Clinical data
Routes of
ATC code
  • none
Legal status
Legal status
  • In general: uncontrolled
  • Ethyl 1-ethyl-4-[2-(propan-2-ylidene)hydrazinyl]-1H-pyrazolo[3,4-b]pyridine-5-carboxylate
CAS Number
PubChem CID
CompTox Dashboard (EPA)
Chemical and physical data
Molar mass289.339 g·mol−1
3D model (JSmol)
  • CCN1C2=NC=C(C(=C2C=N1)NN=C(C)C)C(=O)OCC

Etazolate (SQ-20,009, EHT-0202) is an anxiolytic drug which is a pyrazolopyridine derivative and has unique pharmacological properties.[1][2][3] It acts as a positive allosteric modulator of the GABAA receptor at the barbiturate binding site,[4][5][6][7] as an adenosine antagonist of the A1 and A2 subtypes,[8] and as a phosphodiesterase inhibitor selective for the PDE4 isoform.[9][10][11] It is currently in clinical trials for the treatment of Alzheimer's disease.[12]


Cartazolate and Etazolate synthesis[13]
Cartazolate and Etazolate synthesis[13]

See also


  1. ^ Hall, Judith A.; Morton, Ian (1999). Concise dictionary of pharmacological agents: properties and synonyms. Kluwer Academic. ISBN 0-7514-0499-3.
  2. ^ Williams M (May 1983). "Anxioselective anxiolytics". Journal of Medicinal Chemistry. 26 (5): 619–28. doi:10.1021/jm00359a001. PMID 6132997.
  3. ^ Williams M, Risley EA (February 1979). "Enhancement of the binding of 3H-diazepam to rat brain membranes in vitro by SQ 20009, A novel anxiolytic, gamma-aminobutyric acid (GABA) and muscimol". Life Sciences. 24 (9): 833–41. doi:10.1016/0024-3205(79)90367-9. PMID 449623.
  4. ^ Zezula J, Slany A, Sieghart W (April 1996). "Interaction of allosteric ligands with GABAA receptors containing one, two, or three different subunits". European Journal of Pharmacology. 301 (1–3): 207–14. doi:10.1016/0014-2999(96)00066-0. PMID 8773466.
  5. ^ Remington, Gary; Baskys, Andrius (1996). Brain mechanisms and psychotropic drugs. Boca Raton: CRC Press. ISBN 0-8493-8386-2.
  6. ^ M. Mishina; Kurachi, Yoshihisa (2000). Pharmacology of ionic channel function: activators and inhibitors. Berlin: Springer. ISBN 3-540-66127-1.
  7. ^ Progress in Drug Research / Volume 31 (Progress in Drug Research). Boston: Birkhauser. 1987. p. 526. ISBN 3-7643-1837-6.
  8. ^ Williams M, Jarvis MF (February 1988). "Adenosine antagonists as potential therapeutic agents". Pharmacology Biochemistry and Behavior. 29 (2): 433–41. doi:10.1016/0091-3057(88)90182-7. PMID 3283781. S2CID 35635747.
  9. ^ Chasin M, Harris DN, Phillips MB, Hess SM (September 1972). "1-Ethyl-4-(isopropylidenehydrazino)-1H-pyrazolo-(3,4-b)-pyridine-5-carboxylic acid, ethyl ester, hydrochloride (SQ 20009)--a potent new inhibitor of cyclic 3',5'-nucleotide phosphodiesterases". Biochemical Pharmacology. 21 (18): 2443–50. doi:10.1016/0006-2952(72)90414-5. PMID 4345859.
  10. ^ Wang P, Myers JG, Wu P, Cheewatrakoolpong B, Egan RW, Billah MM (May 1997). "Expression, purification, and characterization of human cAMP-specific phosphodiesterase (PDE4) subtypes A, B, C, and D". Biochemical and Biophysical Research Communications. 234 (2): 320–4. doi:10.1006/bbrc.1997.6636. PMID 9177268.
  11. ^ Gresele, Paolo; Gresele, P. (2002). Platelets in thrombotic and non-thrombotic disorders: pathophysiology, pharmacology and therapeutics. Cambridge, UK: Cambridge University Press. ISBN 0-521-80261-X.
  12. ^ "Pipeline | ExonHit". Archived from the original on 2011-01-11.
  13. ^ DE 2123318, Hoehn, Hans & Denzel, Theodor, "Aminoderivate von Pyrazopyridincarbonsäuren, deren Estern und Salzen, Verfahren zu ihrer Herstellung und ihre Verwendung [Amino derivatives of pyrazolopyridinecarboxylic acids, their esters and salts, processes for their preparation and their use]", published 1971-12-09, assigned to E.R. Squibb & Sons Inc.