Methylsulfonamide AMPA potentiator

Plain-language summaryIntrigue 42 / 100

Farampator (CX-691) is a methylsulfonamide AMPA potentiator. Phase 2 trials in cognitive impairment and depression showed modest signals. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Our opinion on this compoundNiche research probe

47/100

Phase 2 ampakine with an interesting rapid-antidepressant signal that ultimately fizzled out before delivering clear clinical proof

Look, farampator is one of those compounds where the mechanism story is genuinely compelling and the clinical history is genuinely disappointing. It’s a methylsulfonamide AMPA positive allosteric modulator from the Cortex Pharmaceuticals CX-series, licensed through Organon and Schering-Plough before Merck killed the program after acquisition. That corporate graveyard timeline tells you something before you even read the trial results.

The mechanism is the most interesting thing here. AMPA PAMs potentiate fast glutamatergic transmission, augmenting AMPA receptor-mediated currents without direct agonism, and the hypothesis connecting that to rapid antidepressant effects is actually well-reasoned. The dominant theory for ketamine’s rapid antidepressant action leans heavily on downstream AMPA receptor potentiation: NMDA blockade disinhibits AMPA throughput, which drives BDNF release and rapid synaptic strengthening. If thats the key step, then a direct AMPA PAM should shortcut the whole thing. Farampator reached Phase 2 in MDD and produced rapid antidepressant-like effects that reportedly resembled ketamine’s time course. That’s a real data point, and it’s not nothing.

What we don’t like is the overall trajectory. The CX-series ampakines have been promising rapid cognitive and mood tools since the late 1990s, and none of them delivered a clean clinical win. CX-516, the first-generation compound, was weaker. CX-717 was pushed through DARPA-funded sleep deprivation work and also didnt breakthrough. Farampator sits in the middle of that lineage, with intermediate pharmacokinetics and intermediate results. Mixed Phase 2 readouts across MDD, Alzheimer disease, and ADHD is a pattern, not a fluke. Merck walked away, and there’s been no serious revival since.

As a research tool, farampator has real utility specifically for investigators studying the AMPA-centered rapid antidepressant mechanism. If you’re trying to dissect whether AMPA potentiation per se drives the rapid mood effect, or whether you need the upstream NMDA block, farampator lets you probe that question in ways that most competitors don’t. It’s one of a small number of AMPA PAMs with actual Phase 2 human PK and PD data attached, which makes the compound more useful as a translational reference point than the purely preclinical alternatives.

Sourcing is limited and quality verification matters more here than for mainstream compounds. The literature is diffuse, the Phase 2 data hasn’t been fully published in accessible form, and bench investigators should account for that. We think the compound belongs in a serious nootropic or rapid antidepressant research program as a mechanistic probe, not as a lead compound. Interesting enough to have on the shelf; not interesting enough to center a research agenda on.

Novelty: 35
Mechanism promise: 62
In-category differentiation: 45
Evidence quality: 50
Translational signal: 42
Research bench value: 50

Rationale Farampator earns credit for genuine Phase 2 clinical exposure across three indications and for sitting at an intellectually interesting intersection of AMPA potentiation and rapid antidepressant pharmacology, but the development program was discontinued with mixed results, the ampakine class has accumulated two decades of mostly inconclusive clinical output, and the compound itself is not especially novel. Its main research value today is as a probe for the AMPA-mediated synaptic potentiation hypothesis of rapid antidepressant action.

Methylsulfonamide AMPA potentiator

An Organon/Schering-Plough ampakine (CX-691) that reached Phase 2 in major depressive disorder and Alzheimer disease.

Abstract

Farampator (CX-691, ORG-24448; CAS 211735-76-1; molecular formula C16H22N2O3S; molecular weight 322.42) is a methylsulfonamide-class AMPA receptor positive allosteric modulator developed by Cortex Pharmaceuticals and licensed to Organon (subsequently Schering-Plough, then Merck). The compound advanced through Phase 2 trials in major depressive disorder, Alzheimer disease, and adult ADHD with mixed results; the development program was discontinued after the Schering-Plough acquisition by Merck. Mechanism is AMPA receptor positive allosteric modulation with characteristics intermediate between the early CX-516 class and the later sustained-action ampakines. Pharmacokinetics: plasma half-life approximately 5 to 6 hours; oral bioavailability adequate. The compound is sold as a research chemical with limited availability. The clinical evidence base in depression specifically is interesting: rapid antidepressant-like effects analogous to those seen with ketamine were observed in Phase 2, suggesting the ampakine mechanism may share some clinical pharmacology with NMDA-blocking rapid antidepressants.

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The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, sourcing and quality verification, and a curated reference list. Embedded inline below; download for offline reading.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

Tag: Methylsulfonamide AMPA potentiator

Farampator (CX-691)

Abstract

Read the full monograph