KDC-MN-055 – Kodiac biolabs

Plain-language summaryIntrigue 42 / 100

CX-546 is a benzoxazine ampakine developed at Cortex as a successor to CX-516 with longer duration. Used in academic research as a higher-potency AMPA potentiator. 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 Kodiac editorial, not peer-reviewed.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

35/100

Second-gen ampakine with real AMPA kinetic advantages but no clinical translation and limited differentiation in a class that moved on

Look, CX-546 is a genuinely interesting pharmacological object from a chapter of neuropharmacology that deserved better. Cortex Pharmaceuticals spent real money on the ampakine program, and CX-546 was a legitimate iterative advance over CX-516: tighter binding kinetics, deeper AMPA potentiation per receptor event, longer-lasting effect. If you are running AMPA receptor biology in vitro or using rodent models to probe synaptic plasticity mechanisms, CX-546 is a functional tool, and thats worth acknowledging upfront.

Here’s the thing though: the compound belongs to a class defined by two recurring problems. First, the dose window between useful potentiation and convulsant territory is uncomfortably narrow across most ampakines, and CX-546 is no exception even if it showed some pharmacokinetic advantage over its predecessor. Second, and more decisively, the whole Cortex program hit a wall. CX-546 never advanced through pivotal human trials in any indication. The respiratory depression angle, which was the most genuinely promising preclinical story, opioid-reversal in rats being an intellectually compelling hypothesis, never became a human signal worth citing in the context of this compound specifically.

On mechanism, we’d give AMPA positive allosteric modulation more credit here if CX-546 specifically had generated better translational data. The mechanism sits in an important space: LTP, synaptic plasticity, cognitive processing, and potentially respiratory drive regulation. But the class has more capable members now. More modern AMPA PAMs from academic groups and later pharma programs have been characterized with better methodology and more rigorous preclinical packages than anything the Cortex series produced.

On differentiation, CX-546 improves on CX-516, but thats a low bar. Compounds like CX-717 went further into development before the program collapsed. Within the ampakine class CX-546 is neither the first word nor the last. It’s a middle entry in a program that ran out of runway.

The bench value is real but bounded. If your research specifically requires an AMPA PAM with CX-546’s kinetic profile and you have a reason to distinguish it from other available tools, it is accessible as a research chemical. Most investigators who need an AMPA PAM, though, have better-characterized options with cleaner sourcing and more published method validation behind them. Vendor quality and purity certification for Cortex-generation ampakines is genuinely inconsistent across the supply chain.

Honest assessment: CX-546 is worth knowing about if you’re digging into the ampakine literature or running AMPA receptor assays where its specific kinetic profile is the variable of interest. For most bench programs it’s a historical artifact of a failed development program. Failed clinical translation, thin and single-source human data, and a class that has moved past it all point toward the lower third of our scale.

Novelty: 33
Mechanism promise: 52
In-category differentiation: 33
Evidence quality: 28
Translational signal: 20
Research bench value: 45

Rationale CX-546 earns modest mechanism and bench-value credit as a functional AMPA PAM probe with improved kinetics over CX-516 and an intellectually interesting respiratory-depression angle, but the Cortex program ended without pivotal human data in any indication, translational signal is essentially zero, and more modern AMPA PAMs have since been characterized with better methodology. The score reflects a compound that is a usable tool in a narrow context but not a priority research target.

Benzoxazine ampakine

A second-generation Cortex Pharmaceuticals ampakine with improved AMPA receptor modulation kinetics and reduced respiratory depression liability.

Abstract

CX-546 (1-(1,4-benzodioxan-6-ylcarbonyl)piperidine; CAS 215923-54-9; molecular formula C14H17NO3; molecular weight 247.29) is a second-generation Cortex Pharmaceuticals ampakine in the benzoxazine subclass. The compound shows improved AMPA receptor modulation kinetics relative to CX-516, with deeper potentiation per binding event and longer-lasting effect. CX-546 was advanced through preclinical development for cognitive impairment and respiratory disorders (the AMPA potentiation can reverse opioid-induced respiratory depression in animal models). The compound did not advance through pivotal human trials in any indication. Pharmacokinetics: short plasma half-life (2 to 3 hours), oral bioavailability moderate. The compound is sold as a research chemical in jurisdictions where it is not scheduled. Research-grade vendor doses are typically 200 to 500 mg per administration in unvalidated human use, scaled from rodent doses.

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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: KDC-MN-055

CX-546

Abstract

Read the full monograph