Drugs

1. Drugs For better or worse

2. Drug – any substance other than food or water that affects how the body functions

3. Medicine – any drug that has therapeutic value • Recreational drug – any drug either legal or illegal used for nonmedical purposes

4. The DEA classifies drugs by their usefulness, safety, and biological activity • People often classify drugs by social acceptability as well (alcohol ok but not pot, etc) • Half of all Americans take at least one prescription medication • In 2008 Americans spent nearly 300 billion on legal drugs

5. Over-The-Counter • OTC drugs are available to everyone • They are generally safe drugs and are not likely to be addictive. • 15 billion of the 300 billion was spent on these drugs

6. Permitted Nonmedical • Permitted nonmedical drugs are also available to the public • However they tend to be addictive and have side effects so age limits are used for many of them • Alcohol, nicotine

7. Prescription Drugs • Prescription drugs are only available from a Doctor • These are generally nonaddictive drugs but should not be over used • Antibiotics, allergy medicines

8. Table 17-1, p. 352

9. Schedule Drugs • The rest of the drugs fall into certain schedules and are called controlled substances

10. Schedule 1 • No medical value and high addiction/abuse rate • Examples?

11. Table 17-4, p. 365

12. Origins • There are three basic origins for all drugs in use today

13. Drug effects • All drugs have a primary effect like pain relief or anti-nausea • Many of these can have a secondary effect • Aspirin is a pain reliever but also reduces fever (analgesic, anti-inflammatory)

14. Synergy • Synergistic effect is when one drug enhances the effect of another • Thus the two combined drugs have a greater effect than each one alone • Think of this as a 1+1=4

15. Over Dosing • Over dosing usually occurs when someone takes two drugs with the same primary effect due to synergy

16. Synthesizing New Drugs • Starting from scratch and trying to make a new effective drug is very difficult • So chemists have tried to figure out models to explain drug interaction

17. Lock-and-Key • The lock and key mechanism is the best current model for drug interaction • Each drug is like a key that must fit perfectly in a lock to make a reaction

18. The lock in this case is called a Receptor Site • Drugs attach to the receptor site and then a reaction occurs

20. When the drug interacts with the receptor the desired effect occurs • The better the fit between the two, the longer the reaction will occur or the more intense it will be

21. Once the drug releases from the receptor it is degraded by the body and the effect wears off

23. Today, few drugs are designed from scratch • Most drugs are found in plants and then either modified or used directly

24. Taxol • Taxol is a natural product from the bark of the Pacific Yew tree and is useful in treating some cancers

25. Table 17-2, p. 353

26. p. 354

27. Chemotherapy • Chemotherapy is the use of drugs to destroy an infecting agent without killing the host • Pathogen – any disease-causing agent • Chemotherapy takes advantage of how pathogens differ from their host

28. Sulfa Drugs • The first antibacterial drugs – 1930s • Bacteria and animals both need folic acid to survive

29. Most animals can get folic acid from ingestion • Bacteria however must make their folic acid

30. Sulfa drugs are metabolized to sulfanilamide • This chemical is very similar to PABA which is what the bacteria use to make folic acid

32. So sulfanilamide is an inhibitor of the bacterial enzyme • Competitive inhibition

33. Antibiotics • Antibiotics prevent the growth of bacteria • Penicillin was the first discovered antibiotic – 1940s • It is a natural product of a fungus designed to prevent bacteria from competing for its food

34. Penicillin works by disrupting the formation of a bacterial cell wall • This makes the bacteria weak and eventually they explode

35. Cephalosporins – broad ranged antibiotics, also work on the cell wall Tetracyclines and erythromycin – inhibit bacterial protein synthesis Rifampin – inhibits RNA synthesis from DNA

36. Antiviral agents • Virus – submicroscopic infectious agents that are only able to replicate within cells of living hosts

38. Viruses inject their RNA/DNA into a cell and use the cell’s replication machinery to replicate itself • Antiviral agents target replication to stop the virus

39. Antiviral agents are derivatives of nucleosides without the phosphate groups • When a virus incorporates one of these derivatives it stops the replication process

40. Herpes • Simplex-1 and Simplex-2 • Drug – Acyclovir (Zovirax)

41. HIV – Human immunodeficiency virus

42. Fig. 17-1, p. 356

43. HIV is an RNA based virus (retrovirus) • Causes AIDS – acquired immunodeficiency syndrome • Drug – Zidovudine (AZT)

44. Protease Inhibitors • Many viruses like HIV use proteases to break down proteins • New drugs are now being made to inhibit proteases • If the virus can’t make new proteins it can’t replicate

46. For HIV multiple types of antiviral agents are used together • This treatment is very expensive and is not a cure, but it does prolong the lifespan a considerable number of years.

47. Vaccines The only current method of preventing viruses Uses dead viral cells to build the natural defense particles in the body (antibodies)

48. Why are viruses so difficult to control compared to bacteria?