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Ivermectin (Systemic)

Pronunciation

Pronunciation

(eye ver MEK tin)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Stromectol: 3 mg

Generic: 3 mg

Brand Names: U.S.

  • Stromectol

Pharmacologic Category

  • Anthelmintic

Pharmacology

Ivermectin is a semisynthetic anthelminthic agent; it binds selectively and with strong affinity to glutamate-gated chloride ion channels which occur in invertebrate nerve and muscle cells. This leads to increased permeability of cell membranes to chloride ions then hyperpolarization of the nerve or muscle cell, and death of the parasite.

Absorption

Well absorbed (Gonzalez Canga 2008)

Distribution

Vd: 3.1 to 3.5 L/kg (healthy males); high concentration in the liver and adipose tissue; does not readily cross the blood-brain barrier (Gonzalez Canga 2008)

Metabolism

Hepatic via CYP3A4 (major), CYP2D6 (minor), and CYP2E1 (minor)

Excretion

Feces; urine (<1%)

Time to Peak

~4 hours

Half-Life Elimination

18 hours

Protein Binding

~93% primarily to albumin (Gonzalez Canga 2008)

Use: Labeled Indications

Onchocerciasis: Treatment of onchocerciasis due to the immature form of Onchocerca volvulus.

Limitations of use: Ivermectin has no activity against adult Onchocerca volvulus parasites. The adult parasites reside in subcutaneous nodules which are infrequently palpable. Surgical excision may be considered as removal of these nodules will eliminate the microfilariae-producing adult parasites.

Strongyloidiasis, intestinal: Treatment of intestinal (eg, nondisseminated) strongyloidiasis due to Strongyloides stercoralis.

Use: Unlabeled

Treatment of other parasitic infections, including Ancylostoma braziliense, Ascaris lumbricoides, Sarcoptes scabiei (in immunocompromised patients), Gnathostoma spinigerum, Mansonella ozzardi, Mansonella streptocerca, Pediculus humanus capitis, Pediculus humanus corporis, Phthirus pubis, Trichuris trichiura, Wucheria bancrofti; treatment of demodicosis due to hair follicle mites Demodex folliculorum and Demodex brevis

Contraindications

Hypersensitivity to ivermectin or any component of the formulation

Dosing: Adult

Onchocerciasis: Oral: 150 mcg/kg as a single dose; retreatment may be required every 3 to 12 months until asymptomatic

Strongyloidiasis, intestinal: Oral:

Manufacturer's labeling: 200 mcg/kg as a single dose

Alternate dosing: 200 mcg/kg/day for 2 days (CDC 2012)

Ascariasis due to Ascaris lumbricoides (off-label use): Oral: 200 mcg/kg as a single dose (Marti 1996; Naquira 1989)

Cutaneous larva migrans (CLM) due to Ancylostoma braziliense (off-label use): Oral: 200 mcg/kg as a single dose (Vanhaecke 2013)

Demodicosis due to Demodex folliculorum and Demodex brevis (off-label use): Oral: 200 mcg/kg as a single dose, followed by topical permethrin (Eismann 2010)

Gnathostomiasis due to Gnathostoma spinigerum (off-label use): Oral: 200 mcg/kg as a single dose (Nontasut 2000; Kraivichian 2004)

Lice (off-label use): Oral: Note: Treatment generally requires >1 dose; number of doses and dosage intervals have not been established

Pediculus humanus capitis: Oral: 400 mcg/kg/dose every 7 days for 2 doses (Chosidow 2010)

Pediculus humanus corporis: Oral: 200 mcg/kg/dose every 7 days for 3 doses (Foucault 2006)

Pediculosis pubis (due to Phthirus pubis; pubic lice): Oral: 250 mcg/kg/dose every 7 days for 2 doses (Burkhart 2004) or 250 mcg/kg/dose every 14 days for 2 doses (CDC [Workowski 2015])

Loiasis due to Loa loa (off-label use): Oral: 200 mcg/kg as a single dose (Carme 1991; Richard-Lenoble 1988)

Mansonella ozzardi infection (off-label use): Oral: 6 mg as a single dose (Gonzales 1999)

Mansonella streptocerca infection (off-label use): Oral: 150 mcg/kg as a single dose (Fischer 1997)

Scabies due to Sarcoptes scabiei (off-label use):

Immunocompromised or immunocompetent patients, treatment: Oral: 200 mcg/kg as a single dose (CDC [Workowski 2015]; Meinking 1995); repeat dose in 7 to 14 days (CDC 2016; CDC [Workowski 2015])

Crusted scabies (Norwegian Scabies), treatment: Oral: 200 mcg/kg as a single dose on days 1, 2, 8, 9, and 15 in combination with topical permethrin 5% cream. Severe cases may require additional ivermectin treatment on days 22 and 29 (CDC [Workowski 2015]; CDC 2016).

Prevention and control: Oral: 200 mcg/kg as a single dose (Romani 2015)

Trichuriasis due to Trichuris trichiura (off-label use): Oral: 200 mcg/kg as a single dose on day 1; may repeat dose on day 4 (Naquira 1989)

Wucheria bancrofti infection (off-label use): Oral: 200 to 400 mcg/kg as a single dose in combination with albendazole (Addiss 1997; Ismail 2001)

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Parasitic infections: Oral: Children ≥15 kg and Adolescents: Refer to adult dosing.

Dosing: Renal Impairment

There are no dosage adjustments provided in manufacturer’s labeling.

Dosing: Hepatic Impairment

There are no dosage adjustments provided in manufacturer’s labeling.

Administration

Oral: Administer on an empty stomach with water.

Pediculosis pubis and scabies treatment: To increase bioavailability in the epidermis, ivermectin is recommended to be taken with food (CDC [Workowski 2015]; Currie 2010).

Storage

Store at temperatures below 30°C (86°F).

Drug Interactions

Azithromycin (Systemic): May increase the serum concentration of Ivermectin (Systemic). Monitor therapy

BCG (Intravesical): Antibiotics may diminish the therapeutic effect of BCG (Intravesical). Avoid combination

BCG Vaccine (Immunization): Antibiotics may diminish the therapeutic effect of BCG Vaccine (Immunization). Monitor therapy

Cholera Vaccine: Antibiotics may diminish the therapeutic effect of Cholera Vaccine. Avoid combination

Lactobacillus and Estriol: Antibiotics may diminish the therapeutic effect of Lactobacillus and Estriol. Monitor therapy

Lumacaftor: May decrease the serum concentration of P-glycoprotein/ABCB1 Substrates. Lumacaftor may increase the serum concentration of P-glycoprotein/ABCB1 Substrates. Monitor therapy

P-glycoprotein/ABCB1 Inducers: May decrease the serum concentration of P-glycoprotein/ABCB1 Substrates. P-glycoprotein inducers may also further limit the distribution of p-glycoprotein substrates to specific cells/tissues/organs where p-glycoprotein is present in large amounts (e.g., brain, T-lymphocytes, testes, etc.). Monitor therapy

P-glycoprotein/ABCB1 Inhibitors: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates. P-glycoprotein inhibitors may also enhance the distribution of p-glycoprotein substrates to specific cells/tissues/organs where p-glycoprotein is present in large amounts (e.g., brain, T-lymphocytes, testes, etc.). Monitor therapy

Ranolazine: May increase the serum concentration of P-glycoprotein/ABCB1 Substrates. Monitor therapy

Sodium Picosulfate: Antibiotics may diminish the therapeutic effect of Sodium Picosulfate. Management: Consider using an alternative product for bowel cleansing prior to a colonoscopy in patients who have recently used or are concurrently using an antibiotic. Consider therapy modification

Typhoid Vaccine: Antibiotics may diminish the therapeutic effect of Typhoid Vaccine. Only the live attenuated Ty21a strain is affected. Management: Vaccination with live attenuated typhoid vaccine (Ty21a) should be avoided in patients being treated with systemic antibacterial agents. Use of this vaccine should be postponed until at least 3 days after cessation of antibacterial agents. Consider therapy modification

Vitamin K Antagonists (eg, warfarin): Ivermectin (Systemic) may enhance the anticoagulant effect of Vitamin K Antagonists. Monitor therapy

Adverse Reactions

>10%:

Dermatologic: Pruritus (3%; Mazzotti reaction, associated with onchocerciasis: 28%), dermatological reaction (Mazzotti reaction, associated with onchocerciasis: 23%; includes edema, urticarial rash)

Hematologic & oncologic: Lymphadenitis (Mazzotti reaction, associated with onchocerciasis: 1% to 14%)

Neuromuscular & skeletal: Arthralgia (Mazzotti reaction, associated with onchocerciasis: ≤9%), synovitis (Mazzotti reaction, associated with onchocerciasis: ≤9%)

Miscellaneous: Fever (Mazzotti reaction, associated with onchocerciasis: 23%)

1% to 10%:

Cardiovascular: Tachycardia (4%), peripheral edema (3%), facial edema (1%), orthostatic hypotension (1%)

Central nervous system: Dizziness (3%)

Gastrointestinal: Diarrhea (2%), nausea (2%)

Hematologic & oncologic: Eosinophilia (3%), decreased white blood cell count (3%), increased hemoglobin (1%)

Hepatic: Increased serum ALT (2%), increased serum AST (2%)

<1% (Limited to important or life-threatening): Abdominal distention, abdominal pain, abnormal gait, abnormal sensation in eyes, anemia, anorexia, anterior uveitis, ataxia, back pain, brain disease (rare; associated with loiasis), chest discomfort, chorioretinitis, coma, confusion, conjunctival hemorrhage (associated with onchocerciasis), conjunctivitis, constipation, drowsiness, dyspnea, exacerbation of asthma, eye redness, eyelid edema, fatigue, fecal incontinence, headache, hepatitis, hypotension, increased serum bilirubin, keratitis, lethargy, leukopenia, mental status changes, myalgia, neck pain, posterior uveitis, seizure, skin rash, Stevens-Johnson syndrome, stupor, temporary vision loss, toxic epidermal necrolysis, tremor, urinary incontinence, urticaria, vertigo, vomiting, weakness

Warnings/Precautions

Concerns related to adverse effects:

• Cutaneous/systemic reactions: Data have shown that antihelmintic drugs like ivermectin may cause cutaneous and/or systemic reactions (Mazzoti reaction) of varying severity including ophthalmological reactions in patients with onchocerciasis. These reactions are probably due to allergic and inflammatory responses to the death of microfilariae. Patients treated with ivermectin for onchocerciasis may experience these reactions. Treatment of severe Mazzoti reactions is not definitive, but includes supportive care (eg, hydration and/or parenteral corticosteroids) to treat postural hypotension. Antihistamines and/or aspirin have been used for most mild to moderate reactions.

Disease-related concerns:

• Loiasis: Pretreatment assessment and post-treatment follow up for Loa loa infection is recommended in any patient with significant exposure to endemic areas (West and Central Africa); serious and/or fatal encephalopathy has been reported (rarely) during treatment in onchocerciasis patients with concomitant loiasis.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Special populations:

• Immunocompromised patients: Repeated treatment may be required in immunocompromised patients (eg, HIV); control of extraintestinal strongyloidiasis may necessitate suppressive (once monthly) therapy.

Other warnings/precautions:

• Appropriate use: Onchocerca volvulus: Ivermectin has no activity against adult O. volvulus parasites.

Monitoring Parameters

Skin and eye microfilarial counts, periodic ophthalmologic exams; follow up stool examinations

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events have been observed in animal reproduction studies. Although use in pregnancy is likely low risk, other agents are currently recommended for the treatment of pediculosis pubis or scabies in pregnant women (CDC [Workowski 2015]).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience itching. Have patient report immediately to prescriber signs of infection, tachycardia, severe dizziness, passing out, vision changes, eye pain, severe eye irritation, severe skin irritation, joint pain, edema, enlarged lymph nodes, or signs of severe brain problems in patients with Loa-Loa infection (rare) (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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