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Cycloserine

Antibiotics · given by oral

5
Leads
24.4M
People
1
Makers
0
How abandoned
01

What it's made of

Each functional group on the molecule does a specific, predictable job.

No standard functional groups matched.

02

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

Easily
Systemic circulation
Absorbed from the gut and distributed in plasma.
Partly
Central nervous system
Crosses the blood–brain barrier.
No
Intestinal lumen only
Poorly absorbed. Acts locally in the gut with minimal systemic exposure.
Partly
Skin
Crosses the stratum corneum. Viable as a topical.
Easily
Urinary tract
Cleared unchanged in urine. Local concentration exceeds plasma.
03

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

Values are pAct — the negative logarithm of the molar concentration at which the drug half-occupies the target. Each whole step is a tenfold difference in potency: 9.0 = 1 nanomolar, 6.0 = 1 micromolar, 5.0 = 10 micromolar. Oral drugs typically reach 0.1–10 micromolar in plasma, so roughly 6.0 is the threshold below which a target cannot be reached at a tolerated dose. Figures come from DrugCentral’s curated binding data.
GRIN2A
Ion channel ·
5.64
Out of reach
GRIN2B
Ion channel ·
5.64
Out of reach
GRIN2D
Ion channel ·
5.64
Out of reach
GRIN3A
Ion channel ·
5.64
Out of reach
GRIN3B
Ion channel ·
5.64
Out of reach
GRIN2C
Ion channel ·
5.34
Out of reach
GRIN1
Ion channel ·
5.26
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

04

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 65 conditions linked to this drug’s targets have been checked against trial records so far. The rest are not ruled out — they are unchecked.

Not yet used for these — 5

neurodevelopmental disorder with or without hyperkin

Wide open

It acts on a target linked to this disease; untested, and the direction of effect is unverified.

The condition
Any autosomal dominant non-syndromic intellectual disability in which the cause of the disease is a mutation in the GRIN1 gene.
GRIN1 · glutamate ionotropic receptor NMDA type subunit 1
Component of N-methyl-D-aspartate (NMDA) receptors (NMDARs) that function as heterotetrameric, ligand-gated cation channels with high calcium permeability and voltage-dependent block by Mg(2+) (PubMed:21376300, PubMed:26875626, PubMed:26919761, PubMed:28126851, PubMed:28228639, PubMed:36959261, PubMed:7679115, PubMed:7681588, PubMed:7685113). NMDARs participate in synaptic plasticity for learning and memory formation by contributing to the long-term potentiation (LTP) (PubMed:26875626). Channel activation requires
Nobody has tried this
No registered trial of this drug in this condition.
What would kill it. A null trial, or pharmacokinetic data showing the drug does not reach GRIN1 in the relevant tissue at tolerated doses.

Landau-Kleffner syndrome

Wide open

It acts on a target linked to this disease; untested, and the direction of effect is unverified.

The condition
A rare form of epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS) characterized by various combinations of acquired cognitive, language, behavioral, and motor deficits associated with marked spike- and- wave activation in sleep. In Landau-Kleffner syndrome, receptive language is mainly affected, with an acquired auditory verbal agnosia.
GRIN2A
No function on file.
Nobody has tried this
No registered trial of this drug in this condition.
What would kill it. A null trial, or pharmacokinetic data showing the drug does not reach GRIN2A in the relevant tissue at tolerated doses.

intellectual disability, autosomal dominant 6

Wide open

It acts on a target linked to this disease; untested, and the direction of effect is unverified.

The condition
Any autosomal dominant non-syndromic intellectual disability in which the cause of the disease is a mutation in the GRIN2B gene.
GRIN2B
No function on file.
Nobody has tried this
No registered trial of this drug in this condition.
What would kill it. A null trial, or pharmacokinetic data showing the drug does not reach GRIN2B in the relevant tissue at tolerated doses.

developmental and epileptic encephalopathy, 46

Wide open

It acts on a target linked to this disease; untested, and the direction of effect is unverified.

The condition
Any early infantile epileptic encephalopathy in which the cause of the disease is a mutation in the GRIN2D gene.
GRIN2D · glutamate ionotropic receptor NMDA type subunit 2D
Component of N-methyl-D-aspartate (NMDA) receptors (NMDARs) that function as heterotetrameric, ligand-gated cation channels with high calcium permeability and voltage-dependent block by Mg(2+) (PubMed:26875626, PubMed:27616483, PubMed:28126851, PubMed:9489750). Participates in synaptic plasticity for learning and memory formation (By similarity). Channel activation requires binding of the neurotransmitter L-glutamate to the GluN2 subunit, glycine or D-serine binding to the GluN1 subunit, plus membrane depolarizatio
Nobody has tried this
No registered trial of this drug in this condition.
What would kill it. A null trial, or pharmacokinetic data showing the drug does not reach GRIN2D in the relevant tissue at tolerated doses.

developmental and epileptic encephalopathy, 27

Wide open

It acts on a target linked to this disease; untested, and the direction of effect is unverified.

The condition
Any early infantile epileptic encephalopathy in which the cause of the disease is a mutation in the GRIN2B gene.
GRIN2B
No function on file.
Nobody has tried this
No registered trial of this drug in this condition.
What would kill it. A null trial, or pharmacokinetic data showing the drug does not reach GRIN2B in the relevant tissue at tolerated doses.
05

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.

How abandoned it is0 / 100
0 to 100, calculated from manufacturer count, remaining patent or exclusivity, and whether any reformulation route to exclusivity is still open. 100 means no route to commercial return exists. The weights behind it are unsourced.
THE ONE WAY A COMPANY COULD STILL OWN IT
topicalinjectableinhaledmodified-release

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.

06

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

0.75
Lower = bigger effect = smaller trial
8.0%
2 yr
$32K
Unsourced placeholder
379
Events needed
3K
Patients
$93M
Trial cost
assumed
$10.85
Per person reached
assumed

Cost per person reached is the relevant metric for a non-commercial funder, since there is no revenue to set against the outlay.

07

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.

08

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

Federal grants that name this medicine
389 grants on NIH RePORTER
5R01AI168371-04(NIAID · National Institute of Allergy & Infectious Diseases)Active
$358K (2026)
Baseline pRescription According to Direct from Sputum Sequencing and TArgeted drug Concentration Strategy (BRASS TACS)
PI: Tornheim, Jeffrey · Johns Hopkins University, Baltimore, MD · through 2028-03
3R01AI168371-04S1(NIAID · National Institute of Allergy & Infectious Diseases)Active
$292K (2026)
Baseline pRescription According to Direct from Sputum Sequencing and TArgeted drug Concentration Strategy (BRASS TACS)
PI: Tornheim, Jeffrey · Johns Hopkins University, Baltimore, MD · through 2028-03
5R21AI182745-02(NIAID · National Institute of Allergy & Infectious Diseases)Active
$246K (2025)
Investigating ploidy modulation as a strategy to improve antibiotic activity
PI: Brynildsen, Mark P · Princeton University, Princeton, NJ · through 2026-08
Open federal programmes that would fund this work

Open notices with an explicit mandate to fund work on approved or off-patent molecules.

RFA-CA-25-033National Institutes of HealthForecast — not open yet
Glioblastoma Therapeutics Network (GTN; U19 Clinical Trial Required)
RFA-FD-25-020Food and Drug Administrationcloses 05/16/2028
Reissue of RFA-FD-23-001- Clinical Studies of Orphan Products Addressing Unmet
FOR-FD-25-020Food and Drug AdministrationForecast — not open yet
Clinical Studies of Orphan Products Addressing Unmet Needs of Rare Diseases (R
FOR-FD-25-001Food and Drug AdministrationForecast — not open yet
Clinical Trials Addressing Unmet Needs of Rare Neurodegenerative Diseases (R01
RFA-TR-25-002National Institutes of Healthcloses 07/02/2027
Preclinical Proof of Concept Studies for Rare Diseases (R21 Clinical Trial Not
PAR-25-374National Institutes of Healthcloses 05/07/2028
Translational Bioinformatics and Experimental Approaches to Advance Drug Repos
HT942526PRCRPCTADefense Health Agency Contracting Activity -closes 10/05/2026
DoW Peer Reviewed Cancer, Clinical Trial Award
PAR-26-049National Institutes of HealthForecast — not open yet
Establishing Pediatric CNS Pharmacodynamic Measures as Tools to Enable Psychia
Showing 8 of 990 currently open under this category on Grants.gov, matched to the disease areas this drug touches. derived Browse all 990 on Grants.gov ↗
Funders beyond the federal system

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

Matched by disease area, not by molecule — a foundation appearing here funds work in a field this drug touches.
09

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.

Sanaluz Llc
1
Manufacturers
companies with their own approval
1
Approved products
distinct strengths and forms
1
Routes
oral
Oldest product still sold
approval year of the earliest product still on the market
ALSO SOLD AS
SEROMYCIN

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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