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Zidovudina

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Zidovudina

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Method of action: Antivirals For Systemic Use

Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

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Overview of Zidovudina

Property Description
Active ingredient Zidovudine (AZT)
Form Tablet, Capsule, Oral Solution, Injectable Solution
Pharmacological class Nucleoside Reverse Transcriptase Inhibitor (NRTI)
Common use Management of HIV Infection / Prevention of Mother-to-Child Transmission
Origin Synthetic Compound (Thymidine Analogue)

Zidovudina: Core Identity and Pharmacological Class

Zidovudine is a synthetic antiviral drug, recognized by its official designation (INN) and historically referred to by the acronyms AZT or ZDV. This compound is chemically classified as a nucleoside analogue, specifically mimicking the natural nucleoside thymidine. It precisely belongs to the class of Nucleoside Reverse Transcriptase Inhibitors (NRTIs), a grouping clinically recognized for their ability to block the reverse transcriptase enzyme crucial for viral replication. Zidovudine holds a unique distinction as it was one of the first therapeutic agents approved for managing Human Immunodeficiency Virus (HIV) infection, fundamentally altering the course of treatment protocols.


Available Forms and General Composition

Zidovudine is produced as a single-agent product available in multiple dosage forms: oral tablets, oral capsules, an oral solution (syrup), and an injectable solution (parenteral formulation). The inclusion of the oral solution is important, as it simplifies administration to pediatric patients who may be unable to swallow solid forms. The variety of forms ensures the drug can be administered by both the standard oral route and by intravenous infusion when necessitated by clinical scenarios, confirming its essential role in various treatment settings.


What is the General Purpose of Zidovudine?

The general purpose of Zidovudine is to function as an indispensable tool for limiting the damage caused by the Human Immunodeficiency Virus (HIV) by acting as a replication blocker. By suppressing the amount of virus in the body, its clinical benefit is to reduce the viral load and support the immune system against progressive deterioration. The use of Zidovudine is also essential for the medically established protocol aimed at preventing mother-to-child transmission of HIV during pregnancy and birth.

Regulatory References

  1. NIH Guidelines for Prevention of Mother-to-Child Transmission
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What side effects are possible with Zidovudina?

Possible Side Effects and Safety Information

The safety profile of Zidovudine (AZT) is formally classified based on frequency and impact on body systems, as documented by official regulatory authorities. This information is strictly descriptive and is not clinical advice.

Adverse Reactions by Frequency and System

The most commonly documented adverse reactions, classified as Very Common (may affect more than 1 in 10 people), include headache and nausea. Reactions classified as Common (may affect up to 1 in 10 people) often relate to the Blood and Lymphatic System Disorders, manifesting as anaemia (reduction in red blood cells), neutropenia, and leucopenia. Other common effects involve the gastrointestinal tract (vomiting, abdominal pain) and nervous system (dizziness, malaise).

Serious Safety Concerns

The most significant safety concerns, highlighted in official labeling, relate to haematological toxicity, potentially leading to severe anaemia and neutropenia, which may necessitate treatment modification. A rare but critical systemic risk documented for this pharmacological class is lactic acidosis accompanied by severe hepatomegaly with steatosis (fatty liver). Rare adverse reactions also include anaphylaxis and severe conditions like Pure Red Cell Aplasia.

Safety Considerations and Limitations

Official safety documents define specific contexts for use. For instance, the onset of severe anaemia and neutropenia is typically observed after six or more weeks of therapy. The risk of haematological adverse effects is documented as higher in patients with advanced HIV disease. Use is generally contraindicated in individuals with pre-existing abnormally low neutrophil counts or low haemoglobin levels due to the drug's inherent haematological risk.

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Overdose and Emergency Response

Overdose and When to Seek Help

The official regulatory profile for Zidovudine (AZT) overdose is based on documented cases involving high single-dose ingestions, primarily exceeding 40 grams. In these instances, acute overdosage has been associated with documented transient clinical effects. Reported manifestations include fatigue, headache, nausea, vomiting, and anxiety.

A key finding in cases of significant overdosage is the development of transient lactic acidosis, along with mucosal discoloration. The presence of these systemic or clinical signs mandates immediate response.

Mandatory Emergency Action and Management

It is explicitly mandated that any individual who has ingested a dose of Zidovudine higher than prescribed must seek immediate medical attention or contact emergency services.

The management of Zidovudine overdose is strictly symptomatic and supportive, as regulatory documents state that no specific antidote is known. In situations of recent ingestion, general measures such as gastric lavage or the administration of activated charcoal may be considered.

Following intervention, the patient requires close monitoring of clinical signs, symptoms, and laboratory values—especially for transient lactic acidosis—as continuous observation is deemed essential according to official prescribing information. The utility of hemodialysis in acute overdose management remains undetermined in regulatory documents.

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Therapeutic Uses of Zidovudina

Core Management of HIV and Immunological Support

Zidovudine is commonly used to help manage Human Immunodeficiency Virus (HIV) infection, and its use may be part of symptomatic management in conditions where systemic imbalance and immunological decline are present. It is applied in addressing HIV-1 infection in combination with other antiretroviral agents. The therapeutic use is relevant for easing symptoms related to systemic imbalance in conditions marked by heightened physiological stress, including use in adults and children.

It is commonly used to help manage conditions such as HIV-1 infection and applied in therapeutic areas involving the prevention of vertical transmission. The medication is relevant for use in conditions where functional stability becomes affected, providing supportive relief when symptoms interfere with routine activities.

“This intervention provides support that helps ease the overall symptom burden for patients during difficult episodes.”

It is applied in addressing indicators that reflect the body's functional stress, such as elevated viral markers and compromised CD4+ T lymphocyte counts. It plays a role in managing clinical settings involving prevention during the perinatal period and assists with maintaining functional stability during symptomatic periods.


Quick Fact: Relief for Immunological Decline

The medication is relevant for use in conditions where functional stability becomes affected, providing supportive relief when symptoms interfere with routine activities.

Regulatory References

  1. NIH DailyMed drug label
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Eligibility and Restrictions for Use

Zidovudine (AZT) eligibility is strictly defined by regulatory authorities based primarily on specific hematological parameters and organ function status.

Populations That Must Not Use Zidovudine

Use is contraindicated for individuals with a known hypersensitivity to Zidovudine or any of its components. Absolute non-eligibility is also established for patients presenting with pre-existing severe blood disorders, specifically:

  • Severe Anemia: Hemoglobin levels below 7.5 g/dL.
  • Severe Neutropenia: Neutrophil count below 0.75 imes 10^9/L.

Permitted and Restricted Use

Zidovudine is permitted for use in adults, adolescents, and pediatric patients, including infants and neonates. The medicine is indicated for use in pregnant women for the specific goal of preventing maternal-fetal transmission of HIV-1. However, use is not recommended for HIV-positive mothers during lactation.

Use is considered restricted or conditional in patients with severe hepatic or renal impairment; these populations require special consideration due to potential drug accumulation and increased toxicity. Use in older adults should also proceed with caution, as specific data regarding safety and response in the geriatric population may be limited.

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What should I know about interactions with other medicines?

Interactions with other medicines and products

Official regulatory documents define several important interaction patterns that necessitate restrictions or close monitoring when Zidovudine is co-administered with other substances.

Officially Restricted and Avoided Combinations

Combination Type Interacting Agent(s) Regulatory Constraint
Prohibited/Avoided Stavudine (d4T), Doxorubicin Concomitant use should be avoided due to documented in vitro antagonistic relationships with Zidovudine.
Prohibited Other Zidovudine-containing products Must not be administered due to the risk of additive toxicity.

Pharmacokinetic and Pharmacodynamic Interactions

  • Exposure Modification: The plasma exposure (AUC) of Zidovudine is increased by co-administration with inhibitors of its primary metabolic pathway, glucuronidation. For example, Fluconazole is documented to increase Zidovudine exposure through UGT inhibition.
  • Additive Toxicity: Agents known to be bone marrow suppressive, such as Ganciclovir or Interferon alfa, may significantly increase the risk of hematologic toxicity, including severe anemia and neutropenia.

Timing and Population-Specific Notes

  • Timing Separation: Administration of Zidovudine-containing products and Clarithromycin requires separation by at least 2 hours.
  • Population Constraint: Co-administration of Ribavirin is not advised in HIV-1/HCV co-infected patients due to the specific risk of exacerbating anemia. Zidovudine can be taken without regard to food.

The overall interaction structure emphasizes avoiding antagonistic combinations and managing the shared risk of blood-related adverse effects with cytotoxic agents.

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Mechanism of Action

Targeting the Viral Replication Engine: Competitive Inhibition

Zidovudine's mechanism begins as its active form, Zidovudine triphosphate (ZDV-TP), acts as a competitive inhibitor of the essential viral enzyme, HIV-1 reverse transcriptase. This targeted action disrupts the initial stage of the viral replication cycle, which is mandatory for the virus to integrate its genetic code into the host cell.


Blocking DNA Assembly: Chain Termination Cascade

The reverse transcriptase mistakenly incorporates ZDV-TP, which is a structural analogue, into the growing strand of proviral DNA. Because the analogue lacks the necessary chemical group for continuation, this step results in immediate DNA chain termination. This molecular failure halts the synthesis of viral genetic material, leading directly to a reduction in the systemic viral load.


Modulating Immune Cell Homeostasis

The physiological consequence of suppressed viral replication is the reduction of suppressive and destructive signaling imposed by viral replication on the host's primary immune cells, specifically the CD4+ T-cells. This mechanism results in the stabilization of T-cell populations, which represents a modulation of the physiological processes governing immune cell count.

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Dosage and Administration Information

How to Use Zidovudine

Zidovudine is administered via two officially approved routes: the oral route and the intravenous (IV) infusion route. The oral forms include tablets, capsules, and an oral solution (syrup), while the injectable solution is intended for parenteral use.

Standard Dosing and Frequency Patterns

The medicine is typically used in a divided daily dosing pattern to maintain consistent systemic levels. For routine adult treatment of HIV-1 infection, the standard total dose is 600 mg daily, usually given as 300 mg twice daily (BID) or 200 mg three times daily (TID). Dosing may be taken without regard to food.

Context-Specific Administration

Specialized dosing regimens are utilized for the prevention of mother-to-child transmission (PMTCT). This involves distinct protocols across three phases:

  • Antepartum: Oral administration of 100 mg is taken five times daily (q5hr), typically starting after 14 weeks of gestation.
  • Intrapartum: An IV loading dose of 2 mg/kg is followed by a continuous infusion of 1 mg/kg/hour until the umbilical cord is clamped. The IV solution must be administered as a slow infusion over at least 30 to 60 minutes; rapid injection is strictly prohibited.
  • Neonatal: The course for the newborn starts within 12 hours after birth and generally continues for six weeks.

Procedural Adjustments

Dose reduction is required for patients with severe renal impairment (e.g., creatinine clearance below 15 mL/min), often necessitating an adjusted dose of 100 mg every 6 to 8 hours. When dose modification is necessary, the individual Zidovudine formulation must be used; fixed-dose combination products are not suitable for patients requiring such adjustments.

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Recent Clinical Evidence

Research evidence / Overview of studies for Zidovudine

Evidence for Use in Managing HIV-1 Infection

Research examined Zidovudine’s role in the management of Human Immunodeficiency Virus (HIV-1) infection, primarily through initial Randomized Controlled Trials (RCTs). These studies explored Zidovudine both as a single agent and as part of combination antiretroviral therapy (ART). The research monitored specific clinical and laboratory outcomes, tracking changes in virological markers (HIV RNA viral load) and immunological markers (CD4+ T lymphocytes). In these trials, populations included adults and children across various stages of infection. Findings describe patterns where researchers reported changes measured during the study period for both viral load and CD4+ cell counts.

However, the long-term effects of Zidovudine monotherapy research described limitations in maintaining measured long-term changes and is not the focus of current combination therapy guidelines. Data are still emerging regarding the durability of viral suppression when comparing older Zidovudine regimens directly against alternative regimens currently available.

Evidence for Preventing Mother-to-Child Transmission

Zidovudine was also evaluated in research concerning protocols that address mother-to-child (perinatal) transmission of HIV-1. The foundational studies, including a landmark RCT, examined a three-part protocol involving administration to the mother and the newborn infant. Studies monitored the rate of HIV transmission to the infant. Findings describe patterns where the rate of transmission was observed to be lower in the Zidovudine regimen group compared to controls.

However, the independent contribution of each specific phase of the regimen is not isolated in the existing primary trial data. Furthermore, data for certain groups, such as in settings where breastfeeding may be common, remain insufficient.

Long-Term Studies and Limitations

Research explored the longevity of effects observed with Zidovudine through cohort studies and extended follow-up analyses. These studies tracked how patients reported their experience over defined time intervals. The evidence highlights what is known and what is still uncertain about the sustained nature of the initial changes reported.

Key limitations noted in the research include that early studies focused on monotherapy, which is not the focus of current combination therapy guidelines. Also, sample sizes were modest in some original defining trials, and data on its use in older adults remain insufficient.

Key Studies & References

  1. Guidelines for the Use of Antiretroviral Agents in Adults and Adolescents with HIV (U.S. Department of Health and Human Services)
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Frequently Asked Questions (FAQ)

Common questions about Zidovudina (FAQ)


Q: Why is Zidovudina typically used in combination with other medicines?

Official regulatory documents indicate that Zidovudine is approved for the treatment of HIV-1 infection when used in combination with other antiretroviral agents. Using multiple medications is the standard approach described in official protocols to effectively manage the virus and support the immune system.


Q: What kind of blood monitoring is required when taking Zidovudina?

Because Zidovudine is known to affect blood cell production, official product information recommends frequent blood counts for patients, especially those with advanced HIV-1 disease. This regular monitoring checks for conditions such as severe anemia or low white blood cell counts (neutropenia).


Q: Can Zidovudina cause muscle problems or weakness over time?

Yes, regulatory documents note that a condition called symptomatic myopathy (muscle disease) has been associated with the prolonged use of Zidovudine. This is a potential safety concern reported in the official product labeling for the medicine.


Q: What are the signs of muscle problems (myopathy) that may be associated with Zidovudina?

If a person develops symptoms of myopathy, such as muscle weakness or pain, they should be communicated to a healthcare provider. Official guidance describes the importance of communicating these findings to a healthcare provider.


Q: Why do some people experience fat loss in their face and limbs with Zidovudina?

Changes in the way body fat is distributed, specifically fat loss (lipoatrophy) in the face and limbs, have been reported in people taking combination antiretroviral therapy, which can include Zidovudine. This is a known systemic effect documented in official safety information.


Q: Is Zidovudina effective if a person misses a dose occasionally?

Official information provides general guidance regarding a missed dose: if a dose is missed, it should be taken as soon as possible. However, if it is almost time for the next scheduled dose, the missed dose should be skipped to prevent taking too much at one time. Patients are strictly advised not to double up on doses.


Q: Does alcohol consumption affect how Zidovudina works or increase side effects?

Official documentation indicates that caution is warranted for patients who frequently consume alcohol, particularly due to the drug’s potential effects on the blood and liver. Official information suggests discussing alcohol use with a healthcare provider.


Q: Why is Zidovudina no longer a first-line therapy?

Although Zidovudine is approved by regulatory bodies, official treatment guidelines indicate it is no longer commonly recommended as an initial treatment for HIV. This reflects changes in clinical practice as newer, alternative regimens have emerged and become the primary focus of current treatment protocols.


Q: What happens if a person stops taking Zidovudina suddenly?

Official guidance emphasizes that individuals should not change the dosage or discontinue the medicine without consulting their treating physician. Stopping antiretroviral therapy suddenly can potentially affect the management of the condition.


Q: Are there any common over-the-counter medicines known to interact with Zidovudina?

Some commonly used over-the-counter agents, such as acetaminophen (paracetamol), may potentially affect how Zidovudine is processed by the body. Official patient counseling describes the importance of providing a healthcare provider with a complete list of all medications and supplements.


Q: Do supplements or vitamins have known interactions with Zidovudina?

Official patient counseling recommends informing a healthcare provider of all herbs, non-prescription drugs, and dietary supplements being used. This is because certain items can interact with Zidovudine and potentially affect its safety or action.


Q: What is the immune reconstitution inflammatory syndrome (IRIS) mentioned with Zidovudina?

Regulatory information reports that Immune Reconstitution Syndrome has occurred in patients taking combination antiretroviral therapy, including Zidovudine. It is a condition where the recovering immune system responds strongly to pre-existing or residual infections that were not being actively fought before treatment.


Q: Is there a risk of developing a severe skin reaction from Zidovudina?

The official product labeling states that Zidovudine is contraindicated (should not be used) in people with a history of hypersensitivity reactions, which can include severe skin conditions like Stevens-Johnson syndrome.


Q: Are there any age-related concerns for using Zidovudina?

Official documents note that studies did not include enough subjects aged 65 and over to fully determine if their response is different from younger adults. Dosing for the elderly should generally be cautious due to the higher probability of decreased function in organs like the liver or kidneys.


Q: What are the signs of a serious allergic reaction to Zidovudina?

Signs of a serious reaction, according to patient counseling summaries, may include a general ill feeling, fever, sores in the mouth, blistering or peeling skin, or swelling of the face, lips, or throat, leading to trouble breathing. Official documents emphasize the serious nature of these signs.


Q: How long does Zidovudina stay in the body after the last dose is taken?

The official pharmacokinetic section of the drug label states that the elimination half-life of Zidovudine in adults is approximately 1.1 hours. This value describes the time it takes for the concentration of the medicine in the blood to decrease by half.


Q: What kind of monitoring is done to check for potential liver issues while using Zidovudina?

If clinical or laboratory findings are suggestive of severe liver toxicity (pronounced hepatotoxicity), regulatory guidance describes that in such situations, the treating physician should consider suspending the treatment. This monitoring is necessary due to the rare risk of serious liver-related adverse effects.

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How should Zidovudina be stored and disposed of?

How to Store and Dispose of Zidovudine

Official regulatory labeling dictates that Zidovudine tablets and capsules must be stored at Controlled Room Temperature, defined as 20 C to 25 C (68 F to 77 F), in a closed container. The medicine must be protected from excessive heat, moisture, and direct light.

Storage Constraints

  • Freezing is prohibited, a rule applying particularly to the oral solution.
  • The product must be stored out of the sight and reach of children.
  • Capsules should be kept in the original package, and the oral solution container must be kept tightly closed.

Disposal

Do not keep outdated medicine. Unused or expired Zidovudine should not be flushed down a toilet or poured down a drain. Patients must ask a healthcare professional or pharmacist how to properly dispose of any unused product, adhering to local regulations for medicinal waste.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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