Drugs

1. Drugs

2. 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

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

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

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

7. 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

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

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

10. HIV – Human immunodeficiency virus

11. Fig. 17-1, p. 356

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

13. 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

15. 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.

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

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

18. Nerves Drugs affect our nervous system

19. Fig. 17-3, p. 359

20. Neuron Classes • There are two very important classes • Stress neurons • Maintenance neurons

21. Fight or Flight response • Stress neurons direct our fight or flight response • In situations that cause fear our stress neurons become very active • Triggers rapid onset of physiological changes • Mind becomes more alert • Air passages for nose and lungs increase • Heart beat increases • Nonessential activities like digestion stop

22. Epinephrine • Norepinepherine/epinephrine • Chemical signal of the flight or fight response • Medical relevant in instances of • cardiac arrest • Low blood pressure • Acute asthma • Extreme allergic reactions – anaphylactic shock

23. Maintenance • So the maintenance neurons control the other responses • Control the secretion of digestive fluids • Contraction of stomach and intestines • Slowed heart beat

24. 5 primary neurotransmitters • Norepinephrine – stress • Acetylcholine – maintenance • Dopamine – pleasure center of brain • GABA – inhibits nerve transmissions • Serotonin – blocks certain nerve impulses

25. Drugs Mimic Neurotransmitters • Most drugs mimic these neurotransmitters to create their effect

26. Drug doses • All drugs can be beneficial or harmful depending on the amount taken • The dose makes the poison • LD50 – the lethal dose for 50% of a population