Mebendazole
Benzimidazole derivatives · given by oral · on the market since 1995
What it's made of
Each functional group on the molecule does a specific, predictable job.
Ester
What it does. Blood and tissue enzymes cut this bond within minutes. Whatever was attached falls off.
What it opens up. Deliberate short action, or a delivery trick — attach an ester to sneak a molecule somewhere, then let the body cut it loose at the destination.
Carbamate
What it does. Cut far more slowly than an ester. When it sits on the right enzyme it jams it for hours rather than seconds.
What it opens up. Long-lasting enzyme blockade — the basis of several nerve and muscle drugs.
Imidazole ring
What it does. Slots directly onto the iron atom at the centre of haem-containing enzymes. That includes the fungal enzyme that builds cell membranes — and also the human liver's main drug-processing enzymes, which is why these compounds interfere with so many other medicines.
What it opens up. Any haem enzyme. The same ring that kills fungi also blocks human steroid synthesis, which is how an antifungal ended up used against hormone-driven disease.
Where it can get to
Predicted from molecular weight, lipophilicity, polar surface area and hydrogen-bond donor count. A drug can only act where it distributes, so this constrains which conditions are addressable before any biology is considered. derived
What it binds — and whether we can reach it
Binding affinity is only meaningful against the plasma concentration reached at the approved dose. A target requiring higher concentrations cannot be engaged in a patient, whatever the in vitro potency. Most repurposing hypotheses fail at this step, and it is rarely checked before a trial is proposed. measured
| Target | Kind | Action | Affinity (pAct) | Can it be engaged? |
|---|---|---|---|---|
| KDR | Kinase | — | 5.44 | Out of reach |
| ABL1 | Kinase | — | 5.34 | Out of reach |
This molecule concentrates in urine. Local concentration therefore exceeds plasma, so targets that look unreachable on a plasma reading may still be engaged. assumed
New uses, and who is already trying them
One card per candidate indication: the reasoning link by link, the evidence tier that governs how strongly it can be stated, and any registered trials.
5 of the 94 conditions linked to this drug’s targets have been checked against trial records so far. The rest are not ruled out — they are unchecked.
chronic myelogenous leukemia, BCR-ABL1 positive
Wide openIt acts on a target linked to this disease; untested, and the direction of effect is unverified.
acute lymphoblastic leukemia
Wide openIt acts on a target linked to this disease; untested, and the direction of effect is unverified.
neoplasm
Tried in peopleIt showed an effect in a human trial that was not followed up.
hepatocellular carcinoma
Animal models onlyIt reduces disease in animal models; untested in humans.
gastrointestinal stromal tumor
Wide openIt acts on a target linked to this disease; untested, and the direction of effect is unverified.
Why nobody will fund it
Only one company makes this. With that many manufacturers the price has fallen to production cost. A company funding a trial could not recover it — competitors could market the same molecule for the new indication immediately, without contributing.
A new route or dosage form qualifies for a 505(b)(2) application, which carries three years of exclusivity for that formulation. It is the only remaining route to exclusivity on a generic molecule.
What it would cost to find out
Derived, not quoted. Events needed is 4(zα+zβ)²/ln(HR)²; enrolment is that divided by the event rate and follow-up. The 1/ln(HR)² term dominates: halving the detectable effect size roughly quadruples enrolment. derived
Cost per person reached is the relevant metric for a non-commercial funder, since there is no revenue to set against the outlay.
Ask for ideas nobody has listed
Reasons from the functional groups and distribution above, excluding conditions already listed. Output is hypotheses for falsification, not findings. Not medical advice.
Who might pay for the trial
Trials of off-patent drugs are rarely funded by venture capital or pharma. They are paid for by government grants and disease foundations. Here is who has funded work on this molecule before, what federal mechanisms are open now, and which foundations fund trials in the disease areas it touches. measured
Open notices with an explicit mandate to fund work on approved or off-patent molecules.
Grants.gov lists US federal money. Many off-patent drug trials are supported by disease foundations and nonprofits. These are matched to the body systems this drug touches. assumed
Who manufactures it
Companies holding an approved abbreviated application for this molecule in the United States, from the FDA Orange Book. Supply already exists at scale, so a trial would not need a manufacturing programme — but any of these could also be a partner, or an objector.
Nothing on this page is medical advice. Candidate uses are unproven hypotheses derived from public data; established uses are listed for verification only. Figures carry their provenance inline — anything marked assumed or derived is not a measurement.
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