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Anti-protozoal, anti-amebiasis, Anti-fungal drugs
Parsites, ameboids and fungus
30
Pharmacology
09/16/2009

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Cards

Term
Metronidazole (Flagyl)
Definition
  • Class-antibacterial/antiprotozoal/drug for amebiasis (diarrhea)
  • Mechanism-addition of N-groups allowing easy diffusion into bacteria/organisms for DNA disruption
  • Target-intestinal and extraintestinal organisms such as: anaerobic bacteria ("ABC's" like C.diff); used for H.pylori to txt acid reflux; protozoans living in low oxygen environments (Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis)
  • Cidal/Static-Cidal
  • Special-avoid alcohol ingestion; may cause metallic taste and furring of the tongue; Similar drug is Tinidazole; may get nausea due to increased penetration (CNS based, not gut irritation)
  • Term
    Tinidazole
    Definition
  • Class-antibacterial/antiprotozoal/drug for amebiasis (diarrhea)
  • Mechanism-addition of N-groups allowing easy diffusion into bacteria/organisms 
  • Target-intestinal and extraintestinal organisms such as: anaerobic bacteria ("ABC's" like C.diff) and H.pylori; protozoans living in low oxygen environments (Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis)
  • Cidal/Static-Cidal
  • Special-Similar to metronidazole, with shorter txt duration and fewer side effects
  • Term
    Amphotericin B
    Definition
  • Class-antifungal
  • Mechanism-bind to ergosterol to create disruption in fungal cell membrane
  • Target-broad spectrum
  • Special-used for systemic infection; given by slow IV, starting with low dose and work up; can produce chills, fever, headache; often combined with sedative (phenothiazine) or corticosteriod to diminish adverse effects
  • Term
    Nystatin
    Definition
  • Class-antifungal
  • Mechanism-complexes with ergosterol in the cell membrane (creating disruptions)
  • Target-Topical fungal infections (athlete's foot) or vaginal candidiasis
  • Special-works same way as amphotericin B (but given for isolated infections)
  • Term
    Ketoconazole
    Definition
  • Class-antifungal (Imidazoles)
  • Mechanism-affect ergosterol synthesis
  • Target-chronic fungal infections*
  • Special-can be given orally; side effects include blocking synthesis of androgens so men may have increased female sex characterisitics*
  • Term
    Fluconazole
    Definition
  • Class-antifungal (triazoles)
  • Mechanism-interfers with fungal sterols (ergosterol) in cell membrane
  • Target-broad spectrum of fungal infections
  • Special-more toxic than itraconazole; inhibits testosterone synthesis; given oral or IV
  • Term
    Terbinafine
    Definition
  • Class-antifungal (allylamines)
  • Mechanism-blocks synthesis of ergosterol
  • Target-cutaneous mycotic infections like ringworm, nail infections, dermatophytic infections*
  • Special-
  • Term
    Caspofungin
    Definition
  • Class-antifungals
  • Mechanism-inhibits fungal cell wall synthesis
  • Target-Candida; Aspergillus
  • Special-none.
  • Term
    Flucytosine
    Definition
  • Class-antifungal
  • Mechanism-specific transport into fungal cell which is then converted to active form 5FdUMP
  • Target-
  • Special-prodrug; used orally and in combination with other antifungals
  • Term
    Griseofulvin
    Definition
  • Class-antifungal
  • Mechanism-interfers with polymerized microtubules and disrupts mitotic spindle
  • Target-
  • Special-none.
  • Term
    Chloroquine
    Definition
  • Class-antimalarial/antiamebiasis
  • Mechanism-complexes with DNA and prevents replication and transcription* (For Crone: accumulates in food vacuole of parasite and shuts down heme polymerase, leading to toxic accumulation)
  • Target-Plasmodium species (malaria) in the erythrocytic stage; especially used for species Central America, Middle East (NOT sensitive to species in S. America, Africa, Asia). Therapeutic goal by giving this is to txt symptoms.
  • Special-given orally; active against amebas in the liver; in low doses it is not very toxic, but high does or for long duration can cause toxicity of the skin, blood and eyes
  • Term
    Primaquine
    Definition
  • Class-antimalarial
  • Mechanism-mechanism not clear* For Crone: interfers with mitochondrial activity of the parasite
  • Target-Plasmodium species (malaria)
  • Special-kills the LIVER form (exoerythrocytic) of malaria but not the erythrocytic stage (use Chloroquine for that); often used as a prophylaxis
  • Term
    Atovaquone (taken as combination form Malarone)
    Definition
  • Class-antimalarial/parasitic
  • Mechanism-interferes with electron transport chain in malarial mitochondria
  • Target-Plasmodium species (malaria) in SE Asia, sub-Saharan Africa and S. America (different species)
  • Special-taken with proguanil (Malarone)
  • Term
    Proguanil (taken as combination form Malarone)
    Definition
  • Class-antimalarial/parasitic
  • Mechanism-dihydrofolate reductase inhibitor
  • Target-Plasmodium species (malaria) in SE Asia, sub-Saharan Africa and S. America (different species)
  • Special-this drug is combined with Atovaquone (known as Malarone). Proguanil enhances the atovaquone effec on mitochondrial membranes
  • Term
    Pyrimethamine
    Definition
  • Class-antimalarial
  • Mechanism-dihydrofolate reductase inhibitor which inhibits reduction of folic acid, therefore malaria cannot make their own DNA and cannot divide and grow
  • Target-Plasmodium (malaria)
  • Special-bad bacterial/cancer drug*; Folic acid is needed for 1 carbon transfer reaction to make pyramadine/purines to make DNA, without folic acid can't make DNA*; attacks the erythrocytic stage of malaria
  • Comparisons-types of inhibitors of folic acid reductase include Bactrim (Trimethaprim + sulfamethoxazole) for bacteria, Methotrexate  for cancer
  • Term
    Praziquantel
    Definition
  • Class-antihelminthic
  • Mechanism-increases calcium influx to alter parasite muscle function
  • Target-Flatworms (fluke and tapeworm); used to txt schistomiasis (blood fluke)
  • Special-none.
  • Term

    Malaria lifecycle

     

    Definition
    • Vector-female mosquito (Anopheles); mosquito bite injects sporozoites from saliva into blood stream
    • Sporozoites penetrate liver cells and undergo schizogeny (asexual cleavage multiplication) and produce merozoites
    • Merozoites head to RBC; form trophozoites (ring stage) and multiply by fission to create more merozoites
    • Eventually malaria cells mature and sexual gametocytes can be picked up from mosquito for next round
    • Sexual fusion in gut of mosquito; those cells travel to salivary gland of mosquito until infects human
    Term
    Albendazole
    Definition
  • Class-antihelminthic
  • Mechanism-inhibits fumarate reductase which interferes with ATP production. Also inhibits microtuble synthesis-->lack attachment and cant move as well. Organism becomes "tired," and loses grip from intestintal tract, dies.
  • Target-roundworms
  • Special-same as Mebendazole and Thiabendazole
  • Term
    Mebendazole
    Definition
  • Class-antihelminthic
  • Mechanism-inhibits fumarate reductase which interferes with ATP production. Also inhibits microtuble synthesis-->lack attachment and cant move as well. Organism becomes "tired," and loses grip from intestintal tract, dies.
  • Target-roundworms
  • Special-same as Albendazole and Thiabendazole
  • Term
    Thiabendazole
    Definition
  • Class-antihelminthic
  • Mechanism-inhibits fumarate reductase which interferes with ATP production. Also inhibits microtuble synthesis-->lack attachment and cant move as well. Organism becomes "tired," and loses grip from intestintal tract, dies.
  • Target-roundworms
  • Special-same as Mebendazole and Albendazole
  • Term
    Pyrantel pamoate
    Definition
    • Class-antihelminthic
    • Mechanism-neuromuscular paralysis in the helminth
    • Target-pinworm (enterobiasis) and roundworm (ascariasis)
    • Special-none
    Term
    Emetine
    Definition
    • Class-antiprotozoal/antiamebiasis (diarrhea)
    • Mechanism-unknown
    • Target-this is a very potent antiprotozoal; attacks extraintestinal
    • Special-causes nausea (because its derived from ipecac root)
    Term
    Diloxanide
    Definition
    • Class-antiprotozoal/antiamebiasis (diarrhea)
    • Mechanism-unknown
    • Target-attacks intestinal (Entamoeba histolytica)
    • Special-none.
    Term
    Halogenated hydroxyquinolines
    Definition
    • Class-antiprotozoal/antiamebiasis (diarrhea)
    • Mechanism-unknown
    • Target-attacks intestinal
    • Special-none.
    Term
    Antiseptics and Disinfectants
    Definition

    These include:

    • Phenol
    • Iodine
    • Hydrogen Peroxide
    • Ethyl Alcohol 70%
    • Zephiran
    • Mercurochrome
    • Silver Nitrate
    • Nitrofurazone
    Term
    Reasons why a drug may not work
    Definition
    1. Patient compliance
    2. Drug interaction ex) excess presence of another drug in the blood that binds up the active form of the drug you want to give
    3. Resistance-intrinsic resistance is when the organism is already resistant; acquired resistance is when you put pressure on an organism population and it adapts to survive in the presence of the drug
    4. Toxicity-you can't use the full dose to txt because of toxicty, so the drug is not therapeutic
    5. Drug may not be slective and doesn't kill the organism ex) choosing the wrong drug
    6. Infection is in a place in the body where the drug cant get to ex) deep seated wound without blood supply; brain
    7. Superinfection-drug kills 1 organism, but doesn't kill the other that is not proliferating (think of normal flora infections)
    Term
    Chemotherapeutic Index
    Definition
    • LD50 is the lethal dose to kill 50% of the pathogen or inhibit growth by 50%
    • ED50 is the effective dose to produce the therapeutic effect
    • Index = LD50/ED50
    • High index indicates that the drug has a "large therapeutic window," meaning a large dose is needed to produce toxic effects. We want a high index to protect the patient
    Term
    Sites of Selective Toxicity
    Definition
    • Cell Wall-inactivate transpeptidase to inhibit crosslinking within peptidoglycan layer. ie) penicillins; cephalosporins
    • Cell Membrane-disruption of lipid bilayer. ie) polymyxins; most antifungals
    • Essential Nutrient-interference with biosynthetic pathway (folic acid). ie) sulfonamides; antifolates
    • Protein Synthesis-different composition of ribosomes. ie) aminoglycosides (30s); tetracyclines (30s); macrolides (50s)
    • DNA Synthesis-different DNA polymerases. ie) quinolones; antineoplastics
    Term
    Rating of Selective Toxicity
    Definition
    • Excellent-penicillins; cephalosporins; sulfonamides
    • Fair-aminoglycosides; tetracyclines
    • Poor-alkylating agents; pyrimidine analogues; purine analogues
    Term
    Itraconazole
    Definition
  • Class-antifungal (triazoles)
  • Mechanism-interfers with fungal sterols (ergosterol) in cell membrane
  • Target-broad spectrum of fungal infections
  • Special-less toxicity than ketoconazole and no endocrine side effects; inhibits testosterone synthesis; given oral or IV*