Friday, March 17, 2017


Mebendazole is a medicine used to treat pinworms in humans.

The price-per-dose was recently increased from $2 a dose to $600 a dose.  Typically, two doses are used to treat pinworms (up to twelve doses for other, less common types of worms) and everybody who was in contact with the patient should also treated.

That is a big deal because folks often get pinworms when they have a family reunion and bunk out three to a mattress or 24 sleeping bags in the living room.  One of the folks is an asymptomatic carrier.  All the folks at the reunion should be treated.  That is a bunch of $600 pills.

Merck Vet Manual
It would not be a big deal if you were a hog or a dog or a horse.

According to the Merck Vet Manual, Mebendazole belongs to a class of drugs that function by decomposing into the same active agent.  This is what Merck says about benzimidazole:

They are characterized by a broad spectrum of activity against roundworms (nematodes), an ovicidal effect, and a wide safety margin. Those of interest are mebendazole, flubendazole, fenbendazole, oxfendazole, oxibendazole, albendazole, albendazole sulfoxide, thiabendazole, thiophanate, febantel, netobimin, and triclabendazole.
And from

The molecular mode of action of all benzimidazoles, including mebendazole, consists in binding to tubulin, a structural protein of microtubules. These microtubules are important organelles involved in the motility, the division and the secretion processes of cells in all living organisms. In the worms the blocking of microtubules perturbs the uptake of glucose, which eventually empties the glycogen reserves. This blocks the whole energy management mechanism of the worms that are paralyzed and die or are expelled.
Since cell division is also disturbed, worm egg production and development is also blocked by benzimidazoles, i.e. most of them also have an ovicidal effect.

 So how much would it cost to treat 24 people with Vet grade benzimidazoles?

5443 mg of Oxibendazole can be purchased for $6.99.  Since the molecular mass of Oxibendazole is 18% lighter than Mebendazole, that is enough active ingredient for 65 doses the equivalent of 100mg of Mebendazole....assuming that Oxibendazole was approved for use in Humans (it is not).

2500 mg of Fenbendazole can be purchased for $8.99.  That is enough for 25 doses....assuming that Fenbendazole was approved for use in Humans (it is not).

Good article here on parasites

Regarding benzimidazole therapeutic margin:  Horses and dogs have similar metabolisms to humans.  Horses are typically dosed at ten times the rate that humans would be dosed.  The therapeutic margin for horses (at the 10X rate) is ten.  That is, for most non-pregnant adult horses, the owner would have to dose them with 100mg/kg of body weight before common "overdosing" symptoms would be observable.

So would I...
Take a "vet" product if I were twenty days hard paddling from civilization and had symptoms of a severe worm infection (anemia, weakness, worm pieces in my poop)?  Yes I would.  In fact, I would take four doses.  Day One a quarter dose.  Day Two a half dose (to verify lack of reaction).  Days Three and Four full human doses on a mg/kg basis.

Would I give it to my kids here in Eaton Rapids?  Probably not.  Mrs ERJ might take a dim view of that.

1 comment:

  1. Yep, there ARE things out there that will get the job done. And agree with your approach!