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  Discussion on Netobimin
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Member:
leilani

Posted on Saturday, Jan 3, 2009 - 8:37 pm:

Hi Dr O,

I read this article today in the Horse.com. Any thoughts? Leilani

Study: Netobimin Might Be an Effective Equine Anthelmintic
by: Stacey Oke, DVM, MSc
January 03 2009, Article # 13372
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As previously reported on TheHorse.com, common equine internal parasites such as roundworms and strong strongyles are developing resistance against most of the commercially available deworming products. To compound the problem, no new deworming products are likely to become available in the near future.

With no knight in shining armor coming to the rescue, the equine industry must seek alternate strategies to manage internal parasites in horses, such as re-evaluating existing dewormers.

Now, a Turkish research group from the Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine at Adnan Menderes University has done just this.

Netobimin is a pro-drug form of albendazole, which is in the same drug class as fenbendazole. Netobimin is currently used in ruminants, but has not yet been evaluated in horses.

In the study, "Pharmacological assessment of netobimin as a potential anthelmintic for use in horses: Plasma disposition, faecal excretion and efficacy," the researchers found that netobimin was metabolized to various compounds, including albendazole, and effectively reduced fecal strongyle egg counts by 100%, 100%, 77%, 80%, and 75% at weeks 2, 4, 6, 8, and 10 post-treatment, respectively.

Based on these positive results, the authors suggest that, "netobimin could be effective as an anthelminitic in horses." More research to establish safety and tolerance of netobimin are needed.

This study is scheduled to be published in the journal Research in Veterinary Science. The abstract is currently available on PubMed.
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Member:
leilani

Posted on Saturday, Jan 3, 2009 - 8:39 pm:

Don't know why it printed underscored.
Moderator:
DrO

Posted on Sunday, Jan 4, 2009 - 9:34 am:

Hello Leilani,
Netobimin is a drug developed by Schering in the 80's that is seeing a resurgence in interest with the developing avermectin problems but I have little hope this is going to help us with our current problem due to the results of experiments carried out in the 80's and 90's.

Netobimin has been strongly associated with abortion and tetratogenic effects in several experiments. But more important is the nature of this drug as described in the article on TheHorse. Netobimin is a "benzimadazole prodrug" who's efficacy is in part due to the conversion to albendazole in the gi tract. Though it seems somewhat more effective than the benzimadazole itself the problem is that experiments have shown that there is already cross resistance to this drug when used on known benzimadazole resistant parasites in sheep:

Vet Q. 1990 Oct;12(4):241-6.
The efficacy of netobimin against a benzimidazole susceptible and a resistant strain of Haemonchus contortus in sheep in The Netherlands.
Borgsteede FH, Stallinga AP.
Central Veterinary Institute, Department of Parasitology, LeIystad, The Netherlands.

Netobimin was tested for efficacy against Haemonchus contortus using 7 groups of 5 parasite-free lambs of six months age. The lambs in group 1 and 2 were infected with 10,000 larvae of a benzimidazole susceptible strain and those in groups 3-7 with the same dose of a resistant strain. The following treatment scheme was applied 21 days after infection: lambs in groups 2 and 4-7.5 mg kg-1 netobimin, in group 5-20 mg kg-1 netobimin, in group 6-5 mg kg-1 oxfendazole and in group 7--3.8 mg kg-1 albendazole. The lambs in groups 1 and 3 remained untreated. All lambs were slaughtered 28 days after infection. Egg counts decreased in all lambs after treatment, but increased again in lambs in groups 4, 6 and 7. There was a slight increase in lambs in group 5, while those in group 2 remained negative. Post-mortem worm counts showed a reduction of 99.8 per cent in lambs in group 2 compared to those in group 1. In lambs in group 4-7 the reduction of worm counts was respectively 40.9, 89.5, 24.7 and 40.7 per cent compared to those in group 3. Egg development assays carried out 20 days after infection showed an average LD50 of 0.46 mg ml-1 thiabendazole for the resistant strain. After treatment (day 27) the LD50 was 0.53, 0.48, 0.58, 0.56 and 0.47 in lambs in the groups 3-7. It is concluded that netobimin and other (pro)-benzimidazoles should not be used in cases of benzimidazole resistance and that levamisole, pyrantel tartrate or ivermectin are preferable.

If this cross resistance proves not to be true in the horse then there may be hope but as the article states "Based on these positive results, the authors suggest that, "netobimin could be effective as an anthelminitic in horses." More research to establish safety and tolerance of netobimin are needed. ". I would add efficacy against our already benzimadazole resistant population of parasites needs exploration.
DrO
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