Below is a detailed overview of the uses and dosing regimens for Ivermectin, Hydroxychloroquine, and Tamiflu (Oseltamivir) based on their approved indications, off-label uses, and available evidence. Please note that dosing and uses should always be guided by a healthcare professional, as inappropriate use can lead to serious side effects. The information reflects FDA-approved uses, common off-label applications, and relevant warnings, particularly regarding controversial uses (e.g., for COVID-19).
Ivermectin
Overview: Ivermectin is an antiparasitic drug with FDA approval for specific parasitic infections in humans. It has also been studied for antiviral properties, but its use for viral infections like COVID-19 remains controversial and unapproved by the FDA.
Approved Uses and Doses
Ivermectin is primarily used for parasitic infections, with dosing based on body weight and indication:
Onchocerciasis (River Blindness):
Dose: 150 µg/kg (0.15 mg/kg) orally as a single dose, typically repeated every 6–12 months.
Notes: Retreatment may be needed every 3–6 months for heavy ocular infections. Patients with microfilariae in the eye may require more frequent monitoring.
Strongyloidiasis (Intestinal Threadworm):
Dose: 200 µg/kg (0.2 mg/kg) orally as a single dose.
Notes: A second dose may be needed after several months to a year. Stool exams are recommended to confirm clearance. Patients with weakened immune systems may require repeated doses.
Scabies:
Dose: 200 µg/kg (0.2 mg/kg) orally as a single dose, often repeated after 1–2 weeks.
Notes: Commonly used for crusted (Norwegian) scabies in combination with topical treatments.
Head Lice (Topical):
Dose: 0.5% ivermectin lotion (Sklice) applied to dry hair and scalp, rinsed off after 10 minutes.
Notes: Approved for children ≥6 months. A single application is usually sufficient.
Rosacea (Topical):
Dose: 1% ivermectin cream (Soolantra) applied once daily to affected facial areas.
Notes: Used for inflammatory lesions of rosacea in adults.
Off-Label Uses
Other Parasitic Infections: Ivermectin is used off-label for infections like cutaneous larva migrans, filariasis, and certain mite infestations (e.g., Demodex).
COVID-19 (Controversial):
Proposed Doses: Studies and anecdotal reports have suggested doses ranging from 150–600 µg/kg (0.15–0.6 mg/kg) daily or weekly for 3–5 days or until symptom resolution. For example, a trial in Bangladesh used 12 mg daily for 5 days (approximately 0.2 mg/kg for a 60 kg person).
Evidence: In vitro studies showed ivermectin inhibits SARS-CoV-2 replication, but clinical trials have yielded mixed results. The FDA, WHO, and NIH recommend against its use for COVID-19 outside clinical trials due to insufficient evidence of efficacy and safety at antiviral doses, which may exceed approved levels. High doses (e.g., 400–600 µg/kg) have been associated with toxicity.
Warnings: Veterinary formulations are dangerous for human use, and overdoses can cause nausea, vomiting, seizures, coma, or death. Ivermectin can cause birth defects if taken early in pregnancy.
Administration
Oral: Taken on an empty stomach with water, at least 30 minutes before or 2 hours after a meal.
Topical: Applied as directed, avoiding ingestion of lotions or creams.
Monitoring: Stool samples or skin exams may be needed to assess treatment efficacy for parasitic infections.
Side Effects
Common: Dizziness, nausea, diarrhea, rash.
Serious: Low blood pressure, seizures, liver toxicity, neurological effects (especially at high doses).
Contraindications
Allergy to ivermectin.
Pregnancy (especially early pregnancy) or breastfeeding without medical advice.
Children <15 kg (33 lbs).
Hydroxychloroquine
Overview: Hydroxychloroquine (HCQ) is an antimalarial and immunomodulatory drug used for autoimmune diseases and malaria. Its use for COVID-19 was widely studied but is not supported by current evidence.
Approved Uses and Doses
Malaria (Prophylaxis and Treatment):
Prophylaxis:
Dose: 400 mg (310 mg base) orally once weekly, starting 1–2 weeks before travel and continuing 4 weeks after leaving endemic area.
Pediatric: 6.5 mg/kg (5 mg/kg base) weekly, up to 400 mg.
Acute Attack:
Dose: 800 mg (620 mg base) initially, followed by 400 mg (310 mg base) at 6, 24, and 48 hours (total 2,000 mg over 3 days).
Pediatric: 13 mg/kg (10 mg/kg base) initially, then 6.5 mg/kg (5 mg/kg base) at 6, 24, and 48 hours.
Notes: Not effective against chloroquine-resistant strains.
Rheumatoid Arthritis:
Dose: 200–400 mg daily (initially up to 6.5 mg/kg/day), adjusted to lowest effective dose (often 200 mg daily).
Notes: May take weeks to months for effect. Often combined with other therapies.
Systemic Lupus Erythematosus (SLE):
Dose: 200–400 mg daily (up to 5 mg/kg/day).
Notes: Used for skin, joint symptoms, and to reduce flares. Long-term use requires monitoring.
Discoid Lupus Erythematosus:
Dose: 200–400 mg daily.
Notes: Similar to SLE, used for cutaneous manifestations.
Off-Label Uses
Q Fever and Other Infections: Used for chronic Q fever endocarditis or Whipple’s disease.
Porphyria Cutanea Tarda: Low doses (100–200 mg twice weekly) to manage symptoms.
COVID-19 (Controversial):
Proposed Doses: Trials used 400 mg twice daily on day 1, then 200 mg twice daily for 4–5 days. Some protocols suggested 200 mg twice daily for 5 days.
Evidence: Early in vitro studies suggested HCQ could block SARS-CoV-2 entry, but clinical trials (e.g., RECOVERY, WHO Solidarity) showed no benefit in mortality, hospitalization, or viral clearance. The FDA revoked emergency use authorization in June 2020 due to risks (e.g., heart rhythm abnormalities) and lack of efficacy. HCQ is not recommended for COVID-19.
Warnings: HCQ can cause serious heart rhythm issues (QT prolongation), liver inflammation, and kidney failure, especially in unmonitored use.
Administration
Taken with food to reduce gastrointestinal upset.
Tablets can be crushed or split for dosing adjustments.
Side Effects
Common: Nausea, headache, dizziness, rash.
Serious: Retinal toxicity (with long-term use), QT prolongation, cardiomyopathy, hypoglycemia.
Contraindications
Known hypersensitivity to HCQ or 4-aminoquinolines.
Pre-existing retinal or visual field changes (for long-term use).
Caution in patients with cardiac disease or those taking QT-prolonging drugs.
Monitoring
Baseline and periodic eye exams for long-term use (risk of retinopathy).
ECG for patients at risk of QT prolongation.
Liver and kidney function tests.
Tamiflu (Oseltamivir)
Overview: Oseltamivir is an antiviral drug approved for the treatment and prevention of influenza A and B. It is a neuraminidase inhibitor that reduces viral spread in the body.
Approved Uses and Doses
Treatment of Influenza (A and B):
Adults and Adolescents (≥13 years):
Dose: 75 mg orally twice daily for 5 days.
Children (1–12 years):
Weight-based:
≤15 kg: 30 mg twice daily.
15 to 23 kg: 45 mg twice daily.
23 to 40 kg: 60 mg twice daily.
40 kg: 75 mg twice daily.
Duration: 5 days.
Infants (≥2 weeks to <1 year):
Dose: 3 mg/kg twice daily for 5 days.
Notes: Start within 48 hours of symptom onset for best efficacy.
Prophylaxis of Influenza:
Adults and Adolescents (≥13 years):
Dose: 75 mg orally once daily for at least 10 days (post-exposure) or up to 6 weeks (community outbreak).
Children (1–12 years):
Weight-based:
≤15 kg: 30 mg once daily.
15 to 23 kg: 45 mg once daily.
23 to 40 kg: 60 mg once daily.
40 kg: 75 mg once daily.
Duration: 10 days (post-exposure) or up to 6 weeks.
Infants (≥3 months to <1 year):
Dose: 3 mg/kg once daily.
Notes: Not approved for prophylaxis in infants <3 months unless critical. Start within 48 hours of exposure.
Off-Label Uses
H1N1 Influenza (Pandemic Strains): Used at standard treatment doses during pandemics.
Avian Influenza (H5N1): May require higher doses (e.g., 150 mg twice daily) or longer duration (7–10 days) in severe cases.
COVID-19: Not effective or approved for SARS-CoV-2; no significant off-label use reported.
Administration
Taken with or without food; food may reduce nausea.
Oral suspension available for children or those unable to swallow capsules.
Store capsules at room temperature (68–77°F); refrigerate oral suspension (36–46°F) for up to 17 days or store at room temperature for 10 days.
Side Effects
Common: Nausea, vomiting, headache, abdominal pain.
Serious: Rare neuropsychiatric events (e.g., confusion, delirium, especially in children), allergic reactions, skin rashes.
Contraindications
Hypersensitivity to oseltamivir or any component.
Caution in patients with renal impairment (dose adjustment required).
Monitoring
Monitor for neuropsychiatric symptoms, especially in pediatric patients.
Renal function for dose adjustments (e.g., 30 mg daily for creatinine clearance 10–30 mL/min).
Key Warnings and Considerations
Ivermectin:
Veterinary formulations are not safe for humans and can be toxic.
High doses for unapproved uses (e.g., COVID-19) have led to hospitalizations.
Limited evidence supports its use for viral infections; clinical trials are needed.
Hydroxychloroquine:
Not effective for COVID-19; associated with serious cardiac risks.
Long-term use requires regular eye exams to prevent retinal damage.
QT prolongation risk necessitates ECG monitoring in at-risk patients.
Tamiflu:
Most effective when started within 48 hours of influenza symptoms.
Neuropsychiatric side effects are rare but require vigilance, especially in children.
Resistance has been reported in some influenza strains, reducing efficacy.
General Notes
COVID-19 Context: Both ivermectin and hydroxychloroquine were heavily studied for COVID-19, but high-quality evidence (e.g., randomized controlled trials) shows no significant benefit. Their use for this purpose is not recommended outside clinical trials.
Consultation: Always consult a healthcare provider for appropriate dosing, especially for off-label uses or in special populations (e.g., pregnant women, children, or those with comorbidities).
Safety: Overdosing or using unapproved formulations (e.g., animal ivermectin) can lead to severe toxicity.
If you need specific dosing calculations (e.g., based on weight) or further details on a particular use, please provide additional context