Pharmacology of Endoparasitic Control Flashcards
What types of Endoparasitic drugs are there?
Parasiticides
Antiparasitics
Anthelmintics
Parasiticides
Substance used in medicine and veterinary medicine to kill parasites
Antiparasitics
Medications used to manage and treat infections by parasites
Anthelmintics
Drug that acts against infections caused by parasitic worms
Types of parasiticides
Ectoparasiticides
Kills external parasites
Endoparasiticides
Kills Internal parasites
Endectocides
Kills both internal and external
What are helminths?
Flat worms
Trematodes
Tapeworms
Cestodes
Round worms
Nematodes
What classes of anthelmintic drugs are there?
Organophosphates
Benzimidazoles
Salicylanilides
Pyrazinoisoquinolones
Sulphonamides
Tetrahydropyrimidines/
imidazothiazoles
Hexahydropyrazines
Macrocyclic lactones
What are the targets for anthelmintic drugs?
Disruption of microtubule assembly
Beta-tubulin
Interference with neurotransmission
Nicotinergic acetylcholine receptor
GABA receptor and Glutamate-gated chloride channel
Most anthelmintics interfere with neurotransmission
Which anthelmintics affect microtubule assembly
Benzimiadazoles
How do Benzimiadazoles work?
- Bind to β-tubulin
- Inhibition/blockage of polymerisation
- Causes abnormal microtubule formation
- Disrupts intracellular homeostasis and energy metabolism
a. E.g. glucose uptake
What are microtubules?
- Essential component of cytoskeleton of cytoplasm
- Provide platform for intracellular transport
- Involved in many cellular process
- Also involved in cell division and mobility
What are the important antagonistic neurones in helminth locomotion
ACh - excitatory (contraction)
GABA - inhibitory (relaxation)
How do Macrocyclic lactones work?
GABA agonist’
* Causes chloride channels to open and influx of Cl- ions
* Hyperpolarises neurone membrane
* Excessive neural hyperpolarisation
* Attenuation of nerve transmission
* Leads to flaccid paralysis of worms
* Involves pharyngeal muscle so parasite will starve (can’t eat)
○ Female nematodes can’t lay eggs
○ Whole body paralysed
How do Tetrahydropyrimidines/Imidazothiazoles work?
- Act as nicotinic acetylcholine receptor agonist
○ Cholinergic agonist
○ Mimic Ach action- Changes permeability at post synaptic membrane
○ Depolarisation
○ Opens voltage gated sodium ion channels
○ Leads to firing of action potential
○ Excessive stimulation of muscle - Cause spastic paralysis of worms
- Changes permeability at post synaptic membrane
Why we need new anthelmintic drugs?
Resistance
Cost effectiveness
Efficacy
