3. ANTIMALARIALS, ANTHELMINTICS, AND PEPTIDES

Malaria

Life-threatening disease: Eliminated in the US by the 1950s. Most prevalent protozoan disease globally.

Cause of Malaria

Protozoan parasites of the genus Plasmodium

Carrier of Malaria

Anopheles mosquitoes

4 types of Plasmodium

Malaria

• P. malariae

• P. ovale

• P. vivax (most common)

• P. falciparum (most severe)

2 Phases: Tissue Phase

Antimalarial drug

Invasion of body tissue (e.g., liver cells)

2 Phases: Erythrocytic phase

Antimalarial drug

Invasion of red blood cells, leading to clinical symptoms.

General Side Effects and Adverse Reactions: Antimalarial drug

GI upset, cranial nerve VIII involvement (quinine and chloroquine), renal impairment, and cardiovascular effects (quinine).

Chloroquine

Antimalarial drug

Commonly prescribed for malaria.

Quinine

Antimalarial drug

The only antimalarial drug available from 1820 until the early 1940s. Quinidine is an antidysrhythmic drug

Chloroquine and mefloquine

Antimalarial drug

Frequently used to treat an acute malarial attack.

Mefloquine HCl and the combination drug atovaquone/proguanil (Malarone)

Antimalarial drug

Used to treat chloroquine-resistant P. falciparum

Chloroquine and hydroxychloroquine

Antimalarial drug

Toxic to children and may cause death.

Chloroquine Phosphate / Chloroquine HCl

Antimalarial drug

• Drug Class: Antimalarial

• Mechanism of Action: Chloroquine concentrates in the parasite's food vacuole, where it interferes with the polymerization of heme (a toxic byproduct of hemoglobin digestion by the parasite) into hemozoin. This leads to the accumulation of toxic heme within the parasite, ultimately causing its death. It also raises the pH within the food vacuole, inhibiting parasite growth.

• Uses: To treat acute malaria; Prophylaxis for Malaria.

• SE: Anorexia, nausea, diarrhea, visual impairment, insomnia, photosensitivity.

• AE: ECG Changes, hypotension, psychosis, seizures.

• CI: Psoriasis, hypersensitivity, renal disease.

NURSING PROCESS

Antimalarial Drug

• Assessment: Hearing, visual changes, level of consciousness. History of travel to a malaria-endemic area (e.g., Palawan, Davao del Norte, Sultan Kudarat in the Philippines).

• Nursing Diagnoses:

  • Risk for infection related to insufficient knowledge about avoiding exposure to malaria pathogens.

  • Risk for imbalanced nutrition: less than body requirements related to side effects of vomiting and diarrhea.

  • Risk for visual injury related to side effects of blurred vision.

• Planning: Patients will be free of malarial symptoms.

• Nursing Interventions:

  • Monitor renal and liver function tests.

  • Monitor the patients for impaired consciousness, headache, seizure.

• Evaluation: Effectiveness of treatment (absence of malarial symptoms).

Helminths:

Large parasitic worms.

Most common site for helminthiasis (worm infection)

Intestine

Other sites for Helminths

Lymphatic system, blood vessels, and liver

Pathophysiology of Helmninths

They enter the human host via contaminated food, bites of carrier insects, or direct penetration of the skin.

General Side Effects and Adverse Reactions: Anthelmintic Drugs

• The common side effects of anthelmintics (agents that destroy worms) include various manifestations of GI distress, such as: anorexia, nausea, vomiting and occasionally diarrhea and stomach cramps.

• Neurologic Problems: Dizziness, weakness, headache, and drowsiness.

Praziquantel

Anthelmintic drugs

• Mechanism of Action: Causes a rapid influx of calcium into the helminth, leading to severe spasms and paralysis of the worm's musculature. This allows the worm to be dislodged from the host's intestinal wall or blood vessels and subsequently eliminated by the body's immune system. It also makes the worms more susceptible to attack by the host's immune cells.

• Uses: Treatment of beef, pork and fish tapeworms; blood flukes and liver, lung, and intestinal flukes.

• Caution: Dizziness.

Pyrantel Pamoate

Anthelmintic drugs

• Mechanism of Action: Acts as a depolarizing neuromuscular blocking agent in helminths. It stimulates nicotinic acetylcholine receptors on the worm's muscles, leading to persistent activation and spastic paralysis, which causes the worms to lose their grip on the intestinal wall and be expelled in the feces.

• Uses: For giant roundworm, hookworm, and pinworm.

Ivermectin

Anthelmintic drugs

• Drug Class: Synthetic Anthelmintic

• Mechanism of Action: Selectively binds to glutamate-gated chloride ion channels found in invertebrate nerve and muscle cells. This binding increases the permeability of the cell membrane to chloride ions, leading to hyperpolarization and paralysis of the parasite's pharyngeal and somatic muscles, ultimately resulting in its death. It does not readily cross the mammalian blood-brain barrier, reducing its toxicity to humans.

• Uses: Broad-spectrum anthelmintic drug that causes paralysis to the parasite and effective against various mites.

• SE: Dizziness, Nausea, Pruritus.

• AE: Ocular effects and Opacity, Tachycardia, Increased liver enzymes (AST, ALT).

• CI: Asthma.

NURSING PROCESS of Anthelmintic drugs

• Assessment: History of food patient eaten and food preparation. Anal itching and abdominal discomfort. Stool specimen collection.

• Nursing Diagnoses:

  • Defensive coping related to invasion of helminth.

  • Activity intolerance related to dizziness, headache, drowsiness.

  • Disturbed body image related to fear of rejection by others.

  • Deficient knowledge related to inexperience with anthelmintic regime.

• Nursing Interventions:

  • Collect stool specimens in a clean container.

  • Emphasize handwashing before eating and after working in the soil or with animals.

  • Monitor intake and output.

• Evaluation: Proper hygiene observed, absence of worms in stool.

Antimicrobial Peptides

Broad spectrum and bactericidal

• Two groups of peptides (antibiotics):

  • Polymyxins

  • Bacitracin

• Derived from cultures of Bacillus subtilis, which interfere with bacterial cell membrane function.

Polymyxins

Peptides

• Mechanism of Action: Cationic peptides that act as surfactants. They bind to the negatively charged lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria and phospholipids in the inner membrane, disrupting the integrity of the bacterial cell membrane. This leads to increased permeability, leakage of intracellular components, and ultimately bacterial cell death (bactericidal effect).

• Uses: Bactericidal effect.

• SE/AE: Nephrotoxicity, neurotoxicity.

Bacitracin

Peptides

• Mechanism of Action: Primarily inhibits bacterial cell wall synthesis. It interferes with the dephosphorylation of undecaprenyl pyrophosphate, a lipid carrier molecule essential for transporting peptidoglycan precursors across the bacterial cell membrane. This prevents the addition of new units to the growing cell wall, leading to its disruption and damage to the cell membrane.

• Uses: Inhibits bacterial cell-wall synthesis and damages the cell-wall membrane.

• SE: Redness, rash, nausea, and vomiting.

• AE: Ototoxicity.

Metronidazole

Peptides

• Mechanism of Action: A prodrug that is activated intracellularly by reduction of its nitro group in anaerobic bacteria and certain protozoa (e.g., Giardia, Trichomonas, Entamoeba). This reductive activation creates highly reactive cytotoxic compounds that damage DNA and other macromolecules, leading to cell death. It is effective against anaerobic bacteria and protozoa.

• Uses: Used to treat disorders in the GI. Anti-amoebic agent.

• SE and AE: Dizziness, confusion, irritability, weakness. Taking high doses: dark or reddish-brown urine, dry mouth, metallic or bitter taste, and GI distress.

NURSING PROCESS of Peptides

• Assessment: Allergies. Renal function and urinary output. Skin integrity.

• Nursing Diagnosis:

  • Risk for Allergy Response.

  • Risk for Infection.

  • Risk for Injury.

  • Risk for Impaired Tissue Integrity.

• Planning: Liver and kidney laboratory results within normal limits. Skin will be intact without pruritus, swelling, or rash.

• Nursing Interventions:

  • Monitor lab values (e.g., renal, liver function).

  • Monitor urinary output.

  • Monitor the level of consciousness.

• Evaluation: Effectiveness of treatment (e.g., resolution of infection, improved skin integrity).