Acyclovir

What is Acyclovir?

Acyclovir is a prescription antiviral medication widely used to manage infections caused by the herpes simplex virus (HSV), such as genital herpes, cold sores, and shingles.

As a synthetic nucleoside analogue, it is manufactured through chemical synthesis to mimic the building blocks of DNA. This structure integrates into the viral DNA chain, interfering with the replication process and hindering the virus from multiplying.

Generic Names:

• Acyclovir: The widely recognised generic name used in the United States and many international markets.
• Aciclovir: The alternative spelling and British Approved Name (BAN) widely used in the United Kingdom, Hong Kong, and across Europe.

Global Brand Names:

Acyclovir is distributed globally under several prominent brand names.

• Zovirax: The original and most widely recognised brand name for acyclovir across many global markets.
• Sitavig: A prominent brand name often associated with specific tablet formulations.

These names all refer to the same medication. It is important to note that while the active ingredient is the same globally, different countries may have different regulations and available medication formulations.

What is Acyclovir used for?

Acyclovir is used to relieve:

• Genital herpes infections.
• Cold sores caused by the herpes simplex virus.
• Shingles (herpes zoster).
• Chickenpox (varicella-zoster virus).
• Epstein-Barr virus infections.
• Cytomegalovirus (CMV) infection in transplant patients (as a preventative measure).

How do you use Acyclovir?

Availability:

• Oral forms including tablets, capsules, and suspension.
• Dermatologic skin cream.
• Ophthalmic eye ointment.
• Injectable solution for intravenous use.

Suitability:

• Adults: Yes, following prescribed dosages.
• Children: Yes, with paediatric dosages determined by a doctor.
• Elderly: Yes, though dosage adjustments may be necessary for kidney function.
• Pregnant women: Yes, generally safe to use as directed by your physician (US FDA category B drug).
• Nursing mothers: Yes, generally safe to use as directed by your physician.

Dosage Information:

• Adults (Genital Herpes): Initial treatment is typically 200 mg taken five times a day by mouth for 10 days, or 400 mg three times a day for 7-10 days. Consult a professional for recurrent infections.
• Adults (Shingles): 800 mg taken five times a day by mouth for 7-10 days.
• Adults (Cold Sores): 400 mg taken 3 times daily by mouth for 5-10 days.
• Adults (Chickenpox): Acute treatment requires 800 mg 5 times daily by mouth for 7-10 days.
• Children: Paediatric dosages are determined by a doctor based on weight and age.
• Elderly: May require dosage adjustments due to kidney function considerations.

Who cannot take Acyclovir?

• Those with hypersensitivity to acyclovir or valacyclovir.
• Those with certain pre-existing conditions as advised by a healthcare provider.
• Anyone with a known allergy to acyclovir or any ingredients in the formulation.

Allergies and unsuitability:

• Rare, but possible severe allergic reactions to acyclovir or valacyclovir.

Warnings and precautions:

• Stay hydrated to prevent kidney issues.
• Take with or without food, but consistency can help reduce stomach upset.
• Do not touch or rub eyes after applying acyclovir cream to a skin lesion to prevent eye infection.

Interactions and contraindications:

• Check with a doctor if taking other nephrotoxic drugs, as it may have additive effects.
• Avoid concurrent use with drugs affecting kidney function without medical supervision.

Conditions where the drug should not be used:

• Known hypersensitivity to acyclovir.
• Known hypersensitivity to valacyclovir.

Common side effects of acyclovir may include nausea, diarrhoea, and headaches. These are generally mild and are a typical physiological response to the medication.

Severe side effects can include kidney problems and allergic reactions. It is essential to stay hydrated during treatment to help prevent kidney-related issues. If severe reactions occur, consult a healthcare professional.

Warnings and precautions:

• Stay hydrated to prevent kidney issues.
• Take with or without food, but consistency can help reduce stomach upset.
• Do not touch or rub eyes after applying acyclovir cream to a skin lesion to prevent eye infection.

Interactions and contraindications:

• Check with a doctor if taking other nephrotoxic drugs, as it may have additive effects.
• Avoid concurrent use with drugs affecting kidney function without medical supervision.

Conditions where the drug should not be used:

• Known hypersensitivity to acyclovir.
• Known hypersensitivity to valacyclovir.

Storage information:

• Store at room temperature.
• Keep away from moisture and light.

Handling instructions:

• Wash hands immediately after topical application.
• Do not touch or rub eyes after applying acyclovir cream to a skin lesion.
• Use a proper measuring device for liquid suspensions to ensure accurate dosing.

Where is Acyclovir available in Hong Kong?

Acyclovir is classified as a Prescription Only Medicine in Hong Kong. This means that a patient must present a valid doctor's prescription to purchase it.

It can be legally obtained at registered pharmacies displaying an "Rx" logo under the direct supervision of a registered pharmacist, or it can be dispensed directly by healthcare providers at medical clinics and hospitals.