Differences between valtrex and acyclovir

Active Ingredients

Valtrex (Zelitrex, Valaciclovir, Valacyclovir) is a prodrug, which gets transformed into acyclovir in the body. Acyclovir is also known as Aciclovir, acycloguanosine, ACV, Cyclovir, Herpex, Acivir, Acivirax, Zovirax, Aciclovir, and Zovir.

Both of these medications are used to treat the symptoms of herpes simplex and herpes zoster infections in the body. So, these medications contain different active ingredients. Acyclovir contains acyclovir, and Valtrex contains Valacyclovir (the prodrug of acyclovir).

Dosage

Acyclovir is usually prescribed as 200, 400, or 800mg tablets. Patients suffering from herpes zoster usually have to take 800mg of acyclovir, 5 times a day for 7 to 10 days. Genital herpes is treated with a 200mg dose, every 4 hours of the day, also for 10 days.

Valtrex can be found in 500mg or 1g tablets. Cold sores are treated with 2g of Valtrex, 2 times for one day. Genital herpes requires 1g, 2 times a day for 10 days. Recurrent genital herpes is treated differently – the therapy lasts for 3 days, and the patient should use 500mg of Valtrex, 2 times a day.

Treatment

The difference between acyclovir and Valtrex is in the condition they are prescribed for. While Valtrex is used to treat regular herpes virus infections, acyclovir is usually the option for recurrent infections. This shouldn’t be understood as the rule because doctors can prescribe any of these medications whenever they think it is necessary.

Herpes zoster ophthalmicus affects the eye and vision, and is caused by the reactivation of the varicella zoster virus in the distribution of the first division of the trigeminal nerve. An aggressive management of acute herpes zoster ophthalmicus with systemic antiviral medication is generally recommended as the standard first?line treatment for herpes zoster ophthalmicus infections. Both acyclovir and its prodrug valacyclovir are medications that are approved for the systemic treatment of herpes zoster. Although it is known that valacyclovir has an improved bioavailability and steadier plasma concentration, it is currently unclear as to whether this leads to better treatment results and less ocular complications.

We considered all randomised controlled trials (RCTs) in which systemic valacyclovir was compared to systemic acyclovir medication for treatment of herpes zoster ophthalmicus.
Two review authors independently selected trials, evaluated the risk of bias in included trials, and extracted and analysed data. We did not conduct a meta?analysis, as only one study was included. We assessed the certainty of the evidence for the selected outcomes using the GRADE approach.
One study fulfilled the inclusion criteria. In this multicentre, randomised double?masked study carried out in France, 110 immunocompetent people with herpes zoster ophthalmicus, diagnosed within 72 hours of skin eruption, were treated, with 56 participants allocated to the valacyclovir group and 54 to the acyclovir group. The study was poorly reported and we judged it to be unclear risk of bias for most domains.
Persistent ocular lesions after 6 months were observed in 2/56 people in the valacyclovir group compared with 1/54 people in the acyclovir group (risk ratio (RR) 1.93 (95% CI 0.18 to 20.65); very low certainty evidence. Dendritic ulcer appeared in 3/56 patients treated with valacyclovir, while 1/54 suffered in the acyclovir group (RR 2.89; 95% confidence interval (CI) 0.31 to 26.96); very low certainty evidence), uveitis in 7/56 people in the valacyclovir group compared with 9/54 in the acyclovir group (RR 0.96; 95% CI 0.36 to 2.57); very low certainty evidence).
Similarly, there was uncertainty as to the comparative effects of these two treatments on post?herpetic pain, and side effects (vomiting, eyelid or facial edema, disseminated zoster). Due to concerns about imprecision (small number of events and large confidence intervals) and study limitations, the certainty of evidence using the GRADE approach was rated as low to very low for the use of valacyclovir compared to acyclovir.

✓ Fact confirmed: Valacyclovir versus acyclovir for the treatment of herpes zoster ophthalmicus in immunocompetent patients Alexander K. Schuster, Björn C. Harder, Frank C. Schlichtenbrede, Marc N. Jarczok, Jonas Tesarz, and Cochrane Eyes and Vision Group; 2016 Nov 14.

Adverse Effects

Valtrex patients might experience side effects such as nausea, vomiting, diarrhea, tiredness, fever pains, and headaches. In rare cases, people using Valtrex could get aggressive or confused, and experience vertigo, dizziness, abdominal pains, edema, joint pain, constipation, and kidney problems.

Extremely rarely, there were reports of tremors, anorexia, psychotic and anaphylactic reactions to the medication, severe skin and blood problems, hepatitis, and coma.

Acyclovir has more or less similar side effects as Valtrex. Intravenous acyclovir therapy can provoke nausea, vomiting, headaches, and diarrhea. Rarely, acyclovir could lead to reactions on the injection site, vertigo, anxiety, confusion, tiredness, abdominal problems, edemas, and joint pain.

High doses of this medication may cause hallucinations and kidney problems. In less than 0.1% of the patients receiving intravenous acyclovir, there were hepatitis, blood-related problems, seizures, and coma.

Acyclovir cream could cause skin irritation, itching, and redness.

Acyclovir used in eye treatment can be a painful experience for the patients, and in some cases, may cause allergy or keratitis.

Toxicity

Patients using Valtrex should not operate the machinery or drive because the medication might cause them to feel dizziness. Valtrex should not be used in elderly patients, since they might be sensitive to this medication and suffer from excess confusion, anxiety, and kidney problems.

Pregnant women should consult the doctor about the use of this drug. Breastfeeding mothers should know that Valtrex passes into the breast milk and should always consult their doctor before starting the Valtrex treatment.

Acyclovir should also be avoided in pregnant women. It is known to be a mutagen agent, but because it didn’t show effects on unborn children, many pregnant women use this drug. Before the therapy, inform your doctor about the pregnancy and consult him/her about the possible consequences of the acyclovir treatment. Patients suffering from kidney problems have a higher risk of developing side effects such as confusion, lethargy, or sudden muscle twitches.