Antimicrobial Chemotherapy 5

Question 1

Name some anti-fungal drugs.

Answer 1

Polyenes: Amphoterican B, Nystatin.
Azoles: miconazole, ketoconazole, fluconazole.
Allylamines: Terbinafine
Echinocandins: Caspofungin, micafungin.

Question 2

Describe Anti-viral drugs.

Answer 2

All viral drugs are virustatic.
Many anti-viral drugs are nucleoside analogues which interfere with nucleic acid synthesis.

Question 3

Name some anti-viral drugs.

Answer 3

Aciclovir, Valaciclovir, Famciclovir.

Question 4

Describe the anti-HIV-drug; Zidovudine.

Answer 4

The first treatment for HIV.
A nucleoside analogue, interfering with the action of reverse transcriptase (slows replication of virus - doesn’t kill it).
Side effects: anaemic and neutropenia.

Question 5

Describe anti-viral resistance.

Answer 5

Genotypic analysis (i.e. sequencing of part of the viral genome) may help in choosing rational treatment in selected patients (e.g. in HIV infection, where the viral load is rising despite adherence to treatment).

Question 6

Explain how polyenes can treat fungal infections.

Answer 6

Polyenes bind to ergosterol, present in fungal (not bacterial) cell wall.
This increases the permeability.
These drugs can be toxic as they bind to other sterols (e.g. cholesterol).

Question 7

Explain how azoles can treat fungal infection.

Answer 7

Azoles work by inhibiting ergosterol synthesis.
These are used for the oral and parental treatment of yeast infections.

Question 8

Explain how allylamines can treat fungal infections.

Answer 8

Allylamines suppress ergosterol synthesis (at a different stage than azoles).
Mild infections are treated topically and more serious are treated orally.

Question 9

Explain how echinocandins can treat fungal infections.

Answer 9

Echinocandins inhibit the synthesis of glucan polysaccharides in several types of fungi.

Question 10

Name the drugs used to combat Chronic Hepatitis B and C.

Answer 10

Interferon A
Ribavirin
Adefovir dipivoxil / lamivudine (advantage being that these drugs are given orally).

Question 11

Explain interferon-A when combatting chronic hepatitis B and C.

Answer 11

Protein forms most of the hosts immune response.
Low response rate, high cost, serious side effects.

Question 12

Explain ribavirin when combatting chronic hepatitis B and C.

Answer 12

Oral Ribavirin is used in combination therapy with pegylated interferon-a.
This is the common initial treatment for chronic hepatitis C.

Question 13

Name some drugs used to treat viral respiratory infections.

Answer 13

Zanamivir
Oseltamivir
Ribavirin
Remdesivir

Question 14

Explain how zanamivir and oseltamivir treat infection.

Answer 14

Treatment for influenza A or B within 48 hours of the onset of the symptoms and for post-exposure prophylaxis.

Question 15

Explain how ribavirin is used to treat viral respiratory infections.

Answer 15

Occasionally used for treatment of severe RSV.
Respiratory Syncytial Virus infections.
must be inhaled as a fine spray to reach the site of infection in the lungs (administration is difficult).
Reduces mortality in a Lassa fever and is used in combination treatment for chronic hepatitis C.

Question 16

Explain how remdesivir is used to treat viral respiratory infections

Answer 16

Adenosine nucleoside triphosphate analogue, interfering with the action of viral RNA-dependant RNA polymerase.