Antiviral and Anti-parasitic Drugs Flashcards
What is a virus?
a nucleic acid in a protein coat
Why are viruses difficult to target?
- replicate inside the host cell
- use host enzymes
- advanced stage before detection
What are the different ways of targeting viruses?
- target virus outside the host cell
- inhibit genetic replication and integration
When is important to target viral infections?
when the immune system is weakened e.g cancer, HIV
How can you target viruses outside the host cell?
- vaccine (prophylaxis= before virus is contracted)
- neuraminidase inhibitors
How do neuraminidase inhibitors work?
- virus released from cell remains attached via sialic acid residues
- neuraminidase produced by virus which breaks the bond
- so drug prevents virus infecting other cells
What are the NICE guiltiness for prophylaxis/ treatment of influenza?
- vaccine most effective
- use neuraminidase inhibitors for at-risk patients
What types of drugs inhibit genetic replication and integration?
- DNA polymerase inhibitors
- reverse transcriptase inhibitors
- integrase inhibition
- protease inhibitors
How do DNA polymerase inhibitors work?
prevent DNA making DNA copies
How do reverse transcriptase inhibitors work?
prevent RNA making DNA copies
What is a pro-drug?
not active in the form given, have to be converted into the active form
How does acyclovir (a DNA polyermase inhibitor) work?
look at slides
What type of virus do reverse transcriptase inhibitors target?
RNA retrovirus (e.g HIV)
What are the types of reverse transcriptase inhibitors?
- nucleoside analogues
- non-nucleosides
How does lamivudine work (nucleoside analogue)
- analogue of cytosine
- phosphorylated to triphosphate
- inhibits RT (competition)-not DNA polyermase
- terminates viral DNA chain
How do non-nucleosides work?
- active in the given form
- denatures active site of enzyme
How does integrate inhibition work?
- Viral DNA incorporated into chromosomal DNA using the viral integrate enzyme
- the drug inhibits integrase
What are integrase inhibitors used to treat?
HIV
How does lopinavir, a protease inhibitor work?
- inhibits HIV protease
- reduces formation of structural proteins + enzymes
What is lopinavir used with and why?
-combined with a low dose of Ritonavir (inhibits liver enzyme that metabolises protease inhibitors)
What are the side effects of lopinavir?
- rash
- care needs to be taken for people with liver disease
How is HIV usually treated?
-treat with 2 nucleoside RT inhibitors
-plus one of:
non-nucleoside RT inhibitors, boozed protease inhibitor, integrase inhibitor
What are the drawbacks of treating HIV in this way?
- need to be treated for life (as virus is not often cleared completely from the body)
- resistance
What is the major parasitic disease?
malaria
