What are Antiviral Drugs?
Antiviral drugs can be divided into three categories, broadly depending on the virus they target. These categories include nucleic acids, adenoviruses, and the human papillomavirus (HPV). Nucleic acids Antiviral drugs include drugs that prevent the replication of viral DNA. They can work by inhibiting the enzymes that facilitate DNA replication.
Antiviral drugs side effects
Targeted Adenoviruses: These drugs target only a specific viral, such as Epstein-Barr virus, adenovirus, and cytomegalovirus. They also target different viral antigens, which help them to penetrate and kill the virus.
Adenoviruses and Epstein-Barr virus are two examples of viruses whose DNA can be chemically altered. Therefore, targeted adenoviruses and targeted HPV drugs can be used to treat these viruses, but this has not been widely used.
Antiviral drugs side effects
A number of specific anti-viral drugs are well-known, although the specific therapies are still not available for many of the infections. Let’s learn about a few of the main ones.
Methisazone: this drug has action against variola major, variola minor, varicella, adeno-viruses and numerous RNA viruses. The organisms rapidly develop resistance to this drug. The main use of this drug is in contacts of smallpox cases as a prophylactic and in immunosuppressed patients who required vaccination. The drug has no curative action. The dose is 200-400 mg/Kg orally, daily. Gastrointestinal side effects may occur.
Idoxuridine: This is effective against herpes simplex infections, although the organisms develop resistance rapidly. The drug is given intravenously in doses of 220 mg/Kg daily for the treatment of herpes simplex encephalitis or as local application to the eye as 0.1% ointment. Toxic effects include marrow suppression and local allergy.
Amantadine hydrochloride (symmetrel): It is active against RNA viruses of several groups- myxoviruses, paramyxoviruses and togaviruses. The drug is effective particularly against influenza A virus, but not against influenza B. The drug is mainly used for the prophylaxis against influenza A in vulnerable groups.
There is a 50-60% reduction in attack rates. For prophylaxis after exposure it should be given within 24-48 hours after the onset of symptoms. Dose is given orally 100 mg twice a day. Toxic effects include confusion, hallucinations, anxiety and insomnia. It may produce embryopathy when given in pregnancy. This drug is also used in parkinsonism.
Vidarabine: This is a derivative of adenine arabinoside. It inhibits DNA synthesis and is active against several herpes group viruses. It is used therapeutically in herpes simplex, varicella zoster and cytomegalovirus infections. The drug has o be given intravenously as a 12 hour infusion in a dose of 5-15 mg/Kg/day for 10 days. Toxicity occurs in a few cases and this includes nausea, vomiting, diarrhoea and trmors.
For the treatment of herpes simplex encephalitis and neonatal herpes simplex infections, vidarabine has to be given intravenously. Adenine arabinoside is available as a 3% ointment for topical use in herpetic heratoconjuctivitis.
Acyclovir (Acycloguanosin): This is a potent drug which inhibits the multiplication of herpes simplex types 1 and 2, Varicella zoster and EB virus. Acyclovir is given intravenously in a dose of 5 mg/Kg as an infusion running over 1 hour and repeated every 8 hours for 5 days. Side effects include allergy, renal impairment, local necrosis of tissues, and hepatic dysfunction. The dose should be reduced in patients with defective renal function.
Antiviral DrugsThe Good, The Bad, And The Ugly
‘Antiviral drugs work by interfering with viral processes in the body. They can be effective for short periods of time.’ Antivirals have been used to treat viral infections since the 1940s, but they have also made headlines recently as drug-resistant strains of influenza and Ebola have threatened to change this.
Since the past few years, influenza viruses – the most common cause of death from infection – have increased in severity and number.A vaccine provides protection against a particular strain of a virus, and antivirals can help limit the impact of infection. Yet, in 2015-16 in England, 35,000 flu cases were reported; 350 deaths were attributed to the disease.
The best way to prevent the spread of viruses is to avoid getting infected in the first place. It is also important to practice good hand hygiene and avoid contact with others when you are sick. Be sure to clean hands thoroughly and frequently, especially after handling money or food.
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