What is Acyclovir (Zovirax) and what is it used for?
Acyclovir is a drug from the nucleoside group with antiviral properties, which is used for the treatment and prevention of infections caused by the following diseases:
- Herpes simplex virus types 1 and 2;
- Inflammation of the brain due to herpetic infection (herpetic encephalitis);
- Chicken pox virus
Herpes simplex virus causes genital herpes, labial herpes, brain inflammation due to herpetic infection (herpetic encephalitis), herpes simplex keratitis, shingles, herpes zoster, and chicken pox.
Generic Acyclovir is the equivalent of Zovirax. It is important to note that this prescription-only medication can also be used for other viral infections, as directed by your doctor.
Acyclovir: mechanism of action
The active ingredient Acyclovir penetrates virus-infected cells, is selectively activated by the specified viral enzyme, and is incorporated into the virus genome. Because of its chemical structure, no additional building block can be attached to the filamentous genome of the virus.
The result is what is known as “chain breaking” in genetic replication. The incomplete genetic material of the virus cannot be encapsulated, which means that new viruses cannot develop.
In addition, Acyclovir blocks the viral enzyme DNA polymerase, which is essential for the replication of the viral genome.
Acyclovir is not activated in uninfected cells, so severe side effects of the drug are rare.
How long does it take for Acyclovir to work?
Acyclovir generic taken orally is very poorly absorbed in the small intestine (about 10-30 percent).
Acyclovir 400 mg begins to take effect 24-48 hours after starting to take it. It may take 4-5 days for an obvious reduction in symptoms.
The half-life of the drug is relatively short, just less than three hours. From 75 to 80% of the drug is excreted by the kidneys unchanged. In acute infections, the drug is usually used only for a few days.
In special groups of patients, the dose of Acyclovir 400 mg may need to be adjusted. In elderly patients, it is significant to consider the possibility of renal impairment. It's especially important to have sufficient fluid intake during treatment. In children with renal insufficiency, the dose should be adjusted according to the complexity of the renal impairment.
Acyclovir: dose for cold sore
The recommended dose for adult patients with shingles (herpes zoster). Take 2 tablets of Acyclovir 400 mg 5 times a day at intervals of four hours.
Genital herpes. Take 400 mg orally every 8 hours for 7-10 days.
Prevention of genital herpes recurrence. Adults: 200 – 400 mg Acyclovir, 2 – 5 times daily for five days or up to 1 year, depending on how often the infection occurs.
Experience in the treatment of Acyclovir overdose is limited. However, increased side effects should be expected. In case of overdose, it is especially critical to observe hydration in order to reduce the likelihood of crystal formation in the urine. If necessary, the active ingredient should be removed from the bloodstream by hemodialysis. The main symptoms of overdose are nausea, vomiting, diarrhea, and severe headache.
Can you take Acyclovir long-term?
As a rule, a treatment period of up to 10 days is sufficient for effective treatment of the virus. However, to prevent recurrent outbreaks of genital herpes, your doctor may prescribe longer treatment, up to 12 months.
Acyclovir: side effects
The most common side effects of Acyclovir therapy include headaches, dizziness, and upset stomach, and skin reactions can also occur.
The following side effects can occur during therapy:
- Common: Dizziness, headache, nausea, vomiting, diarrhea, abdominal pain, itching, rash.
- Occasionally: urticaria, hair loss, fatigue, fever, burning or tingling on treated skin areas, skin flaking, hemoglobin or red blood cell count.
If any long-term adverse reactions occur, you should consult a physician.
What are Acyclovir interactions?
No clinically important interaction of Acyclovir with other drugs and means has been identified. However, when using Acyclovir tablets, there may be a minor interaction with the following active ingredients: Probenecid, Cimetidine, Theophylline, Lithium, Cyclosporine, Tacrolimus.
Acyclovir and alcohol
No interaction of Acyclovir with alcohol has been found, so taking a small amount of alcohol during treatment with the drug is acceptable. Please note that taking an excessive dose of alcohol can lead to severe poisoning. It is not recommended to abuse alcohol.
Acyclovir (Zovirax) should not be taken if you are hypersensitive to the active ingredient or any element of the medicine you are taking.
There is no evidence that Acyclovir impairs fertility. It should only be used during pregnancy if the benefit to the mother far outweighs the risk to the fetus.
Caution should be exercised when prescribing Acyclovir during breastfeeding, because the drug enters the breast milk, and through the milk penetrates into the body of the child. It is recommended to refrain from breastfeeding during therapy with Acyclovir 400 tablets.
No studies have examined the ability to drive or operate machinery during therapy with Acyclovir. At this time, there are no reported cases of effects of the medication on physical reactions of the body.
Acyclovir: over the counter
Acyclovir over the counter is available at our pharmacy. To avoid adverse reactions if you interact with other medicines you are taking, contact our pharmacists. Specialists will advise you on the possibility of using the medicine in each case.read more