Week 3 Pearls Flashcards
Anitvirals must either block
entry into the cells or be active inside the host cells
Steps of viral replication
- adsorption
- uncoating of the viral nucleic acid
- synthesis of early, regulatory proteins
- synthesis of RNA or DNA
- Synthesis of structural proteins
- Assembly of viral particles
- Release from the cell
Most antivirals work on step
- synthesis of RNA or DNA
Antivirals: Nucleoside Analogues examples
Acyclovir and Valacyclovir
Famciclovir
Ganciclovir
Benefit of valacyclovir
less doses required
Antivirals: Nucleoside Analogues pharmacodynamis
Antiviral drugs must either block entry into the cells or be active inside host cells to be effective.
Acyclovir: active against
herpes simplex viruses 1 and 2 (HSV-1 and HSV-2); varicella-zoster virus (VZV); Epstein-Barr virus (EBV), cytomegalovirus (CMV), and herpes virus 6
Valacyclovir is converted
into acyclovir after oral administration and is active against the same virus
Famciclovir: active against
HSV-1 and HSV-2, HSV-1 and HSV-2, VZV, EBV, and hepatitis B virus
Ganciclovir active against
CMV
ADR Acyclovir/valacyclovir
few ADRs when given orally
Valacyclovir ADR:
may cause thrombocytopenia purpura, hemolytic uremic syndrome in immunocompromised patients
Famciclovir ADR
headach
Granciclovir ADR
granulocytopenia, anemia, and thrombocytopenia
may be carcinogenic**
Nucleoside drug interactions
few
Clincial use and dosing for Antivirals Nucleoside
Herpes simplex: genital herpes, both initial outbreak and suppression therapy Herpes zoster (shingles): start therapy within 3 days of outbreak
Varicella (chickenpox): start within 24 hours of outbreak
Gingivostomatitis in children
Bell’s palsy
When do you start antivirals with Herpes zoster
within three days of the outbreak. Same with simplex
Rational drug selection for antivirals nucleoside
cost and convenience
acyclovir is taken
5 times a day but is inexpensive.
Antivirals: Nucleoside Analogues
Monitoring
Rash for resolution
Temperature
Blood urea nitrogen and creatinine in high-risk patients
Antivirals: Nucleoside Analogues
Patient education
**Drug started at earliest sign of infection
Good hydration
Symptoms of renal failure, encephalopathic changes, blood dyscrasias
Antiviral guidelines for treatment for Hep C
Joint guidelines for treatment by American Association for the Study of Liver Diseases (AASLD) and the Infectious Diseases Society of America (ISDA)
Treatment of Hep C (HCV) infection based on
the genotype and stage of the disease
Antivirals for Hepatitis C Pharmacodynamics
most of HCV antivirals formatted as a fixed-dose combination of two antivirals
Antivirals for Hepatitis C Pharmacokinetics
administered orally and widely distributed
Antivirals for Hepatitis C Contraindications
Black Box warning regarding HBV reactivation and to test before starting HCV treatment
Anivirals for Hep C ADR
headache, fatigue, and nausea are the most frequent ADRs for all
Antivirals for Hep C Drug interactions
co-administration of ledipasvir and sofosbuvir (Harvoni) and amiodarone may cause serious symptomatic bradycardia
Multiple drug interactions
What should you really know about antivirals for Hep C
you will be seen by a specialist and they are given based on genotype and stage of the disease
Antivirals for Hepatitis C
Clinical use and dosing
dependent on the genotype of the HCV virus, renal and hepatic function
Antivirals for Hepatitis C
Monitoring
bilirubin, liver enzymes, and serum creatinine levels
Antivirals for Hepatitis C
Patient education
taking medication daily, ADRs, drug interactions
Antivirals for influenza names
Oseltamivir (Tamiflu), peramivir (Rapivab), zanamivir (Relenza) are used to treat influenza A and B.
Anitvirals for influenza Pharmacodynamics
Sensitivity varies by year.
Resistance to amantadine and rimantadine is common, so these drugs are no longer recommended for influenza.
Oseltamivir is
is well absorbed after oral administration.
Zanamivir is
inhaled; 4% to 17% is absorbed
Peramivir is administered
IV
What will change the evfectiveness of oseltamivir
variences of viruses annually
Osetamir and Zanamivir ADR
Ostemivir - GI upset
Zanamivir - brhonchitis and SOB
Oseltamivir, zanamivir: approved for
the prophylaxis and treatment of influenza type A and B
Peramivir is approved
Peramivir is approved
Antivirals for Influenza Monitoring
Monitoring
Renal function in older and debilitated patients
Older patients: evaluate for confusion, hallucinations, and cognitive impairment
Anitvirals for Influenza Patient Education
Patient education
Taking full course of therapy
ADRs
Annual influenza vaccination
Where do you refer for prescribing guidelines for antivirals
CDC
Systemic Azoles and Other Antifungals
Polyene macrolides:
amphotericin B and nystatin
Systemic Azoles and Other Antifungals
Azoles with broad-spectrum activity
butoconazole, clotrimazole, ketoconazole, minonazole, terconazole, tioconazole, fluconazole, itraconazole
Systemic Azoles and Other Antifungals
Allylamines active against yeast and dermatophytes
naftifine, terbinafine
Systemic Azoles and Other Antifungals
Nuclear acid synthesis inhibitors
flucytosine
Griseofulvin
Absorption of itraconazole is enhanced
food
Absorption of griseofulvin is enhanced by
fat
Fluconazole is an inhibitor of
cytochrome 3A4 (CYP3A4) and CYP2C9.
Itraconazole is an inhibitor of
3A4 (CYP3A4) and CYP2C9
Ketoconazole is an inhibitor of
is an inhibitor of CYP3A4.
Systemic Azoles and Other Antifungals
ADRs
All of the azoles and terbinafine have been associated with hepatotoxicity.
