Istradefylline

AR

384, 43

Common marmosets (Callithrix jacchus) with MPTP treatment

10 mg/kg

2.2 nM (Ki) [1], 2.2 nM (Ki) [1], 2.2 nM (Ki) [1], 2.2 nM (Ki) [1], 2.2 nM (Ki) [1], 2.2 nM (Ki) [1]

Istradefylline reverses CGS21680-induced and reserpine-induced catalepsy with ED50 of 0.05 mg/kg and 0.26 mg/kg, respectively. Istradefylline is over 10 times as potent in these models compared to other adenosine antagonists and dopamine agonist drugs. Administration of Istradefylline in combination with L-dopa (50 mg/kg) exerts prominent effects on haloperidol-induced and reserpine-induced catalepsy. [2] Oral administration of Istradefylline at 10 mg/kg to MPTP-treated common marmosets produces an increase in locomotor activity to approximately twice that of control and improves motor disability. Administration of Istradefylline (10 mg/kg, po, 90 minutes before SKF80723/quinpirole/L-DOPA) in combination with SKF80723 (1 mg/kg, ip), quinpirole (0.06 mg/kg ip), or L-DOPA (2.5 mg/kg po) produces a significant additive effect on locomotor activity and improvement of motor disability but not dyskinesia. [3] In the MPTP mice model, Istradefylline significantly attenuates striatal dopamine depletion under various conditions. Pretreatment with Istradefylline (3.3 mg/kg, i.p.) before a single dose of MPTP attenuates the partial dopamine and DOPAC depletions measured in striata 1 week later. [1] Oral administration of Istradefylline protects against the loss of nigral dopaminergic neuronal cells induced by 6-hydroxydopamine in rats, and prevents the functional loss of dopaminergic nerve terminals in the striatum and the ensuing gliosis caused by MPTP in mice. [4] Chronic Istradefylline treatment does not improve the reversal deficits in dopamine-depleted rats. [7] The tremulous jaw movements induced by pimozide are significantly reduced by co-administration of either Istradefylline or tropicamide. Pimozide-induced increases in ventrolateral striatal c-Fos expression are reduced by a behaviorally effective dose of Istradefylline, in contrast to tropicamide by which c-Fos expression in pimozide-treated rats is actually increased. [8]

Istradefylline (KW-6002) is a selective adenosine A2A receptor (A2AR) antagonist with Ki of 2.2 nM. Phase 3.