Guvacine is an amino acid found in A. catechu (Betel nut).1 It competitively inhibits GABA uptake (IC50 = 10 μM; Ki = 14 μM) in rat hippocampal brain slices.1,2 In vivo, guvacine, at doses ranging from 50-100 mg/kg, decreases spontaneous activity in mice.1 Administration of guvacine also decreases tail flick reaction time in a rat model of morphine analgesia.3
1.Johnston, G.A., Krogsgaard-Larsen, P., and Stephanson, A.Betel nut constituents as inhibitors of γ-aminobutyric acid uptakeNature258(5536)627-628(1975) 2.Pavia, M.R., Lobbestael, S.J., Nugiel, D., et al.Structure-activity studies on benzhydrol-containing nipecotic acid and guvacine derivatives as potent, orally-active inhibitors of GABA uptakeJ. Med. Chem.35(22)4238-4248(1992) 3.Mantegazza, P., Tammiso, R., Vicentini, L., et al.Nipecotic acid and guvacine antagonism on morphine analgesia in ratsPharmacol. Res. Commun.11(8)657-662(1979)