Antiviral Agent: Acyclovir Powder for Injection 500 mg contains the active ingredient acyclovir, a potent synthetic nucleoside analog with strong antiviral activity against herpesviruses.
Formulation: It is supplied as a lyophilized (freeze-dried) powder that requires reconstitution with a suitable diluent (e.g., Sterile Water for Injection) before it can be administered intravenously (IV).1
High Dose: The 500 mg strength is a common dose used in hospital settings for treating severe viral infections, allowing for the delivery of a higher concentration of the drug.
Selectivity: Acyclovir is highly selective for infected cells, as it is converted to its active form only within cells infected by herpesviruses, minimizing its effect on healthy host cells.2
Advantages
High Systemic Concentration: Intravenous administration achieves much higher and more reliable systemic drug levels than oral forms, which is crucial for managing severe or life-threatening infections.
Rapid Onset: The injectable form provides a rapid onset of antiviral action, which is essential for managing serious herpesvirus infections, such as encephalitis or disseminated disease.
Efficacy in Severe Cases: The injectable form is considered the standard of care for serious herpesvirus infections, including herpes simplex encephalitis, severe neonatal herpes, and disseminated varicella zoster virus infections.
Well-Tolerated: The drug has a well-established safety profile, and its use in a hospital setting allows for close monitoring to manage potential side effects.
Uses
Severe Herpes Simplex Infections: Primarily used for severe mucocutaneous herpes simplex virus (HSV) infections in immunocompromised patients and for initial and recurrent genital herpes in the same population.
Herpes Simplex Encephalitis: It is the standard treatment for herpes simplex encephalitis, a life-threatening viral infection of the brain that requires urgent and high-dose therapy.3
Neonatal Herpes: Indicated for the treatment of neonatal herpes, which can be disseminated and life-threatening, requiring prompt and effective antiviral intervention.4
Varicella Zoster Virus (VZV) Infections: Used for severe infections caused by VZV, such as disseminated zoster in immunocompromised patients or complicated chickenpox (e.g., pneumonia).5
Nature
Synthetic Guanosine Analog: Acyclovir is a synthetic analog of the nucleoside guanosine, one of the four building blocks of DNA.6
Mechanism of Action: In infected cells, viral thymidine kinase converts acyclovir to its monophosphate form.7 Host enzymes further convert this to the active acyclovir triphosphate, which then competitively inhibits viral DNA polymerase, leading to the termination of the viral DNA chain.
Inhibition of Viral Replication: By terminating viral DNA synthesis, acyclovir effectively blocks the replication of the herpesvirus, but it does not completely eradicate the virus from the body.8
Pharmacokinetic Profile: Following IV infusion, acyclovir is widely distributed throughout the body, including into the cerebrospinal fluid, which is essential for treating CNS infections like encephalitis.
Storage
Unreconstituted Powder: The powder for injection should be stored at controlled room temperature, typically between 20∘C to 25∘C (68∘F to 77∘F).
Protection: Keep the vial in its original packaging, protected from light and moisture.
Reconstitution & Immediate Use: The powder must be reconstituted with the specified diluent before use. The reconstituted solution must be further diluted for infusion and used within a specific time frame (e.g., 12 hours) to maintain its stability.
Avoid Freezing: The reconstituted solution should not be frozen or refrigerated as precipitation may occur. Any unused portion must be discarded safely.
