Antivirals, Antifungals & Antiprotozoans

Question 1

antiviral agents are designed to do what?

Answer 1

inhibit viral replication or proliferation

Question 2

enveloped or non-enveloped:

can stay on surfaces longer without the fear of drying out

Answer 2

nonenveloped

Question 3

enveloped or nonenveloped:

can be killed with alcohol, hydrogen peroxide, chlorine, etc.

Answer 3

enveloped

Question 4

what are some examples of enveloped viruses?

Answer 4

• herpesvirus
• retrovirus
• coronavirus

Question 5

what are some examples of nonenveloped viruses?

Answer 5

adenovirus & parvovirus

Question 6

what virus is a cold virus that is the most common cause of eye infections? what kind of eye infections does it cause?

Answer 6

adenovirus → highly infectious conjunctivitis and/or keratitis

Question 7

which serotype of adenovirus is the most common cause of epidemic keratoconjunctivitis (EKC)?

Answer 7

adenovirus 8

Question 8

what is the incubation period of adenovirus 8?

Answer 8

~8 days

Question 9

on days 8-16, what signs appear in an adenovirus 8 infection?

Answer 9

conjunctivitis & fine SPK

Question 10

in an adenovirus 8 infection, what appears on day 8?

Answer 10

focal epithelial keratitis

Question 11

in an adenovirus 8 infection, 8 days after day 8, what sign(s) appears?

Answer 11

subepithelial infiltrates

Question 12

what is the treatment for EKC?

Answer 12

no FDA-approved treatment → normally self-resolving

- palliative care & good hygiene

Question 13

what are some clinical findings in EKC?

Answer 13

follicles, palpable PA node, pseudomembranes

Question 14

what treatment is not FDA approved, but can be used to treat EKC?

Answer 14

Betadine protocol (povidone-iodine)

Question 15

which virus is the most common virus of the human body & why?

Answer 15

herpesvirus → resides in nerve ganglia for life

Question 16

purines or pyrimidines?

two-carbon nitrogen ring bases used to produce DNA/RNA nucleotides adenine & guanine

Answer 16

purines

Question 17

purines or pyrimidines?

one-carbon nitrogen ring bases that are used to produce DNA/RNA nucleotides thymine/uracil & cytosine

Answer 17

pyrimidines

Question 18

what antiviral agents are commonly used to treat herpes (simplex & keratitis)?

Answer 18

purine & pyrimidine analogs

Question 19

trifluridine (Viroptic) 1% topical solution is what type of antiviral agent?

Answer 19

pyrimidine analog

Question 20

what is trifluridine uniquely preserved with?

Answer 20

thimerosal 0.001%

Question 21

what is the treatment regimen for herpesvirus with trifluridine 1% (Viroptic)?

Answer 21

1 gtt q2h until re-epithelialized → 1gtt q4h x 7 additional days

Question 22

what is the maximum recommended use for trifluridine 1% & why?

Answer 22

21 days because it is very destructive to the cornea

Question 23

what kind of antiviral agent is ganciclovir?

Answer 23

purine analog

Question 24

what is the treatment regimen with ganciclovir 0.15% (Zirgan) for HSV keratitis?

Answer 24

1gtt 5x/day until healing → 1gtt TID x 7d (or it can come back)

Question 25

why is ganciclovir preferred over trifluridine for HSV keratitis?

Answer 25

less corneal toxicity

Question 26

ganciclovir has cross-resistance with which antiviral agent?

Answer 26

acyclovir

Question 27

what class of antiviral agents is acyclovir?

Answer 27

purine analog

Question 28

what is the therapy regimen for HSK with acyclovir?

Answer 28

400mg PO 5x/d x 7d

Question 29

what is the therapy regimen for HZK with acyclovir?

Answer 29

800mg PO 5x/day x 7-10 days

Question 30

when is it most important to treat HZK & why?

Answer 30

the first 72 hours to prevent postherpetic neuralgia

Question 31

out of all the purine analogs, which has the poorest GI absorption?

Answer 31

acyclovir

Question 32

which antiviral agent is a prodrug of acyclovir & what class is it?

Answer 32

valacyclovir → purine analog

Question 33

what is the therapy regimen for HSK with valacyclovir?

Answer 33

500mg PO TID x 7-10d

Question 34

what is the therapy regimen for HZK with valacyclovir?

Answer 34

1000mg PO TID x 7-10d

Question 35

valacyclovir has cross-sensitivity with which antiviral agent?

Answer 35

acyclovir

Question 36

which antiviral agent is better suited for deeper infections such as stromal keratitis?

Answer 36

valacyclovir

Question 37

which antiviral agent is a penciclovir prodrug with extended plasma life? what class is it?

Answer 37

famciclovir → purine analog

Question 38

what is the therapy regimen for HSK with famciclovir?

Answer 38

250mg TID x 7-10d

Question 39

what is the therapy regimen for HZK with famciclovir?

Answer 39

500 mg TID x 7-10d

Question 40

when someone is allergic to acyclovir or valacyclovir, what antiviral agent can they use?

Answer 40

famciclovir

Question 41

what are the ocular sequelae of viral infections?

Answer 41

blepharitis, conjunctivitis, epithelial & stromal keratitis, uveitis, retinitis, acute retinal necrosis (in severe cases)

Question 42

what are the two types of fungi that can cause fungal infections

Answer 42

- budding unicellular yeasts | - branching filamentous molds

Question 43

what ocular structures are involved in fungal infections?

Answer 43

cornea, conjunctiva, lens, ciliary body, vitreous body, uvea

Question 44

what are the two types of yeast that can cause ocular involvement in an infection?

Answer 44

candida, cryptococcus

Question 45

what are the three types of molds that can cause ocular involvement in an infection?

Answer 45

aspergillus, fusarium, curvularia

Question 46

what can enhance the risk of a fungal infection?

Answer 46

- CL wear - steroids - trauma (including LASIK) - immunocompromised

Question 47

which class of antifungals work by increase membrane permeability?

Answer 47

polyenes

Question 48

what are the two polyenes & what do they treat?

Answer 48

- amphotericin B (yeasts = nonfilamentous) | - natamycin (mold = filamentous)

Question 49

which polyene is the only FDA approved topical?

Answer 49

natamycin

Question 50

are there any adverse reactions with polyenes?

Answer 50

amphotericin B can cause renal toxicity (esp. with IV)

Question 51

what class of antifungals inhibits DNA synthesis?

Answer 51

pyrimidines

Question 52

name a drug that is a pyrimidine, & what is its MOA?

Answer 52

flucytosine → inhibits thymidine synthesis

Question 53

is flucytosine fungistatic or fungicidal?

Answer 53

fungistatic

Question 54

what are the adverse reactions of flucytosine?

Answer 54

bone marrow toxicity & hepatotoxicity

Question 55

what class of antifungals inihibit protein synthesis? what is their MOA?

Answer 55

azoles → impair ergosterol synthesis & inhibit some cytochrome P450 enzymes which may reduce metabolism of other drugs

Question 56

what class of antifungals are these? - ketoconazole - fluconazole - posaconazole - voriconazole - itraconazole - miconazole

Answer 56

azoles

Question 57

which two azoles can cause hepatotoxicity?

Answer 57

ketoconazole & fluconazole

Question 58

what class of antifungals are cell wall inhibitors? what is their MOA?

Answer 58

echinocandins → inhibit glucan synthese which weakens cell walls

Question 59

what are some echinocandins?

Answer 59

casofungin, micafungin, anidulafungin

Question 60

why do echinocandins have less risk of hepatotoxicity?

Answer 60

because they are not metabolized by the liver

Question 61

which classes of antifungals have developing resistance?

Answer 61

pyrimidines & azoles

Question 62

what is one of the most common soil or waterborne protozoa?

Answer 62

acanthamoeba

Question 63

which organism is responsible for the most virulent form of infectious keratitis & has the worst prognosis? what type of organism is it?

Answer 63

acanthamoeba - protozoa

Question 64

most acanthamoeba keratitis cases are caused by what?

Answer 64

CL wear > trauma

Question 65

what medical therapy can be used to for acanthamoeba infections? give some examples

Answer 65

topical biguanides qh-q3h x 3-4wks - polyhexamethylene biguanide 0.02% (PHMB) - bisbiguanide 0.02% (chlorhexidine)

Question 66

what has similar presentation as an acanthamoeba infection?

Answer 66

topical anesthetic abuse syndrome

Question 67

what protozoal infection comes from poorly cooked food, unwashed vegetables, exposure to cat feces?

Answer 67

toxoplasmosis gondii infection

Question 68

- sulfadiazine + pyrimethamine (Sulfadoxine) - sulfamethoxazole + trimethoprim (Bactrim) - clindamycin - spiramycin these are all used to treat what?

Answer 68

acute toxoplasmosis infections

Question 69

what can you use to treat latent toxoplasmosis infections?

Answer 69

atovaquone & clindamycin