Acyclovir

Acyclovir is active against herpes viruses (in order of potency): HSV-l, HSV-2, VZV, Epstein-Barr virus (EBV). It has minimal activity against cytomegalovirus (CMV).

Oral acyclovir is effective for primary and recurrent genital HVS. In primary genital HSV, oral acyclovir 400 mg po tid or 200 mg po q 6 h for 10 days shortens the clinical course, reduces pain, and decreases viral shedding. For episodic recurrences, acyclovir 200 mg q 4 h should be started at first sign of infection. Suppression is more efficacious and should be considered if a patient has more than six outbreaks of genital HSV a year. Adverse effects are infrequent with oral administration, but nausea, vomiting, diarrhea, headache, and rashes have been reported. Dose should be adjusted for renal insufficiency. Patients who have frequent outbreaks may require higher doses. If patients are resistant to acyclovir, alternatives such as foscarnet may be tried.

IV acyclovir is indicated when a higher serum level of drug is required, as in herpes encephalitis. It reduces mortality and improves functional capacity of survivors. The best response is in younger patients who begin therapy before onset of coma. In neonatal herpes infections, acyclovir 30 mg/kg day IV divided q 8 h for 10 to 14 days is more effective than vidarabine and requires less fluid for administration. Adverse effects include phlebitis, rash, and neurotoxicity resulting in lethargy, confusion, seizures, or coma.

Depending on extent of disease and host immune status, either IV or oral acyclovir is effective in primary varicella. It reduces complications of varicella in immunocompromised patients and pregnant women. In immunocompetent adults, oral acyclovir may reduce duration of fever and vesicles. For herpes zoster, 800 mg po 5 times/day has been shown to reduce the time to healing of lesions and, particularly in older patients, the prevalence of postherpetic neuralgia. Acyclovir is also effective in reducing complications of herpes zoster ophthalmicus.

Exercise 3. True or false. Make the false statements true:

1. Acyclovir can be used to treat herpes virus infections.

2. Acyclovir can be used both orally and in injections.

3. Acyclovir is used for nausea, vomiting, diarrhea, headache.

4. In patients with kidney problems, acyclovir is not indicated.

5. Acyclovir is used together with foscarnet.

6. In severe brain infections acyclovir is administered intravenously.

7. Acyclovir can reduce the complications of smallpox.

Exercise 4. What do the abbreviations stand for:

IV po tid q h mg kg

three times daily milligram every kilogram intravenous hour orally

Exercise 5. Write out the diseases mentioned in the text.

Is acyclovir effective for all of them?

Exercise 6. Match a phrase in A with a phrase in B to make statements:

A	B
Acyclovir is effective	nausea, vomiting, diarrhea, headache.
Acyclovir is recommended when	require special attention when treated with acyclovir.
Side effects of acyclovir include	foscarnet may be tried.
Patients with renal diseases	acyclovir shortens the duration of treatment.
If acyclovir is ineffective	the patient has more than six attacks of genital infection a year.
In herpes zoster	for herpes virus infections

Exercise 7. What questions should be asked to restore the missing information:

1. Acyclovir is active against ___.

2. The drug is administered for ___ days.

3. Acyclovir is started ___.

4. Adverse effects may include ___.

5. ___ is given when the patient is resistant to the drug.

6. In patients with chickenpox Acyclovir reduces ___.

Exercise 8. Read the text and fill in the gaps: