Aciclovir is a widely used antiviral medication that belongs to the class of nucleoside analogues. This article covers Aciclovir, available as a generic medication and marketed under brand names such as Zovirax, ACV, and Denavir. It is primarily prescribed for the treatment of herpes simplex virus (HSV) infections and varicella-zoster virus (VZV) infections affecting the skin and mucous membranes. In Hong Kong, Aciclovir is classified as a prescription-only medication and is regulated by the Hong Kong Department of Health.
Aciclovir interferes with viral DNA synthesis, thereby limiting the ability of herpes viruses to replicate. After oral absorption, the drug is phosphorylated by a viral thymidine kinase, which is present only in infected cells. This selective activation concentrates the active form of Aciclovir within virus-infected tissues, reducing damage to healthy cells. The onset of action typically occurs within a few hours, with peak plasma concentrations reached around 1-2 hours after a dose. The drug’s half-life ranges from 2.5 to 3.3 hours in individuals with normal kidney function, allowing for regular dosing schedules.
Aciclovir is approved by regulatory agencies, including the U.S. FDA and the European EMA, for several indications that are also recognized in Hong Kong:
Typical patients include adults experiencing recurrent outbreaks, individuals with compromised immune systems, and those undergoing chemotherapy or organ transplantation. The medication is not indicated for unrelated viral infections such as influenza or COVID-19.
If any of these conditions apply, consultation with a healthcare professional is essential before initiating therapy.
These effects are generally transient and resolve without intervention. If a rash worsens or becomes widespread, medical evaluation is advised.
Patients should disclose all current medications, supplements, and herbal products to their prescriber.
| Indication | Initial Dose | Maintenance Dose | Maximum Daily Dose | ||--||--| | Initial HSV episode | 400 mg five times daily for 5 days | - | - | | Recurrent genital HSV | 400 mg three times daily for 5 days | - | - | | Herpes zoster | 800 mg five times daily for 7-10 days | - | - | | Suppression of genital HSV | 400 mg twice daily | - | - | | Renal impairment | Adjust according to creatinine clearance (e.g., 200 mg twice daily if CrCl < 30 mL/min) | - | - |
The available tablet strengths are 200 mg, 400 mg, and 800 mg.
If a dose is missed, take it as soon as remembered unless it is near the time of the next scheduled dose. Do not double the dose.
Symptoms may include vomiting, lethargy, or seizures. Seek immediate medical attention; supportive care and hydration are the mainstays of treatment. Hemodialysis can remove Aciclovir in severe cases.
Short courses typically do not require tapering. For long-term suppressive therapy, discuss discontinuation with a healthcare provider to assess the risk of recurrence.
Routine laboratory monitoring beyond renal assessment is generally not required for uncomplicated infections.
This article provides educational information about Aciclovir and is not a substitute for professional medical advice. Treatment decisions, including use for unapproved indications, must be made under the guidance of a qualified healthcare provider. The content is intended for informational purposes and does not constitute medical recommendations. Always consult a physician before starting, stopping, or changing any medication regimen.
Aciclovir specifically targets herpes viruses and does not affect the common cold, which is caused by rhinoviruses or other unrelated pathogens. Using Aciclovir for a cold would not provide therapeutic benefit.
When taken at the first sign of a cold sore, Aciclovir can shorten healing time by about 1-2 days compared with no treatment, typically resulting in lesion resolution within 5-7 days.
In Hong Kong, 200 mg tablets are generally smaller and may be scored for splitting, while 400 mg and 800 mg tablets are larger and often unscored. Imprint codes vary by manufacturer but are listed on the product packaging.
Aciclovir is not a prohibited substance in standard workplace or athletic drug screenings. It is not classified as a performance-enhancing or controlled drug.
Yes, Aciclovir is a prescription medication, so you should carry the original prescription label and a copy of the prescription. Some countries may require documentation, so check local regulations before travel.
Storing tablets in a bathroom where humidity fluctuates is not recommended. Keep them in a dry place at room temperature, such as a bedroom drawer or a medicine cabinet away from moisture.
Valacyclovir is converted to Aciclovir in the body and offers higher oral bioavailability, allowing for less frequent dosing. Both share the same antiviral mechanism but differ in pharmacokinetic profiles.
Aciclovir can be taken with or without food. If you experience mild gastrointestinal discomfort, taking the tablet with a small amount of food may help.
Reduced kidney function slows the elimination of Aciclovir, increasing the risk of toxicity. Dose reductions are based on creatinine clearance, and clinicians often monitor renal markers during therapy.
Yes, generic Aciclovir tablets contain the same active ingredient, strength, and meet the same quality standards as brand-named products such as Zovirax. They are considered therapeutically equivalent.
