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Nursing Pharmacology:  Antiparasitic Agents

Amebiasis

  • Drugs used to treat amebiasis:  categories

    • Tissue amebicides

      • Nitroimidazoles

        •  Metronidazole (Flagyl)

          • Very effective in bowel wall and other tissues

          • Partially effective & NOT adequate as luminal amebicides {metronidazole (Flagyl) alone may fail to cure as much as 50% of intestinal disease}

      • Emetines:

        •  Emetine (generic) and dehydroemetine (Mebadin)

        •  Intramuscular injection-act on bowel-wall/tissue organisms; NOT on luminal amebas

      • Chloroquine (Aralen)-primary activity against hepatic amebas

    • Luminal amebicides (active in bowel lumen-not effective against amebas in bowel wall/other tissues)

      •  Dichloroacetamides

        • Diloxanide furoate (Furamide)

        • Others available outside USA-clefamide, teclozan, etofamide

      •  Halogenated hydroxyquinolines

        • Iodoquinol (Yodoxin, Moebequin)

        • Available outside the USA-clioquinol

    • Antibiotics

      •  Paromomycin (Humatin) & erythromycin: directly amebicidal

      •  Oral tetracyclines inhibit bacterial associates of bowel luminal E. histolytica-as a result affect luminal amebas

      •  Paromomycin (Humatin)-highly effective; other antibiotics should not be used as monotherapy because of their limited effectiveness

  • Drug Treatment of Asymptomatic Intestinal Infection

    • Management in endemic areas: asymptomatic carriers not treated due to high-risk of reinfection

    • Management in nonendemic regions:

      • Treat asymptomatic carriers with a luminal amebicide:

        •  Drugs of choice-cure frequency: 80%-90% using a single treatment course

          • Diloxanide furoate (Furamide)-fewer side effects

          • Iodoquinol (Yodoxin, Moebequin)

        • Alternative agents (treatment/re-treatment)

          • Paromomycin (Humatin)

          • Metronidazole (Flagyl) + iodoquinol (Yodoxin, Moebequin) or diloxanide.

Asymptomatic infection (intestinal)

Specific Form of Amebiasis

Drug (s) of Choice

Alternative Drug(s)

Asymptomatic infection (intestinal)

 Diloxanide furoate (Furamide)

Iodoquinol (Yodoxin, Moebequin)- orparomomycin

 

Mild-moderate infection; (nondysenteric colitis)

Specific Form of Amebiasis

Drug (s) of Choice

Alternative Drug(s)

Mild-moderate infection; (nondysenteric colitis)

  •  Metronidazole (Flagyl) plus

    •  diloxanide furoate (Furamide)

    •  idoquinol (Yodoxin) or

    •  paromomycin (Humatin)

  • Diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin) plus

    • a tetracycline followed by chloroquine (Aralen) OR

    • paromomycin (Humatin) followed by chloroquine (Aralen)

 

  • Drug Treatment of Severe Intestinal Amebiasis

    • Drugs of choice include metronidazole (Flagyl) plus diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin);

      • If parenteral administration is initially required, use intravenous metronidazole (Flagyl) then oral treatment when possible

    • Alternative drugs include:

      • A tetracycline + diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin), followed by chloroquine (Aralen)

      • If parenteral treatment is initially required:

        • Dehydroemetine (Mebadin) or emetine (generic), followed by

          • A tetracycline + diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin) followed by

          • Chloroquine (Aralen)

Severe intestinal infection (dysentery)

Specific Form of Amebiasis

Drug (s) of Choice

Alternative Drug(s)

Severe intestinal infection (dysentery)

  •  Metronidazole (Flagyl) plus

    •  Diloxanide furoate (Furamide) or

    •  Idoquinol (Yodoxin) or

  • If parenteral treatment is initially required:

    • IV metronidazole (Flagyl) until oral treatment is possible of then use:

    • Oral metronidazole (Flagyl) + diloxanide furoate (Furamide) are iodoquinol (Yodoxin, Moebequin)

  • A tetracycline plus

    • Diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin) followed by

    • Chloroquine (Aralen)

  • If parenteral treatment is initially required:

    • Dehydroemetine (Mebadin) or emetine (generic), followed by

    • A tetracycline plus diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin), followed by

    • Chloroquine (Aralen)

 

  • Hepatic Abscess

    • Nonpharmacological: bed rest/hospitalization

    •  Drug treatments of choice:

      •  Metronidazole (Flagyl)-ten day protocol/cure rate: > 95% its (uncomplicated cases)

        •  For treatment failure: follow metronidazole (Flagyl) protocol with chloroquine (Aralen)

        •  Additional advantage of metronidazole (Flagyl): effective against bacterial liver abscess, as well -- due to anaerobic bacteria

      • Also required: luminal amebicide {independent of positive stools}

        • Diloxanide furoate (Furamide)

        • Iodoquinol (Yodoxin, Moebequin)

    • Potentially more toxic alternative drugs:

      •  Dehydroemetine (Mebadin)

      •  Emetine (generic)

Hepatic Abscess

Specific Form of Amebiasis

Drug (s) of Choice

Alternative Drug(s)

Hepatic Abscess

  •  Metronidazole (Flagyl) plus

    •  Diloxanide furoate (Furamide) OR  idoquinol (Yodoxin) FOLLOWED BY

    • Chloroquine (Aralen)

  • Dehydroemetine (Mebadin) or emetine (generic) followed by

    • Chloroquine (Aralen) PLUS

    • Diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin)

  • Ameboma/Extraintestinal  amebiasis

    • Drug or choice: metronidazole (Flagyl)

    • Alternative drugs: dehydroemetine (Mebadin) oremetine (generic)

    • Not acceptable: chloroquine (Aralen)-insufficient tissue concentration (except hepatic) to be effective

    • Concurrent luminal amebicide also required.

Ameboma/Extraintestinal infection

Specific Form of Amebiasis

Drug (s) of Choice

Alternative Drug(s)

Ameboma/Extraintestinal infection

  •  Metronidazole (Flagyl) plus

    •  diloxanide furoate (Furamide) OR  idoquinol (Yodoxin)

  • Dehydroemetine (Mebadin) or emetine (generic) plus

    • diloxanide furoate (Furamide) or iodoquinol (Yodoxin, Moebequin)

 

Primary Reference: Goldsmith, R. S., Antiprotozoal Drugs in Basic and Clinical Pharmacology (Katzung, B. G., ed) Appleton-Lange, 1998, p. 838-861.

Primary Reference: Morgan, Juliette and del Rio, Carlos, Amebiasis in Medicine for the Practicing Physician (Hurst, J. W., ed) Appleton-Lange, 1996, pp. 457-459.

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