抗病毒藥品
1. Herpes zoster (shingles), Genital herpes in immunocompetent (including HIV-infected) patients
2. Chickenpox in immunocompetent children
3. Herpes labialis (cold sores)

Antiviral Agent
Valacyclovir is rapidly and nearly completely converted to acyclovir by intestinal and hepatic metabolism. Acyclovir is converted to acyclovir monophosphate by virus-specific thymidine kinase then further converted to acyclovir triphosphate by other cellular enzymes.

1. Distribution: Acyclovir is widely distributed throughout the body including brain, kidney, lungs, liver, spleen, muscle, uterus, vagina, and CSF.
2. Excretion: Urine, primarily as acyclovir (89%)

Hypersensitivity to acyclovir or valacyclovir products.

B

Infant risk is minimal

Headache, nausea, abdominal pain, nasopharyngitis and anorexia, AST/SGOT level raised

Herpes zoster (shingles):
1g TID for 7 days
Herpes labialis (cold sores):
2g Q12H for 1 day; start at the earliest onset of symptoms
Genital herpes:
1. Initial episode: 1g BID for 10 days
2. Recurrent episode: 500 mg BID for 3 days

Chickenpox:
(Children 2 to 18 years) 20 mg/kg/dose TID for 5 days; maximum 1 g TID
Herpes labialis (cold sores):
(Children>12 years) Refer to adult dosing

Herpes zoster (shingles):
1. CrCl ≥50 mL/min: usual dose
2. CrCl 30-49 mL/min: 1 g Q12H
3. CrCl 10-29 mL/min: 1 g Q24H
4. CrCl <10 mL/min: 0.5 g Q24H
Herpes labialis (cold sores):
1. CrCl ≥50 mL/min: usual dose
2. CrCl 30-49 mL/min: 1 g Q12H for 1 day
3. CrCl 10-29 mL/min: 0.5 g Q12H for 1 day
4. CrCl <10 mL/min: single dose of 0.5g
5. Hemodialysis: give recommended renally adjusted dose after hemodialysis
Genital herpes:
Initial episode:
1. CrCl ≥30 mL/min: usual dose
2. CrCl 10-29 mL/min: 1 g Q24H
3. CrCl <10 mL/min: 0.5 g Q24H
Recurrent episode and suppressive therapy:
1. CrCl ≥30 mL/min or greater: usual dose
2. CrCl <30 mL/min: 0.5 g Q24H

No dosage adjustment necessary.