Anthelmintics: Nursing Pharmacology Study Guide

Anthelmintics are drugs used to treat infections caused by susceptible invading worms.

Table of Common Drugs and Generic Names


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

Classification Generic Name Brand Name
Anthelmintics albendazole Albenza
ivermectin Stromectol
mebendazole Vermox
praziquantel Biltricide
pyrantel Antiminth, Pin-Rid

Disease Spotlight: Helminthic infections


  • These are infections in the GI tract or other tissues due to worm infestations. It affects about 1 billion people which make it the most common of all diseases.
  • Infestations are very common in tropical areas. Travelers can contract a helminthic infection and bring it home, where the worms can infect other individuals.
  • Most common infectious helminths are nematodes (roundworms) and platyhelminthes (flatworms) which invade the intestines and the tissues.

Therapeutic Action

The desired and beneficial action of anthelmintics is:

  • They act on metabolic pathways present in the invading worm but are absent or significantly different in human host.

Indications

Anthelmintics are indicated for the following medical conditions:

  • Albendazole for the treatment of active lesions caused by pork tapeworm and cystic disease of the liver, lungs, and peritoneum caused by dog tapeworm.
  • Ivermectin is used for the treatment of threadworm disease or strongyloidiasis and onchocerciasis or river blindness.
  • Mebendazole is for the treatment of diseases caused by pinworms, roundworms, whipworms, and hookworms.
  • Praziquantel is for treatment of a wide number of schistosomes or flukes.
  • Pyrantel is for treatment caused by pinworms and roundworms.

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

Children

  • Culture of the suspected worm is important before beginning any drug therapy.
  • Albendazole, ivermectin, and praziquantel are more toxic so they are avoided in children. Instead, a chewable preparation of mebendazole is usually given.
  • Children may develop serious GI effects during therapy so nurse’s focus must be on nutritional status and hydration.

Adults

  • This age group might be repulsed by the idea that they have a worm infestation, and they may be reluctant to discuss the needed lifestyle adjustments and treatment plans.
  • Pregnant and nursing women should not use these drugs unless the benefits clearly outweigh the risks. Potential risks must be communicated to the patients.

Older adults

  • Older patients are more susceptible to GI and CNS adverse effects of Anthelmintics therapy particularly those with hepatic and renal dysfunctions.

Pharmacokinetics

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

Route Onset Peak Duration
Oral Slow 2-4 h N/A
T1/2: 2.5-9 h
Metabolism: liver
Excretion: colon (feces)

Contraindications and Cautions

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

  • Known allergy to the drug. Prevent hypersensitivity reactions.
  • Lactation. Drug can enter breast milk.
  • Renal and hepatic disease. Interfere with drug metabolism and excretion.
  • Severe diarrhea and malnourishment. Can alter effects of drug on the intestine and any preexisting helminths.
  • Pyrantel has not been established as safe for use in children younger than 2 years.

Adverse Effects

Use of anthelmintics may result to these adverse effects:

  • GI: abdominal discomfort, diarrhea, pain
  • CNS: headache, dizziness,
  • Immunologic: fever, shaking, chills, malaise, rash, pruritus, loss of hair
  • Albendazole is associated with severe bone marrow depression and renal failure.

Interactions

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

  • Dexamethasone, praziquantel, cimetidine. Increased toxic effects of albendazole

Nursing Considerations

Here are important nursing considerations when administering anthelmintics:

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. known allergies, hepatorenal dysfunction, pregnancy and lactation, 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.
  • Assess the patient’s liver function, including liver function tests to determine appropriateness of therapy and to monitor for toxicity.
  • Obtain a culture of stool for ova and parasites to determine the infecting worm and establish appropriate treatment.
  • Assess the abdomen to evaluate for any changes from baseline related to the infection, identify possible adverse effects, and monitor for improvement.

Nursing Diagnoses

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

Implementation with Rationale

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

  • 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 of helminth infestation and improvement in signs and symptoms).
  • Monitor for adverse effects (e.g. orientation and affect, nutritional state, skin color and lesions, hepatic function, and reports of abdominal discomfort and pain, 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 Quiz: Anthelmintics


Here are some practice questions for this study guide:

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1. Which drug is indicated for threadworm infections?

A. albendazole
B. ivermectin
C. pyrantel
D. mebendazole

1. Answer: B. ivermectin.

  • Option A is for tapeworms
  • C for pinworms and roundworms, and
  • D for whipworms and hookworms as well as pinworms and roundworms.

2. A nurse caring for a pediatric patient on anthelmintic therapy should be alarmed of the following adverse drug reactions, except:

A. fever and chills
B. weight loss of 2kg in 3 days
C. difficulty in feeding
D. unusually sleepy child

2. Answer. A. fever and chills.

It might be associated with drug action on worms. Options B,C, and D are manifestations of GI and CNS drug adverse effects.

3. Which of the following physical assessment findings will alert the nurse for anthelmintic drug toxicity in elderly patients?

A. muscle strength +2
B. blunt liver edge upon palpation
C. 10 bowel sounds in one minute on right lower quadrant (RLQ) upon auscultation
D. non-palpable spleen

3. Answer: B. blunt liver edge upon palpation.

This may indicate hepatomegaly or ongoing inflammatory process which is adversely caused by anthelmintics. All other options are normal PE findings.

4. A patient was receiving dexamethasone was prescribed with albendazole. Which of the following is the most appropriate nursing action?

A. Ignore the order and refuse to administer the drug.
B. Increase the dose of albendazole and notify doctor.
C. Discuss with the doctor for possible dose adjustment or change of medication.
D. Decrease the dose of albendazole and notify doctor.

4. Answer: C. Discuss with the doctor for possible adjustment or change of medication.

This combination greatly increases the risk of renal failure.

5. All of the laboratory tests listed below should be arranged by the nurse for patients receiving anthelmintics, except:

A. serum electrolytes
B. T3 and T4 levels
C. prothrombin time
D. stool culture

5. Answer: B. T3 and T4 levels.

  • This is not related to monitoring of client’s condition while under therapy.
  • Serum electrolytes is important as client may have fluid losses as side effect of the drug.
  • Prothrombin time is part of liver function test.
  • Stool culture is important for establishing appropriate treatment.

See Also


Related posts:

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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