antivirals Flashcards
interferons
One of the best known agents of the class of drugs which inhibit viral synthesis in infected cells. One form of human interferon, named interferon alpha, is well-established as a treatment for hepatitis B and C,
viricides
actively deactivate virus particles outside the body.
ffective anti-viral treatment is limited to a small number of viruses:
influenza types A and B and respiratory syncytial virus (R.S.V.). ○ Herpesviruses ○ Cytomegalovirus ○ Human immunodeficiency virus ○ Viral hepatitis B and C
Influenza A
known to occur only in humans. It is often referred to as seasonal flu.
• H1N1 and H3N2 are the most common
strains of influenza A.
• Swine flu, originally designated as novel influenza A (novel A H1N1), is now most often referred to as simply H1N1.
influenza A and B treatment
Tamiflu (Oseltamivir) or Relenza (Zanamivir)
Ribaviran/ Virazole - for both influenza A and B and R.S.V.
Oseltamivir/ Tamiflu
Indication: Treatment (and prevention) of
infections due to influenza A and B virus in adults and in children at least one year of age – when given within 48 hours of symptoms of infection–.
Tamiflu has also shown effectiveness for H5N1 also known as avian flu.
• MOA: Neuramidase inhibition. Tamiflu was the first orally active neuraminidase inhibitor to be commercially developed.
• Char: Oral route. !!!Must be started within 48 hours of onset of symptoms in order to be effective.!!!!

Neuramidase
viral enzyme that allows for the release of viral progeny (virons) from the host cell. If inactivated the virus cannot leave the host cell and eventually dies due to exhausting the cell’s metabolism
Oseltamivir/ Tamiflu dosage
The usual adult dosage for the treatment of influenza is 75 mg twice daily for 5 days, beginning within 2 days of the appearance of symptoms.
- Standard prophylactic dosage is 75 mg once daily for patients aged 13 and older.
- Doses are decreased for children and patients with renal impairment.
Oseltamivir/ Tamiflu SE
- Side effects: Abdominal pain, nausea, vomiting and headache.
- There is concern about potential adverse neurologic effects including delirium, hallucinations, depression and increased suicidal ideation but the data are not definitive.
- As with all anti-microbials, the risk of creating medication-resistant influenza is not only likely, it’s certain.
Zanamivir/ Relenza MOA
- Zanamivir was the first neuraminidase inhibitor to be commercially developed.
- Mode of action consists of blocking the function of the viral neuraminidase protein, thus preventing the virus from budding off from the host cell.
- Relenza has proven to act against both influenza A and influenza B and avian flu, when given within 48 hours of infection.
methods of antiviral action
- interfere with the ability of a virus to attach to the host cell and/ or inhibit entry into the host cell.
- selectively target the processes that allow for the virus to shed its protein coat within the host cell thus blocking release of the virus.
- inhibit viral genome replication by blocking the synthesis of viral components after a virus has invaded the host cell.
- block viral release from a host cell.
***additional treatment option involves stimulation of the body’s immune system to respond to the virus rather than attacking the virus directly.
Zanamivir/ Relenza dosage
Relenza is formulated as a powder that is delivered via the respiratory tract by an oral inhaler.
- The recommended dose of Relenza for the treatment of influenza in adults and pediatric patients 7 years of age and older is 10 mg (two puffs) twice daily for 5 days.
- Two doses should be taken on the first day of treatment whenever possible, provided there is at least 2 hours between doses.
- On subsequent days, doses should be about 12 hours apart (i.e. morning and evening) at approximately the same time each day.
Zanamivir/ Relenza CI
- Relenza is not recommended for the treatment or prophylaxis of influenza in individuals with a history of asthma or COPD due to risk of serious bronchospasm
- Relenza has not been proven effective for prophylaxis of influenza when tested in nursing home settings.
Zanamivir/ Relenza info and se
• Class: Anti-viral
• Indication: Influenza treatment and/or
prophylaxis
• MOA: Neuramidase inhibitor
• Char: Inhaled route only
• Side effects: Nausea and vomiting. As an
anti-viral medication, the incidence of post-treatment diarrhea, vaginal Candidiasis and thrush is negligible.
Amandatine/ Symmetrel
- Amandatine is an anti-viral agent that was recommended as prophylaxis against influenza A or for treatment of influenza A before 2009 but is no longer indicated due to resistant strains.
- Amantadine is also used as a treatment for the early stages of Parkinson’s disease.
- It is best used as short-term therapy (range of 6 to 12 months) for people with early stage mild to moderate symptoms of Parkinson’s disease.
Herpes virus
- There are eight members of the herpes virus family that infect humans.
- These viruses include HSV-1, HSV-2 and VZV (varicella-zoster virus – the cause of chickenpox and shingles).
- Other human herpesviruses include: Epstein- Barr virus (EBV), human cytomegalovirus (CMV), Roseola-associated HHV, Pityriasis Rosea associated virus and Kaposi’s sarcoma associated herpesvirus.