Acyclovir is intended for oral ingestion only. Renal failure, in some cases resulting in death, has been observed with acyclovir therapy (see ADVERSE REACTIONS: Observed During Clinical Practice and OVERDOSAGE:).
Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), which has resulted in death, has occurred in immunocompromised patients receiving acyclovir therapy.
Acyclovir is a synthetic nucleoside analogue active against herpesviruses.
Each teaspoonful (5 mL) of acyclovir oral suspension, USP, for oral administration, contains 200 mg of acyclovir and the inactive ingredients artificial banana flavor, carboxymethylcellulose sodium, glycerin, methylparaben 0.1% (added as a preservative), microcrystalline cellulose, propylparaben 0.02% (added as a preservative), purified water, and sorbitol.
Acyclovir is a white, crystalline powder with the molecular formula C8H11N5O3 and a molecular weight of 225. The maximum solubility in water at 37°C is 2.5 mg/mL. The pka’s of acyclovir are 2.27 and 9.25.
The chemical name of acyclovir is 2-amino-1,9-dihydro-9-[(2-hydroxyethoxy)methyl]- 6H-purin-6-one; it has the following structural formula:
VIROLOGY:
Mechanism of Antiviral Action:
Acyclovir is a synthetic purine nucleoside analogue with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV).
The inhibitory activity of acyclovir is highly selective due to its affinity for the enzyme thymidine kinase (TK) encoded by HSV and VZV. This viral enzyme converts acyclovir into acyclovir monophosphate, a nucleotide analogue. The monophosphate is further converted into diphosphate by cellular guanylate kinase and into triphosphate by a number of cellular enzymes. In vitro, acyclovir triphosphate stops replication of herpes viral DNA. This is accomplished in 3 ways: 1) competitive inhibition of viral DNA polymerase, 2) incorporation into and termination of the growing viral DNA chain, and 3) inactivation of the viral DNA polymerase. The greater antiviral activity of acyclovir against HSV compared with VZV is due to its more efficient phosphorylation by the viral TK.
Antiviral Activities:
The quantitative relationship between the in vitro susceptibility of herpes viruses to antivirals and the clinical response to therapy has not been established in humans, and virus sensitivity testing has not been standardized. Sensitivity testing results, expressed as the concentration of drug required to inhibit by 50% the growth of virus in cell culture (IC50), vary greatly depending upon a number of factors. Using plaque-reduction assays, the IC50 against herpes simplex virus isolates ranges from 0.02 to 13.5 mcg/mL for HSV-1 and from 0.01 to 9.9 mcg/mL for HSV-2. The IC50 for acyclovir against most laboratory strains and clinical isolates of VZV ranges from 0.12 to 10.8 mcg/mL. Acyclovir also demonstrates activity against the Oka vaccine strain of VZV with a mean IC50 of 1.35 mcg/mL.
Drug Resistance:
Resistance of HSV and VZV to acyclovir can result from qualitative and quantitative changes in the viral TK and/or DNA polymerase. Clinical isolates of HSV and VZV with reduced susceptibility to acyclovir have been recovered from immunocompromised patients, especially with advanced HIV infection. While most of the acyclovir-resistant mutants isolated thus far from immunocompromised patients have been found to be TK-deficient mutants, other mutants involving the viral TK gene (TK partial and TK altered) and DNA polymerase have been isolated. TK-negative mutants may cause severe disease in infants and immunocompromised adults. The possibility of viral resistance to acyclovir should be considered in patients who show poor clinical response during therapy.
Acyclovir Suspension | Physicians Total Care, Inc.
Acute Treatment of Herpes Zoster:
800 mg every 4 hours orally, 5 times daily for 7 to 10 days.
Genital Herpes:
Treatment of Initial Genital Herpes:
200 mg every 4 hours, 5 times daily for 10 days.
Chronic Suppressive Therapy for Recurrent Disease:
400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with acyclovir oral suspension.
Intermittent Therapy:
200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
Treatment of Chickenpox:
Children (2 years of age and older):
20 mg/kg per dose orally 4 times daily (80 mg/kg per day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
Adults and Children over 40 kg:
800 mg 4 times daily for 5 days.
Intravenous acyclovir oral suspension is indicated for the treatment of varicellazoster infections in immunocompromised patients.
When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.
Patients With Acute or Chronic Renal Impairment:
In patients with renal impairment, the dose of acyclovir oral suspension should be modified as shown in Table 3:
Table 3: Dosage Modification for Renal Impairment
Normal Dosage Regimen
Creatinine
Clearance (mL/min/1.73 m2)
Adjusted Dosage Regimen
Dose
(mg)
Dosing Interval
200 mg every 4 hours
> 10
0-10
200
200
every 4 hours, 5x daily
every 12 hours
400 mg every 12 hours
> 10
0-10
400
200
every 12 hours
every 12 hours
800 mg every 4 hours
> 25
10-25
0-10
800
800
800
every 4 hours, 5x daily
every 8 hours
every 12 hours
Hemodialysis:
For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Peritoneal Dialysis:
No supplemental dose appears to be necessary after adjustment of the dosing interval.
Acyclovir Suspension | Hi-tech Pharmacal Co., Inc.
Acute Treatment of Herpes Zoster:
800 mg every 4 hours orally, 5 times daily for 7 to 10 days.
Genital Herpes:
Treatment of Initial Genital Herpes:
200 mg every 4 hours, 5 times daily for 10 days.
Chronic Suppressive Therapy for Recurrent Disease:
400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with acyclovir oral suspension.
Intermittent Therapy:
200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
Treatment of Chickenpox:
Children (2 years of age and older):
20 mg/kg per dose orally 4 times daily (80 mg/kg per day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
Adults and Children over 40 kg:
800 mg 4 times daily for 5 days.
Intravenous acyclovir oral suspension is indicated for the treatment of varicellazoster infections in immunocompromised patients.
When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.
Patients With Acute or Chronic Renal Impairment:
In patients with renal impairment, the dose of acyclovir oral suspension should be modified as shown in Table 3:
Table 3: Dosage Modification for Renal Impairment
Normal Dosage Regimen
Creatinine
Clearance (mL/min/1.73 m2)
Adjusted Dosage Regimen
Dose
(mg)
Dosing Interval
200 mg every 4 hours
> 10
0-10
200
200
every 4 hours, 5x daily
every 12 hours
400 mg every 12 hours
> 10
0-10
400
200
every 12 hours
every 12 hours
800 mg every 4 hours
> 25
10-25
0-10
800
800
800
every 4 hours, 5x daily
every 8 hours
every 12 hours
Hemodialysis:
For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Peritoneal Dialysis:
No supplemental dose appears to be necessary after adjustment of the dosing interval.
Acyclovir Suspension | Preferred Pharmaceuticals, Inc.
Acute Treatment Of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days.
Genital Herpes:Treatment Of Initial Genital Herpes: 200 mg every 4 hours, 5 times daily for 10 days.
Chronic Suppressive Therapy For Recurrent Disease: 400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with acyclovir.
Intermittent Therapy: 200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
Treatment Of Chickenpox:Children (2 Years Of Age And Older): 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
Adults And Children Over 40 kg: 800 mg 4 times daily for 5 days.
Intravenous acyclovir is indicated for the treatment of varicella-zoster infections in immunocompromised patients.
When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.
Patients With Acute Or Chronic Renal Impairment:In patients with renal impairment, the dose of Acyclovir Oral Suspension should be modified as shown in Table 3:
Table 3: Dosage Modification for Renal Impairment
Normal Dosage Regimen
Creatinine Clearance (mL/min/1.73m2)
Adjusted Dosage Regimen
Dose (mg)
Dosage Interval
200 mg every 4 hours
>10
0-10
200
200
every 4 hours, 5 x daily every 12 hours
400 mg every 12 hours
>10
0-10
400
200
every 12 hours every 12 hours
800 mg every 4 hours
>25
10-25
0-10
800
800
800
every 4 hours, 5 x daily every 8 hours every 12 hours
Hemodialysis: For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Peritoneal Dialysis: No supplemental dose appears to be necessary after adjustment of the dosing interval.
Bioequivalence Of Dosage Forms: Acyclovir oral suspension was shown to be bioequivalent to acyclovir capsules (n = 20) and 1 acyclovir 800-mg tablet was shown to be bioequivalent to 4 acyclovir 200-mg capsules (n = 24).
Acute Treatment of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days.
Genital Herpes: Treatment of Initial Genital Herpes: 200 mg every 4 hours, 5 times daily for 10 days.
Chronic Suppressive Therapy for Recurrent Disease: 400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with acyclovir.
Intermittent Therapy: 200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
Treatment of Chickenpox: Children (2 Years Of Age And Older): 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
Adults and Children Over 40 kg: 800 mg 4 times daily for 5 days.
Intravenous acyclovir is indicated for the treatment of varicella-zoster infections in immunocompromised patients.
When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.
Patients With Acute or Chronic Renal Impairment: In patients with renal impairment, the dose of acyclovir oral suspension should be modified as shown in Table 3:
Table 3: Dosage Modification for Renal Impairment
Creatinine
Adjusted Dosage Regimen
Normal
Clearance
Dose
Dosage Regimen
(mL/min/1.73m2)
(mg)
Dosage Interval
200 mg every 4 hours
>10
200
every 4 hours, 5 x daily
0-10
200
every 12 hours
400 mg every 12 hours
>10
400
every 12 hours
0-10
200
every 12 hours
800 mg every 4 hours
>25
800
every 4 hours, 5 x daily
10-25
800
every 8 hours
0-10
800
every 12 hours
Hemodialysis: For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Peritoneal Dialysis: No supplemental dose appears to be necessary after adjustment of the dosing interval.
Bioequivalence of Dosage Forms: Acyclovir oral suspension was shown to be bioequivalent to acyclovir capsules (n = 20) and 1 acyclovir 800-mg tablet was shown to be bioequivalent to 4 acyclovir 200-mg capsules (n = 24).
800 mg every 4 hours orally, 5 times daily for 7 to 10 days.
Genital Herpes:
Treatment of Initial Genital Herpes:
200 mg every 4 hours, 5 times daily for 10 days.
Chronic Suppressive Therapy for Recurrent Disease:
400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with acyclovir oral suspension.
Intermittent Therapy:
200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
Treatment of Chickenpox:
Children (2 years of age and older):
20 mg/kg per dose orally 4 times daily (80 mg/kg per day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
Adults and Children over 40 kg:
800 mg 4 times daily for 5 days.
Intravenous acyclovir oral suspension is indicated for the treatment of varicellazoster infections in immunocompromised patients.
When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.
Patients With Acute or Chronic Renal Impairment:
In patients with renal impairment, the dose of acyclovir oral suspension should be modified as shown in Table 3:
Table 3: Dosage Modification for Renal Impairment
Normal Dosage Regimen
Creatinine
Clearance (mL/min/1.73 m2)
Adjusted Dosage Regimen
Dose
(mg)
Dosing Interval
200 mg every 4 hours
> 10
0-10
200
200
every 4 hours, 5x daily
every 12 hours
400 mg every 12 hours
> 10
0-10
400
200
every 12 hours
every 12 hours
800 mg every 4 hours
> 25
10-25
0-10
800
800
800
every 4 hours, 5x daily
every 8 hours
every 12 hours
Hemodialysis:
For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Peritoneal Dialysis:
No supplemental dose appears to be necessary after adjustment of the dosing interval.
800 mg every 4 hours orally, 5 times daily for 7 to 10 days.
Genital Herpes:
Treatment of Initial Genital Herpes:
200 mg every 4 hours, 5 times daily for 10 days.
Chronic Suppressive Therapy for Recurrent Disease:
400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with acyclovir oral suspension.
Intermittent Therapy:
200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
Treatment of Chickenpox:
Children (2 years of age and older):
20 mg/kg orally 4 times daily (80 mg/kg per day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox. per dose
Adults and Children over 40 kg:
800 mg 4 times daily for 5 days.
Intravenous acyclovir oral suspension is indicated for the treatment of varicellazoster infections in immunocompromised patients.
When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.
Patients With Acute or Chronic Renal Impairment:
In patients with renal impairment, the dose of acyclovir oral suspension should be modified as shown in Table 3:
Table 3: Dosage Modification for Renal Impairment
Normal Dosage Regimen
Creatinine
Clearance (mL/min/1.73 m ) 2
Adjusted Dosage Regimen
Dose
(mg)
Dosing Interval
200 mg every 4 hours
> 10
0-10
200
200
every 4 hours, 5x daily
every 12 hours
400 mg every 12 hours
> 10
0-10
400
200
every 12 hours
every 12 hours
800 mg every 4 hours
> 25
10-25
0-10
800
800
800
every 4 hours, 5x daily
every 8 hours
every 12 hours
Hemodialysis:
For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Peritoneal Dialysis:
No supplemental dose appears to be necessary after adjustment of the dosing interval.
Acute Treatment of Herpes Zoster: 800 mg every 4 hours orally, 5 times daily for 7 to 10 days.
Genital Herpes: Treatment of Initial Genital Herpes: 200 mg every 4 hours, 5 times daily for 10 days.
Chronic Suppressive Therapy for Recurrent Disease: 400 mg 2 times daily for up to 12 months, followed by re-evaluation. Alternative regimens have included doses ranging from 200 mg 3 times daily to 200 mg 5 times daily.
The frequency and severity of episodes of untreated genital herpes may change over time. After 1 year of therapy, the frequency and severity of the patient’s genital herpes infection should be re-evaluated to assess the need for continuation of therapy with Acyclovir.
Intermittent Therapy: 200 mg every 4 hours, 5 times daily for 5 days. Therapy should be initiated at the earliest sign or symptom (prodrome) of recurrence.
Treatment of Chickenpox: Children (2 years of age and older): 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox.
Adults and Children over 40 kg: 800 mg 4 times daily for 5 days.
Intravenous Acyclovir is indicated for the treatment of varicella-zoster infections in immunocompromised patients.
When therapy is indicated, it should be initiated at the earliest sign or symptom of chickenpox. There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms.
Patients With Acute or Chronic Renal Impairment: In patients with renal impairment, the dose of Acyclovir Capsules, Tablets, or Suspension should be modified as shown in Table 3.
Table 3. Dosage Modification for Renal Impairment
Normal Dosage Regimen
Creatinine Clearance (mL/min/1.73 m2)
Adjusted Dosage Regimen
Dose (mg)
Dosing Interval
200 mg every 4 hours
>10
200
every 4 hours, 5x daily
0-10
200
every 12 hours
400 mg every 12 hours
>10
400
every 12 hours
0-10
200
every 12 hours
800 mg every 4 hours
>25
800
every 4 hours, 5x daily
10-25
800
every 8 hours
0-10
800
every 12 hours
Hemodialysis: For patients who require hemodialysis, the mean plasma half-life of acyclovir during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a 6-hour dialysis period. Therefore, the patient’s dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Peritoneal Dialysis: No supplemental dose appears to be necessary after adjustment of the dosing interval.
Bioequivalence of Dosage Forms: Acyclovir Suspension was shown to be bioequivalent to Acyclovir Capsules (n = 20) and 1 Acyclovir 800-mg tablet was shown to be bioequivalent to 4 Acyclovir 200-mg capsules (n = 24).