EFFECT OF THE ANTIPARASITIC DRUG MEBENDAZOLE ON CHOLANGIOCARCINOMA GROWTH

Mebendazole (MBZ) is an anthelmintic drug which inhibits tubulin polymerization and eventually causes apoptosis in target organisms. Antitumor activity of MBZ has been reported in various cancers. The aim of this study was to investigate the effect of MBZ on cholangiocarcinoma (CCA) cells in vitro and in vivo. MBZ reduced cell proliferation in the KKU-M213 cell line associated with a remarkable enhancement of caspase-3 gene expression and enzyme activity. Oral administration of MBZ slightly reduced the growth rate of subcutaneously xeno-grafted KKU-M213 in nude mice. The TUNEL assay showed an increase of apoptotic cell numbers in the xenograft tumor tissue of MBZ-treated mice. The data obtained in this study suggested that MBZ can suppress CCA cell proliferation via caspase-3 activated apoptosis. Further investigation of the antitumor effects of MBZ might support the use of MBZ as an alternative drug for CCA treatment.

Assessment of anthelmintic efficacy of mebendazole in school children in six countries where soil-transmitted helminths are endemic

Background

Robust reference values for fecal egg count reduction (FECR) rates of the most widely used anthelmintic drugs in preventive chemotherapy (PC) programs for controlling soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and hookworm) are still lacking. However, they are urgently needed to ensure detection of reduced efficacies that are predicted to occur due to growing drug pressure. Here, using a standardized methodology, we assessed the FECR rate of a single oral dose of mebendazole (MEB; 500 mg) against STHs in six trials in school children in different locations around the world. Our results are compared with those previously obtained for similarly conducted trials of a single oral dose of albendazole (ALB; 400 mg).

Methodology

The efficacy of MEB, as assessed by FECR, was determined in six trials involving 5,830 school children in Brazil, Cambodia, Cameroon, Ethiopia, United Republic of Tanzania, and Vietnam. The efficacy of MEB was compared to that of ALB as previously assessed in 8,841 school children in India and all the above-mentioned study sites, using identical methodologies.

Principal Findings

The estimated FECR rate [95% confidence interval] of MEB was highest for A. lumbricoides (97.6% [95.8; 99.5]), followed by hookworm (79.6% [71.0; 88.3]). For T. trichiura, the estimated FECR rate was 63.1% [51.6; 74.6]. Compared to MEB, ALB was significantly more efficacious against hookworm (96.2% [91.1; 100], p<0.001) and only marginally, although significantly, better against A. lumbricoides infections (99.9% [99.0; 100], p = 0.012), but equally efficacious for T. trichiura infections (64.5% [44.4; 84.7], p = 0.906).

Conclusions/Significance

A minimum FECR rate of 95% for A. lumbricoides, 70% for hookworm, and 50% for T. trichiura is expected in MEB-dependent PC programs. Lower FECR results may indicate the development of potential drug resistance.

Soil-transmitted helminths (STHs; roundworms, whipworms, and hookworms) infect millions of children in sub-tropical and tropical countries, resulting in malnutrition, growth stunting, intellectual retardation, and cognitive deficits. To fight against STH, large-scale deworming programs are implemented in which anthelmintic drugs (either albendazole (ALB) or mebendazole (MEB)) are administered. Currently, these large-scale programs are intensifying, highlighting the need to closely monitor the efficacy of anthelmintic drugs to detect changes in drug efficacy that may arise through the evolution of anthelmintic drug resistance in the parasites. We have previously defined the minimum expected efficacy of ALB based on the fecal egg count reduction (FECR) rate, but these reference values are lacking for MEB. Therefore, we therefore evaluated the FECR rate of MEB against STHs in six STH endemic countries. In addition, we compared the results of the FECR rate for MEB with those we obtained previously for ALB. The results confirm that MEB treatment was highly efficacious against roundworms, and to a lesser extend against hookworms, but not against whipworms. Compared to ALB, MEB is less efficacious against hookworm, but equally efficacious against roundworms and whipworms. Based on this study we propose the minimum expected FECR rate for MEB-dependent large-scale deworming programs.

Mebendazole reduces vascular smooth muscle cell proliferation and neointimal formation following vascular injury in mice

Mebendazole is an antihelminthic drug that exerts its effects via interference with microtubule function in parasites. To determine the utility of mebendazole as a potential treatment for vascular diseases involving proliferation of vascular smooth muscle cells, the effects of mebendazole on vascular smooth muscle cell proliferation were tested in vitro and in a mouse model of arterial injury. In vitro, mebendazole inhibited proliferation and migration of murine vascular smooth muscle cells and this was associated with altered intracellular microtubule organization. To determine in vivo effects of mebendazole following vascular injury, femoral arterial wire injury was induced in wild-type mice treated with either mebendazole or placebo control. Compared with placebo-treated mice, mebendazole-treated mice formed less neointima at the site of injury. Mebendazole is effective at inhibiting vascular smooth muscle cell proliferation and migration, and neointimal formation following arterial injury in mice.

[In vitro effect of seven anthelmintic agents against adult Clonorchis sinensis]

OBJECTIVE

To observe the in vitro effect of praziquantel, tribendimidine, levamisole, artemether, artesunate, albendazole and mebendazole against adult Clonorchis sinensis.

METHODS

Seventy rats infected with 50-100 C. sinensis metacercariae for 5-7 weeks were euthanized, and adult C. sinensis were collected from the common bile duct Three to four worms were placed in each well of a 24-well falcon plate, and treated by Hanks' balanced salt solution-20% calf serum containing aforementioned drugs at various concentrations. The motor activity and morphology change of the worms were observed under an inverted microscope at 4, 24, 48 and 72 h post treatment.

RESULTS

Praziquantel could reduce the motor activity of the worms rapidly which resulted in detachment of oral sucker from the well wall, curl of the worm body and emergence of vacuoles from the tegument. The minimal concentration of praziquantel to kill adult C. sinensis was 0.1 g/ml. After adult C. sinensis exposed to tribendimidine at concentrations of 0.5, 1 and 10 g/ml, they revealed in paralysis, looseness and stretch of the worm body rapidly or immediately. The minimal concentration of tribendimidine to kill adult worms was 0.05 g/ml. When worms exposed to levamisole at 10 and 20 g/ml, there was a gradual decrease in the worm's motor activity accompanied by looseness of the worm body. But 48 h post exposure, most worms showed apparently recovery of motor activity. In a higher levamisole concentration of 50 g/ml, all worms revealed in stretch and paralysis which was similar to that induced by tribendimidine. When adult C. sinensis were exposed to artemether or artesunate 10 and 50 g/ml, the motor activity of worm body and oral sucker reduced which accompanied by worm contraction, then followed by looseness of the worm body and emergence of vacuoles along the tegument. At 72h post exposure, the worm mortalities induced by the two concentrations of the two drugs were about half, respectively. In adult C. sinensis exposed to albendazole and mebendazole at concentrations of 10 and 50 g/ml, only stimulation of motor activity of oral sucker was seen which revealed in vigorous contraction within 24 h post exposure. During 72 h observation period, no any other changes in worm activity and morphology were seen.

CONCLUSION

Praziquantel and tribendimidine exhibit strong in vitro killing effect on adult C. sinensis. The minimal concentration of levamisole used to kill adult worm is 50 times higher than that of tribendimidine. The higher concentrations of artemether and artesunate show slower action to reduce the worm activity and kill part of the worms. Higher concentrations of albendazole and mebendazole exhibit no killing effect on C. sinensis, besides stimulating the motor activity of worm oral sucker.

Modulation of porcine (Sus scrofa domestica) and pheasant (Phasianus colchicus) carbonyl reducing enzymes by anthelmintic therapy with flubendazole

Flubendazole (FLU) is a widely administered benzimidazole anthelmintic indicated for the control of parasitic diseases in farm animals including pigs and pheasants. This study was designed to test the biotransformation of FLU in control animals and animals treated with FLU in recommended therapeutic doses. The activities of several pheasant and porcine hepatic and intestinal carbonyl reducing enzymes and their modulation by FLU were also studied. Twelve adult pheasant hens, approximately 1 year old, were divided into two groups and treated for 7 days with placebo or 6 mg of FLU/kg of body weight. Eight male hog weaners, approximately 3 month old, were divided into two groups and treated for 5 days with placebo or 1.57 mg of FLU/kg of body weight. Subcellular fractions, prepared from livers and small intestines of control and FLU treated animals, were incubated with FLU. In vitro formation of two main FLU metabolites, reduced FLU, and hydrolyzed FLU were analyzed using HPLC. While FLU was reduced significantly more intensively in FLU-treated pheasants than in control animals, no differences were observed in pigs. These results were confirmed by measuring the enzyme activities: carbonyl reducing enzyme activities were increased in pheasants treated by FLU, whereas FLU did not affect these enzymes in pigs.

Study of the reproductive capacity of Trichinella spiralis recovered from experimentally infected mice under-dosed with albendazole or mebendazole

The reproductive capacity of Trichinella spiralis recovered from experimentally infected mice under-dosed with albendazole (ALB) or mebendazole (MEB) was studied. Different groups of male C57/BL mice were infected with 10 +/- 0.5 muscular larvae (ML) per gram of body weight and treated with a single dose by oral (20 mg/kg) of ALB, MEB or praziquantel (PZQ) given at 5th day post infection (DPI), during the intestinal phase of infection. In other group of mice, treatment with the same drugs and dosage was for seven days, starting at day 45 PI through the stage of encapsulating larvae (parenteral phase of infection). A reduction of 72.9 to 89.9% in the parasitic load was observed in ALB or MEB treated groups but not in mice untreated or administered with PZQ. The recovered larvae were used to infect naïve mice and, after 45 DPI, a similar Reproductive Capacity Index (RCI) was observed between the different groups (P=0.323, one-way ANOVA), either from mice infected with larvae recovered from the intestinal treatments (RCI-ALB = 51.6 +/- 12.1 and RCI-MEB = 49.2 +/- 14.) or from the parenteral ones (RCI-ALB = 52.2 +/- 14.0 and RCI-MEB = 51.9 +/- 11.8). The RCI of non-treated ML was 59.5 +/- 7.7 and 57.9 +/- 15.9 for PZQ. This information is significant for practical strategies when under-dosage is dispensed.

Efficacy of thiabendazole, mebendazole, levamisole and ivermectin against gullet worm, Gongylonema pulchrum: in vitro and in vivo studies

In vitro and in vivo studies were conducted to evaluate the effects of thiabendazole, mebendazole, levamisole and ivermectin against Gongylonema pulchrum. For in vitro assays, third-stage larvae (L3) incubated with the drugs were administered orally to mice and the ability of larvae to invade the gastric mucosa of the animals was examined. After incubation, only those larvae treated with high concentrations of levamisole (1 and 10 microg/ml) were tightly coiled with intestines exhibiting morphological abnormalities. Good dose-response data for the drugs tested was observed at the time of worm recovery from mice, with no worms recovered at the two highest concentrations of levamisole. In vivo efficacy of the drugs against adult worms was evaluated in six groups of three rabbits, each of which was infected with 30 L3 of G. pulchrum and treated with thiabendazole at 100 mg/kg for 3 days, mebendazole at 70 mg/kg for 3 days, levamisole as a single dose of 8 mg/kg, and subcutaneously injected ivermectin as a single dose of 0.2 mg/kg or vehicles of the drugs (control) at 4 months post-infection. Necropsy 14 days after treatment revealed that levamisole, mebendazole and ivermectin reduced worm burdens by 63.2%, 22.8% and 25.8%, respectively, with no reductions in worms observed with thiabendazole. The surviving worms were principally found in the esophagus with the remainder distributed among the buccal mucosa, the tongue, and/or pharyngeal mucosa in all groups. A number of morphologically abnormal eggs were observed within the uterus and ovijector in female worms recovered from the thiabendazole-treated group. These findings suggest that levamisole exhibits in vivo efficacy against G. pulchrum infection and that the larval invasion tests using mice could be used to screen for anthelmintic susceptibility of nematodes.

Effects of three benzimidazoles on growth, general morphology and ultrastructure ofTritrichomonas foetus

Tritrichomonas foetus is a venereal pathogen of cattle, which causes infertility, early embryonic death or abortion. In order to evaluate the potential trichomonicidal activity of benzimidazoles, the effects of thiabendazole, mebendazole and albendazole were analyzed on the multiplication, general morphology and ultrastructure of T. foetus. It was found that mebendazole presented the highest IC(50%) (2.3 microM), when compared with albendazole (IC(50%)=9.4 microM) and thiabendazole (IC(50%)=142.6 microM), and that such effects were irreversible. Concerning microscopic analysis, thiabendazole- and mebendazole-treated cells presented increased volume, internalization of the flagella, disruption or multiplication of the nucleus, multiple organelles and cytoplasmic vacuolization. Albendazole-treated cells exhibited slight alterations, because the parasite became slightly rounded, its flagella were not internalized but the cytoplasm was vacuolated. Mebendazole was indeed highly effective as an in vitro trichomonicidal agent, and this might open up new possibilities for the use of mebendazole in the therapy of bovine trichomoniasis.

Activities of biotransformation enzymes in pheasant (Phasianus colchicus) and their modulation by in vivo administration of mebendazole and flubendazole

Basal activities of certain pheasant hepatic and intestinal biotransformation enzymes and modulation of their activities by anthelmintics flubendazole (FLBZ) and mebendazole (MBZ) were investigated in subcellular fractions that were prepared from liver and small intestine of control and FLBZ or MBZ treated birds. Several oxidation, reduction and conjugation enzyme activities were assessed. In the liver, treatment of pheasants by FLBZ or MBZ caused very slight or no changes in monooxygenase activities and conjugation enzymes. More significative changes were detected in small intestine. Metyrapone and daunorubicin reductase activities were increased by both substances in the liver. This is the first evidence that certain benzimidazoles modulate reductases of carbonyl group. With respect to the relatively slight extent of the changes caused by FLBZ or MBZ we can assume that repeated administration of therapeutic doses of both FLBZ and MBZ has probably no serious influence on pheasant biotransformation enzyme system.

Mebendazole inhibits growth of human adrenocortical carcinoma cell lines implanted in nude mice

Adrenocortical carcinoma is a rare tumor of the adrenal gland which requires new therapeutic approaches as its early diagnosis is difficult and prognosis poor despite therapies used. Recently, mebendazole has been proved to be effective against different cancers. The aim of our study was to evaluate whether mebendazole may result therapeutically useful in the treatment of human adrenocortical carcinoma. We analyzed the effect of mebendazole on human adrenocortical carcinoma cells in vitro and after implantation in nude mice. In order to clarify mechanisms of mebendazole action, metastases formation, apoptosis and angiogenesis were also investigated. Mebendazole significantly inhibited cancer cells growth, both in vitro and in vivo, the effects being due to the induction of apoptosis. Moreover, mebendazole inhibited invasion and migration of cancer cells in vitro, and metastases formation in vivo. Overall, these data suggest that treatment with mebendazole, also in combination with standard therapies, could provide a new protocol for the inhibition of adrenocortical carcinoma growth.

Single Low-Dose Mebendazole Administered Quarterly for Ascaris Treatment

BACKGROUND

Intestinal parasites are difficult to eradicate in tropical climates where poor sanitation exists. In addition, pharmaceutical stability is poor making traditional three day dosing for the treatment of A. lumricoides challenging.

METHODS

Single 100 mg doses of mebendazole were administered to persons living along Amazon tributaries in Northeastern Peru. Directly-observed treatment was repeated at 3-month intervals over a 2-year period in a single treatment village. Treatment was repeated at 12-month intervals in the remaining (control) villages. Treatment was accompanied by a regimen of multivitamins with iron to be taken daily for 14 days after each treatment. Subjects were screened for ova and parasites prior to treatment and at 1-year intervals. In addition to A. lumbricoides, other parasites found on screening were recorded.

RESULTS

Treatment resulted in a 92.5% cure rate for A. lumbricoides at the 2-year assessment. Growth and development assessments demonstrated fewer individuals below the 3 percentile for age-adjusted measurements when treated quarterly.

CONCLUSIONS

Based on these limited data, single low-dose mebendazole administered quarterly appears to have a positive effect on the health of isolated village populations in the Amazon River basin.

Low efficacy of mebendazole against hookworm in Vietnam: two randomized controlled trials

Vietnam is participating in a global de-worming effort that aims to treat 650 million school children regularly by 2010. The treatment used in Vietnam is single dose oral mebendazole (Phardazone) 500 mg. We tested the efficacy of single dose mebendazole 500 mg in the therapy of hookworm infection in a randomized double-blind placebo-controlled trial among 271 Vietnamese schoolchildren. The treatment efficacy of single dose mebendazole in children did not differ significantly from placebo, with a reduction in mean eggs per gram of feces relative to placebo of 31% (95% CI -9 to 56%, P = 0.1). In light of these findings we then carried out a similar randomized trial comparing triple dose mebendazole, single dose albendazole, and triple dose albendazole against placebo in 209 adults in the same area. The estimated reduction in mean post-treatment eggs per gram of feces relative to placebo was 63% (95% CI 30-81%) for triple mebendazole, 75% (47-88%) for single albendazole, and 88% (58-97%) for triple albendazole. Our results suggest that single dose oral mebendazole has low efficacy against hookworm infection in Vietnam, and that it should be replaced by albendazole. These findings are of major public health relevance given the opportunity costs of treating entire populations with ineffective therapies. We recommend that efficacy of anti-helminth therapies is pilot tested before implementation of national gut worm control programs.

Duration of anthelmintic effect of three formulations of ivermectin (oral, injectable and pour-on) against multiple anthelmintic-resistant haemonchus contortus in sheep

We report the results of investigations that were conducted in a sheep flock in Uttaranchal, India where repeated failure of anthelmintic medication was noted. The study revealed that Haemonchus contortus in sheep had developed resistance to benzimidazoles (fenbendazole, mebendazole and albendazole), imidazothiazole (levamisole) and salicylanide (rafoxanide), while it was fully susceptible to avermectins (ivermectin). Further, the suppression of nematode egg output in faeces of sheep naturally infected with multiple anthelmintic-resistant H. contortus following treatment with ivermectin tablet (0.4 mg/kg body weight (bw), orally), ivermectin injection (1% w/v, 0.2 mg/kg bw, subcutaneously) and ivermectin pour-on (0.5 w/v, 0.5 mg/kg bw) was also studied over a period of 10 weeks post treatment. It was noted that ivermectin tablet after initial clearance of infection (faecal egg count reduction 100%), could not prevent establishment of new patent natural infection for even a single day, while ivermectin pour-on and injection prevented the establishment of new infection for 7 and 14 days post treatment, respectively. Maximum protection period (duration for which mean faecal egg count of sheep reaches 500 eggs per gram of faeces or more) of 68 days was recorded in sheep treated with injectable ivermectin, followed by pour-on (60 days) and oral (53 days) preparations.

Pro-oxidant effects of Mebendazole in albino rats experimentally infected with Trichinella spiralis

Trichinellosis treated with Mebendazole often leads to complications in the course of the disease in humans and animals as a result of intoxication and hyper-sensitization of an organism due to the massive destruction of parasites. This study was conducted to research Mebendazole incidence on lipid peroxidation processes (LPP) in rats' blood in Trichinella spiralis-infected and parasite-free albino rats. The research was conducted to evaluate erythrocyte superoxide dismutase (SOD) activity and malonic dialdehyde (MDA) concentration in blood serum. The parameters of the SOD-MDA system in infected albino rats, which were treated or untreated with Mebendazole were analyzed. It was concluded that Mebendazole amplifies the LPP in the blood of both infected and parasite-free animals: in a dose of 150 mg/kg anthelmintic causes disturbances of biochemical homeostasis in the SOD-MDA system, thus working as a pro-oxidant.

In vitro and in vivo effects of flubendazole on Echinococcus granulosus metacestodes

The aim of the present work was to determine the efficacy of flubendazole (FLBZ) against Echinococcus granulosus metacestodes by using in vitro and in vivo models. Groups of 50 microcysts developed in vitro, and groups of 10 peritoneal cysts were obtained from Balb C mice with experimental secondary infections of 8 months. The cysts were placed in Leighton tubes containing 10 ml of culture medium. FLBZ was added to the medium resulting in final concentrations of 5 and 1 microg/ml for mycrocysts treatment and 10, 5, and 1 microg/ml for murine cysts treatment. In vivo treatment was performed on 20 mice that developed an experimental secondary hydatid disease over a period of 11 months. FLBZ was given (1.5 mg/kg) by the oral route once a day for 50 days. A loss of turgidity was detected in all in vitro drug treated cysts irrespective of the drug concentration or parasite origin. Inspection of treated cysts by scanning electron microscopy (SEM) revealed that the germinal layer lost it characteristic multicelular structure. These results were confirmed on the ultrastructural level by transmission electron microscopy (TEM), treated metacestodes had undergone considerable degenerative changes after the in vitro treatment. The results obtained after the in vivo treatment with FLBZ showed no significant difference between the control and treated groups related to the weight of cyst masses. However, the ultrastructural study at TEM of cysts that developed in mice from the treated group revealed alterations in the germinal layer with the presence of numerous vacuoles. With regard to the ultrastructural study at SEM, only cellular debris of the germinal layer could be seen. In conclusion, the data obtained clearly demonstrate that in vitro and in vivo treatment with FLBZ is effective against E. granulosus metacestodes.

Angiostrongylus cantonensis: apoptosis of inflammatory cells induced by treatment with mebendazole or/and interleukin 12 in mice

Angiostrongylus cantonensis is the major cause of human eosinophilic meningoencephalitis. ICR mice were infected orally with 35 infective larvae and sacrificed at 4-14 days, 25 days or 32 days post infection (dpi) for pathological and immunocytochemical examinations. In the non-treated group, no apoptosis signal was found in the meninges or parenchyma of the brains (4-14 dpi). Only a few apoptotic cells were noticed at 25 dpi (3%) and 32 dpi (10%). In the groups, the animals were given a single dose of mebendazole (20 mg/kg, per os at various times) or injections of interleukin 12 (IL-12) (10 ng/daily, intraperitoneally), all the animals were sacrificed at 14 dpi; the number of apoptotic cells was increased (17-21%). In the group that received a single dose of mebendazole (4 dpi) in combination with IL-12 injections (4-13 dpi), mild meningitis was observed, and most of the infiltrated inflammatory cells were in the apoptotic program (55%). Taken together, apoptosis of the inflammatory cells (most were eosinophils) could be induced when the infected mice were treated with mebendazole or/and IL-12.

Phenantroline, lovastatin, and mebendazole do not inhibit oviposition in the murine experimental infection with Angiostrongylus costaricensis

Abdominal angiostrongyliasis is a zoonotic infection produced by a metastrongylid intra-arterial nematode, Angiostrongylus costaricensis. Human accidental infection may result in abdominal lesions. The presence of the eggs in the tissues plays an essential role in morbidity of abdominal angiostrongyliasis. The objective of this study is to evaluate and compare the effects of lovastatin, phenanthrolin, and mebendazole on oviposition of A. costaricensis in a murine experimental model. Each group of 12 male Swiss mice (Mus musculus) was orally infected with 10 L3 of the "Santa Rosa" strain of A. costaricensis. Two control groups were established: (1) mice were infected and not treated; (2) noninfected and nontreated animals. The experimental groups received (1) lovastatin TL), at a daily dose of 250 mg/kg for 10 consecutive days 16 days after infection; (2) phenanthroline at a daily dose of 20 mg/kg for 5 consecutive days 21 days after infection; and (3) mebendazole at a daily dose of 5 mg/kg for 5 consecutive days 21 days after infection. There was no significant inhibition of oviposition for lovastatin- and mebendazole-treated animals, whereas phenanthroline was associated with the lowest averages of larviposition per postinfection day and significant reduction of mortality.

In vitro effects of flubendazole on Echinococcus granulosus protoscoleces

The aim of the present work was to determine the in vitro protoscolicidal effect of flubendazole (FLBZ) against Echinococcus granulosus. Protoscoleces of E. granulosus were incubated with FLBZ at concentrations of 10, 5 and 1 microg/ml. The first signs of FLBZ-induced damage were observed 3 days post-incubation. A clear protoscolicidal effect, reducing the vitality of protoscoleces to 35.6+/-0.7%, was observed after 18 days of incubation. After 25 days of FLBZ incubation (5 microg/ml), the percentage of vital protoscoleces was 13.9+/-5.9%. Protoscolex mortality was 100% (10 and 1 microg/ml) and 0.7+/-0.7% (5 microg/ml) after FLBZ incubation for 30 days. Results of vitality tests were consistent with the tissue damage observed at the ultrastructural level. The primary site of damage was the tegument of the parasite. The morphological changes included contraction of the soma region, formation of blebs on the tegument, rostellar disorganization, loss of hooks and destruction of microtriches. The data reported in this article demonstrate a clear in vitro effect of FLBZ against E. granulosus protoscoleces.

The effects of flubendazole and mebendazole on cytochromes P4501A in pheasant hepatocytes

Many benzimidazoles are known inducers of cytochromes P4501A (CYP1A) in laboratory animals and cell lines. As flubendazole and mebendazole are benzimidazole anthelmintics often used in a pheasant, in the present study an effect of these drugs in primary cultures of pheasant (Phasianus colchicus) hepatocytes was investigated. After 48 h incubation of the hepatocytes with the benzimidazoles (0.2-5 microM), CYP1A activities -- ethoxyresorufin O-deethylation (EROD) and methoxyresorufin O-demethylation (MROD) activities were measured and the CYP1A protein levels were determined by Western blotting. None of the tested benzimidazoles influenced the CYP1A protein content. No pharmacologically significant enhancement of CYP1A after exposure of the hepatocytes to flubendazole and mebendazole was found. Inhibition of the EROD/MROD activities caused by both tested substances was observed only at the highest concentration (5 microM). From a point of view of CYP1A induction or inhibition, the treatment of pheasants by both anthelmintics tested seems to be safe. Our study demonstrates the inter-species differences in CYP1A inducibility and the importance of induction/inhibition studies on target animals.

Population-based case-control study of mebendazole in pregnant women for birth outcomes

The objectives of the study was to check the embryotoxic-teratogenic and fetotoxic effect of mebendazole (Vermox; Richter, Budapest, Hungary) treatment during pregnancy. Mebendazole use during pregnancy was evaluated in mothers of babies born with congenital abnormalities and in matched control mothers of babies born without congenital abnormalities in the population-based data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 1996. Of 22,843 women who had newborns or fetuses with congenital abnormalities, 14 were found to have been treated with mebendazole for intestinal nematoda infections/diseases during pregnancy (crude POR: 1.8 with 95% CI: 0.7-4.2). Of 38,151 women who had newborns without any defects (controls), the same number (14) were found to have been treated with mebendazole during pregnancy. Six different congenital abnormality groups were evaluated and a higher prevalence of mebendazole use in these mothers throughout pregnancy was not found. Gestational age and birth weight were analyzed in control infants born to mothers with or without mebendazole treatment. The mean gestational age was somewhat longer and mean birth weight was larger in newborn infants born to mothers with mebendazole treatment. Thus, treatment with mebendazole during pregnancy did not indicate a teratogenic and fetotoxic risk to the embryo or fetus, though the numbers of treated cases and controls in this study were limited.

Modulation of porcine biotransformation enzymes by anthelmintic therapy with fenbendazole and flubendazole

Fenbendazole (FEN) and flubendazole (FLU) are benzimidazole anthelmintics often used in pig management for the control of nematodoses. The in vivo study presented here was designed to test the influence of FLU and FEN on cytochrome P4501A and other cytochrome P450 (CYP) isoforms, UDP-glucuronosyl transferase and several carbonyl reducing enzymes. The results indicated that FEN (in a single therapeutic dose as well as in repeated therapeutic doses) caused significant induction of pig CYP1A, while FLU did not show an inductive effect towards this isoform. Some of the other hepatic and intestinal biotransformation enzymes that were assayed were moderately influenced by FEN or FLU. Strong CYP1A induction following FEN therapy in pigs may negatively affect the efficacy and pharmacokinetics of FEN itself or other simultaneously or consecutively administered drugs. From the perspective of biotransformation enzyme modulation, FLU would appear to be a more convenient anthelmintic therapy of pigs than FEN.

A comparative study of albendazole and mebendazole-induced, time-dependent oxidative stress

Albendazole (ABZ) and mebendazole (MBZ) are two benzimidazole-derived drugs that show remarkable antihelmintic activity and are widely used in the treatment and control of helminths. Some antihelmintic drugs seem to act through the deleterious generation of reactive oxygen and nitrogen species (ROS and RNS, respectively) to which helminths have no, or relatively low, antioxidant defences (AD), when compared to aerobic organisms. The main objective of the present study consisted of the evaluation of the effect of both drugs on the AD and on some oxidative stress indicators in the host liver. Adult, male, Wistar rats were treated with ABZ or MBZ at doses of 40 mg/kg for different periods of time (2, 4, 8 and 10 days). After treatment, the activities of superoxide dismutase, catalase, glutathione reductase, and glutathione S-transferase, as well as the concentrations of TBARS, reduced glutathione, oxidized glutathione and total glutathione, were evaluated in rat hepatocytes. The serum nitrogen monoxide, usually known as nitric oxide (NO) levels, was also measured. The results showed that both drugs provoked an oxidative stress condition, demonstrated through the elevation of TBARS contents and through the decrease of some AD. Moreover, ABZ showed to be a strong ROS and RNS generator while MBZ showed a low and transient effect on ROS generation. It is suggested that MBZ could be the first-choice drug in the treatment of helminthiasis because it shares a similar therapeutic indication with ABZ, and because it causes only a mild oxidative stress to the host.