Antibiotics 3

Question 1

Mycobacteria

Answer 1

-slow growth
-low permeability
-lipid rich mycobacterial cell enevelope (waxy coat)
-resistant to drying and disinfectant
-bioactive - active and suppression of immune system

Question 2

Antimycobacterial Drugs

Answer 2

resistant to most antibiotics
-slow growth
-lipid-rich cell wall
-intracellular

TM of tuberculosis
-isoniazid: inh mycobacterial cell wall synthesis
-ethanmbutol: inh mycobacterial cell wall synthesis
-rifampin: inh RNA synthesis

Question 3

Fungal Infection

Answer 3

opportunistic pathogen
-surgery, TM of cancer, organ transplant, HIV, antibiotics overuse
common fungal pathogen - mycosis, dermatophyte, aflatoxin structural similarity to mammalian cells
-challenge for selective toxicity

Question 4

Amphotericin B

Answer 4

bactericidal
* Binds to ergosterol and increase cell wall permeability

Question 5

Azole

Answer 5

found in anti-dandruff
* Inhibit ergosterol synthesis by blocking fungal CYP450

Question 6

Echinocandins

Answer 6

Inhibit fungal glucan synthesis

Question 7

Antifungal Agents

Answer 7

• Polyene
• amphotericin B (natamycin); binds to ergosterol and increase cell wall permeability
• Pyrimidines
• flucytosine; thymidine synthesis inhibitors
• sig. resistance
• Azoles
• ketocon-; flucon-; micon- etc. ; ergosterol synthesis inhibitor
• CYP3A4 inhibitior
• Echinocandins (-fungins)
• caspo-, mica-, anidula-
• glucan synthesis (essential for intact fungal cell wall) inhibitor

Question 8

Antiviral Drugs

Answer 8

• Virus
• intracellular
• replication depends on synthetic processes of host cell

Question 9

Topical Antiviral Options for HSV

Answer 9

• Idoxuridine (nucleoside analogue)
• sig. corneal toxicity & poor ocular bioavailability
• Vidarabine (nucleoside analogue)
• limited accessibility, alternative for trifluridine hypersensitivity
• Trifluridine (thymidine synthetase inhibitor)
• drug of topical choice for HSV, less use than oral
• topical side effects common but generally well tolerated

Question 10

Oral Antiviral Options for HSV

Answer 10

• Acyclovir (DNA polymerase inhibitor)
• highly selective
• topical formulation not available in US
• oral formulation for both prophylactic and
  therapeutic use
  □ require higher dosage for HZV
• well tolerated
• Valacyclovir - prodrug of acyclovir w. improved
  bioavailability & longer t1/2
• Famciclovir - prodrug of penciclovir (long t1/2)
• Gancyclorvir (available as topical gel)