Antimicrobials IV Flashcards
name the 9 steps of the viral lifecycle that can be inhibited
- recognition
- attachment
- penetration
- uncoating
- transcription
- protein synthesis
- replication
- assembly
- lysis and release
describe the M2 protein inhibitors
Adamantanes e.g. Amantadine
- viral RNA in virion is protein-bound, including to M1 protein
- must be released from M1 in order to enter nucleus
- M2 protein in viral membrane forms channel
- channel enables entry of protons from endosome into virion
- entry of protons lowers pH –> release of viral RNA from M1
- Adamantanes block mechanism of action of M2
- no protons enter virion –> no acidification –> no release of viral RNA –> no viral replication
- resistance via changes to M2 an increasing issue
name the types of reverse-transcriptase inhibitors (RTIs)
- nucleoside analog RTIs (NRTIs)
- nucleotide analog RTIs (NtRTIs)
- non-nucleoside RTIs (NNRTIs)
- NRTIs and NtRTIs are functionally similar
- lack 3-hydroxyl group (N3 instead)
- once incorporated into DNA –> chain termination
- many must be intracellularly activated
- phosphorylation to triphosphate form
- NNRTIs
- non-competitive inhibitors of RT: bind directly to enzyme
describe acyclic guanosine inhibitors and what it treats
what can be used to monitor treatment efficacy?
viral load (burden/titer) can be used to monitor treatment efficacy
- quantify amounts of virus present in plasma, CSF and other fluids
- usually NA-amplification based
- look at # of copies of nucleic acid per mL
- most frequently used to monitor antiretroviral therapy
- aim to reduce viral load to below level of detection : 20-80 copies RNA/mL
describe the various factors that contribute to antiviral drug resistance
- resistance has increased alongside expanded clinical use of antiviral agents
- primarily a problem in specific patients with:
-
long-term or progressive infections
- particularly if exposed to long-term or repeated therapy
- impaired immune systems
-
long-term or progressive infections
- contributing factors:
- sub-therapeutic drug concentrations
- plasticity of viral genomes –> high mutation rate
- mutation might change target but leave function unaffected
describe the plaque reduction assay
plaque reduction assay is the gold standard for phenotypic analysis of clinical isolates
describe the function of integrase strand transfer inhibitors (ISTIs) and reverse transcriptase inhibitors (RTIs)
describe the factors contributing to unsuccessful chemotherapeutic treatment of parasitic infections
- similarities between eukaryotic parasites and human host
- limited money and resources to commit to treatment/control in resource-limited countries (high % of infxns occur)
- inidividuals can be infected by multiple parasites
- high level re-exposure –> risk of re-infection
- immunocompromise: inadequate nutrient intake and other infections
- poverty and poor sanitation (liitle/no sewage disposal, clean water access limited)
summarize the target and effect of metronidazole and pentamidine (antiprotozoal drugs)
name the 3 groups of anti-protozoal drugs
in general, single drug usually targets single stage of Plasmodium life cycle
- quinines
- chloroquine
- quinine
- mefloquine
- protein synthesis inhibitors
- doxycycline
- artemisinins
describe the function of quinine
- interferes with parasite’s hematin detoxification
- blood schizotocides
describe the function of doxycycline
- member of cycline antibiotic family
- synthetic tetracycline
- protein synthesis inhibitor
- mitochondrial ribosomes (70s)
- interferes with apicoplast
- organelle containing survival-relevant biosynthetic pathways
- targets both blood and liver stages of the malaria parasite
describe the function of sesquiterpenes
Artemisinin
- mechanism: release free-radicals into parasite vacuoles, damaging membranes
- effect: inhibition of major metabolic processes including glycolysis
- usually combined, e.g. with aminoquinolone = Artemisinin Combination Therapy (ACT)
- to delay development of resistance
describe the challenges with treatment of helminthic infections
- high incidence of infection in all age groups
- limited range of current drugs
- potential for development of resistance
- repeated, regular treatments necessary
- polyparasitism
- drugs can be specific to one stage
- e.g. many of antifilarial drugs treat microfilariae; limited activity against adult worms
summarize the antihelminthic drugs
