Antivirals, Antifungals & Anthelminthics

Question 1

Acyclovir (Zovirax)

Answer 1

Active against most infections caused by herpes simplex viruses and varicella-zoster virus.
After conversion to its active form, acyclovir suppresses viral reproduction by inhibiting viral DNAP, and causing premature termination of viral DNA strand growth. Because the active form of acyclovir is not a good inhibitor of human DNA polymerase, cells of the host are spared.
Active against HSV-1 and HSV-2; varicella-zoster virus; Epstein-Barr virus; cytomegalovirus; herpes virus 6.
Short half-life, dosed 5 x daily.

Question 2

Valacyclovir (Valtrex)

Answer 2

Prodrug form of acyclovir. Converted to acyclovir after oral administration and is active against the same viruses.
Has a longer half-life so is dosed BID.

In some immunocompromised patients, thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS)

Question 3

Famciclovir (Famvir)

Answer 3

Active against HSV-1 and HSV-2, VZV, EBV, and hepatitis B virus

Adverse effects are minimal.

Question 4

Ganciclovir

Answer 4

Active against CMV.

Question 5

ADRs of Acyclovir (Zovirax)

Answer 5

Intravenous therapy: Phlebitis, Reversible nephrotoxicity
Oral therapy: Gastrointestinal, Vertigo
Topical therapy: Stinging sensations