This is a study on the effectiveness of inserting Medincell's gadget that secretes ivermectin, on 10 cows for the prevention of Onchocerca ochengi, a parasite closely related to the worm that causes river blindness.

Only one ivermectin-treated animal (belonging to group A) had skin mf (microfilaria, the larval form) 12 months after treatment (0.9 mf/g). At 24 months, another animal in group A showed skin mf (10.0 mf/g).

The study is relevant to this sub because Medincell has Gates Foundation money for them to theoretically adapt this technology for injecting ivermectin into people, hoping that will prevent catching covid-19. Theoretically Medincell is going to do a trial to see if prophylaxis happens, i.e. do people with the device catch the virus less or not at all. I emphasize theoretically because I've been following Medincell since early April, and so far there's no sign that they are actually doing anything, esp. there's no evidence that they have started this trial. Maybe they are being coy. :(

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Looking at this study again, I picked out some interesting facts:

As the plasma half-life of IVM in man ranges between 12 h and 56 h following oral administration, we hypothesized that longer and continuous exposure of the parasite to the drug could have a stronger macrofilaricidal effect. Presently, several commercial long-acting formulations of IVM exist, one of the best known being the subcutaneous injectable formulation Ivomec® Gold for cattle

1) I'm really surprised by the half-life data. I've "known" the half-life of ivermectin is 18 hours for a long time. Wrong, apparently: this says it ranges between 12 and 56 hours!

Source: our old friend Safety, tolerability, and pharmacokinetics of escalating high doses of ivermectin in healthy adult subjects! TLATODO: Get the full PDF

2) There are long-acting formulations of ivermectin! Sounds like the perfect thing for prophylaxis? Cattle only, of course, and no one will pay the $$$ to put it through the FDA process to get approval for humans. :(

I can't find Ivomec® Gold for cattle with Google.

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A human trial of this tech began on 2020-09-29.

Abstract
The availability of a safe macrofilaricidal drug would help to accelerate onchocerciasis elimination. A trial was conducted in Cameroon to evaluate the effects of a subcutaneous injectable long-acting formulation of ivermectin (LAFI) on the microfilariae (mf) and adult stages of Onchocerca ochengi. Ten zebu cattle naturally infected with the parasite were injected subcutaneously with either 500 mg (group A, N = 4), or 1000 mg long-acting ivermectin (group B, N = 4) or the vehicle (group C, N = 2). Skin samples were collected from each animal before, and 6, 12, and 24 months after treatment to after treatment to measure microfilarial densities (MFDs). Nodules excised before, and 6 and 12 months after treatment were examined histologically to assess the adult worms’ viability and reproductive status. Blood samples were collected at pre-determined time-points to obtain pharmacokinetic data. Before treatment, the average O. ochengi MFDs were similar in the three groups. Six months after treatment, all animals in groups A and B were free of skin mf, whereas those in group C still showed high MFDs (mean = 324.5 mf/g). Only one ivermectin-treated animal (belonging to group A) had skin mf 12 months after treatment (0.9 mf/g). At 24 months, another animal in group A showed skin mf (10.0 mf/g). The histologic examination of nodules at 6 and 12 months showed that LAFI was not macrofilaricidal but had a strong effect on embryogenesis. The new LAFI regimen might be an additional tool to accelerate the elimination of human onchocerciasis in specific settings.

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