Anthelmintics

Anthelmintic Classes - Worms, Be Gone!

• Benzimidazoles (e.g., Albendazole, Mebendazole): Inhibit microtubule synthesis.
  • Broad-spectrum: nematodes (roundworms, pinworms, hookworms) & cestodes (tapeworms).
• Praziquantel: Increases calcium permeability, causing paralysis & death.
  • Treats cestodes (tapeworms) & trematodes (flukes like Schistosoma).
• Pyrantel Pamoate: Depolarizing neuromuscular blocker, causing paralysis.
  • Effective for pinworms, roundworms, and hookworms.

⭐ High-Yield: Albendazole is the drug of choice for neurocysticercosis (pork tapeworm larvae in the brain). Co-administer with corticosteroids to reduce inflammation from dying cysticerci.

Drugs for Nematodes - Roundworm Roundup

• Benzimidazoles (Albendazole, Mebendazole)

  • MOA: Inhibit microtubule polymerization by binding to β-tubulin, disrupting cellular transport and energy metabolism.
  • Spectrum: Broad. Effective for Ascaris lumbricoides (giant roundworm), Trichuris trichiura (whipworm), Enterobius vermicularis (pinworm), and hookworms (Ancylostoma, Necator).
  • 📌 Mnemonic: Worms get bent out of shape.

• Ivermectin

  • MOA: Potentiates glutamate-gated chloride channels in invertebrate nerve and muscle cells → hyperpolarization and paralysis.
  • Spectrum: Drug of choice for Strongyloides stercoralis and Onchocerca volvulus (River Blindness).

• Pyrantel Pamoate

  • MOA: Depolarizing neuromuscular blocking agent → spastic paralysis of worms.
  • Spectrum: Pinworms and roundworms. Available over-the-counter.

⭐ For neurocysticercosis (a CNS infection with tapeworm larvae), Albendazole is used with corticosteroids to manage the inflammatory response to dying cysts.

Drugs for Trematodes & Cestodes - Flatworm Finishers

• Praziquantel: The primary drug for flukes (trematodes) and tapeworms (cestodes).
  • MoA: Increases cell membrane permeability to Ca²⁺, causing spastic paralysis, dislodgement, and death of the worm.
  • 📌 Praziquantel paralyzes the worms.

High‑Yield Points - ⚡ Biggest Takeaways

• Benzimidazoles (e.g., albendazole) inhibit parasitic microtubule synthesis. They are broad-spectrum agents for most nematode (roundworm) infections.
• Praziquantel increases calcium permeability, causing spastic paralysis of trematodes (flukes) and cestodes (tapeworms). It is the drug of choice for schistosomiasis.
• Ivermectin activates glutamate-gated chloride channels, leading to flaccid paralysis. It is first-line for onchocerciasis and strongyloidiasis.
• Pyrantel pamoate is a depolarizing neuromuscular blocker causing paralysis.