Charles River CD (Sprague-Dawley) rats were given suspensions of Aciclovin by gavage. There were 50 male and 50 female rats at each of the following dose levels: 0, 50, 150 and 450 mg/kg. After 30 and 52 weeks of treatment, 10 male and 10 female rats from each group were necropsied. The remaining rats were dosed each day until natural mortality decreased a group size to approximately 20% of the number of animals of that sex present in the test groups when the study was started. All remaining rats were killed and necropsied when the 20% cut-off point was reached. This was during week 110 for the male rats and week 122 for the female rats. Tissues from control rats and those in the high-dose group were evaluated by light microscopy. Tissues from rats in the low and mid-dose groups having masses, nodules or unusual lesions were also examined by light microscopy. Fixed tissues from rats that were found dead during the first 52 weeks of the study were also evaluated by light microscopy.
No signs of toxicosis were observed. Plasma samples were collected 1.5 hours after dosing on days 7, 90, 209, 369, 771 (males only) and 852 (females only). Mean plasma levels found in high-dose males (450 mg/kg/day) at the times indicated above were as follows: 1.54, 1.63, 1.39, 1.60 and 1.70 μg/mL (6.84, 7.26, 6.17, 7.10 and 7.56 μM). Corresponding mean plasma levels for the high-dose females for the corresponding time periods were 1.76, 2.38, 2.12, 1.71 and 1.81 μg/mL (7.82, 10.58, 9.44, 7.62 and 8.03 μM). Plasma levels in both males and females at all dose levels after one year of treatment were generally comparable to plasma levels obtained at earlier samplings. Values for laboratory tests including hematology, clinical chemistry and ophthalmoscopy were all within the normal range. There were no drug-induced gross or microscopic lesions and there was no evidence that Aciclovin affected survival.
Why is this medication prescribed?
Aciclovin is used to decrease pain and speed the healing of sores or blisters in people who have varicella (chickenpox), herpes zoster (shingles; a rash that can occur in people who have had chickenpox in the past), and first-time or repeat outbreaks of genital herpes (a herpes virus infection that causes sores to form around the genitals and rectum from time to time). Aciclovin is also sometimes used to prevent outbreaks of genital herpes in people who are infected with the virus. Aciclovin is in a class of antiviral medications called synthetic nucleoside analogues. It works by stopping the spread of the herpes virus in the body. Aciclovin will not cure genital herpes and may not stop the spread of genital herpes to other people.
An overdose of Aciclovin can cause kidney damage.
Symptoms of an overdose may include:
- Extreme sleepiness
- Loss of consciousness
- Kidney failure (no urine production)
If you think that you or someone else has overdosed, call a poison control center at 1-800-222-1222.
If you or someone else has any severe symptoms after an overdose, call 9-1-1.
Q: I am in stage 1 of multiple myeloma. I was diagnosed nearly 3 years ago. The last 3 summers I have had attacks of shingles, the 1st year I took 1000 mg of Aciclovin daily and avoided the painful stage. Last year I missed the spots as they were on my back and suffered greatly for 2 to 3 months and I am still taking 1000 mg Aciclovin per day. Each time I stop the medication the fever returns for a couple of days followed by the first few spots. I am on my 5th lot of Aciclovin, starting with 1000 mg per day, increasing to 2,400 per day and 2 weeks ago was prescribed 4000 mg per day for 21 days. I have managed 10 days at this level but there are so many side effects, including kidney pain, so I have reduced to 3 tablets of 800 mg each. I feel less "in a fog" and slightly better already but am afraid when I stop the shingles will return. I am concerned about the side effects. Can you give me advice please? The side effects are basically 90% of the ones mentioned on the leaflet in the box of 800 mg tablets at 5 per day.
A: Shingles is a painful rash that is caused by the same virus (varicella virus) that causes the chickenpox. Only people who were infected with the virus and got chickenpox can get shingles. Unfortunately, people with weakened immune systems, from other diseases like cancer or treatments like chemotherapy, are at much greater risk of developing shingles. Drugs like Aciclovin (Zovirax) work to reduce the ability of the virus to multiply and spread in the body. Aciclovin has been shown to reduce the duration of infection and the severity of symptoms, but it relies on an individual's immune system to attack the virus. The drug itself does not kill the virus and that is likely the reason you continue to have symptoms and relapses. It is possible that some of the painful effects you are experiencing are the result of complications of shingles. One of these complications is called postherpetic neuralgia, which is the painful, tingling, and stinging pain at the site of the initial rash. There are medications that are used to help treat the pain associated with the nerve damage of shingles. These drugs include the anticonvulsants, such as Neurontin (gabapentin), Lyrica (pregabalin), and Tegretol (carbamazepine) and tricyclic antidepressants like Elavil (amitriptyline). For more specific information, consult with your doctor or pharmacist for guidance based on your health status and current medications, particularly before taking any action. Michelle McDermott, PharmD
What special dietary instructions should I follow?
Drink plenty of fluids while you are taking or using Aciclovin.
More common side effects
Some of the more common side effects of Aciclovin oral tablet include:
Is Aciclovin safe to take if I'm pregnant or breastfeeding?
There are no adequate studies of Aciclovin in pregnant women. In a patient registry of women who used Aciclovin during the first trimester, the rate of birth defects was similar to the rate of birth defects in the general population.
Aciclovin is excreted in breast milk, and a significant amount may be transferred to the infant.
Aciclovin side effects
Get emergency medical help if you have any signs of an allergic reaction to Aciclovin: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
easy bruising or bleeding, purple or red pinpoint spots under your skin; or
signs of a kidney problem -little or no urinating; painful or difficult urination; swelling in your feet or ankles; feeling tired or short of breath.
Common Aciclovin side effects may include:
general ill feeling;
mouth pain while using an Aciclovin buccal tablet.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What Is Aciclovin (Zovirax)?
Aciclovin is the generic name for Zovirax, a prescription medication used to treat certain virus infections.
The Food and Drug Administration (FDA) approved Aciclovin to treat viral infections from the varicella virus that causes chicken pox and shingles, as well as infections from the virus that causes genital herpes.
Sometimes doctors prescribe Aciclovin to treat herpes infections in people with HIV.
The drug works by preventing viruses from dividing and multiplying. The FDA approved Aciclovin in the 1980s.
Aciclovin is available as a generic, made by several companies, or under the brand name Zovirax, made by GlaxoSmithKline and available in tablet, capsule, and liquid form.
Aciclovin is one of the oldest drugs used to treat herpes simplex viruses and remains the first line of treatment for these infections.
However, research shows that Aciclovin is not as effective as it used to be.
A 2013 study, published in the journal Current Opinion in Infectious Diseases, found that Aciclovin-resistant herpes strains could develop over time.
Resistance happens in people with a healthy immune system as well as in those with a weakened immune system.
Aciclovin can make your skin more sensitive to the sun. This increases your risk of sunburn. Avoid the sun if you can. If you can’t, be sure to wear protective clothing and apply sunscreen.
Dosage Forms, Composition And Packaging
Suspension: Each teaspoonful (5 mL) of ZOVIRAX® Suspension contains 200 mg Aciclovin and the non-medicinal ingredients banana flavour, cellulose, glycerin, methylparaben, propylparaben, sorbitol, vanillin, and water.
Tablets: Each ZOVIRAX® 200 Tablet contains 200 mg Aciclovin and the non-medicinal ingredients cellulose, indigotine, lactose, magnesium stearate, povidone, and sodium starch glycolate.
ZOVIRAX® Suspension is available in bottles of 125 mL* and 475 mL. Each teaspoonful (5 mL) of off-white, banana-flavoured suspension contains 200 mg Aciclovin.
*125 mL bottle not available in Canada
ZOVIRAX® 200 Tablets are available in bottles of 100 tablets. Each blue, shield-shaped, bevel-edged, compressed tablet contains 200 mg Aciclovin, and is imprinted with “ZOVIRAX” on one side and a triangle on the reverse.
GlaxoSmithKline Inc., 7333 Mississauga Road, Mississauga, Ontario, L5N 6L4 1-800-387-7374. Revised: November 10, 2014
For management of a suspected drug overdose, contact your regional Poison Control Centre.
Activated charcoal may be administered to aid in the removal of unabsorbed drug. General supportive measures are recommended.
Aciclovin is only partly absorbed in the gastrointestinal tract. Patients have ingested up to 20 g Aciclovin on a single occasion, with no unexpected adverse effects. In clinical studies, the highest plasma concentration observed in a single patient at these doses was 10.0 μg/mL. Accidental, repeated overdoses of oral Aciclovin over several days have been associated with gastrointestinal effects (such as nausea and vomiting) and neurological effects (headache and confusion).
Intravenous doses administered to humans have been as high as 1,200 mg/m² (28 mg/kg) 3 times daily for up to 2 weeks. Peak plasma concentrations have reached 80 μg/mL. Overdosage of intravenous Aciclovin has resulted in elevations of serum creatinine, blood urea nitrogen and subsequent renal failure. Neurological effects including confusion, hallucinations, agitation, seizures and coma have been described in association with intravenous overdosage.
Patients should be observed closely for signs of toxicity. Hemodialysis significantly enhances the removal of Aciclovin from the blood and may, therefore be considered a management option in the event of symptomatic overdose. Precipitation of Aciclovin in renal tubules may occur if the solubility (2.5 mg/mL) in the intratubular fluid is exceeded. In the event of renal failure and anuria, the patient may benefit from hemodialysis until renal function is restored (see DOSAGE AND ADMINISTRATION).
For patients who require hemodialysis, the mean plasma half-life of Aciclovin during hemodialysis is approximately 5 hours. This results in a 60% decrease in plasma concentrations following a six-hour dialysis period. Therefore, the patient's dosing schedule should be adjusted so that an additional dose is administered after each dialysis.
Other uses for this medicine
Aciclovin is also sometimes used to treat eczema herpeticum (a skin infection caused by the herpes virus) to treat and prevent herpes infections of the skin, eyes, nose, and mouth in patients with human immunodeficiency virus (HIV), and to treat oral hairy leukoplakia (condition that causes hairy white or gray-colored patches on the tongue or inside of the cheek).
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.
- The dosage of ZOVIRAX® (Aciclovin) should be reduced in patients with impaired renal function.
- Therapy should be initiated as soon as possible after a diagnosis of chickenpox or herpes zoster, or at the first sign or symptoms of an outbreak of genital herpes.
- The recommended dose and duration of use is dependent on the indication.