Table 1.

IC₅₀ (μM) values for (2-oxaadamant-1-yl)amines as NMDA antagonists^a,b

Compound	Glutamate (100 μM)	NMDA (100 μM)
10b	223 ± 52	83 ± 6
10c	350 ± 108	226 ± 37
10d	>500	94 ± 13
11b	106 ± 10	55 ± 12
12	22 ± 7	14 ± 3
15	108 ± 17	32 ± 9
Amantadine	358 ± 130	92 ± 29
Memantine	55 ± 12	1.5 ± 0.1

^aFunctional data were obtained from primary cultures of cerebellar granule neurons using the method described in the experimental section by measuring the intracellular calcium concentration. Cells were challenged with glutamate (2nd column) or NMDA (3rd column) as indicated. Data shown are means ± SEM of at least three separate experiments carried out on three different batches of cultured cells.

^bCompounds 2a, 2b, 3a, 3b, 4, 7, 8, 9a, 10a, 11a, 13, and 14 were found to have low potency as glutamate (IC₅₀ > 500 μM) and NMDA receptor antagonists (IC₅₀ > 200 μM). Hydrazines 9b and 9c were not evaluated.