STROMECTOL- ivermectin tablet
Merck Sharp & Dohme Corp.
DESCRIPTION
STROMECTOL 1 (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 A1a and less than 10% 5-O -demethyl-25-de(1-methylpropyl)-22,23-dihydro-25-(1-methylethyl)avermectin A1a , generally referred to as 22,23-dihydroavermectin B1a and B1b , or H2 B1a and H2 B1b , respectively. The respective empirical formulas are C48 H74 O14 and C47 H72 O14 , with molecular weights of 875.10 and 861.07, respectively.
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.
STROMECTOL is available in 3-mg tablets containing the following inactive ingredients: microcrystalline cellulose, pregelatinized starch, magnesium stearate, butylated hydroxyanisole, and citric acid powder (anhydrous).
1
Registered trademark of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.
Copyright � 1996, 2007 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc. All rights reserved
CLINICAL PHARMACOLOGY
Pharmacokinetics
Following oral administration of ivermectin, plasma concentrations are approximately proportional to the dose. In two studies, after single 12-mg doses of STROMECTOL in fasting healthy volunteers (representing a mean dose of 165 mcg/kg), the mean peak plasma concentrations of the major component (H2 B1a ) were 46.6 (�21.9) (range: 16.4-101.1) and 30.6 (�15.6) (range: 13.9-68.4) ng/mL, respectively, at approximately 4 hours after dosing. Ivermectin is metabolized in the liver, and ivermectin and/or its metabolites are excreted almost exclusively in the feces over an estimated 12 days, with less than 1% of the administered dose excreted in the urine. The plasma half-life of ivermectin in man is approximately 18 hours following oral administration.
Microbiology
Ivermectin is a member of the avermectin class of broad-spectrum antiparasitic agents which have a unique mode of action. Compounds of the class bind selectively and with high affinity to glutamate-gated chloride ion channels which occur in invertebrate nerve and muscle cells. This leads to an increase in the permeability of the cell membrane to chloride ions with hyperpolarization of the nerve or muscle cell, resulting in paralysis and death of the parasite. Compounds of this class may also interact with other ligand-gated chloride channels, such as those gated by the neurotransmitter gamma-aminobutyric acid (GABA).
The selective activity of compounds of this class is attributable to the facts that some mammals do not have glutamate-gated chloride channels and that the avermectins have a low affinity for mammalian ligand-gated chloride channels. In addition, ivermectin does not readily cross the blood-brain barrier in humans.
Ivermectin is active against various life-cycle stages of many but not all nematodes. It is active against the tissue microfilariae of Onchocerca volvulus but not against the adult form. Its activity against Strongyloides stercoralis is limited to the intestinal stages.
INDICATIONS AND USAGE
STROMECTOL is indicated for the treatment of the following infections:
Strongyloidiasis of the intestinal tract. STROMECTOL 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. STROMECTOL 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: STROMECTOL 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
Strongyloidiasis
The recommended dosage of STROMECTOL 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 STROMECTOL 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 STROMECTOL 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.