Zidovudine

Overview

Zidovudine, or azidothymidine (AZT), is a form of antiretroviral medication which is used in both the prevention and treatment of HIV/AIDS. It is used frequently in the treatment of unborn babies in order to prevent their exposure to the disease, as well as being administered to those who may have been exposed via a needle stick injury or open wound.

Zidovudine has changed the landscape for children born to mothers who have been infected with HIV/AIDS. Without the use of the drug, up to 15% of babies born to mothers with the condition will be born with HIV themselves. After use of the drug in a combination of pre-natal, in-labor and post-delivery treatments, Zidovudine has been proven to reduce the risk down to as little as 8%. When the drug is combined with vigilance and precautionary action such as delivery via a C-section, extreme clinical hygiene, protective clothing and face masks and extreme caution surrounding the handling of disposable diapers, the risk of the infection spreading from mother to child is reduced to between 1 and 2%.

Sometimes people are exposed to HIV through being stuck with a contaminated hypodermic needle, or through a cut or scratch. In these cases, patients can be administered Zidovudine as a preventative measure. It has proven to be greatly effective in preventing the patient from developing the infection if they are treated quickly enough.

For patients who have already been infected with HIV, Zidovudine is usually prescribed to be taken twice a day, usually as part of a treatment plan with other antiretroviral drugs. The treatment plans usually consist of taking at least three different antiretroviral medications at the same time. Three or more different drugs are used to reduce the chance of the virus developing a resistance to the medication. Zidovudine belongs to a group of different pharmaceuticals used to treat HIV which are known as Nucleoside Reverse Transcriptase Inhibitors (NRTIs). Along with all other NRTIs, Zidovudine works by blocking an enzyme associated with HIV which helps the disease to reproduce and attack at a faster rate. Blocking this enzyme slows down the rate at which the HIV can spread and develop throughout the body and, in some cases, NRTIs can actually reduce the presence of the infection in the patient’s system.

It is important to note that Zidovudine is not a cure for HIV/AIDS. It is an effective treatment program which allows people infected with HIV to live for longer and in a healthier condition. In many cases, daily doses of Zidovudine in combination with other antiretroviral drugs can actually allow people infected with HIV to live relatively normal lives. Thanks to antiretroviral drugs such as Zidovudine, the mortality rate for those infected with HIV has been reduced dramatically, providing a vital lifeline for millions of people.

Condition(s) treated?

  • Prevention of transfer of HIV from mother to child
  • Prevention of HIV in patients who have been exposed to the infection
  • Treatment of HIV once contracted

Type of medicine

  • Antiretroviral

Side Effects

The majority of patients do not experience serious side effects when taking Zidovudine, but the most common side effects of the drug are:

  • Nausea
  • Heartburn
  • Acid reflux
  • Headaches
  • Vomiting
  • Loss of appetite
  • Loss of body fat
  • Difficulty sleeping
  • Joint pain

The use of Zidovudine can also cause a number of different side effects which are less common but still reported. These side effects include:

  • Numbness and tingling in the hands and feet
  • Discoloration of fingernails
  • Mood changes

In some very rare cases, the drug has been known to cause seizures.

If Zidovudine is taken in higher doses, more serious side effects can be experienced, however these side effects are usually completely reversible and patients cease to be affected once the dose is lowered. These possible side effects include myopathy, cardiomyopathy, neutropenia, anemia and hepatotoxicity.

It is very rare that a patient has an allergic reaction to Zidovudine, however, it does happen very occasionally. Patients experiencing an allergic reaction are likely to develop a rash, experience severe dizziness and swelling of the throat and tongue as well as difficulty breathing. These symptoms will not go away if the patient continues to take the drug, so medical advice should be sought immediately.

Zidovudine is a drug used to strengthen the immune system. As the drug begins to take effect and the immune system becomes more resistant, the body can start fighting off illnesses, infections and diseases which the patient already had. This can cause the symptoms from those illnesses and infections to resurface as the body tries to tackle them.

Dosage

Zidovudine should only be taken by patients who have been given medical prescriptions for the drug from their doctor. The prescription should be followed closely; patients should not take more or less than the dose which has been advised. If side effects are experienced, patients should consult with the doctor before increasing or decreasing their dose.

Zidovudine comes in the form of tablets, capsules, syrup, single-use injections and IV fluids. Adult patients who are prescribed Zidovudine to slow down the development of HIV are usually prescribed tablets which amount to 600mg of the drug each day. These tables can be taken with or without food. If patients are hospitalized, Zidovudine can be administered through an intravenous drip. Zidovudine can be prescribed for child patients, and the dosage will vary greatly depending on the age and weight of the child.

Pregnant mothers who are prescribed Zidovudine in order to prevent the transmission of the disease to their unborn baby are usually prescribed a dose of 100mg to be taken five times a day. This dose then changes once labor has begun, as the drug is administered via an intravenous drip continuously until the umbilical cord has been clamped.

All doses of Zidovudine may be reduced if the patient is known to have impaired kidney or liver function. If the patient begins to show signs of anemia and/or neutropenia, the dose can be lowered or even withdrawn completely until recovery signs are identified.

Missed doses

Patients who forget to take their Zidovudine at the given time should take the dose as soon as they remember. If the time of the next dose is approaching very soon, then this dose should be taken instead of the missed one. It is not advised to double up on a dose to compensate for the missed one.

Overdoses

Overdoses of Zidovudine are very rare, but there have been several reported cases of both children and adults who have received acute overdoses of this drug. In these instances, the patients were exposed to up to 50 grams of the drug at one time. Adverse symptoms of a Zidovudine overdose have been reported to include:

  • Fatigue
  • Headaches
  • Vomiting
  • Anemia

Dialysis has proven to have very little effect on the removal of zidovudine from the bloodstream, and where overdose occurs, patients are monitored and treated as and when they show signs of toxicity from the overdose.

Interactions

Zidovudine is often prescribed alongside other antiretroviral medication, and the majority of drugs can be taken alongside zidovudine with few or no interactions at all. However, the effectiveness of Zidovudine may be compromised if taken in conjunction with some other prescription and non-prescription drugs. Some interactions between drugs can cause exaggerated or serious side effects for patients. The possibility of interaction between different types of drugs is always present, but even known interactions do not occur in all cases. It always advisable to keep a list of all of the drugs being taken at once to be able to present a record to pharmacists or doctors in the event of unwanted side effects.

This is not a comprehensive list, but the following medications are known to interact with Zidovudine:

  • Orlistat
  • Probenecid
  • Ribavirin
  • Stavudine
  • Denzapine
  • Deferiprone
  • Renflexis
  • Clozapine
  • Bexarotene
  • Drugs which hinder bone marrow function eg. Ganciclovir, dapsone, trimethoprim, doxorubicin, vincristine
  • Drugs which affect the kidneys eg. Ibuprofen, naproxen

There are also some drugs which affect the way in which the body removes the Zidovudine from its systems once the drug has been used. These drugs include, but are not limited to:

  • Methadone
  • Rifampin
  • Phenytoin
  • Valproic Acid

If the body is not able to remove the Zidovudine effectively, this can start to cause a buildup of the drug in the system and affect the way in which it operates.

It is impossible to list all of the interactions, many of which may not be known yet. It is imperative to stay vigilant and to contact a doctor if any interactions are suspected. It is vital for patients to attend regular checkups with doctors in order to monitor the progress of the treatment and to look out for any potential interactions or side effect.

Patients who are prescribed Zidovudine should let their health care provider known if any of the following are true:

  • You are allergic to any medications
  • You are suffering from, or have ever suffered from, liver or kidney disease
  • You are anemic or have previously been anemic
  • You are currently breastfeeding or wish to in the future
  • You are currently pregnant
  • You are taking any prescription or non-prescription medication
  • You are an alcoholic or have a history of alcohol or substance abuse
  • You have any pre-existing medical conditions
  • You are prone to muscle weakness or cramps
  • You are pregnant or trying to become pregnant

All of the situations listed above can restrict the effectiveness of Zidovudine as a treatment for HIV and/or cause serious, potentially life-threatening side effects for patients taking Zidovudine.

Warnings

Zidovudine should only ever be taken following prescription from a qualified medical professional. It is a powerful drug which in some cases can cause serious side effects which have the potential to be life-threatening. Conditions such as hypersensitivity, blood disorders, neutropenia, anemia, liver malfunction and serious muscle weakness can all be provoked by the consumption of Zidovudine.

Patients should contact their doctor immediately if they begin to experience any of the following symptoms while taking Zidovudine:

  • Unexplained rash
  • Uncharacteristic shortness of breath
  • Difficulty breathing
  • Unexplained bleeding
  • Sudden or unexplained tiredness or weakness
  • Pale skin
  • Fever
  • Inability to get warm
  • Fatigue
  • Sudden or prolonged loss of appetite
  • Abdominal cramps, vomiting and/or diarrhea
  • Urine which is dark in color
  • Unusual bowel movements
  • Jaundice
  • Muscle weakness or loss of physical strength
  • Muscle cramps or aches

For patients with pre-existing medical conditions, reporting any changes in their symptoms or any side effects they are experiencing is particularly important. Zidovudine has been linked with the worsening of the condition of patients with liver disease. This has occurred in patients who have been infected with Hepatitis C at the same time as HIV. There have been cases of patients taking medication for liver disease at the same time as Zidovudine in which the patient has died as a result.

Storage

Zidovudine should be stored in the packaging in which it arrives from the doctor or pharmacist. It is important that it is clearly labelled so that others do not take it by mistake. As with all medication, Zidovudine should be kept in a safe place, well away from the reach of pets and children.

Zidovudine should be stored in a dark, dry place at room temperature, anywhere between 60 and 77 degrees Fahrenheit. It should be kept somewhere where the temperature does not vary dramatically and is kept fairly consistent. The drug needs to be kept free from moisture so it is not advisable to store Zidovudine in the bathroom or kitchen.

As Zidovudine is often taken more than once a day, many patients choose to carry it with them so that they can take it wherever they are. There is no problem with doing this, but whilst being transported Zidovudine should still be kept in a dark, dry place which is kept at a relatively consistent temperature.

Summary

Zidovudine is a drug which has played a vital part in the prevention and treatment of HIV/AIDS. In combination with other antiretroviral drugs, it has been instrumental in changing the fate of many people who are exposed to the disease, decreasing the mortality rate and allowing people to continue with their lives after infection. Through pioneering medical advancements, Zidovudine has been proven to reduce the risk of mothers infected with HIV passing on the infection to their unborn children.

Despite the excellent results which Zidovudine has achieved, it must not be forgotten that it is a powerful pharmaceutical which can be dangerous if used incorrectly. Zidovudine is commonly prescribed and is deemed to be safe to use but, as with all pharmaceuticals, there is always the possibility that the drug could have a negative interaction with a pre-existing medical condition or with another drug. Patients should always be honest and forthcoming with their health care providers as to the exact nature of their current health conditions and any prescription or non-prescription drugs which they are currently taking.

It is imperative that patients follow the advice of the health care provider or medical professional making the prescription, and that they do not exceed the stated dose. Serious side effects of Zidovudine are not common, but can occasionally become life-threatening. Patients taking Zidovudine should be careful to monitor their own health and to report any changes in their condition to their doctor as soon as possible so that they do not escalate into something more serious.

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Last Reviewed:
December 23, 2017
Last Updated:
December 22, 2017
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