3.10. Antihelmínticos
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HELMINTOS
NEMATODOSIntestinales y extraint
CESTODOSIntestinales y quísticos (extraint)
TREMATODOSIntestinales, Hepáticos, Pulmonares y
Sanguíneos
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DROGAS ANTI-HELMINTOS
Grupos de acuerdo accion contra
las clases de helmintos:
1. Anti-Nematodos
2. Anti-Cestodos y
3. Anti-Trematodos
4. Amplio espectro (nitaz, pzq, paromo,
pzq, alb)
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1. NEMATODOS
INTESTINALES: TISULARES:
• Ascaris lumbricoides - Filarias
• Trichuris trichiura - Trichinella sp
• Enterob vermicularis - Toxocara sp (LMV)
• Strongyl stercoralis - Gnathostoma
• Uncinarias -Angiostrongylus
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2. CESTODOS
INTESTINALES: TISULARES:
• Taenia solium - NCC
• Taenia saginata -Quiste hidatidico
• Hymenolepis - Espirometra
• Diphyllobothrium
• Dipylidium
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3. TREMATODOS
INTESTINALES
• Fasciolopsis, Heterophies, Metagonimus.
HEPATICOS
• Fasciola hepatica, Clonorchis, Opistorchis, Amphimerus.
PULMONARES
• Paragonimus sp
SANGUINEOS
• Schistosoma haematobium (vasos de vejiga),
• S. mansoni y japonicum (sistema porta)
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DROGAS ANTIHELMINTICAS
Intestinales y Extraintestinales
Benzimidazoles:Albendazol,
Mebendazol
Tiabendazol
Flubendazol
Triclabendazol
Pamoatos: Pirantel,
Oxantel
Pirvinio
Carbamazinas:
Piperazina y
Dietilcarbamazina
Tetramizol
Levamisol
Pirazinisoquinolinas:
Praziquantel
Nitrotiazoles:
Nitaxozanide, Niridazol
y Niclosamida
Avermectinas:
Ivermectina
Organofosforados:
metrifonato
Antibioticos
Otros: TBD, Befenio, quinacrina.
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2. DROGAS ANTI-Cestodos intestinales
Praziquantel
Niclosamida
Paromomicina
Quinacrina
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2. Cestodos extraintestinales (quistes)
• Albendazol o
mebendazol
• Praziquantel +
corticoides.
• Mixto
NCC
QUISTE
HIDATIDICO
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3. DROGAS ANTI-TREMATODOS
1. Triclabendazol
2. Praziquantel
3. Bitionol
4. Emetina-dehidroemetina (P)
5. Niridazol
6. Oxamniquina
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• Obstrucción de
conductos y obst
completa intestinal =
CIRUGIA.
• Obstrucción parcial
intestinal por Ascaris
lumbricoides =
PIPERAZINA
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• Larva migrans
cutanea
= Ivermectina
Albendazol,
Tiabendazol
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1. ANTI-NEMATODOS
• Flia Benzimidazoles: Albendazol (too Giardiasis x 5 d y
microsporidiosis), Mebendazol, Flubendazol, Tiabendazol y
Triclabendazol (trematodos).
• Pamoatos: pirantel, oxantel y pirvinio
• Piperazina y su derivado Dietilcarbamazina
• Ivermectina (nematodos y ectoparasitos)
• Levamisol
• Befenio (ascaris y anquilostoma).
• Nitazoxanida (+amplio espectro, protoz y helm)
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2. DROGAS ANTI-
CESTODOS
• Praziquantel .. intra y extraint (too anti-Trematodos)
• Niclosamida
• Paromomicina (too anti-protozoos)
• Nitazoxanida (+ amplio espectro)
• Albendazol (too anti-Nematod)
• Quinacrina
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3. DROGAS ANTI-
TREMATODOS
1. Triclabendazol
2. Praziquantel
3. Bitionol
4. Emetina-dehidroemetina (AHA)
5. Niridazol
6. Oxamniquina
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BENZIMIDAZOLES: MEBENDAZOL, ALBENDAZOL, FLUBENDAZOL,
TIABENDAZOL y TRICLABENDAZOL
• Anti-nematodos intest y extra.
• Too: quiste hidatidico (alb y meb) y fasciola y Paragonimus (triclab).
• Nematocida, Ovicida?
MEC ACCION
-Destruccion microtubulos citoplasmaticos de c. tegumentarias e intestinales
-Inhibicion de absorcion de glucosa y depleccion glucogeno.
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BENZIMIDAZOLES
Mecanismo de acción antihelmintica
-Inhiben la polimerización de los microtubulos en
la estructura parasitaria uniéndose a su B-
tubulina.
-Además, inducen cambios bioquímicos en los
parásitos adultos y larvas que incluyen:
-Inhibición de la Z fumarato reductasa a nivel
mitocondrial.
-Reducen el transporte de glucosa e
-Inhiben la fosforilación oxidativa. Depleccion
glucogeno.
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FCOCINETICA
• Absorcion intestinal (+Tiabendazol, +Albendazol y–
mebendazol).
• Metab 1er paso (+mebendazol)conc plasmaticas . Ligan proteinas (95% el sulfoxido de
albendazol) y metabolizados en H (+mebendazol)
• orina
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PRECAUCIONES
• Efectos embriotoxicos y
teratogenicos (ratas).
• NO embarazadas ni ñ<2 a
USOS:
• Ascariasis, oxiuriasis,
uncinariasis y trichuriasis
• Quistes hidatidicos y
triquinosis a dosis .
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2. ALBENDAZOL
• Amplio espectro. Vermicida,
larvicida y ov?
• Buena absorcion (…en extraint) y
ampliamente metabolizado a
Sulfoxido de albend (activo). Vida
½ 8h orina.
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ALBENDAZOL
USOS
• Amplio espectro
-Intest: (ascariasis, oxiuriasis, uncinariasis,
strongyloidiasis, trichuriasis)
-Extraint: Teniasis y NCC, hidatidosis, LMC.
Filariasis linfatica, Capillariasis.
-Protozoos: Giardiasis x 5 d, Microsporidiosis.
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3. TIABENDAZOL (mintezol)
• Util en LMC y estrongiloidiasis
pero…efectos toxicos e… ivermectina
• Eleccion en Triquinosis.
DOSIS:
• 25mg/kg BID x 3 d (5d in diseminacion St
st y LMV).
• Topica xa LMC
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TIABENDAZOL
FCOPATOLOGIA• MEBENDAZOL y ALBENDAZOL: seguras
• G-intestinales: n-v, diarrea.
• SNC. Vertigo, debilidad, somnoliencia, cefalea, alucinaciones, disturbios sensoriales (trabajo!).
• Hipersensibilidad: fiebre, erupciones cutaneas, eritema multiforme, Sd St Johnson
• Raro: edema angioneurotico, shock, tinnitus, convulsiones, colestasis intrahepatica.
• Precaucion: Pctes E.H y E.renal.
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PAMOATOS
1. PAMOATO DE PIRANTEL
• Accion intestinal vermifuga(pobremente absorbido) 50% x heces, 7% en orina.
• Inmoviliza a los parasitos (despolarizante neuromuscular)
paralisis espastica
Piperazina (flacida).
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Mecanismo de acción
El pamoato de pirantel actúa como un
despolarizante neuromuscular e
inmoviliza (parálisis espástica o
tónica) a los parásitos susceptibles
que luego son expulsados del
intestino sin producir excitación ni
migración de las lombrices
afectadas.
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PAMOATO DE PIRANTEL
FCOPATOLOGIA
• Bien tolerado. Anorexia, n-v, diarrea,
calambres abd, vertigo, rash y somnolencia.
• Precaucion en pctes disfuncion hepatica
(SGOT).
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PAMOATO DE PIRANTEL
UTILIDAD:
• Ascariasis y enterobiasis 11mg/kg dosis unica
• Uncinariasis y T. orientalis20mg/kg x 2d
• + Pamoato de oxantel xa Trichuris trichiura
DOSIS:
Ad. 6 tab de 125mg
niños: 4 tab
NO Embarazadas, NO niños <2a
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2. PAMOATO DE OXANTEL
• Parecido anterior
• Selectivo para T. trichiura.
• Dosis: 750 mg adultos
3. PAMOATO DE PIRVINIO• Util en oxiuriasis en dosis unica
• No absorcion int—No toxicidad
• Tiñe heces color rojo brillante.
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PIPERAZINA• Poca absorcion intestinal
MEC ACCION
• Bloquea Acth en musculo--paralisis
flacida—expulsados (vermifugo).
FCOPATOLOGIA
• N-v, diarrea y reacciones alergicas
• Dosis o acumulacion x insuf renal:
debilidad muscular, vertigo,
confusion y convulsiones.
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PIPERAZINA
Mecanismo de acciónLa piperazina causa parálisis flácida de los
músculos del parásito bloqueando el efecto
de acetilcolina, por lo tanto los áscaridos no
son destruidos por la droga, sino paralizados
y luego expulsados por el peristaltismo
normal del intestino (efecto vermifugo).
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PIPERAZINA
USOS
• Ascaridiasis (riesgo de
migracion) y oxiuriasis
• Obstruccion intestinal parcial.
DOSIS: Ascariasis—75mg/kg x
3d. 8d—oxiuros
• CONTRAINDICADA: IR, IH y epilepsia
• Metabolismo H (20% inalteradoorina)
• Matabolismosust nitrosas (potencial carcinogenico)
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DIETILCARBAMAZINA
• Derivado de piperazina
• Efectiva: filariasis linfatica y oncocercosis
• Buena absorcion intestinal—metab parcialm—
orina (30%).
• Efectos adversos inflamatorios por muerte de
parasitos (fiebre, cefalea, leucocitosis, nodulos
dolorosos, taquicardia, vomito). Loa loa (evitar)
Antihistaminicos o corticoides
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DIETILCARBAMAZINA
USOS:
• Filariasis linfatica (W. bancrofti y B. malayi)
• Oncocercosis, eosinofilia tropical y
toxocariasis.
DOSIS:
2 mg/kg x 21-28 d
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LEVAMISOL (Decaris 50 y 150 mg)
• Derivado levogiro del tetramizol
• Util: ascaris, strongyloides y uncinarias.
• Actua I succindeshidrogenasa—paralisis.
• Dolor abdominal, nausea, hipotension
• Inmunoestimulante.
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BEFENIO
• Compuesto de amonio
• Util en Uncinariasis y ascariasis
• Pobre absorcion-- N-v
• Dosis: 5g/d
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IVERMECTINA(Stromectol, Kilox, mectizan, ivermectina-Genfar)
• Proviene de las avermectinas. Es lactona macrociclica.
• Antiparasitario:
1. intestinal,
2. tisular (piel y
linfaticos) y
3. ectoparasiticida
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IVERMECTINA
MEC ACCION
• Potenciando liberacion y ligadura del GABA
en sinapsis Paralisis tonica musc periferica
(inmovilizacion, acc embriostatica).
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• IVR causa inmovilización de los parásitos sensibles
produciendo parálisis tónica de la musculatura
periférica. El mecanismo de acción no está bien
entendido, aunque la potenciación en la liberación y
ligadura de ácido gama aminobutírico (GABA) en
ciertas sinápsis.
• Además, ivermectina probablemente se une a los
canales de cloro glutamato-activados que se
encuentran en los nervios y células musculares de los
nematodos, lo cual causa hiperpolarización por
incremento de la permeabilidad al ion cloro a través
de la membrana celular; resultando en la parálisis del
parásito.
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IVERMECTINA
1. Nematodos Intestinales:
Eleccion: St stercoralis
Otros: ascariasis, enterobiasis, trichuriasis. Uncinarias.
2. Nematodos tisulares.
Accion microfilaricida en piel (onco) y sangre (filariasis linfatica) x 6-12 m. Gnathostomiasis, LMC.
3. Ectoparasitos:
Scabies, pediculosis, miasis, garrapatas.
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IVERMECTINA
FCOCINETICA
• Conc mx 4h—vida ½ 10h—heces 98%.
Conc H y tejido graso. Niveles bajos en
cerebro (GABA).
FCOPATOLOGIA
• Efectos indeseables x … muerte parasitos
No carcinogenico. No teratogenico
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IVERMECTINA
USOS CLINICOS. Eleccion:
• Oncocercosis,
• Filariasis linfatica,
• Strongyloidiasis
• Larva migrans cutanea,
• Ectoparasitosis: Escabiosis, Miasis, Pediculosis, Pulicosis, garrapatas.
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Ivermectina en Ectoparasitosis
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2. CESTODOS (Intestinales y Tisulares)
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B. ANTI-CESTODOS
Intestinales
Praziquantel, Niclosamida, Paromomicina y
Quinacrina. Tribendimidina y Nitazoxanide
(amplio espectro)
Tisulares
Praziquantel, Albendazol y mebendazol.
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PRAZIQUANTEL
• Amplio espectro (cestodos y trematodos) tanto
intestinales como tisulares. NO en nematodos.
MEC ACCION
• Incremento actividad muscular—contraccion y
paralisis espastica.
• Dosis. Vacuolizacion y vesiculizacion
tegumentos—destruyendo—necrosis--muerte
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PRAZIQUANTEL
FCOCINETICA
• Excelente absorcion intestinal. Conc mx 1-3h—
metaboliza rapida y complet—orina (80%).
FCOPATOLOGIA
• Molestias abd: dolor, nausea. Cefalea y vertigo.
Fiebre, eosinofilia y rash.
• NEGATIVO para mutagenesis, carcinogenesis y
teratogenesis ---- SI en embarazo.
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PRAZIQUANTEL
USOS CLINICOS
• Trematodos: schistosomas, distomatosis intestinal, hepatica y pulmonar.
• Cestodos: taenias intestinales y NCC y Quiste hidatidico.
Dosis: NCC x 8-15-30 dias
T. intestinales: dosis unica
Distomatosis: 2-3 dias
Hidatidosis: 3-6 meses
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NICLOSAMIDA(Yomessan)
• Cestodos (Taenias intestinales). No NCC
• Riesgo: destruccion proglotides … precauciones…
MEC ACCION
• Inhibe respiracion. Bloquea captacion glucosa.
• Bien tolerada
• T. solium—purgante
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PAROMOMICINA(Humatin)
• Aminoglucosido
• No se absorbe en intestino
• T. saginata/
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QUINACRINA
• Vermifugo (el escolex se desprende de la
pared intestinal).
• Nausea y vomito (+antiemetico)
• E. adversos: Estimulante SNC (inquietud-
reacciones psicoticas).
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3. TREMATODOS(pulmonares, hepáticos, intestinales y sanguíneos)
Triclabendazole
Praziquantel
Nitrotiazoles
metrifonato
Oxamniquina
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ANTI-TREMATODOS
• Praziquantel
• Triclabendazole
• Oxamniquina (Schist mansoni)
• Nitrotiazoles: Niridazol (Schistosomiasis) y
Nitazoxanida (amplio espectro).
• Metrifonato (Schist haematobium)
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NITROTIAZOLES:
niridazol y nitazoxanida
NIRIDAZOL
• Esquistosomiasis
• Depauperacion de glucogeno x bloqueo de
la inactivacion de la fosforilasa.
• Efectos indeseables: astenia, anorexia,
nausea, cefalea, dolor abd, mialgias,
palpitaciones, cambios EKG. Convulsiones
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NIRIDAZOL
PRECAUCIONES
• IH, IR, alteraciones neuropsiquiatricas,
cardiopatias descompensadas.
• No junto a INH (potencian efectos
adversos)
• NO embarazadas
• Dosis: 25mg/kg en BID o TID x 7d
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NITAZOXANIDE(Colufase, Abanix)
• +Amplio espectro: protozoos y helmintos
• Higado—a tizoxanida (met activo)
• Adm con alimentos
• 99% a proteinas—75% heces y resto x orina
MEC ACCION
Protozoos: interfiere enz piruvato-ferrodoxina oxido-reductasa
Helmintos: i polimerizacion de tubulina
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Mecanismo de Acción
El mecanismo de acción es diferente según el grupo
de parásitos en los que actúa, así, en los helmintos
inhibe la polimerización de la tubulina y en los
protozoos interfiere con la enzima piruvato-
ferrodoxina óxido-reductasa fundamental para el
metabolismo anaerobio de los parásitos.
Nitazoxanida parece no producir daños en el ADN
parasitario por cuanto es diferente a los
nitroimidazoles por ejm metronidazol. Hasta el
momento no se ha reportado resistencia por parte
de ningún microorganismo patógeno.
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NITAZOXANIDE
• No trastornos en la descendencia ni en fertilidad.
FCOPATOLOGIA
• Dolor abd, n, diarrea, anorexia, astenia, fiebre, disuria.
USOS
Protozoos: amebiasis, giardiasis, tricomoniasis, criptosporidiosis.
Helmintos: nematodos y cestodos int.
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METRIFONATO
• Organofosforado (insecticida-antihelmintico)
• Uso en esquistosomiasis urinaria.
• Efectos indeseables: vertigo, debilidad,
nausea.
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OXAMNIQUINA
• S. mansoni (macho)
• Comida retarda su absorcion
• Fcopatologia: nausea, diarrea. Vertigo y
disturbios neurologicos, psiquiatricos y
convulsiones.
• En combinacion con oxamniquina xa inf
mixtas.
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• Parasites: Learning a Worm-Killer’s Modus Operandi
• By DONALD G. McNEIL Jr.
• Published: November 15, 2010
•
Researchers have finally discovered how ivermectin, one of the most important worm-killing drugs used in both
humans and animals for
• decades, actually works.
Ivermectin, extracted from a soil fungus in the 1970s, was originally sold under names like Heartgard to deworm
pets.
•
Beginning in 1987, Merck began donating millions of doses to fight onchocerciasis, or river blindness, which is
caused by microscopic worms that are spread by black fly bites and migrate into victims’ eyes. It is now also
used against lymphatic filariasis, which is caused by worms spread by mosquitoes; worms nesting in the
lymph nodes distort them and cause the grotesquely swollen legs and scrotums known as elephantiasis.
•
In a study posted online in The Proceedings of the National Academy of Sciences, researchers from McGill and
Michigan State Universities showed that ivermectin does not kill the worms directly. It binds to proteins
secreted by young worms to block the host’s immune system. With the worm’s defenses down, white blood
cells move in for the kill. Luckily for humans, said Charles D. Mackenzie, a Michigan State professor of
veterinary pathology and study author, the killing is slow, letting the worms leave the eyes. Older drugs, he
said, killed so fast that dead worm bodies worsened the blindness. Ivermectin ―is an extraordinarily safe
drug,‖ Dr. Mackenzie added. ―We’ve given out 25 million doses in Tanzania and had only two minor side
effects.‖
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Ivermectin disrupts the function of the excretory-secretory apparatus in microfilariae of Brugia
malayi
• Yovany Morenoa, Joseph F. Nabhana, Jonathan Solomona, Charles D. Mackenzieb, and
Timothy G. Gearya,1
• a Institute of Parasitology, McGill University–Macdonald Campus,
• NJ, and approved October 12, 2010 (received for review August 17, 2010)
Abstract
Ivermectin (IVM) is a broad-spectrum anthelmintic used in filariasis control programs. By binding to
nematode glutamate-gated chloride channels (GluCls), IVM disrupts neurotransmission processes
regulated by GluCl activity. IVM treatment of filarial infections is characterized by an initial
dramatic drop in the levels of circulating microfilariae, followed by long-term suppression of their
production, but the drug has little direct effect on microfilariae in culture at pharmacologically
relevant concentrations. We localized Brugia malayi GluCl expression solely in a muscle structure
that surrounds the microfilarial excretory-secretory (ES) vesicle, which suggests that protein release
from the ES vesicle is regulated by GluCl activity. Consistent with this hypothesis, exposure to
IVM in vitro decreased the amount of protein released from microfilariae. To better understand the
scope of IVM effects on protein release by the parasite, three different expression patterns were
identified from immunolocalization assays on a representative group of five microfilarial ES
products. Patterns of expression suggest that the ES apparatus is the main source of regulated ES
product release from microfilariae, as it is the only compartment that appears to be under
neuromuscular control. Our results show that IVM treatment of microfilariae results in a marked
reduction of protein release from the ES apparatus. Under in vivo conditions, the rapid microfilarial
clearance induced by IVM treatment is proposed to result from suppression of the ability of the
parasite to secrete proteins that enable evasion of the host immune system.