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Antimalarial, Antiprotozoal, and Anthelmintic Drugs
Chapter 43 Antimalarial, Antiprotozoal, and Anthelmintic Drugs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Protozoal Infections Parasitic protozoa: live in or on humans Malaria Leishmaniasis Amebiasis Giardiasis Trichomoniasis Trypanosomiasis Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Malaria Caused by Plasmodium protozoa Four different Plasmodium species Transmitted by the bite of an infected adult female anopheline mosquito Can also be transmitted by infected individuals via blood transfusion, congenitally, or from infected needles by drug abusers Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Malarial Parasite (Plasmodium)
Two interdependent life cycles Sexual cycle: occurs in the mosquito Asexual cycle: occurs in the human Knowledge of the life cycles is essential in understanding antimalarial drug treatment Drugs are effective only during the asexual cycle Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Plasmodium Life Cycle Asexual cycle: two phases Exoerythrocytic phase Occurs “outside” the erythrocyte Also known as the tissue phase Erythrocytic phase Occurs “inside” the erythrocyte Also known as the blood phase Erythrocytes = RBCs Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Classic Malaria Paroxysm
Chills and rigors, followed by fever of up to 104° F (40° C) and diaphoresis, frequently leading to extreme fatigue and prolonged sleep This syndrome often repeats itself periodically in 48- to 72-hour cycles Other common symptoms include headache, nausea, and joint pain Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Treatment of Malaria Not initiated until the diagnosis has been confirmed with diagnostic tests Treatment is guided by: The infecting Plasmodium species Clinical status of the patient Drug susceptibility of the infecting parasites as determined by the geographic area where the infection was acquired Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Antimalarial Drugs Attack the parasite during the asexual phase, when it is vulnerable Erythrocytic phase drugs: chloroquine, hydroxychloroquine, quinine, mefloquine, pyrimethamine Primaquine: kills parasite in both phases May be used together or with a sulfonamide for synergistic or additive killing power Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antimalarial Drugs: Mechanism of Action
4-Aminoquinoline derivatives: chloroquine and hydroxychloroquine Bind to parasite nucleoproteins and interfere with protein synthesis; also alter pH within the parasite Interfere with parasite’s ability to metabolize and use erythrocyte hemoglobin Effective only during the erythrocytic phase Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antimalarial Drugs: Mechanism of Action (cont’d)
Quinine and mefloquine Alter pH within the parasite Interfere with parasite’s ability to metabolize and use erythrocyte hemoglobin Effective only during the erythrocytic phase Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antimalarial Drugs: Mechanism of Action (cont’d)
Diaminopyrimidines (pyrimethamine and trimethoprim) Inhibit protein synthesis essential for growth and survival Only effective during the erythrocytic phase May be used with sulfadoxine or dapsone for synergistic effects Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Classroom Response Question
When pyrimethamine is used to treat malaria, a sulfonamide antibiotic is often also used. The purpose of the antibiotic is to: treat the bacterial infections that often accompany malaria. allow the antimalarial drug to be effective in the exoerythrocytic phase. cause synergism, allowing for a stronger antimalarial effect. allow for reduced adverse effects because smaller doses of each drug are used. Correct answer: C Rationale: The combination of some antimalarial drugs with specific antibiotics results in synergistic effects, thus making the drugs more effective against the malarial infection. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.
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Antimalarial Drugs: Mechanism of Action (cont’d)
Primaquine Only exoerythrocytic drug (works in both phases) Binds and alters parasitic DNA Sulfonamides, tetracyclines, clindamycin Used in combination with antimalarials for synergistic effects Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Classroom Response Question
Before administration of primaquine, it is most important for the nurse to assess the patient for a history of which condition? Asthma Diabetes mellitus Hypertension Rheumatoid arthritis Correct answer: D Rationale: Primaquine is contraindicated in patients with allergy or any disease states that may cause granulocytopenia (rheumatoid arthritis, systemic lupus erythematosus). Primaquine must be used with caution in patients with methemoglobinemia, porphyria, methemoglobin reductase deficiency, and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.
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Antimalarial Drugs: Drug Effects
Kill parasitic organisms Hydroxychloroquine Has antiinflammatory effects Sometimes used in the treatment of rheumatoid arthritis and systemic lupus erythematosus Quinine and quinidine Decrease the excitability of both cardiac and skeletal muscles Quinidine is still currently used to treat certain types of cardiac dysrhythmias Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antimalarial Drugs: Indications
Used to kill Plasmodium organisms, the parasites that cause malaria The drugs have varying effectiveness on the different malaria organisms Some drugs are used for prophylaxis against malaria Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antimalarial Drugs: Adverse Effects
Many adverse effects for the various drugs Primarily gastrointestinal Nausea Vomiting Diarrhea Anorexia Abdominal pain Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Antiprotozoal Drugs atovaquone (Mepron) metronidazole (Flagyl) pentamidine (Pentam 300) paromomycin (Humatin) Several drugs used to treat malaria are also used to treat nonmalarial protozoal infections Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Protozoal Infections Amebiasis Giardiasis Pneumocystosis Toxoplasmosis Trichomoniasis Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Protozoal Infections (cont’d)
Transmission Person to person Ingestion of contaminated water or food Direct contact with the parasite Insect bite (mosquito or tick) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Protozoal Infections (cont’d)
Patients with compromised immune systems are at risk for acquiring these infections Patients taking immunosuppressive drugs after a transplant Patients with leukemia AIDS patients Protozoal infections are often fatal in these cases Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antiprotozoal Drugs: Mechanism of Action and Indications
atovaquone (Mepron) Protozoal energy comes from the mitochondria Atovaquone: selective inhibition of mitochondrial electron transport Result: no energy, leading to cellular death Used to treat mild to moderate Pneumocystis jirovecii Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antiprotozoal Drugs: Mechanism of Action and Indications (cont’d)
metronidazole (Flagyl) Disruption of DNA synthesis as well as nucleic acid synthesis Bactericidal, amebicidal, trichomonacidal Used for treatment of trichomoniasis, amebiasis, giardiasis, and antibiotic-associated pseudomembranous colitis Tinidazole (Tindamax) is a newer, similar drug. Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antiprotozoal Drugs: Mechanism of Action and Indications (cont’d)
pentamidine (NebuPent, Pentam 300) Inhibits protein and nucleic acid synthesis Used mainly for the treatment of active P. jirovecii pneumonia and for prophylaxis of P. jirovecii pneumonia in patients at high risk for initial or recurrent Pneumocystis infection, such as patients with HIV infection and AIDS Sometimes used to treat various other protozoal infections Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Classroom Response Question
A male patient with an HIV infection has a severe case of P. jirovecii pneumonia (PJP) and needs to be treated with pentamidine. However, he is allergic to the inhaled form of this medication. Considering the seriousness of his condition, what does the nurse expect will be done in this situation? He will be given the inhaled form of pentamidine and be monitored closely. He will be given the pentamidine in an IM or IV injection and be monitored closely. Another drug, such as metronidazole (Flagyl), will be ordered. He will receive supportive care because he is unable to take the pentamidine. Correct answer: B Rationale: Hypersensitivity is more common when the drug is administered by inhalation. An allergic reaction to the inhalational form does not preclude its administration by either the intramuscular or intravenous route, due to the seriousness of the Pneumocystis infection. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.
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Antiprotozoal Drugs: Adverse Effects
atovaquone (Mepron) Nausea, anorexia, constipation, increased liver enzyme levels, many others metronidazole (Flagyl) Metallic taste, vomiting, diarrhea, headache, many others Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Classroom Response Question
A patient is taking metronidazole for amebiasis. What information should the nurse include in the patient teaching? How to check stool samples correctly and safely Metronidazole may precipitate hypertension Blurred vision is an expected effect of this medication, which will resolve with time To take the medication on an empty stomach Correct answer: A Rationale: When the patient is taking metronidazole for amebiasis, the nurse should include in the instructions how to check stool samples correctly and safely, and how to dispose of samples properly. Metronidazole may precipitate dizziness, so encourage the patient to be cautious in all activities until a response to the drug is noted and is consistent. Encourage the patient to contact the prescriber if there is any visual disturbance noted. The medication should be taken with food to decrease gastrointestinal upset. Copyright © 2014 by Mosby, an imprint of Elsevier Inc. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.
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Antiprotozoal Drugs: Adverse Effects (cont’d)
pentamidine Bronchospasms Leukopenia Thrombocytopenia Acute pancreatitis Nephrotoxicity Increased liver enzyme levels Hypotension Many others Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Anthelmintic Drugs Drugs used to treat parasitic worm infections: helminthic infections Unlike protozoa, helminths are large and have complex cellular structures Drug treatment is very specific to the organism Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Anthelmintic Drugs (cont’d)
albendazole (Albenza) ivermectin (Stromectol) praziquantel (Biltricide) pyrantel (Pin-X) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Anthelmintic Drugs (cont’d)
It is very important to identify the causative worm Done by finding the parasite ova or larvae in feces, urine, blood, sputum, or tissue Cestodes (tapeworms) Nematodes (roundworms) Trematodes (flukes) Platyhelminthes (flatworms) Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Anthelmintic Drugs: Mechanism of Action and Indications
praziquantel (Biltricide) Paralyzes worms’ musculature and immobilizes their suckers Causes worms to dislodge from mesenteric veins to the liver; then killed by host tissue reactions Used to treat fluke infections, some tapeworms Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Anthelmintic Drugs: Mechanism of Action and Indications (cont’d)
pyrantel (Pin-X) Pyrimidine-derived anthelmintic drug that is indicated for the treatment of infection with intestinal roundworms, including ascariasis, enterobiasis, and other helminthic infections Only anthelmintic available in the United States without a prescription Available only for oral use Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Anthelmintic Drugs: Adverse Effects
Effects will vary with each drug Common adverse effects Nausea Vomiting Diarrhea Dizziness Headache Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Nursing Implications Before beginning therapy, perform a thorough health history and medication history, and assess for allergies Be sure to collect specimens before beginning drug therapy Check baseline vital signs Check for conditions that may contraindicate use, and for potential drug interactions Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Nursing Implications (cont’d)
Some drugs may cause the urine to have an asparagus-like odor, or cause an unusual skin odor or a metallic taste; be sure to warn the patient ahead of time Administer all drugs as ordered and for the prescribed length of time Most drugs should be taken with food to reduce GI upset Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antimalarial Drugs: Nursing Implications
Assess for presence of malarial symptoms When used for prophylaxis, these drugs should be started 1 to 2 weeks before potential exposure to malaria, and for 4 to 8 weeks after leaving the area Medications are taken weekly, with 8 ounces of water Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Antimalarial Drugs: Nursing Implications (cont’d)
Instruct patient to notify prescriber immediately if ringing in the ears, hearing decrease, visual difficulties, nausea, vomiting, profuse diarrhea, or abdominal pain occurs Alert patient to the possible recurrence of the symptoms of malaria so that he or she will know to seek immediate treatment Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Nursing Implications (cont’d)
Monitor for adverse effects Ensure that patients know the adverse effects that should be reported Monitor for therapeutic effects and adverse effects with long-term therapy Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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