Valacyclovir with Zidovudine Interaction Details
Brand Names Associated with Valacyclovir
- Valacyclovir
- Valtrex®
Brand Names Associated with Zidovudine
- AZT
- Retrovir®
- ZDV
- Zidovudine
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 17, 2023
Interaction Effect
Increased lethargy and fatigue
Interaction Summary
In a patient previously taking acyclovir (250 mg every eight hours) for severe herpetic stomatitis, the addition of zidovudine resulted in lethargy and fatigue. However, it has been demonstrated that acyclovir does not alter the disposition of zidovudine.
Severity
Minor
Onset
Rapid
Evidence
Probable
How To Manage Interaction
Patients should be warned about excessive fatigue which may occur with concurrent use. If severe, bed rest is advised.
Mechanism Of Interaction
Unknown
Literature Reports
A) Concomitant administration of acyclovir and zidovudine has been reported to result in severe drowsiness and lethargy in a 30-year-old patient with pneumocystis carinii pneumonia. The patient developed a fever while on cotrimoxazole therapy, which persisted despite discontinuation. Intravenous acyclovir therapy (250 mg every eight hours) was begun for the treatment of herpes simplex infection which occurred during the febrile episode. Zidovudine therapy (200 mg PO Q4H) was begun 3 days after acyclovir therapy. Within 1 hour the patient demonstrated fatigue and lethargy and was barely able to stay awake. Improvement was seen when acyclovir was switched to the oral form (200 mg Q4H). Discontinuation of acyclovir resulted in a return to baseline alertness. Rechallenge confirmed these effects .
B) A regimen of zidovudine and acyclovir was administered to eight patients with AIDS or AIDS-related complex . The pharmacokinetics of the two drugs were independent of each other. Six of the patients received the drug combination for at least 10 weeks; all had increased numbers of T4 lymphocytes and two of three assessable patients had reversal of anergy. Two patients, P24 antigen-positive at entry, became negative with treatment. The authors suggest that this drug combination can be tolerated in patients with severe HIV infection.
C) A Phase I study of zidovudine (500 mg daily) plus acyclovir (2 g or 4 g daily) was performed in asymptomatic patients infected with HIV to investigate pharmacokinetics, safety, tolerance, and immunologic effects of the combination . Pharmacokinetic analysis on 20 patients over a 24-week period showed no drug interaction. The combination was generally well tolerated, and hematologic parameters remained stable through 24 weeks. There were no significant changes in total lymphocytes, T4 lymphocyte, overall skin test reactivity, or ability to culture virus from peripheral blood.
Valacyclovir Overview
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Valacyclovir is used to treat herpes zoster (shingles) and genital herpes. It does not cure herpes infections but decreases pain and itching, helps sores to heal, and prevents new ones from forming.
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This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
Zidovudine Overview
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Zidovudine is used along with other medications to treat human immunodeficiency virus (HIV) infection. Zidovudine is given to HIV-positive pregnant women to reduce the chance of passing the infection to the baby. Zidovudine is in a class of medications called nucleoside reverse transcriptase inhibitors (NRTIs). It works by decreasing the amount of HIV in the blood. Although zidovudine does not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other life-style changes may decrease the risk of transmitting (spreading) the HIV virus to other people.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.