Antiparasitic Therapy

Antiparasitic Drugs: Overview - The Bug Busters

• Primary Aim: Eliminate ectoparasites (e.g., scabies, lice) and some endoparasites affecting skin.
• Mechanisms: Primarily neurotoxicity to parasites; others disrupt parasite metabolism or have unknown actions.
• Key Topical Agents:
  • Permethrin: Na+ channel modulator.
  • Ivermectin (lotion): Glutamate-gated Cl- channel agonist.
  • Benzyl Benzoate: Toxic to mite nervous system.
  • Lindane: Organochloride; CNS toxicity risk. ⚠️ Use restricted.
  • Crotamiton: Scabicidal, antipruritic.
• Key Systemic Agents:
  • Ivermectin (oral): For severe/crusted scabies, strongyloidiasis.
  • Albendazole: Inhibits microtubule synthesis. For cutaneous larva migrans.

⭐ Permethrin 5% cream is a first-line treatment for scabies, requiring application from neck down for 8-14 hours before washing off.

Scabicides & Pediculicides: Key Drugs - Itch-Nixing Heroes

• Permethrin
  • Scabies: 5% cream (neck-down, 8-14h).
  • Pediculosis: 1% (hair, 10 min).
  • DOC; Safe: Pregnancy (B), >2mo.
• Ivermectin
  • Oral: Scabies (200 µg/kg), crusted.
  • Topical: 0.5% (lice ≥6mo).
  • Avoid: <15 kg, pregnancy.
• Lindane (1%)
  • Scabies (8-12h), Lice (4 min).
  • ⚠️ Neurotoxic. Avoid: infants, seizures. 2nd line.
• Benzyl Benzoate (10-25%)
  • Scabies: 24h, 2-3 nights. Irritant. Used in pregnancy.
• Crotamiton (10%)
  • Scabicide, antipruritic. Less effective.
• Malathion (0.5%)
  • Pediculicide (ovicidal). 8-12h. Flammable.
• Spinosad (0.9%)
  • Pediculicide (ovicidal). 10 min. No nit combing. ≥6mo.

⭐ For scabies, Permethrin 5% cream is applied from neck down, left for 8-14 hours, then washed off. Treatment may be repeated in 7-10 days.

CLM & Myiasis: Targeted Meds - Wanderer Wreckers

• Cutaneous Larva Migrans (CLM): Hookworm larvae causing itchy, serpiginous "creeping eruption".
  • Drug of Choice (DOC): Ivermectin 200 µg/kg single dose.
  • Alternative: Albendazole 400 mg daily for 3-7 days.
  • Topical: Thiabendazole 10-15% for limited lesions.
• Myiasis: Tissue infestation by fly larvae (maggots).
  • Management: Occlusion (e.g., petroleum jelly) to promote larval emergence, followed by surgical removal.
  • Systemic: Oral Ivermectin (200 µg/kg) for extensive, cavitary, or difficult-to-access lesions.
  • 📌 "Iver"mectin "I"s "Ver"y effective for these "wanderers".

⭐ For furuncular myiasis, the larva's breathing pore (punctum) is key for diagnosis and occlusive therapy anoxia induction prior to mechanical extraction of the larva from the skin lesion or wound site where it is embedded and causing inflammation or tissue damage due to its presence and metabolic activities within the host tissues which can lead to secondary bacterial infections if not properly managed with appropriate wound care and sometimes antibiotic therapy depending on the clinical presentation and extent of the infection or infestation by the fly larvae which are commonly known as maggots in this particular parasitic skin condition affecting humans and animals alike globally but more prevalent in tropical and subtropical regions with poor sanitation and hygiene practices contributing to higher incidence rates of myiasis cases reported annually in endemic areas where flies are abundant and can easily lay eggs on open wounds or intact skin surfaces leading to larval penetration and subsequent development within the host tissues causing characteristic lesions and symptoms requiring medical intervention for effective treatment and resolution of the parasitic infestation and associated complications such as cellulitis or abscess formation if left untreated or improperly managed by healthcare providers or individuals themselves attempting self-treatment without adequate knowledge or resources available to them in remote or underserved communities where access to healthcare services may be limited or non-existent altogether posing a significant public health challenge in certain parts of the world where myiasis is a common occurrence among vulnerable populations including children and elderly individuals with compromised immune systems or underlying health conditions that predispose them to parasitic infections of the skin and soft tissues requiring prompt diagnosis and appropriate therapeutic measures to prevent further morbidity and mortality associated with this neglected tropical disease that affects millions of people worldwide each year with varying degrees of severity and clinical manifestations depending on the species of fly involved and the site of infestation on the body of the host organism which can range from superficial skin lesions to deep tissue invasion and organ damage in severe cases necessitating aggressive medical and surgical management strategies for optimal patient outcomes and recovery from this debilitating parasitic condition that can have significant impact on quality of life and overall well-being of affected individuals and communities living in endemic regions where myiasis is a persistent threat to public health and safety requiring concerted efforts for prevention control and elimination of this preventable parasitic disease through integrated vector management strategies and improved sanitation and hygiene practices at individual and community levels to reduce the burden of myiasis and other parasitic skin infections in vulnerable populations worldwide. The larva's breathing pore (punctum) is key for diagnosis and occlusive therapy.

Antiparasitic Tx: Challenges & Pearls - Smart Strategy Central

• Core Challenges:
  • Drug resistance (e.g., permethrin-R scabies).
  • Special populations (pregnancy, infants, immunocompromised).
  • Compliance, contact tracing, fomite control.
• Pearls & Strategies:
  • Pregnancy: Permethrin, Benzyl Benzoate. Avoid Lindane.
  • Infants (<2mo): 5-10% Sulphur ppt.
  • Ivermectin: Crusted/resistant scabies, outbreaks.
  • Adjuncts: Antihistamines, emollients, topical steroids for post-tx itch.

⭐ Scabies: Crucial to treat ALL close contacts simultaneously, even if asymptomatic, to break transmission cycle.

High‑Yield Points - ⚡ Biggest Takeaways

• Permethrin 5% cream: DOC for scabies; apply neck-down, wash after 8-14 hours.
• Oral Ivermectin (200 µg/kg): Effective for scabies (crusted) & pediculosis.
• Lindane: Neurotoxic (seizures); avoid in children <2 yrs, pregnancy, extensive dermatitis.
• Benzyl Benzoate: Scabies alternative; risk of irritant dermatitis.
• Crotamiton: Antipruritic & scabicidal; less effective than permethrin.
• Scabies: Treat all contacts simultaneously to prevent re-infestation.
• Pediculosis capitis: Treat with Permethrin 1%, Malathion, or oral Ivermectin_