Antiviral Drugs Flashcards
Antiviral Drugs Introduction
High transmissibility of many respiratory viruses
Dependent on cells to replicate; cannot perpetuate without them
Vary in size, but much smaller than eukaryotes and even some prokaryotes
Outnumber all life forms on Earth
Highly diverse but share some traits
Many covered by viral envelope as outermost layer (composed of elements of host cell membrane, endoplasmic reticulum, or nuclear envelope
Envelope covers the capsid (shell composed of identical building blocks of capsomeres); capsid protects viral nucleic acid (either DNA or RNA but not both; DNA or RNA can be single or double stranded)
Many contain enzymes that catalyze reactions that lead to their replication or cell entry
Cannot synthesize their own components to replicate (dependent on host cellular processes for all synthetic functions
Virions are individual complete particles of virus
Life cycles differ but follow same basic pathway
Spread from host to host via various means (direct inhalation, direct fluid exchange, vectors like mosquitos)
Once it reaches target cell, must penetrate cell membrane; specific receptors on the cell and viral surfaces
Then virus uncoats and releases genetic information from capsule into host cell; host cell reads the genetic material and begins to translate it into viral proteins (this process varies- for some RNA viruses host cell ribosomes translate RNA into proteins; retroviruses- reverse transcriptase translates RNA into DNA before integrating into the host genome; for retroviruses or DNA viruses transcription into mRNA occurs followed by translation into proteins
Once pieces built, viral enzymes assemble them into complete virions and released into the cell
Drugs may target a specific step for one virus or general steps for multiple viruses
For HIV, susceptibility testing is standard of care
For others, usually choose therapy based on general patterns of susceptibility for that type of virus
Many viral illnesses diagnosed through genetic testing for viral antigens or nucleic acids
Symptoms usually followed
Most common viral infections have no drug treatment (no treatment for common cold)
Antiretroviral Drugs
Only zidovudine was available in mid 1980s
Some agents are in their second or third generation
Come with challenges: adherence, resistance toxicities, interactions
Don’t use abbreviations in prescriptions or patient documentation
