Dihydrexidine (DAR-0100) is a moderately selective full agonist at the dopamine D1 and D5 receptors.

[2] Although dihydrexidine has some affinity for the D2 receptor, it has functionally selective (highly biased) D2 signaling,[3] thereby explaining why it lacks D2 agonist behavioral qualities.

[4] Dihydrexidine has shown impressive antiparkinson effects in the MPTP-primate model,[5] and has been investigated for the treatment of Parkinson's disease.

[6] In an early clinical trial the drug was given intravenously and led to profound hypotension so development was halted.

[7] The drug was resurrected when it was shown that smaller subcutaneous doses were safe.