Available dosages of oral antivirals

• Acyclovir: 200mg cap, 400 mg and 800mg tabs
• Valtrex: 500 or 1000 mg tabs
• Famvir: 125, 250 & 500 mg tabs

In general, when prescribing oral antivirals, use caution in renal impairment. The drug is excreted through the renal system, so you need to know a patient's creatinine clearance to decide on the dosage in patients with poor kidney function. Work with a physician to titrate drugs from there. Adverse reactions include GI upset, headache, dizziness, and abdominal pain. All are pregnancy Category C except Famvir which is Category B.

Acyclovir for the treatment of Herpes simplex lid lesions is 400mg 5x/day. The dosage for Herpes zoster is 800mg 5x/day. The dosage for the prevention of corneal stromal herpetic disease is 400mg BID (according to HEDS Study).

Oral Acyclovir

Oral acyclovir is a very well tolerated medication and does so much good for patients. It plays a significant role in preventing long-term complications and minimizing course of disease. It gets the patient better faster. Oral acyclovir hastens resolution of signs and symptoms, reduces viral shedding and formation of new skin lesions, and decreases both the incidence and severity of ocular complications. It also reduces the corneal complications (e.g., dendritic keratitis, stromal keratitis, and anterior uveitis).

The main side effect is intestinal disturbance such as nausea and vomiting. Dr. Grogg, who treats a lot of herpes patients, recalls only one patient in the past 10 years who complained about the drug.

	Herpes simplex Signs and symptoms include lip, nose (especially nares), and lid lesions. The lesions are localized and vesicular with intense pain and erythematous base. Vesicles rupture to ragged shallow ulcers. LEFT: Typical herpes patient . . . big blister on lower lid and other lesions in crusting stage. Even though the lesions have crusted, he's still actively spreading Herpes virus because of the active blister. This patient certainly needs oral meds. Would Dr. Grogg put him on a topical? Maybe not since his eye is so white and quiet. If he had lid lesions and conjunctivitis, she would put him on Viroptic ophthalmic solution 4 times a day. When treating these patients, keep in mind that topical Viroptic is about $180 for a bottle, so it's less pricey for the patients if you can get the job done with just orals.
	This patient's simplex lid lesion was wrongly treated at a walk-in clinic as hordeoli. The patient subsequently developed Herpes simplex keratitis (HSK). The rate of recurrence of HSK is 80 percent. Dr. Grogg believes in aggressive treatment for H. simplex.
	Herpes zoster Pain prior to the onset of the rash is very common and often misdiagnosed. The ideal scenario is to catch these patients in the first 72 hours of developing zoster lesions. It is a misconception that H. zoster doesn't happen in young people . . . . Or, if it does happen, they have AIDS. It is not the case. Zoster is very common in young people. Dr. Grogg commonly sees it in college students. A typical college student is stressed, doesn't get enough sleep, and doesn't eat well. This sets the perfect environment for his/her immune system to be stressed and, thus, the student develops Herpes zoster. Dr. Grogg cites a specific example of zoster occuring in a young person. A 4-year-old female patient presented with Herpes zoster. The young patient's mother was pregnant, and apparently the little girl was rather stressed due to the anticipated arrival of a her baby brother! LEFT: Patient with Herpes zoster.
	NEI Herpetic Eye Disease Study Acyclovir Prevention Trial Recurrence rate of any form of ocular herpes was significantly lower in the acyclovir group (19%) than placebo group (32%). This represents a reduction by 41%. Rate of recurrence of stromal keratitis was reduced from 28% to 14%--a 50% reduction. Oral acyclovir 400 mg BID x 1 year was used. This dosage is highly recommended if a patient has more than one recurrence per year. After that, treatment is up to the doctor and patient.

What we are trying to prevent when treating herpes: stromal keratitis and neovascularization. Herpetic disease is one of the top five reasons why patients end up with penetrating keratoplasty procedure.

If compliance is an issue because of the 5-times-a-day dosage schedule of acyclovir, one can consider Valtrex or Famvir. Valtrex is well tolerated and has the same general side effects as other antivirals.

Valtrex (prodrug of acyclovir) is used to treat Herpes simplex and Herpes zoster. For Herpes simplex, a common dosage for a first occurrence is 500 mg TID x 7 days. Recurrent cases: 500 mg TID x 5 days. For treatment of Herpes labialis (cold sores around mouth): 2g BID x 1day. Herpes zoster is treated with 1 gram TID x 7 days. The cost of Valtrex can be lessened by prescribing the less expensive 1000 mg tablets and instructing patients to snap them in half. An easy way to remember treatment for simplex versus zoster is that simplex treatment is half of zoster treatment.

Cost of Antivirals [2007]

• Acyclovir 800 mg 5x day x 7 days = $15.06
• Valacyclovir (Valtrex) 1 gr TID x 7days = 238.46
• Famciclovir (Famvir) 500 mg TID x 7days = $230.25

Until recently, Valtrex was moderately priced and Famvir was so much more expensive. Valtrex cost has risen dramatically in the past few years. So, talk to your patient. If he/she has a copay and is OK with the cost, then Valtrex may be your drug of choice because of the ease in dosing. The downside of acyclovir is the 5x/day dose, but if patients can do that, there is no reason not to prescribe acyclovir.