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Anthelmintic Drugs

Anthelmintic drugs are used to treat infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease caused by parasitic helminths. Helminths include both flatworms (flukes and tapeworms) and roundworms. Anthelmintic medications are categorized on the basis of the class of helminths they are used for. Nematicidal agents include the benzimidazoles (albendazole, mebendazole, and triclabendazole), diethylcarbamazine, ivermectin, and pyrantel pamoate Pyrantel pamoate Broad spectrum antinematodal anthelmintic used also in veterinary medicine. Enterobius/Enterobiasis. Praziquantel is a trematocidal and cestodicidal agent. The mechanisms of action of the anthelmintic drugs vary, but many work by disrupting the normal function of the organism, inducing paralysis, and/or causing death. Most of these drugs are well absorbed, which can allow for treatment of systemic infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease. Pyrantel pamoate Pyrantel pamoate Broad spectrum antinematodal anthelmintic used also in veterinary medicine. Enterobius/Enterobiasis, on the other hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy, is poorly absorbed and is better suited to treating luminal nematodes. The benzimidazoles’ absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption is changed by the presence of food, which allows for some control in treating luminal or invasive infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease (such as cysticercosis Cysticercosis Infection with cysticercus, the larval form of the various tapeworms of the genus taenia (usually T. solium in man). In humans they penetrate the intestinal wall and invade subcutaneous tissue, brain, eye, muscle, heart, liver, lung, and peritoneum. Brain involvement results in neurocysticercosis. Taenia/Taeniasis). Adverse effects of anthelmintics vary, but all classes of these drugs are associated with GI side effects.

Last updated: Aug 18, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Overview

Classification of helminths

The different classes of helminths are: 

  • Roundworms (nematodes)
  • Flatworms (platyhelminths):
    • Tapeworms (cestodes)
    • Flukes (trematodes)

Classification of anthelmintic drugs

The most commonly used anthelmintic drugs are: 

  • Nematicidal agents:
  • Trematocidal and cestodicidal agents: 
    • Praziquantel 
    • Niclosamide (discontinued in the United States)

Benzimidazoles

Medications in this class

  • Albendazole
  • Mebendazole
  • Triclabendazole

Mechanism of action

  • Bind BIND Hyperbilirubinemia of the Newborn to free beta-tubulin → prevent polymerization into microtubules Microtubules Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein tubulin and are influenced by tubulin modulators. The Cell: Cytosol and Cytoskeleton
  • Effects:
    • ↓ Microtubule-dependent glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance uptake → ↓ ATP production → energy depletion 
    • Worm immobilization Immobilization Delirium 
    • Disrupted reproduction
    • Death

Pharmacokinetics Pharmacokinetics Pharmacokinetics is the science that analyzes how the human body interacts with a drug. Pharmacokinetics examines how the drug is absorbed, distributed, metabolized, and excreted by the body. Pharmacokinetics and Pharmacodynamics

  • Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption:
    • Poorly absorbed orally
    • Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption ↑ with food (fatty meals).
  • Distribution: highly protein-bound
  • Metabolism:
    • 1st-pass metabolism in the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy
    • Albendazole and triclabendazole have active metabolites.
  • Excretion: mostly in the feces

Indications

Albendazole and mebendazole have activity against a broad spectrum Broad Spectrum Macrolides and Ketolides of: 

  • Nematodes:
    • Ascaris Ascaris Ascaris is a genus of parasitic nematodes. The infection, ascariasis, is most often caused by A. lumbricoides. Transmission occurs primarily via ingestion of water or food contaminated with Ascaris eggs. Most patients with ascariasis are asymptomatic. Ascaris/Ascariasis lumbricoides
    • Ancylostoma duodenale Ancylostoma Duodenale Hookworm Infections and A. caninum
    • Enterobius Enterobius Enterobiasis is a helminth infection caused by Enterobius vermicularis, also known as a pinworm. This infection is typically seen in children and is transmitted through the fecal-oral route. The primary clinical feature is anal pruritus, but patients are often asymptomatic. Enterobius/Enterobiasis vermicularis 
    • Necator americanus Necator americanus A common parasite of humans in the moist tropics and subtropics. These organisms attach to villi in the small intestine and suck blood causing diarrhea, anorexia, and anemia. Hookworm Infections
    • Strongyloides stercoralis Strongyloides stercoralis A species of parasitic nematode widely distributed in tropical and subtropical countries. The females and their larvae inhabit the mucosa of the intestinal tract, where they cause ulceration and diarrhea. Strongyloidiasis 
    • Toxocara Toxocara A genus of ascarid nematodes commonly parasitic in the intestines of cats and dogs. Toxocariasis species
    • Trichinella spiralis Trichinella spiralis A parasite of carnivorous mammals that causes trichinellosis. It is especially common in rats and in swine fed uncooked garbage. Human infection is initiated by the consumption of raw or insufficiently cooked pork or other meat containing the encysted larvae. Trichinella/Trichinellosis 
    • Trichuris trichiura 
  • Trematodes:
    • Clonorchis sinensis (Chinese liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy fluke)
    • Opisthorchis viverrini (Southeast Asian liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy fluke)
  • Cestodes:
    • Echinococcus Echinococcus Echinococcosis is a parasitic disease caused by Echinococcus tapeworms. Infection most often occurs from the ingestion of Echinococcus eggs in food or water contaminated with dog feces. Signs and symptoms are caused by hydatid cyst development in visceral organs and depend on the species. Echinococcus/Echinococcosis granulosus (dog tapeworm)
    • Taenia Taenia Taenia belong to the Cestoda class of helminths. Humans are infected with these tapeworms by eating undercooked beef (T. saginata) or pork (T. solium and T. asiatica). Taeniasis is often asymptomatic, but the ingestion of larvae can cause abdominal discomfort, nausea, and constipation or diarrhea. Taenia/Taeniasis saginata (beef tapeworm) 
    • Taenia Taenia Taenia belong to the Cestoda class of helminths. Humans are infected with these tapeworms by eating undercooked beef (T. saginata) or pork (T. solium and T. asiatica). Taeniasis is often asymptomatic, but the ingestion of larvae can cause abdominal discomfort, nausea, and constipation or diarrhea. Taenia/Taeniasis solium (pork tapeworm) 
  • Others:
    • Giardia Giardia A genus of flagellate intestinal eukaryotes parasitic in various vertebrates, including humans. Characteristics include the presence of four pairs of flagella arising from a complicated system of axonemes and cysts that are ellipsoidal to ovoidal in shape. Nitroimidazoles duodenalis
    • Microsporidia Microsporidia Microsporidia are a group of obligate intracellular organisms that were recently reclassified as fungi. The most common species of Microsporidia is Enterocytozoon bieneusi. Microsporidia species are ubiquitous, with a wide range of reservoirs. Immunocompromised individuals (particularly those with AIDS and a CD4 count < 100 cells/µL) most commonly develop symptomatic microsporidiosis. Microsporidia/Microsporidiosis

Adverse effects

  • Headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess 
  • Abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
  • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia
  • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes 
  • Neutropenia Neutropenia Neutrophils are an important component of the immune system and play a significant role in the eradication of infections. Low numbers of circulating neutrophils, referred to as neutropenia, predispose the body to recurrent infections or sepsis, though patients can also be asymptomatic. Neutropenia
  • Agranulocytosis Agranulocytosis A decrease in the number of granulocytes; (basophils; eosinophils; and neutrophils). Lincosamides

Diethylcarbamazine

Mechanism of action

  • Not completely understood
  • Works on microfilariae Microfilariae The prelarval stage of filarioidea found in the blood and tissues of mammals, birds and intermediate hosts (vector). Lymphatic Filariasis (Elephantiasis) (early stage of certain nematodes, usually in the circulatory system or tissues):

Pharmacokinetics Pharmacokinetics Pharmacokinetics is the science that analyzes how the human body interacts with a drug. Pharmacokinetics examines how the drug is absorbed, distributed, metabolized, and excreted by the body. Pharmacokinetics and Pharmacodynamics

  • Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption:
    • Well absorbed
    • Rapid
  • Distribution: widely to most tissues (except adipose)
  • Excretion: urine (approximately 50% as unchanged drug)

Indications

Diethylcarbamazine is indicated for the following nematode Nematode A phylum of unsegmented helminths with fundamental bilateral symmetry and secondary triradiate symmetry of the oral and esophageal structures. Many species are parasites. Toxocariasis infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease:

  • Lymphatic filariasis Lymphatic filariasis Lymphatic filariasis, also known as elephantiasis, is a chronic mosquito-borne infection caused by Wuchereria bancrofti, Brugia malayi, and B. timori. The majority of causes are due to W. bancrofti. Mosquitos are the vectors, and humans are the primary reservoir. Patients with acute infection can present with fever, adenolymphangitis, dermatolymphangioadenitis, and tropical pulmonary eosinophilia. Lymphatic Filariasis (Elephantiasis) caused by: 
    • Wuchereria bancrofti Wuchereria bancrofti A white threadlike worm which causes elephantiasis, lymphangitis, and chyluria by interfering with the lymphatic circulation. The microfilaria are found in the circulating blood and are carried by mosquitoes. Lymphatic Filariasis (Elephantiasis)
    • Brugia malayi Brugia malayi A species of parasitic nematode causing malayan filariasis and having a distribution centering roughly on the malay peninsula. The life cycle of B. malayi is similar to that of Wuchereria bancrofti, except that in most areas the principal mosquito vectors belong to the genus Mansonia. Lymphatic Filariasis (Elephantiasis)
    • Brugia timori 
  • Loiasis Loiasis A parasitic infection caused by the nematode loa loa. The vector in the transmission of this infection is the horsefly (tabanus) or the deerfly or mango fly (chrysops). The larvae may be seen just beneath the skin or passing through the conjunctiva. Eye lesions are not uncommon. The disease is generally mild and painless. Lymphatic Filariasis (Elephantiasis) (Loa loa)
  • Visceral larva migrans Visceral larva migrans A condition produced in man by the prolonged migration of animal nematode larvae in extraintestinal tissues other than skin; characterized by persistent hypereosinophilia, hepatomegaly, and frequently pneumonitis, commonly caused by toxocara canis and toxocara cati. Toxocariasis ( Toxocara Toxocara A genus of ascarid nematodes commonly parasitic in the intestines of cats and dogs. Toxocariasis spp.)

Adverse effects

Ivermectin

Chemistry

  • Semisynthetic macrocyclic lactone 
  • Derived from avermectin (from the mold Mold Mycology Streptomyces avermitilis)
  • Lipophilic

Mechanism of action

  • Selectively binds to glutamate-gated chloride Chloride Inorganic compounds derived from hydrochloric acid that contain the Cl- ion. Electrolytes ion channels Channels The Cell: Cell Membrane 
  • ↑ Permeability of the cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane to chloride Chloride Inorganic compounds derived from hydrochloric acid that contain the Cl- ion. Electrolytes ions
  • Hyperpolarization Hyperpolarization Membrane Potential → paralysis of organisms

Pharmacokinetics Pharmacokinetics Pharmacokinetics is the science that analyzes how the human body interacts with a drug. Pharmacokinetics examines how the drug is absorbed, distributed, metabolized, and excreted by the body. Pharmacokinetics and Pharmacodynamics

  • Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption:
    • Well absorbed
    • Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption with high-fat meals
  • Distribution: 
    • High concentration in the liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy and adipose tissue Adipose tissue Adipose tissue is a specialized type of connective tissue that has both structural and highly complex metabolic functions, including energy storage, glucose homeostasis, and a multitude of endocrine capabilities. There are three types of adipose tissue, white adipose tissue, brown adipose tissue, and beige or “brite” adipose tissue, which is a transitional form. Adipose Tissue: Histology 
    • Does not cross the blood– brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification barrier 
    • Highly protein-bound
  • Metabolism: 
    • Hepatic
    • By cytochrome P450 Cytochrome P450 A superfamily of hundreds of closely related hemeproteins found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (mixed function oxygenases). In animals, these p450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (biotransformation). They are classified, according to their sequence similarities rather than functions, into cyp gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the cyp1, cyp2, and cyp3 gene families are responsible for most drug metabolism. Drug-induced Liver Injury enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes
  • Excretion: mainly in feces

Indications

  • Nematodes:
    • Ascaris Ascaris Ascaris is a genus of parasitic nematodes. The infection, ascariasis, is most often caused by A. lumbricoides. Transmission occurs primarily via ingestion of water or food contaminated with Ascaris eggs. Most patients with ascariasis are asymptomatic. Ascaris/Ascariasis lumbricoides
    • Onchocerca volvulus Volvulus A volvulus is the twisting or axial rotation of a portion of the bowel around its mesentery. The most common site of volvulus in adults is the colon; most frequently the sigmoid volvulus. Patients typically present with symptoms of bowel obstruction such as abdominal pain, distension, vomiting, and constipation/obstipation. Volvulus (river blindness Blindness The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of eye diseases; optic nerve diseases; optic chiasm diseases; or brain diseases affecting the visual pathways or occipital lobe. Retinopathy of Prematurity)
    • Strongyloides stercoralis Strongyloides stercoralis A species of parasitic nematode widely distributed in tropical and subtropical countries. The females and their larvae inhabit the mucosa of the intestinal tract, where they cause ulceration and diarrhea. Strongyloidiasis
    • Wuchereria bancrofti Wuchereria bancrofti A white threadlike worm which causes elephantiasis, lymphangitis, and chyluria by interfering with the lymphatic circulation. The microfilaria are found in the circulating blood and are carried by mosquitoes. Lymphatic Filariasis (Elephantiasis) infection ( lymphatic filariasis Lymphatic filariasis Lymphatic filariasis, also known as elephantiasis, is a chronic mosquito-borne infection caused by Wuchereria bancrofti, Brugia malayi, and B. timori. The majority of causes are due to W. bancrofti. Mosquitos are the vectors, and humans are the primary reservoir. Patients with acute infection can present with fever, adenolymphangitis, dermatolymphangioadenitis, and tropical pulmonary eosinophilia. Lymphatic Filariasis (Elephantiasis))
  • Other: 
    • Prevention and control of scabies Scabies Scabies is an infestation of the skin by the Sarcoptes scabiei mite, which presents most commonly with intense pruritus, characteristic linear burrows, and erythematous papules, particularly in the interdigital folds and the flexor aspects of the wrists. Scabies infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease
    • Pediculus humanus Pediculus humanus Lice of the genus pediculus, family pediculidae. Pediculus humanus corporis is the human body louse and pediculus humanus capitis is the human head louse. Bartonella capitis (head lice)

Adverse effects

  • Dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome)
  • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia
  • Abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
  • Myalgias Myalgias Painful sensation in the muscles. Tick-borne Encephalitis Virus
  • Pruritus Pruritus An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief. Atopic Dermatitis (Eczema)
  • Rash Rash Rocky Mountain Spotted Fever
  • Stevens-Johnson syndrome Stevens-Johnson syndrome Stevens-Johnson syndrome (SJS) is a cutaneous, immune-mediated hypersensitivity reaction that is commonly triggered by medications, including antiepileptics and antibiotics. The condition runs on a spectrum with toxic epidermal necrolysis (TEN) based on the amount of body surface area (BSA) involved. Stevens-Johnson Syndrome
  • Orthostatic hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension
  • Confusion
  • Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures 
  • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes

Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation

  • Extreme caution in children: ↑ risk of CNS effects
  • Avoid in pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care

Drug interactions

Enhanced GABA GABA The most common inhibitory neurotransmitter in the central nervous system. Receptors and Neurotransmitters of the CNS activity may occur with:

  • Barbiturates Barbiturates A class of chemicals derived from barbituric acid or thiobarbituric acid. Many of these are gaba modulators used as hypnotics and sedatives, as anesthetics, or as anticonvulsants. Intravenous Anesthetics
  • Benzodiazepines Benzodiazepines Benzodiazepines work on the gamma-aminobutyric acid type A (GABAA) receptor to produce inhibitory effects on the CNS. Benzodiazepines do not mimic GABA, the main inhibitory neurotransmitter in humans, but instead potentiate GABA activity. Benzodiazepines
  • Valproic acid Valproic acid A fatty acid with anticonvulsant and anti-manic properties that is used in the treatment of epilepsy and bipolar disorder. The mechanisms of its therapeutic actions are not well understood. It may act by increasing gamma-aminobutyric acid levels in the brain or by altering the properties of voltage-gated sodium channels. First-Generation Anticonvulsant Drugs

Pyrantel Pamoate

Mechanism of action

  • Works mainly against luminal organisms
  • Acts as a depolarizing neuromuscular blocking agent → paralyzes helminths → expulsion:
    • Causes acetylcholine Acetylcholine A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system. Receptors and Neurotransmitters of the CNS release Release Release of a virus from the host cell following virus assembly and maturation. Egress can occur by host cell lysis, exocytosis, or budding through the plasma membrane. Virology
    • Inhibits cholinesterase Cholinesterase Liver Function Tests

Pharmacokinetics Pharmacokinetics Pharmacokinetics is the science that analyzes how the human body interacts with a drug. Pharmacokinetics examines how the drug is absorbed, distributed, metabolized, and excreted by the body. Pharmacokinetics and Pharmacodynamics

  • Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption: poor oral absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption 
  • Excretion: feces

Indications

Pyrantel pamoate Pyrantel pamoate Broad spectrum antinematodal anthelmintic used also in veterinary medicine. Enterobius/Enterobiasis is used for intestinal nematodes, including:

  • Ascaris Ascaris Ascaris is a genus of parasitic nematodes. The infection, ascariasis, is most often caused by A. lumbricoides. Transmission occurs primarily via ingestion of water or food contaminated with Ascaris eggs. Most patients with ascariasis are asymptomatic. Ascaris/Ascariasis lumbricoides 
  • Ancylostoma duodenale Ancylostoma Duodenale Hookworm Infections
  • Enterobius Enterobius Enterobiasis is a helminth infection caused by Enterobius vermicularis, also known as a pinworm. This infection is typically seen in children and is transmitted through the fecal-oral route. The primary clinical feature is anal pruritus, but patients are often asymptomatic. Enterobius/Enterobiasis vermicularis 
  • Necator americanus Necator americanus A common parasite of humans in the moist tropics and subtropics. These organisms attach to villi in the small intestine and suck blood causing diarrhea, anorexia, and anemia. Hookworm Infections
  • Trichostrongylus spp.

Adverse effects

  • Abdominal cramps Cramps Ion Channel Myopathy
  • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
  • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia 
  • Headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
  • Dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome)

Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation

  • Severe liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy disease (use with caution)
  • Known hypersensitivity

Praziquantel

Mechanism of action

  • ↑ Cell permeability to calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes → uncontrolled calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes influx → muscle contraction and paralysis 
  • Tegument Tegument Herpes Simplex Virus 1 and 2 vacuolization and disintegration

Pharmacokinetics Pharmacokinetics Pharmacokinetics is the science that analyzes how the human body interacts with a drug. Pharmacokinetics examines how the drug is absorbed, distributed, metabolized, and excreted by the body. Pharmacokinetics and Pharmacodynamics

  • Absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption: well absorbed
  • Distribution:
    • Protein-bound
    • Crosses blood– brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification barrier
  • Metabolism:
    • Extensive 1st-pass metabolism 
    • Hepatic
  • Excretion: urine (approximately 99% as metabolites)

Indications

Praziquantel is used for many trematode Trematode Class of parasitic flukes consisting of three subclasses, monogenea, aspidogastrea, and digenea. The digenetic trematodes are the only ones found in man. They are endoparasites and require two hosts to complete their life cycle. Schistosoma/Schistosomiasis and cestode Cestode A subclass of segmented worms comprising the tapeworms. Diphyllobothrium/Diphyllobothriasis infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease:

  • Trematodes:
    • Schistosoma Schistosoma Schistosomiasis is an infection caused by Schistosoma, a trematode. Schistosomiasis occurs in developing countries with poor sanitation. Freshwater snails are the intermediate host and are transmitted to humans through skin contact with contaminated fresh water. The clinical presentation occurs as a result of the host’s immune response to antigens from the eggs. Schistosoma/Schistosomiasis spp.
    • Clonorchis sinensis 
    • Opisthorchis viverrini
  • Cestodes:
    • Taenia Taenia Taenia belong to the Cestoda class of helminths. Humans are infected with these tapeworms by eating undercooked beef (T. saginata) or pork (T. solium and T. asiatica). Taeniasis is often asymptomatic, but the ingestion of larvae can cause abdominal discomfort, nausea, and constipation or diarrhea. Taenia/Taeniasis spp.
    • Diphyllobothrium Diphyllobothrium Diphyllobothriasis represents an intestinal parasitic infection caused by the cestode Diphyllobothrium. Diphyllobothriasis is acquired by ingestion of late larvae in undercooked or raw fish. The clinical presentation of diphyllobothriasis varies from asymptomatic, nonspecific symptoms to intestinal obstruction, and/or vitamin B12 deficiency. Diphyllobothrium/Diphyllobothriasis latum
    • Echinococcus Echinococcus Echinococcosis is a parasitic disease caused by Echinococcus tapeworms. Infection most often occurs from the ingestion of Echinococcus eggs in food or water contaminated with dog feces. Signs and symptoms are caused by hydatid cyst development in visceral organs and depend on the species. Echinococcus/Echinococcosis spp.

Adverse effects

  • Dizziness Dizziness An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness. Lateral Medullary Syndrome (Wallenberg Syndrome) 
  • Headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
  • Drowsiness 
  • Urticaria Urticaria Urticaria is raised, well-circumscribed areas (wheals) of edema (swelling) and erythema (redness) involving the dermis and epidermis with associated pruritus (itch). Urticaria is not a single disease but rather is a reaction pattern representing cutaneous mast cell degranulation. Urticaria (Hives) 
  • Abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
  • Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever 
  • Cardiac arrhythmias
  • Mild ↑ liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy enzymes Enzymes Enzymes are complex protein biocatalysts that accelerate chemical reactions without being consumed by them. Due to the body’s constant metabolic needs, the absence of enzymes would make life unsustainable, as reactions would occur too slowly without these molecules. Basics of Enzymes
  • Exacerbation of neurologic abnormalities (in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with CNS infection, such as neurocysticercosis Neurocysticercosis Infection of the brain, spinal cord, or perimeningeal structures with the larval forms of the genus taenia (primarily T. solium in humans). Lesions formed by the organism are referred to as cysticerci. The infection may be subacute or chronic, and the severity of symptoms depends on the severity of the host immune response and the location and number of lesions. Seizures represent the most common clinical manifestation although focal neurologic deficits may occur. Taenia/Taeniasis)

Contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation

  • Known hypersensitivity
  • Ocular cysticercosis Cysticercosis Infection with cysticercus, the larval form of the various tapeworms of the genus taenia (usually T. solium in man). In humans they penetrate the intestinal wall and invade subcutaneous tissue, brain, eye, muscle, heart, liver, lung, and peritoneum. Brain involvement results in neurocysticercosis. Taenia/Taeniasis (parasite destruction may cause irreparable eye damage)
  • Use with caution with:
    • Severe liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy disease
    • Atrioventricular block Atrioventricular block Atrioventricular (AV) block is a bradyarrhythmia caused by delay, or interruption, in the electrical conduction between the atria and the ventricles. Atrioventricular block occurs due to either anatomic or functional impairment, and is classified into 3 types. Atrioventricular block (AV block)
    • Arrhythmias

References

  1. Holden-Dye L, Walker RJ. (2007). Antihelminthic drugs. WormBook 2:1–13. https://pubmed.ncbi.nlm.nih.gov/17988075/
  2. Liu LX, Weller PF. (1996). Antiparasitic drugs. NEJM. 334(18), 1178-84. https://pubmed.ncbi.nlm.nih.gov/8602186/
  3. Weller PF. (2021). Anthelminthic therapies. UpToDate. Retrieved August 5, 2021, from https://www.uptodate.com/contents/anthelminthic-therapies
  4. UptoDate Lexicomp. Retrieved September 4, 2021, from:
  5. Campbell S, Soman-Faulkner K. (2020). Antiparasitic drugs. StatPearls. Retrieved September 4, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK544251/
  6. Rosenthal PJ. (2012). Clinical pharmacology of the antihelminthic drugs. In: Katzung BG, Masters SB, Trevor AJ (Eds.), Basic & Clinical Pharmacology. 12th ed. McGraw-Hill, pp. 937–947). https://pharmacomedicale.org/images/cnpm/CNPM_2016/katzung-pharmacology.pdf

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