Antiviral Agent: Acyclovir is a synthetic nucleoside analog with highly selective and potent antiviral activity against herpes simplex virus (HSV) and varicella-zoster virus (VZV).
Sterile Powder for Injection: The 250 mg formulation is a sterile, lyophilized powder contained in a vial. It is intended for intravenous infusion after being reconstituted and diluted.
Intravenous Administration: The injectable form is used for treating severe or life-threatening herpesvirus infections, where high plasma concentrations of the drug are required rapidly.
Prophylactic and Therapeutic Use: It can be used for both the treatment of active infections and for prophylaxis to prevent the recurrence of infections in high-risk, immunocompromised patients.
Advantages
High Bioavailability: The intravenous route bypasses the oral absorption process, ensuring 100% bioavailability. This allows for therapeutic drug concentrations to be reached quickly in the blood and central nervous system.
Effective for Severe Infections: It is the preferred and often only effective treatment for serious infections like herpes simplex encephalitis and neonatal herpes, where oral medication would be insufficient.
Use in Immunocompromised Patients: The injectable form is critical for treating severe VZV infections (shingles) and mucocutaneous HSV infections in immunocompromised patients, where the disease is more likely to be disseminated and life-threatening.
Improved Compliance: The injectable route is essential for patients who are unconscious, unable to swallow, or have severe gastrointestinal issues that would prevent the absorption of oral medication.
Uses
Herpes Simplex Encephalitis: The primary indication is for the treatment of herpes simplex encephalitis, a severe and life-threatening infection of the brain.
Neonatal Herpes Infections: It is used to treat both localized and disseminated herpes simplex virus infections in newborns.
Severe Varicella-Zoster (Shingles): Indicated for the treatment of severe or disseminated shingles, especially in immunocompromised patients.
Prophylaxis: It is used for the prophylaxis of cytomegalovirus (CMV) infections in bone marrow transplant recipients.
Nature
Synthetic Guanosine Analog: Acyclovir is a synthetic analog of the naturally occurring nucleoside, guanosine.
Mechanism of Action: Acyclovir is a prodrug that is converted to its active triphosphate form primarily by viral thymidine kinase. This active form then inhibits viral DNA polymerase, leading to the termination of the viral DNA chain.
Selective Toxicity: The selective activation by the viral enzyme is a key feature of acyclovir. It has very little effect on host cellular enzymes, which is why it is highly effective against the virus with minimal harm to human cells.
Renal Excretion: Acyclovir is primarily eliminated from the body unchanged by the kidneys. Therefore, dose adjustments are necessary for patients with renal impairment.
Storage
Temperature: The unopened vials should be stored at a controlled room temperature, typically between 20∘C to 25∘C (68∘F to 77∘F).
Reconstitution: The powder must be reconstituted with sterile water for injection. The reconstituted solution must be further diluted for intravenous infusion.
Administration: The diluted solution should be administered as a slow intravenous infusion over a period of one hour to prevent renal toxicity and precipitation of the drug in the kidney tubules.
Shelf Life: The reconstituted solution should be used within a specific time frame, typically 12 hours, though this may vary by manufacturer. It should be discarded if it appears discolored or contains particulate matter.
