How it is administered

Acyclovir is available in several forms for administration:

• Oral tablets and capsules: These are taken by mouth, with or without food. Common strengths include 200 mg, 400 mg, and 800 mg.
• Topical cream and ointment: These are applied directly to the skin on affected areas.
• Intravenous (IV) formulation: This is used in hospital settings for severe infections or for patients who cannot take oral medications.

For blood cancer patients, especially those with weakened immune systems, oral or IV forms may be used to prevent or treat viral infections.

How it works

Acyclovir is an antiviral medication that works by stopping the growth and spread of certain viruses, mainly herpes viruses. It is a synthetic nucleoside analogue, which means it mimics the building blocks of viral DNA. When acyclovir enters infected cells, it is converted into its active form by a viral enzyme called thymidine kinase. This active form then blocks the action of viral DNA polymerase, an enzyme the virus needs to replicate its genetic material.

By interfering with viral DNA synthesis, acyclovir prevents the virus from multiplying and spreading to new cells. This helps control the infection and allows the immune system to clear the virus more effectively. It does not cure viral infections, but it can reduce the severity and duration of symptoms, and in some cases, prevent outbreaks.

Who Should take it

Acyclovir is used to treat and prevent infections caused by herpes viruses, such as herpes simplex (causing cold sores and genital herpes), varicella-zoster (causing chickenpox and shingles), and sometimes for other related viruses.

For patients with blood cancers like Chronic Lymphocytic Leukemia (CLL), acyclovir may be prescribed to prevent or treat viral infections, especially if the immune system is weakened by the disease or its treatments. It is particularly important for immunocompromised patients, as they are at higher risk for severe or recurrent viral infections.

Who should not take it

Acyclovir should not be taken by anyone who has had a previous allergic reaction (hypersensitivity) to acyclovir or valacyclovir, or to any of the ingredients in the formulation.

Caution should be used in patients with kidney problems, as acyclovir is eliminated from the body through the kidneys. Dose adjustments may be needed for those with impaired kidney function. It is also important to discuss with your doctor if you are pregnant, planning to become pregnant, or breastfeeding before starting acyclovir.

Commonly used with

In patients with blood cancers, acyclovir may be used alongside chemotherapy, immunosuppressive drugs, or other antiviral medications to prevent or treat infections. It is sometimes given with medications like probenecid, which can increase acyclovir levels in the body, but this combination is used with caution and under medical supervision.

Commonly tested with

Acyclovir has been tested in combination with other antiviral agents (such as famciclovir, penciclovir, and foscarnet) in studies of viral resistance. In clinical practice for blood cancer patients, it may be given alongside other supportive care medications, but specific drug combinations should always be managed by your healthcare team.