Antiprotozoal Drugs Nursing Pharmacology Study Guide - Nurseslabs

Antiprotozoals are agents used to treat protozoan infections. Protozoan infections are common in tropical areas.

Protozoans are single-celled organisms that pass through several stages in their life cycles, including at least one phase as a human parasite. While protozoans thrive in tropical climate, they may also survive and reproduce in any area where people live in very crowded and unsanitary conditions.

Contents

Table of Common Drugs and Generic Names


Here is a table of commonly encountered antiprotozoals, their generic names, and brand names:

Classification Generic Name Brand Name
Antimalarials chloroquine Aralen
mefloquine Lariam
primaquine *generic
pyrimethamine Daraprim
quinine Qualaquin
Other Antiprotozoals atovaquone Mepron
metronidazole Flagyl
nitazoxanide Alinia
pentamidine Pentam 300
tinidazole Tindamax

Disease Spotlight: Protozoal Diseases


Malaria

  • It is a disease characterized by a cycle of fever and chills transmitted through a bite of a female Anopheles mosquito. Identified causes include Plasmodium falciparum, vivax, malariae, and ovale. Malaria is endemic in many parts of the world.
  • Sporozoites travel through bloodstream and become lodged in the liver and other tissues.

Amebiasis

  • It is an intestinal infection caused by Entamoeba histolytica. It is often known as amoebic dysentery. The disease is transmitted through fecal-oral route.
  • Amebiasis is characterized by mild to fulminant diarrhea. In worst cases, it is able to invade extraintestinal tissue.

Leishmaniasis

  • Is a disease caused by a protozoan that is passed from sand flies to humans. It is characterized by serious lesions in the skin, viscera, and mucous membranes of host.

Trypanosomiasis

  • Is caused by Trypanosoma leading to African sleeping sickness and Chagas’ disease.
  • African sleeping sickness is caused by T.brucei gambiense and is transmitted by tsetse fly. It is characterized by lethargy, prolonged sleep, and even death.
  • Chagas’ disease is caused by T.cruzi and is passed to humans by common housefly. It is characterized by severe cardiomyopathy.

Trichomoniasis

  • Is caused by T.vaginalis, a common cause of vaginitis (reddened, inflamed vaginal mucosa, itching, burning, and yellowish-green discharge).
  • It is usually transmitted through sexual intercourse.
  • Asymptomatic in men

Giardiasis

  • Is caused by G.lamblia, the most commonly diagnosed intestinal parasite in the United States.
  • Transmission is through contaminated water or food, and trophozoites.
  • Characterized by diarrhea, rotten egg-smelling stool, and pale and mucus-filled stool. Some patients experience epigastric pain, weight loss, and malnutrition.

Antimalarials


Description

  • Antimalarials are agents used to attack Plasmodium at various stages of its life cycle. Through this, it becomes possible to prevent acute malarial reaction in individuals who have been infected by the parasite.
  • These agents can be schizonticidal (acting against the red-blood-cell phase of the life cycle), gametocytocidal (acting against the gametocytes), sporontocidal (acting against the parasites that are developing in the mosquito), or work against tissue schizonts as prophylactic or antirelapse agent.
  • Quinine (Qualaquine) was the first drug found to be effective in the treatment of malaria.

Therapeutic Action

The desired and beneficial action of antimalarials is:

  • Entering human red blood cells and changing the metabolic pathways necessary for the reproduction. Chloroquine, the mainstay of treatment, in addition to this main mechanism, is directly toxic to parasites and decreases the ability of the parasite to synthesize DNA.

Indications

Antimalarials are indicated for the following medical conditions:

  • Treatment of malaria, prevention of relapse, and other protozoal diseases like extraintestinal amoebiasis (chloroquine) and toxoplasmosis (pyrimethamine). 

Here are some important aspects to remember for indication antiprotozoals in different age groups:

Children

  • This age group is very sensitive to the effects of most antiprotozoals and therefore more severe reactions can be expected.
  • In addition, many antivirals do not have proven safety and efficacy in children. 

Adults

  • This age group should be well advised about the need for prophylaxis against various protozoal infections and the need for immediate treatment if disease is contracted.
  • Administration of drug in pregnant and nursing women is only justified if benefits clearly outweigh the risk.
  • Women of childbearing age are advised to use barrier contraceptives when any antiprotozoal drug is being taken. 

Older adults

  • Older patients are more susceptible to adverse effects of antiprotozoal therapy, particularly those with hepatic and renal dysfunctions.

Pharmacokinetics

Here are the characteristic interactions of antimalarials and the body in terms of absorption, distribution, metabolism, and excretion:

Route Onset Peak Duration
Oral Varies 1-2 h 1 wk
T1/2: 70-120 h
Metabolism: liver
Excretion: kidney (urine)

Contraindications and Cautions

The following are contraindications and cautions for the use of antimalarials:

  • Known allergy to the drug. Prevent hypersensitivity reactions.
  • Liver disease or alcoholism. Parasitic invasion of the liver and need for hepatic metabolism to prevent toxicity.
  • Lactation. Drugs can enter breast milk and could be toxic to infant.
  • Pregnancy. Associated with birth defects. Pregnancy should be avoided two months after completion of therapy using mefloquine.
  • Retinal disease or damage. Drugs can affect vision and retina, and the likelihood of problems increase if the retina is already damaged.
  • Psoriasis or porphyria. Skin damage as a result of drugs on proteins and protein synthesis.

Adverse Effects

Use of antimalarials may result to these adverse effects:

  • CNS: headache, dizziness
  • Immunological: fever, shaking, chills, malaise
  • GI: nausea, vomiting, dyspepsia, anorexia, hepatic dysfunction
  • Dermatological: rash, pruritus, loss of hair associated with changes in protein synthesis
  • Eyes: visual changes, possible blindness
  • Ears: ototoxicity related to nerve damage
  • Cinchonism (nausea, vomiting, tinnitus, and vertigo) may occur with high levels of quinine or primaquine.

Interactions

The following are drug-drug interactions involved in the use of antimalarials:

  • Quinine and quinine derivatives: increased risk for cardiac toxicity and convulsions
  • Anti-folate drugs (methotrexate, sulfonamides): increased bone marrow suppression with pyrimethamine. Discontinue pyrimethamine if signs of folate deficiency develop (diarrhea, fatigue, weight loss, anemia).

Nursing Considerations

Here are important nursing considerations when administering antimalarials:

Nursing Assessment

These are the important things the nurse should include in conducting assessment, history taking, and examination:

  • Assess for the mentioned cautions and contraindications (e.g. drug allergies, hepatorenal impairment, pregnancy and lactation, visual disturbances, etc.) to prevent any untoward complications.
  • Perform a thorough physical assessment (other medications taken, reflexes and muscle strength, skin color, temperature, texture, etc.) to establish baseline data before drug therapy begins, to determine effectiveness of therapy, and to evaluate for occurrence of any adverse effects associated with drug therapy.
  • Perform ophthalmic and retinal examinations and auditory screening to determine the need for cautious administration and to evaluate changes that occur as a result of drug therapy.
  • Assess the patient’s liver function, including liver function tests to determine appropriateness of therapy and to monitor for toxicity.
  • Obtain blood culture to identify the causative Plasmodium species and ensure appropriate use of the drug.
Nursing Diagnoses

Here are some of the nursing diagnoses that can be formulated in the use of these drugs for therapy:

  • Acute pain related to GI, CNS, and skin effects of the drug
  • Disturbed sensory perception (kinaesthetic, visual) related to CNS effects of the drug
  • Risk for injury related to CNS changes
Implementation with Rationale

These are vital nursing interventions done in patients who are taking antimalarials:

  • Arrange for appropriate culture and sensitivity tests before beginning therapy to ensure proper drug for susceptible Plasmodium species.
  • Administer the complete course of the drug to get the full beneficial effects.
  • Monitor hepatic function and perform ophthalmological examination before and periodically during treatment to ensure early detection and prompt intervention with cessation of drug if signs of failure or deteriorating vision occur.
  • Provide comfort and safety measures if CNS effects occur (e.g. side rails and assistance with ambulation if dizziness and weakness are present) to prevent patient injury. Provide oral hygiene and ready access to bathroom facilities as needed to cope with GI effects.
  • Educate client on drug therapy to promote understanding and compliance.
Evaluation

Here are aspects of care that should be evaluated to determine effectiveness of drug     therapy:

  • Monitor patient response to therapy (resolution or prevention of malaria).
  • Monitor for adverse effects (e.g. orientation and affect, nutritional state, skin color and lesions, hepatic function, and visual and auditory changes, etc).
  • Evaluate patient understanding on drug therapy by asking patient to name the drug, its indication, and adverse effects to watch for.
  • Monitor patient compliance to drug therapy.

Other Antiprotozoal Agents


Therapeutic Action

The desired and beneficial action of other antiprotozoal agents is:

  • Inhibiting DNA synthesis in susceptible protozoa, interfering with cell’s ability to reproduce, subsequently leading to cell death.

Indications

Other antiprotozoal agents are indicated for the following medical conditions:

  • Treatment of infections caused by susceptible protozoa.

Pharmacokinetics

Here are the characteristic interactions of other antiprotozoal agents and the body in terms of absorption, distribution, metabolism, and excretion:

Route Onset Peak Duration
Oral Varies 1-2 h N/A
IV Rapid 1-2 h N/A
T1/2: 6-8 h
Metabolism: liver
Excretion: kidney (urine), colon (feces)

Contraindications and Cautions

The following are contraindications and cautions for the use of other antiprotozoal agents:

  • Known allergy to the drug. Prevent hypersensitivity reactions.
  • Pregnancy. Drug effects on developing fetal DNA and proteins can cause fetal abnormalities and even death.
  • CNS disease. Possible disease exacerbation due to drug effects on the CNS.
  • Hepatic disease. Possible exacerbation when hepatic drug effects occur.
  • Candidiasis. Risk of superinfection
  • Lactation. Can pass breast milk and cause severe adverse effects to the infant.
  • Tinidazole should never be combined with alcohol.

Adverse Effects

Use of other antiprotozoal agents may result to these adverse effects:

  • CNS: headache, dizziness, ataxia, loss of coordination, peripheral neuropathy
  • GI: nausea, vomiting, diarrhea, unpleasant taste, cramps, changes in liver function
  • Superinfections

Interactions

The following are drug-drug interactions involved in the use of other antiprotozoal agents:

  • Alcohol: severe adverse effects with tinidazole and metronidazole. Avoid alcohol for at least 3 days after treatment.
  • Oral anticoagulants: increased bleeding with metronidazole and tinidazole
  • Disulfiram: increased psychotic reactions with metronidazole and tinidazole. Two weeks should elapse between tinidazole therapy and start of disulfiram.

Nursing Considerations

Here are important nursing considerations when administering other antiprotozoal agents:

Nursing Assessment

These are the important things the nurse should include in conducting assessment, history taking, and examination:

  • Assess for the mentioned cautions and contraindications (e.g. drug allergies, hepatorenal impairment, pregnancy and lactation, etc.) to prevent any untoward complications.
  • Perform a thorough physical assessment (other medications taken, reflexes and muscle strength, skin and mucous membrane color, temperature, texture, etc.) to establish baseline data before drug therapy begins, to determine effectiveness of therapy, and to evaluate for occurrence of any adverse effects associated with drug therapy.
  • Assess the patient’s liver function, including liver function tests to determine appropriateness of therapy and to monitor for toxicity.
  • Obtain cultures to determine the exact protozoal species causing the disease.
Nursing Diagnoses

Here are some of the nursing diagnoses that can be formulated in the use of these drugs for therapy:

  • Acute pain related to GI and CNS effects of the drug
  • Imbalanced nutrition: less than body requirements related to severe GI effects of the drug.
  • Disturbed sensory perception (kinaesthetic, visual) related to CNS effects of the drug
Implementation with Rationale

These are vital nursing interventions done in patients who are taking other antiprotozoal agents:

  • Arrange for appropriate culture and sensitivity tests before beginning therapy to ensure proper drug for susceptible species.
  • Administer the complete course of the drug to get the full beneficial effects.
  • Monitor hepatic function before and periodically during treatment to ensure early detection and prompt intervention with cessation of drug if signs of failure occur.
  • Provide comfort and safety measures if CNS effects occur (e.g. side rails and assistance with ambulation if dizziness and weakness are present) to prevent patient injury. Provide oral hygiene and ready access to bathroom facilities as needed to cope with GI effects.
  • Educate client on drug therapy to promote understanding and compliance.
Evaluation

Here are aspects of care that should be evaluated to determine effectiveness of drug     therapy:

  • Monitor patient response to therapy (resolution of infection and negative cultures for parasite).
  • Monitor for adverse effects (e.g. orientation and affect, nutritional state, skin color and lesions, hepatic function, and occurrence of superinfections, etc).
  • Evaluate patient understanding on drug therapy by asking patient to name the drug, its indication, and adverse effects to watch for.
  • Monitor patient compliance to drug therapy.

Practice Test: Antiprotozoal Agents


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1. Chagas’ disease is passed to humans by which of the following vector?

A. female Anopheles mosquito
B. housefly
C. tsetse fly
D. dragonfly

1. Answer: B. housefly.

Option A is for malaria while option C is for African sleeping sickness.

2. Which of the following patient statements should alert the nurse for possible high levels of quinine?

A. “I feel weak, especially after ambulating.”
B. “My throat is sore. I think I’m down with a flu.”
C. “When I went out of my bed, it felt like the room swayed.”
D. “I don’t feel like eating anything. I just want to sleep.”

2. Answer: C. “When I went out of my bed, it felt like the room swayed.”

This might be vertigo which is part of the constellation of manifestations of cinchonism which is associated with high levels of quinine or primaquine.

3. A traveler diagnosed with malaria is also receiving sulfonamide for a respiratory infection. What should the nurse watch out for in this drug combination?

A. increased intracranial pressure
B. urinary retention
C. blood component levels
D. serum BUN and creatinine

3. Answer: C. blood component levels.

This combination can lead to bone marrow suppression.

4. How many days should the patient avoid alcohol after treatment with metronidazole?

A. 1 day
B. 3 days
C. 5 days
D. 7 days

4. Answer: B. 3 days.

5. Disulfiram and tinidazole therapy can lead to increased psychotic reactions. How long after tinidazole therapy can we safely start disulfiram therapy?

A. 7-10 days
B. 14 days
C. 3 days
D. One month

5. Answer. B. 14 days.

See Also


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Further Reading and Resources


Recommended resources and books:
  1. Focus on Nursing Pharmacology - Easy to follow guide for Pharmacology
  2. NCLEX-RN Drug Guide: 300 Medications You Need to Know for the Exam - Great if you're reviewing for the NCLEX
  3. Nursing 2017 Drug Handbook (Nursing Drug Handbook) - Reliable nursing drug handbook!
  4. Lehne's Pharmacology for Nursing Care - Provides key information on commonly used drugs in nursing
  5. Pharmacology and the Nursing Process - Learn how to administer drugs correctly and safely!
  6. Pharm Phlash Cards!: Pharmacology Flash Cards - Flash Cards for Nursing Pharmacology
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