Antiviral Agents (Non HIV) 3-4 Flashcards
Antiviral general
-virus use host cell
-work nonselective = ALSO hurt your own cells
Acyclovir (Zovirax)
-1st choice: for herpes virus group (HSV, varicella-zoster)
-oral and genital sores (can spread even if sores not present)
-lvls in CSF 50% in blood plasma: viral meningitis –> need to be on med longer
-MOA: converts to acyclo-GMP (thymidine kinase) –> direct inhibit DNA synthesis and DNA polymerase
Acyclovir resistance
develops resistance by:
1. decrease production thymidine kinase
2. alteration thymidine kinase –> Acyclovir no longer converts to acyclo-GMP
3. alteration of viral polymerase so less sensitive to inhibition
-HSV: Acyclovir very active against
-varicella: Acyclovir moderately active against
-CMV: mostly resistant to Acyclovir
Acyclovir administration and considerations
-serious side effects are uncommon
-give SLOWLY over 1h minimum
–> more absorption and protect kidneys (can renal dose)
-also hydrate them before and after to protect renal
-NO pregnant use or give care
-for varicella (chickenpox): airborne precautions until lesions are dry and crusted
-high doses of ORAL: to treat
-severe infections in immunocompromised will need IV Acyclovir
acyclovir adverse
-neurotoxic (IV): agitate, tremors, delirum, a
-common (due to PO): nvd, ha, vertigo (dizzy)
-phlebitis: most common
-reversible nephrotoxic (IV): elevated BUN and crt
-neurotoxicitiy (IV): agitate, tremors, delirium, hallucinate, myoclonus (twitch, rare)
Valacyclovir (Valtrex)
-prodrug of Acyclovir: breaks down IN the body –> more bioavailable inside (instead of 15-30%, its now 55%) –> more effective
-oral form converts to Acyclovir
Valacyclovir adverse
in immunocompromised: can cause TTP or HUS
-thrombotic thrombocytopenic purpura: low PLT cause both small clots & bleeding at same time (looks like bursted vessels)
-hemolytic uremic syndrome: kidneys unwell and impair organs with uremia buildup
Cytomegalovirus (CMV)
-member of herpes
-direct contact transmission with bodily fluids
-very common; most are asymptomatic
-s/s similar to mono in immunocompromised
-CMV is resistant to Acyclovir
Ganciclovir (Cytovene, Vitrasert)
-prevents and treats CMV (not for Herpes, varicella)
-need maintenance therapy indefinitely
-avoid preg 90 days after treatment
-possible infertility and sterility of BOTH genders
-hazardous drug: safe handle with double gloves (same precautions as chemo drugs)
Ganciclovir adverse
-Thrombocytopenia: monitor PLT (stop below 25,000)
-Granulocytopenia: stop if ANC below 500
==> monitor CBC very well
Valganciclovir
-CMV retinitis
-prevent CMV in transplant pts
-prodrug: more bioavailble in body (PO)
-doesnt have to give as often
Valganciclovir adverse
similar to Ganciclovir
-granulocytopenia, neutropenia, & thrombocytopenia = monitor CBC
-NVD, headache, fever
-special precautions due to exposure risk (carcinogenic and mutagenic)
Inteferon Alpha
-MOA: affect viral replication cycle
-short acting: IM or SQ (best for hep C) (admin few times/week)
-long acting: once a week (Peginterferon alpha 2a/b) –> blood levels remain high between doses = better clinical response
Inteferon Alpha adverse
-flu like s/s (fever, ha, chills)
-neuropsychiatric effects: depression –> suicidal thought
-GI disturbances
-alopecia
-injection site reactions
-bone marrow suppression
