Therapeutics ID Santanello Flashcard

Protozoal Overview

  • Single-Celled Eukaryotes
  • Can replicate intracellularly (Plasmodium spp.) OR extracellularly in intestines (Giardia lamblia), blood (Trypanosoma), urogenital (Trichomonas vaginalis)
  • All protozoa surrounded by a unit membrane similar to cell membrane of all eukaryotes
  • Some have a very thin plasmalemma whereas others have a rigid body wall (flagellates and ciliates) called a pellicle

Targeted Therapy: Entamoeba histolytica
Metronidazole
Targeted Therapy: Giardia lamblia
Metronidazole
Targeted Therapy: Toxoplasma gondii
Pyrimethamine/Sulfadiazine
Targeted Therapy: Trichomonas vaginalis
Metronidazole
Metronidazole is first line therapy for:

Symptomatic Amoebiasis

 

Metronidazole: ADR

  • Abdominal discomfort
  • Loss of appetite
  • Metallic taste
  • Disulfiram-Like Reaction – wait at least 3 days after cessation of therapy to drink alcohol

Pyrimethamine/Sulfadiazine is used to treat:
Toxoplasmosis
Pyrimethamine/Sulfadiazine: ADR

  • Black Box Warning: May cause severe dermatologic reactions including Stevens-Johnson Syndrome
  • Causes photosensitivity
  • Take with plenty of water to prevent crystallization in the kidneys
  • The drug is a folic acid synthesis inhibitor — take with Folic Acid

Helminths Overview

  • Multicellular eukaryotes
  • Most alternate between sexual reproduction in definitive host and asexual in intermediate host or vector
  • Adults don’t multiply in hosts but do generate eggs or larvae — they can do damage and it depends on infective load

Trematode: Classification
Flukes
Cestodes: Classification
Tapeworms
4 Examples of Nematodes

Trichinella spiralis

Necator americanus

Enterobius vermicularis

Ascaris lumbricoides

Structure of Adult Trematode

  • Outer protective cuticle (tegument)
  • Outer portion of tegument has glycocalyx, a protective zone that inhibits the action of digestive enzymes
  • Some have tegumental spines
  • Layer of muscle below

Targeted Therapy: Tapeworms
Praziquantel
Targeted Therapy: Flukes

Praziquantel

 

Targeted Therapy: Trichinella spiralis

  • Mebendazole
  • Pyrantel pamoate
  • Albendazole

Targeted Therapy: Necator americanus

 

  • Mebendazole
  • Pyrantel pamoate
  • Albendazole

Targeted Therapy: Enterobius vermicularis

  • Mebendazole
  • Pyrantel pamoate
  • Albendazole

Targeted Therapy: Ascaris lumbricoides

  • Mebendazole
  • Pyrantel pamoate
  • Albendazole

Praziquantel: Spectrum of Activity

Broad spectrum antihelminthic action

 

Praziquantel: Clinical Pearls

  • Single day treatment, TID
  • CYP450 Metabolism — possibility for drug interactions
  • Lack of serious toxicity
  • Take with liquid at meals

Mebendazole: MOA

Inhibits polymerization of tubulin into microtubules of helminths –> depletes glycogen stores –> decrease in ATP

    Albendazole: MOA
    Inhibits polymerization of tubulin into microtubules of helminths –> depletes glycogen stores –> decrease in ATP
    Albendazole: ADR

    • Hepatotoxic (caution with liver disease)
    • Poorly absorbed systemically
    • May cause abdominal pain, nausea, vomiting, or headache

    Pyrantel Pamoate: Clinical Pearls, ADR

    • The only OTC medicine to treat pinworms
    • Repeat dose in 2 weeks — only kills the adult pinworms, NOT the eggs — give again in 2 weeks because the eggs can survive and become adults
    • Caution with liver disease

    Examples of Ectoparasites
    Arthropods: Insects (lice, fleas, bedbugs, mosquitoes), or Arachnids (mites, ticks, spiders)
    How to ectoparasites damage the host?

    • Attach to or live on the skin
    • Directly damage the host or indirectly by depositing feces, saliva, or pathogen
    • At the site of the bite, mouthparts may be associated with lymphocytes, eosinophils, macrophages which is a response to what is being deposited (feces, saliva, pathogen)

    Arthropods have a _________ exoskeleton

    • Chitinous exoskeleton (cuticle)
    • The exoskeleton limits growth so periodic molting is required

    Permethrin: MOA, Indications

    • Causes paralysis of the louse or mite
    • Indicated for lice, ticks, mites, and fleas

    Lindane: Indications, ADR

    • Only indicated for patients that have failed first line treatment (permethrin)
    • Black Box Warning: Seizures and deaths with repeat or prolonged application — should not be given to children who weigh < 110 lbs because it increases risk of neurotoxicity

     

    Praziquantel: MOA
    Increases membrane permeability of parasite and increases muscle contractility — allows us to void the parasite

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