Acyclovir Ointment

Name: Acyclovir Ointment

Overdose

Overdosage by topical application of ZOVIRAX Ointment 5% is unlikely because of limited transcutaneous absorption (see CLINICAL PHARMACOLOGY).

How is this medicine (Acyclovir Ointment) best taken?

Use this medicine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Use as you have been told, even if your signs get better.
  • Do not take acyclovir ointment by mouth. Use on your skin only. Keep out of your mouth, nose, and eyes (may burn).
  • Wash your hands before and after use.
  • Clean affected part before use. Make sure to dry well.
  • Put a thin layer on the affected skin and rub in gently.
  • Use a rubber glove to put on the ointment. This helps to prevent the spread of infection.

What do I do if I miss a dose?

  • Put on a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not put on 2 doses or extra doses.

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 to 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.

Clinical Trials

In clinical trials of initial genital herpes infections, Acyclovir Ointment 5% has shown a decrease in healing time and, in some cases, a decrease in duration of viral shedding and duration of pain. In studies in immunocompromised patients mainly with herpes labialis, there was a decrease in duration of viral shedding and a slight decrease in duration of pain.

In studies of recurrent genital herpes and of herpes labialis in nonimmunocompromised patients, there was no evidence of clinical benefit; there was some decrease in duration of viral shedding.

Warnings

Acyclovir Ointment 5% is intended for cutaneous use only and should not be used in the eye.

How is Acyclovir Ointment Supplied

Each gram of Acyclovir Ointment USP, 5% contains 50 mg acyclovir USP in a polyethylene glycol base. Acyclovir Ointment USP, 5% is a white to off-white translucent ointment. It is supplied as follows:

  NDC 68462-746-17 15 gram tubes (1 tube per carton)
NDC 68462-746-35 30 gram tubes (1 tube per carton)

Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [See USP Controlled Room Temperature].

Manufactured by:

Glenmark Pharmaceuticals Ltd.
Colvale-Bardez, Goa 403 513, India

Manufactured for:

Glenmark Pharmaceuticals Inc., USA
Mahwah, NJ 07430

Questions? 1 (888)721-7115
www.glenmarkpharma.com/usa

September 2016

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