Ivermectin

# Ivermectin ## Overview - **Classification**: Antihelminthic/Antiparasitic agent. - **Mechanism**: Binds selectively to **glutamate-gated chloride ion channels** in invertebrate nerve and muscle cells, leading to paralysis and death of the parasite. ## Primary Indications 1. **Strongyloides stercoralis (Threadworm)** - Treatment of intestinal infection. 2. **Onchocerca volvulus (River Blindness)** - Treatment to reduce microfilariae load. 3. **Scabies (Sarcoptes scabiei)** - Treatment of infestation (Off-label/Approved in some regions). ## Adult Dosing ### Standard Dosing **Strongyloidiasis** (Intestinal) - **Dose**: **200 mcg/kg** (0.2 mg/kg) - **Frequency**: Single dose - **Route**: Oral (PO) - **Duration**: Repeat dose may be needed 7-14 days later. **Onchocerciasis** (River Blindness) - **Dose**: **150 mcg/kg** (0.15 mg/kg) - **Frequency**: Single dose - **Route**: Oral (PO) - **Duration**: Dosed every 6 to 12 months until adult worms die. **Scabies** (Crusted/Refractory) - **Dose**: **200 mcg/kg** - **Frequency**: Single dose - **Route**: Oral (PO) - **Duration**: Repeat dose in 7-14 days is often required. ### Dose Adjustments - **Renal Impairment**: No specific dose adjustment generally needed. - **Hepatic Impairment**: Use with caution. Drug is primarily **hepatic metabolized**. Safety data is limited. - **Elderly Patients**: Dosing based on body weight (mg/kg). No special reduction required unless significant comorbidity exists. ## Pediatric Dosing ### Neonates (0-28 days) - **Dose**: **Not recommended**. Safety and efficacy is not established. - **Special Notes**: Risk of CNS toxicity is unknown in this age group. ### Infants (1-12 months) - **Note**: **Generally avoided** in children **under 15 kg** or **under 2 years** of age. - **Specific use**: Only in severe or refractory cases under expert guidance. ### Children (1-12 years) - **Indication**: Strongyloidiasis, Onchocerciasis, Scabies (Must weigh **> 15 kg**) - **Dose**: **200 mcg/kg** (standard dose for indication) - **Frequency**: Single dose - **Maximum**: Do not exceed **200 mcg/kg** or adult dose (usually **24 mg**). ### Adolescents (13-18 years) - **Dose**: Treat as **adult dosing** based on actual body weight (mg/kg). - **Maximum**: **200 mcg/kg** per dose. ## Safety Information ### Contraindications - **Absolute**: Hypersensitivity to Ivermectin or components. - **Absolute**: **Meningitis** or other conditions impairing blood-brain barrier integrity (risk of neurotoxicity). ### Common Adverse Effects - **Very Common (>10%)**: Dizziness (dermal route), Fatigue. - **Common (1-10%)**: Pruritus, rash, arthralgia/myalgia (often due to parasite killing), headache. - **Serious but Rare**: **Mazzotti reaction** (hypertension, fever, edema, lymphadenopathy) following Onchocerciasis treatment; Seizures; Ocular toxicity. ### Key Drug Interactions - **Warfarin**: Possible enhanced **anticoagulant effect** (monitor INR closely). - **CYP450 Inducers/Inhibitors**: Ivermectin is a substrate (monitor efficacy). - **Benzodiazepines/Barbiturates**: Potential for increased CNS depression. ## Monitoring & Follow-up - **Before Treatment**: Baseline weight (crucial for accurate mg/kg dosing). - **During Treatment**: Monitor for signs of the **Mazzotti reaction** (especially in Onchocerciasis). - **Clinical Signs**: Assess for resolution of symptoms; repeat stool or skin tests 1-3 months post-treatment. ## Clinical Pearls - 💡 **Tip 1**: Administer doses with a full glass of water and **on an empty stomach** (1 hour before or 2 hours after meals) for optimal absorption of the tablet formulation. - 💡 **Tip 2**: For scabies, treat **all close contacts simultaneously** to prevent reinfection. - 💡 **Tip 3**: The Mazzotti reaction is a **hypersensitivity response** to dead microfilariae, not the drug itself; treat with antihistamines and NSAIDs. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.