Anti-Viral Agents Flashcards
Drugs used for chemoprophylaxis influenza
Amantadine
Rimantadine
Amantadine (Symmetrel) is used for tx of Parkinson’s disease and excreted largely unchanged in urine,
True
4-10x more active than amantadine and it has fewer side-effects due to extensive biotransformation
Rimantadine (Flumadine)
Mechanism of action of Amantadine and Rimantadine.
- Inhibit viral uncoating
- Interferes with hemagglutinin processing which inhibits viral assembly
- Interferes with M2 protein
Uses of drugs for chemoprophylaxis influenza
Tx of influenza type A
Seasonal tx with 70-90% protection against Type a
Not effective to type B
Drugs acts as Neuraminidase Inhibitors
Oseltamivir, Zanamivir
MOA of Neuraminidase Inhibitor Drugs
Inhibits neuraminidase which prevents enhancing of penetration of viruses to host cells = the viruses tend to aggregate and migration of viruses to host cells are inhibited
Uses of Neuraminidase Inhibitor Drugs
Effective against Influenza types A and B
Effective for pre and post exposure to Influenza virus and used as a dry powder for oral inhalation.
Zanamivir
A prodrug in ethyl ester form and the first effective drug against influenza types A and B
Oseltamivir
These are extremely potent cytokines with antiviral, immunomodulating and antiproliferative actions which is synthesized by infected cells in response to inducers which elicit antiviral state or natural killer cell response
Interferons
Two interferons drugs
Interferon alfa Interferon beta (Betaseron)
Use of Interferons
With broad spectrum anti-viral activity against DNA and RNA viruses
Interferons are not orally available, thus given IM/SC/topical or nasal spray.
T or F
True
Nucleoside Antimetabolites are inhibitors of DNA Polymerase
True
Nucleoside antimetabolite introduced for treatment of herpes simplex keratitis in 1963.
Idoxuridine
MOA of Idoxuridine
Inhibits replication of DNA viruses such as herpesvirus, poxvirus
Phosphorylated to triphosphate form which inhibits viral DNA synthesis by inhibiting viral DNA polymerase and leads to strand breakage and faulty transcription
Iodinated analog of thymidine
Idoxuridine
Pyrimidine nucleoside, related to Idoxuridine used for the treatment of shingles, herpetic keratitis, Idoxuridine resistant-viral infections.
Cytarabine
MOA of cytarabine
Phosphorylated to triphosphate form which blocks DNA polymerase and blocks cellular utilization of deoxycytidine which inhibits viral DNA replication
Trifluorinated pyrimidine nucleoside with inhibitory action against HSV-1 and HSV-2, CMV, vaccinia, adenovirus.
Trifluridine
The following statements are NOT true about Trifluridine, EXCEPT:
I. Has brand name Viroptic
II. Tx of primary keratoconjunctivitis, recurrent epithelial keratitis by HSV 1 and 2
III. For Acyclovir-resistant HSV infections
a. III only
b. I only
c. I, II, III
d. NOTA
c. I, II, III
MOA of Trifluridine
Triphosphate form inhibits thymidine triphosphate incorporation into DNA by DNA polymerase = fragile, poorly functioning viral DNA
Obtained from Streptomyces antibioticus and is used an alternative to Idoxuridie for tx of HSV keratitis and encephalitis.
Vidarabine
MOA of Vidarabine
Activity confined to DNA viruses – triphosphate form competes with deoxyadenosine triphosphate for viral DNA polymerase
L-valyl ester of acyclovir and increases BA by increasing lipophilicity.
Valacyclovir
T or F
Valacyclovir is used as tx of shingles in immunocompromised patient.
True
Nucleoside antimetabolite that is administered orally and parenterally which is used for the treatment of herpesvirus infections.
Acyclovir
Acyclovir is most active against HSV-1, 2x less active to HSV-2, 10x less potent to VZV.
Uninfected human cells are unaffected by acyclovir.
a. First statement is correct.
b. Second statement is correct.
c. Both statements are correct.
d. Both statements are incorrect.
C.
Orally active prodrug for chronic form of Hepatitis B
Adefovir
Its diphosphate form inhibits Hepatitis B Virus DNA polymerase
Dipivoxil
Analog of acyclovir and used against Herpes simplex viruses, Varicella-Zoster Virus (VZV), and Cytomegalovirus.
Ganciclovir
MOA of Ganciclovir
Triphosphate form inhibits DNA polymerase and is incorporated into viral DNA leading to strand breakage and cessation of elongation
The use Ganciclovir is limited because it causes myelosuppression such as neutropenia, thrombocytopenia, anemia.
T or F
True
100-fold less potent than acyclovir and tx for HSV I and 2
Penciclovir
The triphosphate form of this drug is a competitive inhibitor of viral DNA polymerase
Penciclovir
Diacetyl inactive prodrug thus lacks antiviral activity
Famciclovir
A nucleoside antimetabolite with high therapeutic index against Cytomegalovirus (CMV)
Cidofovir
MOA of Cidofovir
Diphosphate form is a competitive inhibitor of viral DNA polymerase and is incorporated into growing viral DNA strand causing DNA chain termination
Cidofovir has dose-limiting toxicity that can lead renal impairment, so it must be given with rehydration and probenecid.
T or F
True
A nucleoside antimetabolite with synergistic activity with Zidovudine and Didanosine.
Foscarnet sodium
Second line for CMV in AIDS patient
Foscarnet sodium
MOA of Foscarnet sodium
No significant intracellular metabolism – reversible non competitive inhibitor of pyrophosphate binding site of
