Anti-Infective Medications Used in Eyecare Part 2 Flashcards
Exam 2
What are the common viruses encountered in eye care?
Adenovirus Herpes Virus (Simplex/Zoster/CMV)
What does adenovirus cause?
Conjunctivitis and EKC (Epidemic Keratoconjunctivitis)
What are the most common serotypes of adenovirus that cause EKC?
8, 19, 37
What medications are approved for the treatment of adenovirus?
None currently
What is the effect of topical corticosteroids on EKC?
It delays viral shedding and enhances adenovirus replications. This makes things worse
What is the rule of 8’s for adenovirus infection?
First 8 days: White and quiet, virus is replicating and the patient is contagious
Second 8 days: Patient is miserable, eyes are often not symmetrical and pseudomembranes are formed
Third 8 days: Infiltrates are present confirming EKC
What is a common treatment for EKC? When is it most effective?
Off label use of Povidone-iodine (Betadine)
It is most effective when the virus is replicating. This is a problem because patients are asymptomatic while the virus replicates! (First 8 days!)
What is the Melton and Thomas protocol for Betadine usage to treat EKC?
- Anesthetize both eyes with proparacaine
- Instill 2-3 drops betadine and have patient roll eyes around to enhance distribution
- Rub lid margins to kill any resident virus
- Flush betadine out (Irrigate, Irrigate, Irrigate)
What is the MOA of anti-herpetic drugs?
Inhibit cellular metabolism in infected cells
When are anti-herpetic drugs most effective?
When the virus is replicating (first 3 days)
What are the topical anti-herpetic drugs?
Trifluridine 0.1% solution
Zirgan 0.15% gel
What are the oral anti-herpetic drugs?
Acyclovir
Valacyclovir
Famciclovir
How do oral anti-herpetic drugs differ from one another?
Acyclovir has been the drug of choice for a long period of time, but it has poor bioavailability and short half-life.
Valacyclovir is a prodrug of acyclovir and has a bioavailability that is 3-5 times higher than acyclovir
Famciclovir is 100x less potent than acyclovir but has a better half-life than acyclovir.
What are the adverse effects of anti-herpetic medications?
Burning/redness/blur (topical (blur specific to ointment))
Headache/nausea
Which anti-herpetic drug should be used with caution in patients with HIV? Why?
Valacyclovir, due to risk of vascular issues
What was the HEDs 1 study about? What were the results?
HEDs 1 dealt with more severe herpetic disease like stromal keratitis.
Outcome 1:
Using corticosteroids with a topical antiviral resulted in fewer treatment failures and faster resolution of stromal keratitis.
Outcome 2:
No benefit of the addition of oral acyclovir to a current regimen consisting of a topical steroid and topical antiviral
Outcome 3:
Adding oral acyclovir to topical steroid and trifluridine has a benefit when treating iridocyclitis
What was the HEDs 2 study about? What were the results?
HEDs 2 delt with epithelial keratitis and recurrence of HSV epithelial keratitis.
Outcome 1:
No benefit of oral acyclovir to topical trifluridine in preventing the development of stromal keratitis from epithelial keratitis
Outcome 2:
Oral acyclovir reduced the incidence of epithelial keratitis and stromal keratitis by 41% and 50% reduction in the return rate of more severe forms of keratitis while taking oral acyclovir
Outcome 3:
No significant behavioral factors associated with recurrence of HSV
Explain how to treat HSV epithelial keratitis.
When active replication is occurring, a dendritic lesion may be apparent. Antiviral medication should be used to reduce replication and spread of the virus. Avoid topical steroids!
Explain how to treat HSV stromal keratitis.
Use topical steroid with oral antiviral to balance immune response reduction with antiviral therapy
Explain how to treats HSV endothelial keratitis.
A topical steroid with oral antiviral is preferred.
What are some scenarios that would warrant the use of antivirals for prophylaxis? (4)
- Multiple recurrences of any type, especially stromal
- Recurrent inflammation approaching visual axis
- More than one episode of HSV with ulceration
- History of ocular HSV during immunosuppressive treatment
What are three prophylaxis treatment options with antivirals?
- Acyclovir 400mg BID x 1 year +
- Valacyclovir 500mg QD x 1 year +
- Famciclovir 250mg BID x 1 year+
What is the treatment of choice for CMV retinitis?
CMV retinitis is the most common opportunistic eye infection in persons with AIDs/Immunocompromised transplant patients
Treat with Ganciclovir Insert
Valganciclovir
Foscarnet
What are the indications for Viroptic (trifluridine)?
HSV keratoconjunctivitis
HSV epithelial keratitis
What is the adult dose of Viroptic (trifluridine)?
1gtt q2h while awake until reepithelization
1gtt q4h while awake x 7 days
What is the minimum dose of Viroptic (trifluridine) after reepithelization in adults? What is the max dose of Viroptic after reepithelialization in adults? ?
Min: 5 gtt/eye/day
Max: 9gtt/eye/day x 21 days
Dosage is same in kids
What is the age limit for Viroptic (trifluridine)?
Must be >6 years
What is the preservative of Viroptic (trifluridine)?
Thimerosal, which is toxic to the cornea
What is the indication for Zirgan (gancyclovir)?
Acute HSV keratitis
What is the adult dose of Zirgan (gancyclovir)?
5x/day until reepithelization
TID x 7 days after reepithelization
What is the age limit for Zirgan (gancyclovir)?
2 years
same dose as adults
What is the preservative of Zirgan (gancyclovir)?
BAK, less toxic than Viroptic (trifluridine)
What are the indications for Zovirax (acyclovir)?
HSV keratitis
HSV prophylaxis
HZO
What are the adult dosages of Zovirax (acyclovir) for HSV? HZO?
HSV: 400mg 5 times per day x 7-10 days
HZO: 800mg 5 times per day x 7-10 days
What is the dosage of Zovirax (acyclovir) for HSV prophylaxis?
400mg BID x 12 months
When must you administer Zovirax (acyclovir) when treating zoster?
Within 72 hours of rash onset
What are the indications for Valtrex (valacyclovir)?
HSV keratitis
HSV prophylaxis
HZO
What are the adult dosages for Valtrex (valacyclovir) when treating HSV? HZO?
HSV: 500mg TID x 7-10 days
HZO: 1000mg TID x 7-10 days
What is the HSV prophylaxis dosage of Valtrex (valacyclovir)?
500-1000mg daily
What are the indications for Famvir (famciclovir)?
HSV keratitis
HSV prophylaxis
HZO
What are the dosages of Famvir (famciclovir) for HSV? HZO?
HSV: 250mg TID x 7-10 days
HZO: 500mg TID x 7-10 days
What is the prophylaxis dosage of Famvir (famciclovir)?
125-250mg BID
What are the indications for Valcyte (valganciclovir)?
CMV retinitis (AIDS-Association)
What is the dosage of Valcyte (valganciclovir)?
900mg BID for a week and then 900mg daily
What is the age limit for Valcyte (valganciclovir)?
1 month and older depending on condition
What are the indications of Foscavir (foscarnet)?
Acyclovir resistant mucocutaneous HSV/HZO/CMV retinitis, AIDS-association
What is the dosage for Foscavir (foscarnet)?
90mg BID for a week and then 90-120 mg/kg daily (through IV)
What are the fungi that are encountered in eye care?
Yeast: Candida
Molds: Aspergillus, Fusarium, Curvularia
What are a few predisposing factors for fungal infection?
CL wear
Topical steroids
Trauma
Immunocompromised
What are the specific antifungal drugs we need to know?
Natamycin
Amphotericin B
Ketoconazole tabs
Fluconazole tabs
What is the MOA for natamycin?
Creates pores in cell membranes
What are the indications of natamycin?
Fungal keratitis
Fungal blepharitis
Fungal conjunctivitis
What is the only approved topical antifungal agent?
Natamycin 5%
What is Ketoconazole used for?
Severe fungal corneal ulcers
What is Fluconazole used for?
Severe fungal corneal ulcers?
What is the most common protozoa encountered in eye care?
Acanthamoeba
What medications are approved to treat acanthamoeba?
None, you must treat with compounded drugs
What are the three treatments for acanthamoeba?
PHMB: Pool cleaner
Chlorohexidine: Surgical scrub
Propamidine isethionate: Disinfectant
All are disinfectants
