Antiviral drugs

Antiviral Drugs: Uses, Most Common Drugs, Side Effects, Abuse

Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do not destroy their target pathogen; instead, they inhibit its development.

They do this by being able to enter the cells infected with virus, interfere with viral nucleic acid synthesis and/or regulation, some agents interfere with the virus’s ability to bind with the cell while others stimulate the body’s immune system.

How They Were Discovered

The emergence of antivirals is the product of our newly acquired knowledge of the genetic and molecular function of organisms letting us better understand the structure and function of viruses, major advances in the techniques for finding new drugs, and the pressure placed on the medical profession to deal with the human immunodeficiency virus (HIV), the cause of acquired immunodeficiency syndrome (AIDS).

The first experimental antivirals were developed in the 1960s, mostly to deal with herpes viruses, and were found using traditional trial-and-error drug discovery methods.

Only in the 1980s, when the full genetic sequences of viruses began to be unraveled, did researchers begin to learn how viruses worked in detail, and exactly what chemicals were needed to thwart their reproductive cycle.

Few drugs are selective enough to prevent viral replication without injury to the infected host cells. Therapy for viral diseases is further complicated by the fact that the clinical symptoms appear late in the course of the disease, at a time when most of the virus particles have replicated.

Most Common Antiviral Drugs

Antiviral medications help the body fight off harmful viruses. The drugs can ease symptoms and shorten the length of a viral infection. Antivirals also lower the risk of getting or spreading viruses that cause herpes and HIV.

The most common antiviral drugs include:

1.      Acyclovir (Zovirax): Acyclovir is an antiviral drug primarily used for the treatment of infections caused by the herpes simplex virus (HSV), including genital herpes, cold sores (oral herpes), and shingles (herpes zoster). It works by inhibiting the replication of the virus. Acyclovir is available in various forms, including oral tablets, topical creams, and intravenous (IV) injections.

2.      Oseltamivir (Tamiflu): Oseltamivir is an antiviral medication used for the treatment and prevention of influenza (flu) caused by influenza A and B viruses. It is particularly effective when taken within 48 hours of the onset of flu symptoms. Oseltamivir works by inhibiting the enzyme neuraminidase, which is essential for the release of new virus particles from infected cells. It is available in oral capsule or suspension form.

3.      Ribavirin (Copegus, Rebetol): Ribavirin is an antiviral drug used in combination with other medications for the treatment of hepatitis C virus (HCV) infection and respiratory syncytial virus (RSV) infection. It can be taken orally or administered through inhalation or intravenous infusion. Ribavirin works by interfering with the replication process of the virus.

4.      Ganciclovir (Cytovene): Ganciclovir is primarily used to treat cytomegalovirus (CMV) infections, which can occur in immunocompromised individuals, such as transplant recipients or people with HIV/AIDS. It is available in oral, intravenous, and intravitreal (injected into the eye) formulations. Ganciclovir inhibits viral replication by interfering with viral DNA synthesis.

5.      Zidovudine (AZT, Retrovir): Zidovudine is an antiretroviral drug used in the treatment of human immunodeficiency virus (HIV) infection. It belongs to a class of medications called nucleoside reverse transcriptase inhibitors (NRTIs) and works by inhibiting the reverse transcriptase enzyme that is essential for HIV replication. Zidovudine is available in oral capsule, tablet, and syrup forms.

6.      Lamivudine (Epivir): Lamivudine is another NRTI used for the treatment of HIV infection as well as chronic hepatitis B virus (HBV) infection. It can be taken orally and is available as tablets or oral solution. Lamivudine inhibits the reverse transcriptase enzyme, preventing viral replication.

7.      Interferons (IFNs): Interferons are a group of naturally occurring proteins that have antiviral properties. They can be used to treat chronic viral infections such as hepatitis B and C. Interferons work by activating the immune system’s response against the virus and inhibiting viral replication. They are available in various forms, including interferon-alpha injections and pegylated interferon-alpha injections, which have a longer duration of action.

8.      Sofosbuvir (Sovaldi): Sofosbuvir is a direct-acting antiviral (DAA) medication used in combination with other medications to treat chronic HCV infection. It specifically targets the HCV polymerase enzyme, inhibiting viral replication. Sofosbuvir is taken orally in tablet form.

9.      Remdesivir (Veklury): Remdesivir is an antiviral drug that gained attention during the COVID-19 pandemic. It is used for the treatment of severe cases of COVID-19 in hospitalized patients. Remdesivir works by inhibiting the replication of the SARS-CoV-2 virus, which causes COVID-19. It is administered intravenously.

It’s important to note that each antiviral drug has specific indications, dosing regimens, potential side effects, and contraindications. The choice of antiviral treatment depends on factors such as the specific viral infection, the patient’s medical history, and individual patient considerations. Always consult a healthcare professional for proper diagnosis and guidance on antiviral treatment options.

What are the side effects of antiviral drugs?

The side effects of antiviral drugs can vary depending on the specific medication and the individual patient. Here are some common side effects associated with antiviral drugs:

1.      Nausea and vomiting: Many antiviral drugs can cause gastrointestinal discomfort, leading to symptoms such as nausea and vomiting. This side effect is often temporary and can be managed by taking the medication with food or adjusting the dosage.

2.      Diarrhea: Some antiviral drugs, particularly those used to treat HIV and HCV infections, can cause diarrhea. It is important to stay hydrated and inform your healthcare provider if this side effect becomes severe or persistent.

3.      Headache: Headaches are a common side effect of certain antiviral medications. They are usually mild and temporary, but if they persist or worsen, it’s advisable to consult a healthcare professional.

4.      Fatigue: Antiviral drugs can sometimes cause fatigue or general weakness. It is important to get enough rest and inform your healthcare provider if fatigue becomes severe or affects your daily activities.

5.      Skin rash: Skin rashes can occur as a side effect of some antiviral medications. These rashes are typically mild and resolve on their own, but it’s important to notify your healthcare provider if you develop a rash or any other skin-related symptoms.

6.      Hair loss: Some antiviral drugs, particularly those used in the treatment of hepatitis C, may cause temporary hair loss. This side effect is usually reversible once the medication is discontinued.

7.      Liver toxicity: Certain antiviral drugs, such as those used for the treatment of hepatitis B and C, can potentially cause liver toxicity. Regular monitoring of liver function is typically recommended during treatment.

8.      Bone marrow suppression: Some antiviral medications can suppress the bone marrow’s ability to produce blood cells, leading to decreased red blood cells, white blood cells, and platelets. Regular blood tests may be necessary to monitor blood cell counts during treatment.

9.      Neurological side effects: In some cases, antiviral drugs can cause neurological side effects such as dizziness, confusion, or mood changes. It’s important to report any significant changes in mental health or neurological symptoms to your healthcare provider.

It’s worth noting that not all individuals will experience these side effects, and the severity and frequency can vary. It’s important to discuss potential side effects with your healthcare provider before starting any antiviral medication, and to promptly report any unusual or severe symptoms during treatment.

Antiviral drugs Safety

Antiviral drugs, like all medications, have safety considerations that should be taken into account. Here are some key points regarding the safety of antiviral drugs:

1.      Prescription and medical supervision: Antiviral drugs are typically prescribed by healthcare professionals who evaluate the benefits and risks based on an individual’s specific condition. It is important to follow the prescribed dosage, frequency, and duration of treatment as directed by your healthcare provider.

2.      Adverse reactions: Antiviral drugs can have potential side effects and adverse reactions. These can range from mild symptoms like nausea or headache to more serious effects like liver toxicity or bone marrow suppression. It’s important to be aware of possible side effects and promptly report any unusual or severe symptoms to your healthcare provider.

3.      Drug interactions: Antiviral drugs may interact with other medications, including over-the-counter drugs, herbal supplements, or prescription medications. These interactions can affect the efficacy or safety of the antiviral treatment. It is important to inform your healthcare provider about all the medications you are taking to avoid potential interactions.

4.      Allergic reactions: Some individuals may experience allergic reactions to antiviral drugs. Symptoms of an allergic reaction can include rash, itching, swelling, dizziness, or difficulty breathing. If you experience any signs of an allergic reaction, seek immediate medical attention.

5.      Special populations: Certain populations, such as pregnant women, breastfeeding mothers, or individuals with specific medical conditions, may require special considerations when it comes to antiviral drug safety. It is important to discuss any pre-existing conditions or concerns with your healthcare provider to ensure the medication’s safety and efficacy.

6.      Resistance: In some cases, viruses can develop resistance to antiviral drugs. This can occur if the medication is not taken as prescribed or if the virus mutates over time. Adherence to the prescribed treatment regimen is crucial to minimize the risk of resistance. The use of Whoonga a drug cocktail in South Africa that contains illicit drugs and HIV antiretroviral (ARV) medication may adversely impact adherence to HIV treatment and may have the potential to generate ARV resistance.

7.      Monitoring and follow-up: Depending on the specific antiviral drug, regular monitoring of blood tests, liver function, or other parameters may be necessary during treatment. This is done to assess the drug’s effectiveness and monitor for any potential side effects.

It’s important to note that the safety profile of each antiviral drug can vary, and not all individuals will experience adverse effects. Your healthcare provider will consider your medical history and individual circumstances when prescribing antiviral medication and will provide guidance on its safety and proper use.


Dr. Oche Otorkpa PG Cert, MPH, PhD

Dr. Oche is a seasoned Public Health specialist who holds a post graduate certificate in Pharmacology and Therapeutics, an MPH, and a PhD both from Texila American University. He is a member of the International Society of Substance Use Professionals and a Fellow of the Royal Society for Public Health in the UK. He authored two books: "The Unseen Terrorist," published by AuthorHouse UK, and "The Night Before I Killed Addiction."
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