Ivermectin

Description

DESCRIPTION Ivermectin is a semisynthetic, anthelmintic agent for oral administration. Ivermectin is derived from the avermectins, a class of highly active broad-spectrum, anti-parasitic agents isolated from the fermentation products of Streptomyces avermitilis . Ivermectin is a mixture containing at least 90% 5- O -demethyl-22,23-dihydroavermectin A 1a and less than 10% 5- O- demethyl-25-de(1-methylpropyl)-22,23-dihydro-25-(1-methylethyl)avermectin A 1a , generally referred to as 22,23-dihydroavermectin B 1a and B 1b , or H 2 B 1a and H 2 B 1b , respectively. The respective empirical formulas are C 48 H 74 O 14 and C 47 H 72 O 14 , with molecular weights of 875.10 and 861.07, respectively. The structural formulas are: Ivermectin is a white to yellowish-white, nonhygroscopic, crystalline powder with a melting point of about 155°C. It is insoluble in water but is freely soluble in methanol and soluble in 95% ethanol. Ivermectin tablets are available as 3-mg tablets containing the following inactive ingredients: colloidal silicon dioxide, croscarmellose sodium, magnesium stearate, microcrystalline cellulose, and pregelatinized starch. Chemical Structure

What Is Ivermectin Used For?

INDICATIONS AND USAGE Ivermectin is indicated for the treatment of the following infections: Strongyloidiasis of the intestinal tract Ivermectin is indicated for the treatment of intestinal (i.e., nondisseminated) strongyloidiasis due to the nematode parasite Strongyloides stercoralis . This indication is based on clinical studies of both comparative and open-label designs, in which 64-100% of infected patients were cured following a single 200-mcg/kg dose of ivermectin (See CLINICAL PHARMACOLOGY, Clinical Studies ). Onchocerciasis Ivermectin is indicated for the treatment of onchocerciasis due to the nematode parasite Onchocerca volvulus . This indication is based on randomized, double-blind, placebo-controlled and comparative studies conducted in 1427 patients in onchocerciasis-endemic areas of West Africa. The comparative studies used diethylcarbamazine citrate (DEC-C). NOTE: Ivermectin has no activity against adult Onchocerca volvulus parasites. The adult parasites reside in subcutaneous nodules which are infrequently palpable. Surgical excision of these nodules (nodulectomy) may be considered in the management of patients with onchocerciasis, since this procedure will eliminate the microfilariae-producing adult parasites.

Dosage and Administration

DOSAGE AND ADMINISTRATION Strongyloidiasis The recommended dosage of ivermectin Tablets for the treatment of strongyloidiasis is a single oral dose designed to provide approximately 200 mcg of ivermectin per kg of body weight. See Table 1 for dosage guidelines. Patients should take tablets on an empty stomach with water (See CLINICAL PHARMACOLOGY, Pharmacokinetics ). In general, additional doses are not necessary. However, follow-up stool examinations should be performed to verify eradication of infection (See CLINICAL PHARMACOLOGY, Clinical Studies ). Table 1: Dosage Guidelines for Ivermectin Tablets for Strongyloidiasis Body Weight (kg) Single Oral Dose Number of 3-mg Tablets 15-24 1 tablet 25-35 2 tablets 36-50 3 tablets 51-65 4 tablets 66-79 5 tablets ≥ 80 200 mcg/kg Onchocerciasis The recommended dosage of ivermectin Tablets for the treatment of onchocerciasis is a single oral dose designed to provide approximately 150 mcg of ivermectin per kg of body weight. See Table 2 for dosage guidelines. Patients should take tablets on an empty stomach with water (See CLINICAL PHARMACOLOGY, Pharmacokinetics ). In mass distribution campaigns in international treatment programs, the most commonly used dose interval is 12 months. For the treatment of individual patients, retreatment may be considered at intervals as short as 3 months. Table 2: Dosage Guidelines for Ivermectin Tablets for Onchocerciasis Body Weight (kg) Single Oral Dose Number of 3-mg Tablets 15-25 1 tablet 26-44 2 tablets 45-64 3 tablets 65-84 4 tablets ≥ 85 150 mcg/kg

Side Effects (Adverse Reactions)

ADVERSE REACTIONS Strongyloidiasis In four clinical studies involving a total of 109 patients given either one or two doses of 170 to 200 mcg/kg of ivermectin, the following adverse reactions were reported as possibly, probably, or definitely related to ivermectin: Body as a Whole: asthenia/fatigue (0.9%), abdominal pain (0.9%) Gastrointestinal: anorexia (0.9%), constipation (0.9%), diarrhea (1.8%), nausea (1.8%), vomiting (0.9%) Nervous System/Psychiatric: dizziness (2.8%), somnolence (0.9%), vertigo (0.9%), tremor (0.9%) Skin: pruritus (2.8%), rash (0.9%), and urticaria (0.9%). In comparative trials, patients treated with ivermectin experienced more abdominal distention and chest discomfort than patients treated with albendazole. However, ivermectin was better tolerated than thiabendazole in comparative studies involving 37 patients treated with thiabendazole. The Mazzotti-type and ophthalmologic reactions associated with the treatment of onchocerciasis or the disease itself would not be expected to occur in strongyloidiasis patients treated with ivermectin (See ADVERSE REACTIONS, Onchocerciasis ). Laboratory Test Findings In clinical trials involving 109 patients given either one or two doses of 170 to 200 mcg/kg ivermectin, the following laboratory abnormalities were seen regardless of drug relationship: elevation in ALT and/or AST (2%), decrease in leukocyte count (3%). Leukopenia and anemia were seen in one patient. Onchocerciasis In clinical trials involving 963 adult patients treated with 100 to 200 mcg/kg ivermectin, worsening of the following Mazzotti reactions during the first 4 days post-treatment were reported: arthralgia/synovitis (9.3%), axillary lymph node enlargement and tenderness (11.0% and 4.4%, respectively), cervical lymph node enlargement and tenderness (5.3% and 1.2%, respectively), inguinal lymph node enlargement and tenderness (12.6% and 13.9%, respectively), other lymph node enlargement and tenderness (3.0% and 1.9%, respectively), pruritus (27.5%), skin involvement including edema, papular and pustular or frank urticarial rash (22.7%), and fever (22.6%) (See WARNINGS ). In clinical trials, ophthalmological conditions were examined in 963 adult patients before treatment, at day 3, and months 3 and 6 after treatment with 100 to 200 mcg/kg ivermectin. Changes observed were primarily deterioration from baseline 3 days post-treatment. Most changes either returned to baseline condition or improved over baseline severity at the month 3 and 6 visits. The percentages of patients with worsening of the following conditions at day 3, month 3 and 6, respectively, were: limbitis: 5.5%, 4.8%, and 3.5% and punctate opacity: 1.8%, 1.8%, and 1.4%. The corresponding percentages for patients treated with placebo were: limbitis: 6.2%, 9.9%, and 9.4% and punctate opacity: 2.0%, 6.4%, and 7.2% (See WARNINGS ). In clinical trials involving 963 adult patients who received 100 to 200 mcg/kg ivermectin, the following clinical adverse reactions were reported as possibly, probably, or definitely related to the drug in ≥ 1% of the patients: facial edema (1.2%), peripheral edema (3.2%), orthostatic hypotension (1.1%), and tachycardia (3.5%). Drug-related headache and myalgia occurred in < 1% of patients (0.2% and 0.4%, respectively). However, these were the most common adverse experiences reported overall during these trials regardless of causality (22.3% and 19.7%, respectively). A similar safety profile was observed in an open study in pediatric patients ages 6 to 13. The following ophthalmological side effects do occur due to the disease itself but have also been reported after treatment with ivermectin: abnormal sensation in the eyes, eyelid edema, anterior uveitis, conjunctivitis, limbitis, keratitis, and chorioretinitis or choroiditis. These have rarely been severe or associated with loss of vision and have generally resolved without corticosteroid treatment. Laboratory Test Findings In controlled clinical trials, the...

Drug Interactions

Drug Interactions Post-marketing reports of increased INR (International Normalized Ratio) have been rarely reported when ivermectin was co-administered with warfarin.

Contraindications

CONTRAINDICATIONS Ivermectin Tablets are contraindicated in patients who are hypersensitive to any component of this product.

Pregnancy and Breastfeeding

Pregnancy, Teratogenic Effects Ivermectin has been shown to be teratogenic in mice, rats, and rabbits when given in repeated doses of 0.2, 8.1, and 4.5 times the maximum recommended human dose, respectively (on a mg/m2/day basis). Teratogenicity was characterized in the three species tested by cleft palate; clubbed forepaws were additionally observed in rabbits. These developmental effects were found only at or near doses that were maternotoxic to the pregnant female. Therefore, ivermectin does not appear to be selectively fetotoxic to the developing fetus. There are, however, no adequate and well-controlled studies in pregnant women. Ivermectin should not be used during pregnancy since safety in pregnancy has not been established.

Nursing Mothers Ivermectin is excreted in human milk in low concentrations. Treatment of mothers who intend to breast-feed should only be undertaken when the risk of delayed treatment to the mother outweighs the possible risk to the newborn.

Overdosage

OVERDOSAGE Cases of neurotoxicity, including alteration of consciousness of variable severity (e.g., somnolence/drowsiness, stupor, and coma), confusion, disorientation and death have been reported with recommended dosage and overdosage of ivermectin (see WARNINGS ). Significant lethality was observed in mice and rats after single oral doses of 25 to 50 mg/kg and 40 to 50 mg/kg, respectively. No significant lethality was observed in dogs after single oral doses of up to 10 mg/kg. At these doses, the treatment-related signs that were observed in these animals include ataxia, bradypnea, tremors, ptosis, decreased activity, emesis, and mydriasis. In accidental intoxication with, or significant exposure to, unknown quantities of veterinary formulations of ivermectin in humans, either by ingestion, inhalation, injection, or exposure to body surfaces, the following adverse effects have been reported most frequently: rash, edema, headache, dizziness, asthenia, nausea, vomiting, and diarrhea. Other adverse effects that have been reported include: seizure, ataxia, dyspnea, abdominal pain, paresthesia, urticaria, and contact dermatitis. In case of accidental poisoning, supportive therapy, if indicated, should include parenteral fluids and electrolytes, respiratory support (oxygen and mechanical ventilation if necessary) and pressor agents if clinically significant hypotension is present. Induction of emesis and/or gastric lavage as soon as possible, followed by purgatives and other routine anti-poison measures, may be indicated if needed to prevent absorption of ingested material.

How Supplied

HOW SUPPLIED Ivermectin tablets USP, 3 mg are white, round, flat, bevel-edged tablets debossed with "806" on one side and plain on the other side. They are supplied as follows: NDC 76420-619-20 unit dose packages of 20. (relabeled from NDC 42799-806-01) Storage Store at temperatures below 30°C (86°F).