PD-102807 is a selective and competitive M4 muscarinic receptor antagonist (IC50 = 90.7 nM), with IC50 values of 950–7412 nM for M1, M2, M3, and M5 receptors, and can be used for Parkinson's disease research, as well as to inhibit airway smooth muscle (ASM) contraction.

Methods:
To evaluate the antagonistic selectivity of PD-102807 toward different subtypes of muscarinic receptors, [^35S]-GTPγS binding assays were performed to measure its inhibitory effect on agonist-induced G protein activation at M1, M2, M3, and M4 receptors. The pK_B values for each receptor subtype were determined to assess its antagonistic potency and selectivity.[1]
Results:
PD-102807 significantly inhibited M4 receptor-mediated G protein activation, with a pK_B value of 7.40, which was substantially higher than its potency at M1 (5.60), M2 (5.88), and M3 (6.39) receptors, indicating strong selectivity for the M4 receptor.

Methods:
To evaluate the effects of PD-102807 on L-DOPA-induced abnormal involuntary movements (AIMs) and neurotransmitter release, male Sprague-Dawley rats were used. A 3 μM concentration of PD-102807 was perfused starting 40 minutes before administration of L-DOPA and benserazide, and microdialysis was used to measure GABA and glutamate (Glu) levels in the substantia nigra pars reticulata (SNr) and striatum.[2]
Results:
PD-102807 significantly inhibited the L-DOPA-induced increases in GABA and Glu levels in the SNr and striatum, and reduced the axial-limb-orolingual (ALO) AIMs score from 70.75 ± 5.64 to 25.38 ± 6.64, effectively alleviating abnormal involuntary movements.