7.6 Antiparasitic and Anthelminthic Drugs
3 min read•june 18, 2024
Parasitic and helminthic infections pose significant health challenges worldwide. These invaders, ranging from tiny to larger worms, can wreak havoc on the human body, causing a variety of symptoms and complications.
Understanding the mechanisms of infection and available treatments is crucial for healthcare providers. From antiprotozoal drugs to anthelmintics, a range of medications can combat these parasites, but careful consideration of effectiveness and side effects is essential for optimal patient care.
Parasitic and Helminthic Infections
Mechanisms of parasitic infections
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- Parasitic protozoa or invade and multiply within a host organism, deriving nutrients and causing harm to the host
- Protozoan parasites (Giardia, ) typically infect the gastrointestinal tract, leading to diarrhea and malabsorption
- Helminthic parasites, including roundworms (Ascaris), tapeworms (), and flukes (), can infect various organs and tissues, resulting in a wide range of symptoms
- Parasites are transmitted through ingestion of contaminated food or water (Giardia), contact with infected feces (), penetration of skin by larvae (), or via insect vectors ()
- Some parasites can be transmitted between animals and humans ()
Symptoms and diagnosis of infections
- Gastrointestinal symptoms manifest as diarrhea, abdominal pain, cramping, nausea, vomiting, weight loss, and malnutrition
- Systemic symptoms include fever, chills, fatigue, weakness, anemia, and nutrient deficiencies
- Microscopic examination of stool, blood, or tissue samples aids in identifying parasites or their eggs
- Serological tests detect antibodies or antigens specific to the parasite
- Imaging techniques (X-rays, CT scans) help visualize internal damage caused by
Antiparasitic and Anthelminthic Drugs
Major antiparasitic drugs
- Antiprotozoal drugs target specific protozoan parasites
- disrupts DNA synthesis, causing cell death in anaerobic protozoa (Giardia, )
- interferes with heme detoxification in malaria parasites ()
- inhibits the pyruvate ferredoxin oxidoreductase enzyme, disrupting energy metabolism in protozoa (Cryptosporidium)
- Anthelmintic drugs combat parasitic worms
- (, ) inhibit microtubule formation, impairing glucose uptake and causing paralysis in helminths
- acts as a neuromuscular blocking agent, leading to paralysis in roundworms
- increases cell membrane permeability, causing calcium influx and paralysis in tapeworms and flukes
Effectiveness vs side effects
- Drug effectiveness varies based on the specific parasite, chosen medication, dosage, treatment duration, and potential
- Common side effects include gastrointestinal disturbances (nausea, vomiting, diarrhea), headache, dizziness, and fatigue
- Rarely, severe reactions such as liver toxicity or blood disorders may occur
- Antacids and iron supplements may reduce the absorption of some
- Anticonvulsants and rifampin can decrease the effectiveness of certain anthelmintics
- Caution is needed when combining or drugs with medications that have similar side effects
Pharmacology of antiparasitic drugs
- : The study of how the body processes antiparasitic drugs, including absorption, distribution, metabolism, and excretion
- : The examination of how antiparasitic drugs interact with their targets and produce therapeutic effects
- Understanding these processes helps optimize dosing regimens and predict potential drug interactions
Nursing considerations for administration
- Assess for contraindications and allergies before administering medications
- Administer drugs with food or milk to minimize gastrointestinal side effects
- Monitor patients closely for adverse reactions and promptly report severe symptoms
- Ensure proper hydration and electrolyte balance, especially in patients experiencing diarrhea
- Educate patients on the importance of completing the full course of treatment
- Implement infection control measures to prevent the spread of parasitic or helminthic infections
Patient education for medications
- Explain the purpose and expected outcomes of the prescribed medication to the patient
- Provide clear instructions on dosage, administration, and duration of treatment
- Discuss potential side effects and when to seek medical attention
- Emphasize the importance of personal hygiene and sanitation to prevent reinfection
- Encourage frequent handwashing, proper food cooking, and drinking clean water
- Advise patients to avoid swimming in contaminated water sources and to wear protective clothing when necessary
Global impact of infections
- Parasitic and helminthic infections are highly prevalent in developing countries with poor sanitation and limited access to clean water
- These infections contribute to malnutrition, anemia, and impaired cognitive development, especially in children
- The burden of disease strains healthcare systems, requiring ongoing treatment and prevention efforts
- Challenges include developing effective vaccines, managing drug resistance, and improving diagnostic tools in resource-limited settings
- Public health interventions, such as mass drug administration and health education campaigns, are crucial for controlling and eliminating these infections
Key Terms to Review (67)
Albendazole: Albendazole is an antiparasitic and anthelminthic drug used to treat a variety of parasitic infections, including those caused by tapeworms, roundworms, and other intestinal parasites. It works by interfering with the parasite's ability to absorb glucose, leading to its starvation and death.
Alinia: Alinia (nitazoxanide) is an antiparasitic and antiviral medication used to treat infections caused by protozoa such as Giardia lamblia and Cryptosporidium parvum. It works by interfering with the energy production of the parasites.
Anthelminthic: Anthelminthics are a class of drugs used to treat infections caused by parasitic worms, also known as helminths. These medications work by either killing the worms or expelling them from the body, helping to resolve the parasitic infection.
Anthelminthic agents: Anthelminthic agents are drugs used to treat infections caused by parasitic worms. They work by either killing the parasites or expelling them from the body.
Antibiotic drug resistance: Antibiotic drug resistance occurs when bacteria develop the ability to defeat the drugs designed to kill them. This makes infections harder to treat and increases the risk of disease spread, severe illness, and death.
Antibody mediated/humoral immunity: Antibody-mediated (humoral) immunity is a specific immune response where B cells produce antibodies that neutralize pathogens and mark them for destruction. This process is crucial for defending the body against extracellular organisms.
Antiparasitic: Antiparasitic refers to substances or agents that are used to treat or prevent infections caused by parasitic organisms, such as protozoa, helminths, and ectoparasites. These drugs target and disrupt the life cycle, growth, or reproduction of parasites, thereby eliminating or reducing their presence in the host organism.
Antiparasitic drugs: Antiparasitic drugs are medications designed to treat infections caused by parasites, including protozoa, helminths, and ectoparasites. These drugs work by killing or inhibiting the growth and reproduction of the parasitic organisms.
Ascaris lumbricoides: Ascaris lumbricoides is a large parasitic roundworm that infects the human gastrointestinal tract. It is the most common and widespread human helminth infection, affecting millions of people globally, particularly in developing countries with poor sanitation and hygiene conditions.
Benzimidazoles: Benzimidazoles are a class of heterocyclic organic compounds that contain a fused benzene and imidazole ring. They are widely used in the development of antiparasitic and anthelminthic drugs due to their potent biological activities.
Chloroquine: Chloroquine is a medication primarily used to prevent and treat malaria, a parasitic infection transmitted by mosquitoes. It works by interfering with the life cycle of the malaria parasite within the human body, making it an important antiparasitic drug.
Complete Blood Count: A complete blood count (CBC) is a common blood test that measures the number and characteristics of different types of blood cells, including red blood cells, white blood cells, and platelets. It provides valuable information about an individual's overall health and can help diagnose and monitor various medical conditions, including those related to antiparasitic and anthelminthic drug therapy.
Cryptosporidium: Cryptosporidium is a genus of parasitic protozoans that can cause the diarrheal disease cryptosporidiosis in humans and animals. It is a significant public health concern, particularly for individuals with weakened immune systems, and is classified as an antiparasitic drug target.
CYP3A4 Inhibitors: CYP3A4 inhibitors are a class of drugs or substances that reduce the activity or expression of the CYP3A4 enzyme, a key player in the metabolism of many medications. This interaction can lead to increased blood levels and potential toxicity of drugs that are primarily metabolized by CYP3A4, making CYP3A4 inhibitors an important consideration in pharmacotherapy across various therapeutic areas.
Drug Resistance: Drug resistance refers to the ability of a pathogen, such as a virus, bacteria, parasite, or cancer cell, to withstand the effects of a drug or medication that is designed to kill or inhibit its growth. This phenomenon can significantly impact the effectiveness of various treatments, including those for HIV/AIDS, sexually transmitted infections, parasitic infections, and cancer.
Efflux Pumps: Efflux pumps are specialized transport proteins found in the cell membranes of various organisms, including bacteria, fungi, and even human cells. These pumps actively expel harmful or unwanted substances, such as toxins, drugs, and metabolic byproducts, from the cell, playing a crucial role in maintaining cellular homeostasis and conferring resistance to certain medications.
Elimite: Elimite is a topical medication used primarily to treat scabies and lice infestations. It contains permethrin, an insecticide that kills parasites by disrupting their nervous system.
Emverm: Emverm is a brand name for mebendazole, an anthelmintic medication used to treat parasitic worm infections such as pinworm, roundworm, and hookworm. It works by inhibiting the worms' ability to absorb sugars, which leads to their eventual death.
Entamoeba: Entamoeba is a genus of parasitic amoebozoans that can infect the human gastrointestinal tract, leading to a condition known as amebiasis. These single-celled organisms are important in the context of antiparasitic and anthelminthic drugs, as they can cause significant health issues if left untreated.
Flagyl: Flagyl, also known as metronidazole, is an antibiotic and antiprotozoal medication used to treat various infections including sexually transmitted infections (STIs) and parasitic infections. It is commonly administered orally or intravenously.
GABA Potentiation: GABA potentiation refers to the enhancement or amplification of the inhibitory effects of the neurotransmitter gamma-aminobutyric acid (GABA) in the central nervous system. This process is particularly relevant in the context of antiparasitic and anthelminthic drugs, as it can contribute to their mechanisms of action and therapeutic effects.
Giardia lamblia: Giardia lamblia, also known as Giardia intestinalis or Giardia duodenalis, is a flagellated protozoan parasite that infects the small intestine of humans and other vertebrates. It is a common cause of waterborne diarrheal disease worldwide, particularly in developing countries with poor sanitation and water treatment systems.
Helminthology: Helminthology is the scientific study of parasitic worms, also known as helminths. It encompasses the investigation of the biology, life cycles, and impact of these organisms, which can infect and cause disease in humans and other animals.
Helminths: Helminths are parasitic worms, including flatworms, roundworms, and flukes, that infect the gastrointestinal tract and other tissues. They can cause significant health issues and are treated with anthelmintic drugs.
Hepatic Metabolism: Hepatic metabolism refers to the biochemical processes that occur within the liver to break down, transform, and eliminate various substances, including drugs and other xenobiotics. It is a crucial aspect of pharmacokinetics, as the liver plays a central role in the metabolism and clearance of many medications.
Hepatotoxicity: Hepatotoxicity is the occurrence of liver damage due to exposure to certain substances, including drugs. It can lead to serious health complications and requires careful monitoring.
Hepatotoxicity: Hepatotoxicity refers to the potential for certain drugs, chemicals, or other substances to cause liver damage or dysfunction. It is a critical consideration in the development and use of various medications and treatments.
Hookworms: Hookworms are parasitic nematode worms that infect the small intestine of humans and other mammals. They are a significant public health concern in many developing countries, causing a condition known as hookworm disease or ancylostomiasis.
Ivermectin: Ivermectin is a broad-spectrum antiparasitic drug that is primarily used to treat various parasitic infections, including those caused by nematodes (roundworms), ectoparasites (such as lice and scabies), and some protozoans. It is a key medication in the context of antiparasitic and anthelminthic drugs, which are used to eliminate or control parasitic infestations.
Lactation: Lactation is the process of milk production and secretion by the mammary glands in female mammals, including humans. It is a crucial physiological function that provides nourishment and immunological protection for newborns and infants. This term is particularly relevant in the context of various drug classes and their potential impact on the lactation process.
Lindane: Lindane is an organochlorine chemical used as a second-line treatment for scabies and lice infestations. It is available in topical formulations such as lotions and shampoos.
Liver Function Tests: Liver function tests (LFTs) are a group of blood tests that provide information about the state of a person's liver. These tests measure the levels of certain enzymes and proteins in the blood, which can indicate liver damage or disease.
Malaria: Malaria is a serious and sometimes fatal disease caused by a parasite that infects a certain type of mosquito, which feeds on humans. The parasite is called Plasmodium, and it is transmitted to humans through the bites of infected mosquitoes. Malaria is a significant public health concern, particularly in tropical and subtropical regions of the world.
Mebendazole: Mebendazole is an antiparasitic and anthelminthic drug used to treat various types of parasitic worm infections, including roundworm, hookworm, and whipworm infestations. It works by interfering with the parasites' ability to absorb glucose, leading to their starvation and death.
Metronidazole: Metronidazole is a nitroimidazole antibiotic and antiparasitic medication used to treat a variety of infections, including sexually transmitted infections, parasitic infections, and alcohol use disorder. It works by disrupting the DNA of anaerobic bacteria and protozoa, leading to their death or inhibition of growth.
Microtubule Inhibition: Microtubule inhibition refers to the disruption or prevention of the normal function and structure of microtubules, which are essential cytoskeletal components involved in various cellular processes. This mechanism of action is particularly relevant in the context of antiparasitic and anthelminthic drugs, as it can disrupt critical functions in parasitic organisms, leading to their death or inhibition of growth and proliferation.
Natroba: Natroba (spinosad) is a topical antiparasitic medication used to treat head lice infestations. It works by causing neuronal excitation, leading to paralysis and death of the lice.
Neurotoxicity: Neurotoxicity refers to the harmful or adverse effects that certain substances, chemicals, or agents can have on the structure and/or function of the nervous system, including the brain, spinal cord, and peripheral nerves. It is a critical consideration in the context of various drug classes and their potential to cause neurological complications.
Nitazoxanide: Nitazoxanide is an antiparasitic and anthelminthic drug used to treat a variety of parasitic infections, including giardiasis, cryptosporidiosis, and infections caused by certain helminths. It works by interfering with the energy production of the parasites, leading to their death or inhibition of their growth.
Onchocerciasis: Onchocerciasis, also known as river blindness, is a parasitic disease caused by the filarial worm Onchocerca volvulus. It is a major public health concern in parts of Africa and Latin America, leading to severe skin disease and vision impairment, including permanent blindness.
Oral: Oral refers to anything related to the mouth or administered through the mouth. It is a route of administration for various drugs and treatments, particularly in the context of antiparasitic, anthelminthic, and multiple sclerosis therapies.
Oral Suspension: An oral suspension is a liquid dosage form that contains finely dispersed solid particles suspended in a liquid vehicle. It is designed for oral administration and is often used to deliver medications that are not easily soluble or palatable in their pure form.
Parasitic infections: Parasitic infections are diseases caused by parasites such as protozoa, helminths, and ectoparasites. These infections often require specific anti-parasitic medications for treatment.
Parasitology: Parasitology is the study of parasites, their hosts, and the relationship between them. It encompasses the identification, classification, biology, ecology, and impact of parasitic organisms on human, animal, and plant health. Parasitology is a critical field within the broader context of antiparasitic and anthelminthic drug development and usage.
Parenteral: Parenteral refers to the administration of drugs or other substances through routes other than the gastrointestinal (GI) tract, such as intravenous, intramuscular, subcutaneous, or other non-oral methods. This mode of drug delivery is commonly used in the context of antiparasitic and anthelminthic drugs, where the parenteral route can provide more reliable and effective therapeutic outcomes.
Permethrin: Permethrin is a synthetic chemical widely used as an insecticide, acaricide, and insect repellent. It is commonly applied in the treatment of lice and scabies infestations.
Pharmacodynamics: Pharmacodynamics is the study of how drugs affect the body, including mechanisms of action and drug-receptor interactions. It examines the relationship between drug concentration and effect.
Pharmacodynamics: Pharmacodynamics is the study of the biochemical and physiological effects of drugs and their mechanisms of action within the body. It examines how drugs interact with the body's biological systems to produce their desired therapeutic effects or undesired side effects.
Pharmacokinetics: Pharmacokinetics is the study of how the body affects a drug, including the processes of absorption, distribution, metabolism, and elimination. It examines the movement of drugs within the body and how these processes impact the drug's concentration and duration of action.
Pinworms: Pinworms, also known as Enterobius vermicularis, are a type of parasitic worm that commonly infect the human gastrointestinal tract. They are one of the most common types of intestinal parasites, particularly in children.
Plasmodium: Plasmodium is a genus of parasitic protozoans that are the causative agents of malaria, a serious and potentially life-threatening infectious disease. These unicellular eukaryotic organisms are transmitted to humans through the bites of infected mosquitoes, where they undergo a complex life cycle within the human host, leading to the characteristic symptoms and complications of malaria.
Praziquantel: Praziquantel is a medication used to treat various parasitic infections, particularly those caused by flatworms or trematodes. It is a key drug in the context of antiparasitic and anthelminthic drugs, which are used to combat parasitic infestations in the body.
Pregnancy: Pregnancy is the period during which a fertilized egg develops into a fetus inside the uterus. It typically lasts around 40 weeks from the last menstrual period to childbirth.
Pregnancy: Pregnancy is the state of carrying a developing embryo or fetus within the female body. It is a crucial life event that involves significant physiological, hormonal, and metabolic changes in the mother's body to support the growth and development of the unborn child. Understanding the implications of pregnancy is essential in the context of various medical fields, including pharmacology, obstetrics, and gynecology.
Protozoa: Protozoa are single-celled eukaryotic organisms that can cause various infectious diseases in humans. They are often transmitted through contaminated water, food, or vectors like mosquitoes.
Pyrantel Pamoate: Pyrantel pamoate is an antiparasitic and anthelminthic drug used to treat infections caused by certain types of intestinal worms. It works by paralyzing the worms, causing them to be expelled from the body.
Renal Excretion: Renal excretion is the process by which the kidneys remove waste products, excess water, and other unwanted substances from the bloodstream and eliminate them from the body through urine. This process is crucial for maintaining the body's homeostasis and is an essential component of both antiparasitic and anthelminthic drug metabolism, as well as the metabolism of Class I sodium channel blockers.
Scabies: Scabies is a highly contagious skin infestation caused by the microscopic mite Sarcoptes scabiei. This parasitic infection leads to intense itching and the formation of a rash or skin lesions as the mites burrow into the outer layer of the skin.
Schistosoma: Schistosoma is a genus of parasitic flatworms, also known as blood flukes, that cause the tropical disease schistosomiasis. These trematode worms are responsible for significant morbidity and mortality in many parts of the world, particularly in developing countries.
Skin Snip Biopsy: A skin snip biopsy is a diagnostic procedure used to detect the presence of parasitic infections, particularly onchocerciasis (river blindness), by taking a small sample of skin for microscopic examination. It is a crucial tool in the context of antiparasitic and anthelminthic drug therapy.
Spinosad: Spinosad is a natural insecticide derived from the fermentation of Saccharopolyspora spinosa. It is used to treat parasitic infestations such as head lice and certain external parasites in animals.
Stool Examination: Stool examination, also known as fecal examination, is the analysis of a patient's stool sample to detect the presence of parasites, bacteria, or other abnormalities that may indicate underlying gastrointestinal conditions. This process is particularly relevant in the context of antiparasitic and anthelminthic drugs, as it can help diagnose and monitor the treatment of parasitic infections.
Taenia: Taenia is a genus of tapeworms that infect humans and other mammals. These parasitic flatworms are known for their long, segmented bodies and can cause serious health issues if left untreated.
Target Modification: Target modification refers to the process by which drugs or other therapeutic agents alter the structure or function of their target molecules, typically proteins, in order to elicit a desired pharmacological effect. This term is particularly relevant in the context of antiparasitic and anthelminthic drugs, which aim to selectively target and disrupt key processes within parasitic organisms to eliminate or control the infection.
Topical: Topical refers to the application of a drug or medication directly to the affected area or surface of the body, rather than administering it systemically. It is a mode of drug delivery that targets a specific site or region for localized treatment.
Topical Cream: A topical cream is a semi-solid preparation designed to be applied to the skin or other external body surfaces. Topical creams are commonly used in the context of antiparasitic and anthelminthic drugs, as they can be an effective delivery method for these types of medications.
Zoonotic Transmission: Zoonotic transmission refers to the transmission of infectious diseases from animals to humans. It is a crucial concept in the context of antiparasitic and anthelminthic drugs, as many parasitic and helminthic infections can be transmitted from animals to humans through various routes.