RESEARCH MONOGRAPH · KDC-MN-059

PEPA

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

47/100

Underrated sulfonamide AMPA potentiator with interesting allosteric site selectivity

PEPA (4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluorophenoxyacetamide) is the AMPA potentiator that nobody talks about and probably should. The Sekiguchi group at Kyoto worked it out in the late 90s, and the receptor pharmacology is genuinely distinct from the CX-series compounds. Unlike most ampakines which act at the cyclothiazide-binding site, PEPA appears to bind at an allosteric site with different subunit selectivity, preferentially potentiating GluR3 and GluR4 over GluR1 and GluR2.

This subunit selectivity is potentially important. The CX-series ampakines hit AMPA receptors broadly, which is fine for some questions but limiting for others. If you want to ask what specifically GluR3/GluR4-containing receptors contribute to a behavioral or cellular response, PEPA is one of the few tools that can address it. The flop/flip splice variant selectivity is also distinct, with PEPA showing strong preference for the flip variants.

The behavioral and synaptic pharmacology has been worked out in a handful of papers (Sekiguchi, Yamashita, Partin and colleagues), and the LTP enhancement profile is real if more limited in magnitude than some of the CX compounds. Whether the subunit selectivity matters in behavioral assays at the whole-animal level is still debated.

What we like: receptor subtype selectivity is genuinely useful for medicinal chemistry and receptor pharmacology work, the molecule fills an experimental niche that the CX compounds dont, and the published electrophysiology is detailed enough that you can plan experiments confidently.

What we dont like: behavioral pharmacology literature is thin, the molecule never advanced to clinical development, and the published synthesis is more complex than for some of the simpler ampakines. The sulfonamide chemistry is also stable but slightly demanding to handle.

Sourcing is genuinely poor. Few suppliers produce PEPA at meaningful purity, characterization quality varies, and reference standards are hard to find. HPLC and ideally NMR verification are necessary because the published synthesis allows several impurity routes that affect biology.

For research, PEPA is the tool you reach for if AMPA subunit selectivity matters to your question. For broader AMPA-PAM behavioral work, the CX compounds are more practical. Useful in a narrow but real niche.

Evidence: 30
Mechanism: 70
Reliability: 55
Safety: 50
Sourcing: 40
Value: 40
Signal: 45
Staying power: 45

Plain-language summary Intrigue 32 / 100

PEPA is a sulfonamide AMPA potentiator developed in Japan. Used as a research probe for AMPA receptor pharmacology. 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.

Sulfonamide AMPA potentiator

A potent benzothiazide AMPA potentiator used principally as a research probe for AMPA receptor pharmacology.

Abstract

PEPA (4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetamide; CAS 158235-23-7) is a potent sulfonamide-class AMPA receptor positive allosteric modulator developed as a research tool compound. The compound shows substantially greater AMPA potentiation per molecule than the marketed and Phase 2 ampakines, but with poor pharmacokinetic properties (low oral bioavailability, short plasma half-life) that limit clinical translation. PEPA is used principally as a research probe for AMPA receptor pharmacology in vitro and ex vivo. The compound has not been advanced to human clinical trials and has no significant research-chemical-grade availability outside academic research supply chains.

Mechanism of action

Potent AMPA potentiator (sulfonamide class). Research tool compound.

Reported research dose ranges

No established research dose range; in vitro and ex vivo research tool compound only.

References

Sekiguchi M, et al. A novel compound, 4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetamide, selectively augments AMPA receptor function. Br J Pharmacol 1998.

Read the full monograph

The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, reported research dose ranges, sourcing and quality verification, reconstitution and handling, stack interaction considerations, and a curated reference list. Available as a research-use-only PDF download.

KDC-MN-059

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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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.

Kodiac sells research compounds for investigative use only.

PEPA

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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