Antiviral Drugs Flashcards
Why are viruses hard to treat?
Effective tx requires that the drug must enter the host cell
Most antivirals agents inhibit single steps in viral replication and are virusatic
Inhibitors of viral attachment, uncoating or release
Pleconaril Docosanol Amantadine Rimantadine Osteltamivir Zanamivir
Amantadine and Rimatadine- Inhibitors of Viral Attachment
Bind viral protein M2 and inhibit viral uncoating
Used to tx and prophylaxis of influenza type A, no effect on type B-lack M2
Large volume distribution
Amatadine-90% excreted unchanged in urine (used in parkinson’s disease)
Rimantadine- metabilized by the liver
Neuraminidase Inhibitors- Oseltamivir and Zanamivir
Selective inhibitors of viral neuraminidases which are essential for release of virus from the infected cell.
Tx of influenza A and B, duration 5 days
Prophylaxis before or after exposure to influenza A or B
Oseitamivir- oral
Zanamivir- intranasal or inhalation of dry powder
Inhibit attachment- Pleconaril
Prevents attachment of the virus and viral uncoating within the human cell
Effective against picornavirus- not FDA approved
Inhibit attachment- Docasanol
Prevents attachment of the virus to the human cell
OTC cream- recurrent oral/genital herpes
Drugs that block DNA synthesis from Viral DNA
Active against herpes family of viruses
Guanosine analogs- acyclovir, valacyclovir, penciclovir, famiciclovir, ganciclovir
Adenosine analog- vidarabine
Cytosine analog- cidfovir
Drugs that block DNA synthesis from viral DNA- Acyclovir, valacyclovir, penciclovir, ganciclovir, valganciclovir
Phosphorylated by viral thymidine kinase
Mechanism of viral resistance
Antiviral activity limited to replicating viruses
Acyclovir and Valacyclovir (oral prodrug of acyclovir)
Tx and prophylaxix prevention of herpes simplex (type I and II), and zoster
Varicella zoster- treatment
Drugs that block DNA synthesis from viral DNA- penciclovir and Famciclovir (oral prodrug of penciclovir)
Used to tx herpes zoster, herpes simplex Type II, topical tx of oral/labial herpes simplex virus
Drugs that block DNA synthesis from viral DNA- acyclovir and penciclovir
Pregnancy category B
Drugs that block DNA synthesis from viral DNA- Ganciclovir and Valganciclovir (oral prodrug)
Active against all herpes virus
Tx of CMV in immunocompromised patients
Neutropenia, thrombocytopenia, teratogenic- catergory C
Vitasert- an intraocular sustained release implant for CMV retinitis.
Drugs that block DNA synthesis from viral DNA- vidarabine
Broad spectrum antiviral activity- herpes, pox viruses, rhabdoviruses, hepadenaviruses, some RNA tumor viruses
Primary use- keratitis, keratoconjunctivitis, life threatening herpes simplex virus, varicella zoster infections
Side effects- N/V, bone marrow suppression, neurotoxicity, peripheral neuropathy.
Drugs that block DNA synthesis from viral DNA- cidofovir
Broad spectrum antiviral activity- herpes and pox viruses, adenoviruses, papilloma viruses, and hepadenavirus
Primary use for tx of cytomegalovirus in AIDS pts who are intolerant, relapsed, or nonresponsive to ganciclovir or foscarnet
Neutropenia and nephrotoxicty
Drugs that block DNA synthesis from viral DNA- Foscarnet
Does not require phosphorylation- broad spectrum
Active against all herpes viruses, influenza, and HIV
Primary uses- CMV (cytomegalvirus) infections, acyclovir, resistant herpes simplex or varicella zoster
Nephrotoxicty
