30 Antiviral drugs Flashcards
30.01 REVERSE TRANSCRIPTASE INHIBITORS
Zidovudine - actions
inhibit the action of the viral reverse transcriptase of HIV viruses
30.01 REVERSE TRANSCRIPTASE INHIBITORS
Zidovudine - MOA
phosphorylated by host cell enzymes to give zidovudine trisphosphate which interferes with viral DNA synthesis
30.01 REVERSE TRANSCRIPTASE INHIBITORS
Zidovudine - abs/distrib/elim
given orally but can be given by IV infusion
CSF concentration is 65% of blood level
the half-life of the false trisphosphate is 3h
30.01 REVERSE TRANSCRIPTASE INHIBITORS
Zidovudine - clinical use
HIV virus infection in combination with other agents
slows progress of the disease without curing the infection
reverse transcriptase inhibitors are also used in hepatitis B
30.01 REVERSE TRANSCRIPTASE INHIBITORS
Zidovudine - adverse effects
with long-term use: blood dyscrasias, GIT disturbances, myopathy, rashes, fever and a flu-like syndrome
30.01 REVERSE TRANSCRIPTASE INHIBITORS
Zidovudine - special points
resistance is likely to occur
to reduce this possibility, the drug is used in combination with other antiretrovirals
30.02 REVERSE TRANSCRIPTASE INHIBITORS
Non-nucleoside agents: nevirapine, efavirenz - actions
inhibit the action of the viral reverse transcriptase of HIV viruses
active against HIV-1 but not HIV-2
30.02 REVERSE TRANSCRIPTASE INHIBITORS
Non-nucleoside agents: nevirapine, efavirenz - MOA
bind to and denature the viral reverse transcriptase enzyme
30.02 REVERSE TRANSCRIPTASE INHIBITORS
Non-nucleoside agents: nevirapine, efavirenz - abs/distrib/elim
given orally
nevirapine: good oral bioavailability, CSF concentration is 45% of plasma level, metabolised in liver
efavirenz: plasma half-life ~50h, 99% bound to plasma albumin, CSF concentration is ~1% of plasma level
30.02 REVERSE TRANSCRIPTASE INHIBITORS
Non-nucleoside agents: nevirapine, efavirenz - clinical use
HIV-1 infection in combination with other antiretrovirals
can reduce mother-to-foetus transmission of the virus by ~50%
30.02 REVERSE TRANSCRIPTASE INHIBITORS
Non-nucleoside agents: nevirapine, efavirenz - adverse effects
hepatotoxicity, rash, Stevens-Johnson syndrome
less common: GIT disturbances, myalgia
efavirenz can cause disturbances of sleep and dreaming, and is teratogenic
30.03 PROTEASE INHIBITORS
Darunavir, ritanovir - actions
protease inhibitor
30.03 PROTEASE INHIBITORS
Darunavir, ritanovir - MOA
reversibly inhibits the viral-specific protease that, during assembly and budding, cleaves precursor viral proteins to give the structural and functional proteins of the new virions
HIV infection generates Gag and Gag-Pol proteins
hepatitis C - two protease targets identified: non-structural (NS) protein 3 and NS 5A
30.03 PROTEASE INHIBITORS
Darunavir, ritanovir - abs/distrib/elim
given orally
extensive first-pass metabolism
30.03 PROTEASE INHIBITORS
Darunavir, ritanovir - clinical use
HIV-1 infection in combination with other antiretrovirals
can reduce mother-to-foetus transmission of the virus by ~50%
hepatitis C
30.03 PROTEASE INHIBITORS
Darunavir, ritanovir - adverse effects
GIT disturbances, rhinitis, insulin resistance, lipodystrophy
CNS effects (dizziness, headaches, insomnia)
anaemia, neutropenia
30.04 DNA POLYMERASE INHIBITORS
Aciclovir, ganciclovir - actions
interfere with viral nucleic acid synthesis
30.04 DNA POLYMERASE INHIBITORS
Aciclovir, ganciclovir - MOA
aciclovir - converted by viral and host cell kinases to aciclovir triphosphate which selectively inhibits viral DNA polymerase
ganciclovir - converted by viral and host cell kinases to ganciclovir triphosphate which competes with guanosine triphosphate for incorporation into viral DNA, and suppresses viral DNA replication