What is Zidovudine: Uses, Dosage, Side Effects and More

Zidovudine is an antiviral medication that helps fight HIV, the virus that causes AIDS. It belongs to a group of medicines called nucleoside reverse transcriptase inhibitors, which work by blocking HIV from multiplying in your body.

This medication has been around since the 1980s and was actually the first approved treatment for HIV. While newer HIV medicines are often preferred today, zidovudine still plays an important role in HIV treatment, especially for preventing mother-to-child transmission during pregnancy.

What is Zidovudine?

Zidovudine is an HIV medication that slows down the virus's ability to reproduce inside your cells. You might also hear it called by its abbreviation AZT or its brand name Retrovir.

Think of HIV as trying to make copies of itself using your body's cellular machinery. Zidovudine acts like a defective building block that gets incorporated into these copies, causing them to be incomplete and non-functional. This helps reduce the amount of virus in your blood, which is called your viral load.

The medication comes as capsules and oral solution, making it accessible for both adults and children who need HIV treatment.

What is Zidovudine Used For?

Zidovudine treats HIV infection in adults and children who weigh at least 4 kilograms (about 9 pounds). It's always used in combination with other HIV medicines, never alone.

The medication serves several important purposes in HIV care. First, it helps reduce the viral load in people with established HIV infection when combined with other antiretroviral drugs. Second, it's particularly valuable for preventing HIV transmission from pregnant mothers to their babies during pregnancy, labor, and delivery.

Healthcare providers also sometimes prescribe zidovudine to newborns whose mothers have HIV, typically for the first six weeks of life. This helps protect babies who may have been exposed to the virus during birth.

How Does Zidovudine Work?

Zidovudine works by interfering with HIV's ability to reproduce itself inside your immune cells. It's considered a moderately strong HIV medication that targets a specific step in the virus's life cycle.

When HIV infects your cells, it uses an enzyme called reverse transcriptase to convert its genetic material into a form that can be integrated into your cell's DNA. Zidovudine mimics one of the natural building blocks that this enzyme needs, but it's actually a fake version.

Once the enzyme incorporates zidovudine into the growing viral DNA chain, the chain gets terminated early and becomes useless. This prevents the virus from completing its replication cycle and making new copies of itself.

How Should I Take Zidovudine?

Take zidovudine exactly as your doctor prescribes it, usually every 12 hours or as directed. You can take it with or without food, though some people find it easier on their stomach when taken with a light meal.

Swallow the capsules whole with a full glass of water. If you're using the oral solution, measure your dose carefully with the provided measuring device, not a household spoon. The liquid can be mixed with a small amount of food if needed to make it more palatable.

Try to take your doses at the same times each day to maintain steady levels of the medication in your body. Setting phone alarms or using a pill organizer can help you stay on track with your dosing schedule.

How Long Should I Take Zidovudine For?

You'll typically need to take zidovudine for as long as your doctor recommends, which is usually long-term for HIV treatment. HIV medications work best when taken consistently over time.

For adults and children with HIV infection, zidovudine is generally part of a lifelong treatment plan. Stopping the medication can allow the virus to multiply again and potentially develop resistance to the drugs.

If you're taking zidovudine during pregnancy to prevent mother-to-child transmission, your doctor will provide specific guidance about how long to continue treatment. Newborn babies typically receive it for about six weeks after birth.

What Are the Side Effects of Zidovudine?

Like all medications, zidovudine can cause side effects, though not everyone experiences them. Most side effects are manageable and often improve as your body adjusts to the medication.

Here are the more common side effects you might experience:

• Headache and fatigue
• Nausea and loss of appetite
• Muscle pain and weakness
• Trouble sleeping
• Diarrhea or stomach discomfort

These symptoms are usually mild to moderate and often become less noticeable after a few weeks of treatment.

More serious side effects can occur, though they're less common. These include severe anemia (low red blood cell count), which can make you feel very tired and weak. Some people may also experience a decrease in white blood cells, which can affect your body's ability to fight infections.

Very rarely, zidovudine can cause a serious condition called lactic acidosis, where acid builds up in your blood. Signs include unusual fatigue, stomach pain, nausea, vomiting, and difficulty breathing. Another rare but serious side effect is severe liver problems, which might cause yellowing of your skin or eyes, dark urine, or severe stomach pain.

Contact your healthcare provider right away if you experience any severe or persistent side effects, especially unusual fatigue, shortness of breath, or signs of liver problems.

Who Should Not Take Zidovudine?

Zidovudine isn't suitable for everyone, and your doctor will carefully consider whether it's right for you. You shouldn't take this medication if you're allergic to zidovudine or any of its ingredients.

People with certain medical conditions need special consideration before starting zidovudine. If you have severe anemia or low white blood cell counts, your doctor may need to treat these conditions first or choose a different HIV medication.

Those with liver disease, kidney problems, or a history of pancreatitis require careful monitoring while taking zidovudine. Your healthcare provider will likely order regular blood tests to check your liver function, kidney function, and blood cell counts.

Let your doctor know about all other medications you're taking, including over-the-counter drugs and supplements. Some medications can interact with zidovudine, particularly other drugs that can affect your blood cells or liver function.

Zidovudine Brand Names

Zidovudine is available under several brand names, with Retrovir being the most commonly known. This brand name version is manufactured by ViiV Healthcare and comes in both capsule and oral solution forms.

Generic versions of zidovudine are also available from various manufacturers. These generic forms contain the same active ingredient and work just as effectively as the brand name version, often at a lower cost.

Your pharmacy may substitute generic zidovudine for the brand name version unless your doctor specifically requests the brand name. Both versions meet the same quality and safety standards.

Zidovudine Alternatives

Several other HIV medications can serve as alternatives to zidovudine, depending on your specific situation and treatment needs. Your doctor will consider factors like your viral load, other medical conditions, and potential drug interactions when selecting the best option for you.

Other nucleoside reverse transcriptase inhibitors include emtricitabine, tenofovir, and abacavir. These medications work similarly to zidovudine but may have different side effect profiles or dosing schedules.

Modern HIV treatment often uses combination pills that contain multiple medications in a single tablet. Examples include Biktarvy, Descovy, and Truvada, which combine different types of HIV drugs for more convenient dosing.

Your healthcare provider will work with you to find the most appropriate HIV treatment regimen based on your individual circumstances and medical history.

Is Zidovudine Better Than Tenofovir?

Both zidovudine and tenofovir are effective HIV medications, but they each have different advantages and considerations. The "better" choice depends on your individual health profile and treatment goals.

Tenofovir is often preferred in current HIV treatment guidelines because it typically causes fewer blood-related side effects than zidovudine. It's also available in convenient combination pills that you only need to take once daily.

However, zidovudine remains particularly valuable during pregnancy because it has a longer track record of safety for preventing mother-to-child HIV transmission. It's also an important option for people who can't tolerate other HIV medications.

Your doctor will consider factors like your kidney function, bone health, other medications you're taking, and your specific circumstances to determine which medication is most appropriate for you.