Antivirals Flashcards
Neuraminidase Inhibitors
Oseltamivir and Zanamivir
Nucleotide/Nucleoside Analog used for Respiratory Infections
Ribavirin
Ion Channel Blockers
Amantadine
Drugs for Respiratory Infections
Neuraminidase Inhibitors, Nucleoside/Nucleotide Analog, Ion Channel Blockers
Interferon used for Hepatic infections
Interferon alpha
Nucleotide/Nucleoside Analogs used for Hepatic Infections
Lamivudine and Entecavir
Protease Inhibitors used for Hepatic Infections
Boceprevir and Telaprevir
Purine and Pyrimidine Analogs used for Herpes Infections
Ganciclovir, Acyclovir, Cidofovir, Penciclovir, Trifluridine, Foscarnet
MOA of Neuraminidase Inhibitors
Inhibit release of virus by inhibiting sialic acid (substrate for Neuraminidase)
MOA of Ribavirin
Inhibits GTP formation and prevents viral mRNA capping; Inhibits RNA-dependent RNA polymerase –> inhibiting viral protein synthesis
Contraindications of Ribavirin
Category X; must have -ve pregnancy test before and during treatment
Contraindications of Amantadine and Rimantadine
Category X and contraindicated in nursing; crosses BBB
MOA of Amantadine and Rimantadine
Uncoating Inhibitors; block viral M2 protein (H+ channel) needed for viral uncoating
Indications of Neuraminidase Inhibitors
Influenza A & B
PK/PD of Oseltamivir
Oral prodrug hydrolyzed in the liver
PK/PD of Zanamivir
Inhalation
Contraindications of Zanamivir
Asthma, COPD
AE of Zanamivir
Airway irritation
AE of Amantadaine
Hallucinations, ataxia, seizures; monitor in psych patients
Synthetic guanosine analog effective against RNA and DNA viruses
Ribavirin
Indications of Ribavirin
RSV, HCV (combined with IFN alpha), and Lassa Fever
Indications for Amantadine and Rimantadine
Influenza A only
AE of Ribavirin
Transient anemia, GI, CNS
MOA of Interferon alpha
Induces expression of proteins that inhibit RNA and DNA synthesis and viral infection
AE of Interferon alpha
Flu-like symptoms and mental depression
Nucleoside/Nucleotide Analog for Hepatic Infections that is found in monophosphate and triphosphate forms
Lamivudine
What does the triphosphate form of Lamivudine do?
Inhibits HBV and HIV Reverse Transcriptase
What does the monophosphate form of Lamivudine do?
Incorporated into DNA to cause chain termination
Indications of Lamivudine
HBV and HIV
Drug Interactions of Interferon alpha
May potentiate myelosuppression by Zidovudine and may cause accumulation of Theophylline
Indications of Interferon alpha
HBV, HCV, condyloma acuminata, Hairy Cell Leukemia, Kaposi Sarcoma
Pegylated to improve PK profile
Interferon alpha
Must be phosphorylated to triphosphate (active form)
Lamivudine and Entecavir (Nucleoside/Nucleotide Analogs for Hepatic Infections)
Indications of Entecavir
Lamivudine-resistant strains of HBV and HIV
AE of Entecavir
Exacerbation of hepatitis upon discontinuation
MOA of Entecavir
Phosphorylated form competes with natural substrates for viral polymerase –> inhibition of polymerase blocs RT activity
MOA of Boceprevir and Telaprevir
Reversible binding to non-structural protein 3 (NS3) serine protease to decrease replication
Used to treat HCV in adults who failed treatment with IFN alpha and Ribavirin, or treatment-naive
Boceprevir, Telaprevir
AE of Boceprevir and Telaprevir
Dysgeusia, headache, etc.
Prodrug of Acyclovir with greater oral bioavailability
Vancyclovir
Acyclovir Indications
Genital Herpes, prophylaxis in immunocompromised and transplant patients
Why is CMV resistant to Acyclovir?
It does not encode Thymidine Kinase, which is needed for monophosphorylation of Acyclovir
MOA of Acyclovir
3 phosphorylation steps for activation; viral THYMIDINE KINASE does monophosphorylation while host enzymes complete phosphorylation to di- and triphosphate forms –> competes with dGTP for incorporation into DNA –> chain termination and inhibition of viral DNA polymerase
PK/PD of Acyclovir
Partial metabolism causes accumulation in Renal Failure
AE of Acyclovir
Local irritation (topical administration), Acute Renal Failure (IV administration)
Prodrug of Ganciclovir with greater oral bioavailability
Valganciclovir
Analog of Acyclovir with activity against CMV
Ganciclovir
MOA of Ganciclovir
Phosphorylated by viral (UL97) and cell kinases
DNA chain termination and inhibits DNA Polymerase
PK/PD of Valganciclovir
Rapid hydrolysis to Ganciclovir in liver and intestine; excreted in urine
Contraindications of Ganciclovir
Category C
AE of Ganciclovir
Myelosuppression, Neutropenia
Resistance mechanisms against Ganciclovir
Decreased intracellular phosphorylation or mutations in viral kinase (UL97) or viral DNA polymerase
MOA of Cidofovir
Activated by HOST cell kinases –> DNA chain termination and DNA polymerase inhibitor
Indications of Cidofovir
CMV retinitis, Ganciclovir-resistant HSV
Must be co-administered with Probenicid to block renal secretion
Cidofovir
AE of Cidofovir
Nephrotoxicity (administered with Probenicid to avoid this)
Resistance mechanism against Cidofovir
Mutations in viral DNA polymerase
Indication of Penciclovir
HSV-1, HSV-2, and VZV
PK/PD of Penciclovir
Topical treatment for cold sores (HSV)
MOA of Penciclovir
Monophosphorylated by VIRAL Thymidine Kinase –> activated form is triphosphate
Inhibits HSV DNA polymerase –> chain termination
AE of Penciclovir
Mild erythema
AE of Trifluridine
Palpebral edema and light intolerance
MOA of Trifluridine
Triphosphate form incorporated into DNA to cause DNA fragmentation
Trifluridine is the DOC for?
HSV Keratoconjunctivitis and recurrent epithelia keratitis
Indications of Trifluridine
Vaccina virus, HSV-1, HSV-2
PK/PD of Trifluridine
Ophthalmic ointment
Organic analog of inorganic pyrophosphate that DOES NOT REQUIRE PHOSPHORYLATION
Foscarnet
MOA of Foscarnet
Selectively inhibits pyrophosphate binding site on viral DNA polymerase
Indications of Foscarnet
CMV retinitis in immunocompromised, Acyclovir-resistant HSV and CMV retintis, and Ganciclovir-resistant VZV and CMV
Resistance to Foscarnet
Point mutations in DNA Polymerase
AE of Foscarnet
Nephrotoxicity and electrolyte disturbances (Ca, Mg, K, PO4), genital ulceration in men, hallucinations