Home » Drug Information » FDA Approved Drugs » 1997
Medical Areas: Immunology
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The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Approval Status: Approved March 1997
Treatment Area: nondisseminated intestinal threadworm
Stromectol (ivermectin) has been approved as a treatment for
infection with nondisseminated intestinal threadworm
(strongyloidiasis). Stromectol is a very effective anti-parasitic
medicine which often cures intestinal (i.e., nondisseminated)
strongyloidiasis, an infection caused by the threadworm
Strongyloides stercoralis, with a single oral dose.
The recommended dose of Stromectol for the treatment of
intestinal (i.e., nondisseminated) strongyloidiasis is a single
oral dose, based on weight (200 micrograms of Stromectol per
kilogram of body weight). In clinical trials, the most common adult
dose used was two 6 mg tablets, which is recommended for people
weighting 51-65 kg (112-143). Stromectol can also be used in
children who weigh 15 kg (33 lb.) or more, at a dose ranging from
1/2 to 2 tablets; again, the dosage is based on weight. After
treatment, at least three stool examinations should be conducted
over the three months following treatment to ensure
Stromectol has also been cleared by the U.S. Food and Drug
Administration to treat onchocerciasis, or river blindness. The
recommended dose of Stromectol for the treatment of onchocerciasis
is a single oral dose based on weight (150 micrograms per kilogram
of body weight). Stromectol is available under the name Mectizanr
in many regions of the world including Africa, Central and South
America, the Middle East and others. Onchocerciasis occurs very
rarely in the U.S.
Stromectol does not kill the adult Onchocerca parasites, and
therefore repeated follow-up and retreatment is usually required.
For the treatment of individual patients, retreatment may be
considered at intervals as short as 3 months. Surgical removal of
nodules containing adult Onchocerca parasites may be considered in
the management of patients with onchocerciasis, since this
procedure will eliminate the adult parasite.
Merck’s catalog price for Stromectol is $7.50 per tablet, or
approximately $15 for an average single dose.
Most of the 200 patients treated with Stromectol (64 to 100
percent in five clinical trials) had their intestinal threadworm
infection eradicated after one dose. In these trials, Stromectol
was generally well tolerated.
In clinical trials on Strongyloidiasis, the following adverse
experiences occurred in greater than 1 percent of the patients:
diarrhea (1.8 percent), nausea (1.8 percent), dizziness (2.8
percent) and pruritus (itching) (2.8 percent).
Patients treated with Stromectol for onchocerciasis may
experience allergic and inflammatory responses to the death of
microfilariae. These adverse events may include
arthralgia/synovitis (9.3 percent), axillary lymph node enlargement
and tenderness (11.0 and 4.4. percent, respectively), inguinal
lymph node enlargement and tenderness (12.6 percent and 13.9
percent, respectively), other lymph node enlargement and tenderness
(3.0 percent and 1.9 percent, respectively), pruritus (27.5
percent), skin involvement including edema, papular and pustular or
frankurticarial rash (22.7 percent) and fever (22.6 percent).
Up to four percent of the population in some parts of the United
States are infected with intestinal threadworm, although the vast
majority remain asymptomatic and undiagnosed. Symptoms include
gastric pain and tenderness, vomiting and diarrhea. Infection with
intestinal threadworm most often is caused when the threadworm
penetrates the skin of the feet through contaminated soil or
through eating contaminated food. Infection with threadworm is most
common in tropical climates and unsanitary living conditions.