body.

12. Example: Clomiphene citrate • This drug induces ovulation

13. B. Terminology related to effects of drugs • 1. therapeutic effect/indication: the intended effect of the drug; the uses of a drug

14. 2. contraindication: when the drug should not be used (see Warnings on label)

15. example: celecoxib (Celebrex) • indication: relief of signs and symptoms of osteoarthritis; relief of signs and symptoms of rheumatoid arthritis

16. example: celecoxib (Celebrex) • contraindicated in: hypersensitivity; history of allergic-type reactions to sulfonamides; history of asthma, urticaria (hives), or allergic-type reactions to aspirin or other NSAIDs

17. 3. undesirable effects: These are effects of the drug, other than the therapeutic effect.

18. Undesirable effects may be further classified as side effects, adverse effects, toxic effects, or allergic reactions.

19. a. side effects: nuisance effects (dry mouth, altered taste, flatulence)

20. b. adverse effects: effects that may be harmful (diarrhea, vomiting) or effects that with prolonged treatment of the drug, may affect the function of vital organs such as the liver or kidneys

21. c. toxic effects: extremely harmful, life-threatening

22. A drug may cause all 3 undesirable effects: • example: rosuvastatin (Crestor)

23. side effects: headache and insomnia

24. as well as constipation, flatulence, heartburn, altered taste, dyspepsia, and nausea

25. adverse effects: dizziness, diarrhea, drug-induced hepatitis, elevated liver enzymes, pancreatitis

26. toxic effects: rhabdomyolysis (release of muscle cell contents into the plasma)

27. From rosuvastatin

28. d. allergic reactions: this type of side effect has a different underlying cause compared to the previous types, it is due to the systemic release of histamine.

29. A hypersensitive person’s immune system identifies a foreign substance (antigen) and initiates a response (antibody).

30. The combination of antibody-antigen stimulates the histamine release.

31. This results in a range of symptoms, from mild (itching, swelling, redness, sneezing) to severe or life-threatening (bronchospasm, edema, shock, and death).

33. The severest symptoms are collectively referred to as anaphylaxis or anaphylactic shock.

34. 4. drug idiosyncrasy: Idiosyncrasy refers to a type of reaction that is not dose-related or allergic.

35. It occurs in a small percentage of patients given a drug. It is an individual’s unique response and may be related to genetics.

36. One example is cholinesterase deficiency, a condition where the effects of anesthetic agent, suxamethonium, are prolonged well beyond the usual few minutes, because the individual lacks the enzyme that normally limits its effects to a short time.

37. The patient’s muscles are paralyzed for longer than normal so assistance with breathing must be given for much longer than usual.

38. 5. LD50 • Before a drug receives approval for human use it must undergo several years of animal testing and evaluation.

39. One of the first tests that is performed is the lethal dose 50, (LD50) which is the dose that will kill 50% of the animals tested.

40. The results of this test are used to predict the safety of a drug.

41. Example: Tetrahydrocannibinol or THC • LD50 between approximately 50-86 g for a 68 kg (150 lb) person.

42. This would be equivalent to 1-1.8 kg of cannabis with a 5% THC content taken orally.

43. Example: batrachotoxins • These are extremely potent alkaloids found in certain species of frogs (poison dart frog) and beetles (Melyridae beetles)

44. The lethal dose of this alkaloid in humans is estimated to be 1 to 2 µg/kg.

45. For a 68 kg (150 pound) person this would be approximately equal to the weight of two grains of salt

46. Example: botulinum toxin • It is generally accepted as the most toxic substance known, with a median lethal dose of about 1 ng/kg, which means that a few hundred grams could theoretically kill every human on earth.

47. C. Drug names • 3 basic types: chemical, generic, and trade

48. 1. chemical name: Each drug has only one chemical name, which is assigned using the nomenclature established by IUPAC and is based on the chemical structure.

49. Its name is usually long, very complicated, and impossible to remember.

50. 2. generic name: this is assigned by the U.S. Adopted Names Council, and is easier to remember.