RESEARCH MONOGRAPH · KDC-MN-317

Ropinirole

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

75/100

Solid non-ergot D2/D3 agonist, less interesting than pramipexole for research purposes

Ropinirole is the SmithKline-Beecham non-ergot that came up alongside pramipexole and never quite distinguished itself. It hits D2 and D3 with similar affinity, no real selectivity between them, which makes it a less useful pharmacological probe than pramipexole when you're trying to isolate D3 contributions.

The clinical record is fine. It works for Parkinson's, works for restless legs syndrome, and there's an extensive prescribing literature. The CALM-PD trial put it on the map as a delay-of-levodopa strategy and the modified-release formulation extended its commercial life. Mechanism is straightforward dopaminergic agonism with the same ICD-risk profile as pramipexole.

For research purposes the interesting question is mostly comparative. If you want a non-ergot D2/D3 reference compound, ropinirole works. But pramipexole gives you D3 bias, quinpirole gives you better binding for in vitro work, and sumanirole gives you cleaner D2 selectivity. Ropinirole sits awkwardly in the middle without a strong niche.

Pharmacokinetics are reasonable: ~50% oral bioavailability, hepatic metabolism via CYP1A2 (which matters if you're doing combination studies with anything that touches that enzyme), half-life ~6 hours for IR. The hydrochloride salt is the standard form. Sourcing is straightforward, the patent expired a while back, generic-equivalent USP material is cheap and reliable.

What we like is the boring competence of it. No real surprises, well-documented PK, predictable behavior in standard assays. For a Parkinson's model where you just need 'a dopamine agonist that isnt an ergot,' ropinirole does the job without any drama.

What we dont like is the lack of a distinctive angle. Theres no breakthrough mechanism story here, no surprising clinical reuse, no compelling preclinical literature outside the standard PD models. It's a competent member of a class where other compounds offer more interesting biology.

Reliable tool, not particularly exciting. We'd reach for pramipexole first 9 times out of 10 unless we needed exactly its receptor profile.

Evidence: 85
Mechanism: 80
Reliability: 80
Safety: 72
Sourcing: 88
Value: 78
Signal: 55
Staying power: 65

Plain-language summary Intrigue 50 / 100

Ropinirole, sold as Requip, is a non-ergot dopamine agonist that hits D2 and D3 receptors about equally, distinguishing it from the D3-preferring pramipexole. It is FDA-approved for Parkinson disease and restless legs syndrome, with broadly comparable efficacy to pramipexole in head-to-head studies. The same impulse control disorder risk applies, and clinicians choose between the two largely on side-effect tolerability and dosing schedule. Mechanistically and clinically it offers no clear advantage over pramipexole, which is why pramipexole tends to dominate prescribing in most regions. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Non-ergot D2/D3 dopamine agonist

A non-ergot indolone D2/D3 dopamine receptor agonist; alternative to pramipexole in Parkinson disease and restless legs syndrome.

Abstract

Ropinirole (4-[2-(dipropylamino)ethyl]-1,3-dihydro-2H-indol-2-one; CAS 91374-21-9; molecular formula C16H24N2O; molecular weight 260.38) is a non-ergot indolone D2/D3 dopamine receptor agonist developed at SmithKline Beecham (now GSK) and approved by the FDA in 1997 under the trade name Requip. Affinity is approximately balanced at D2 and D3 (Ki approximately 24 and 30 nM respectively), distinguishing it from the more D3-preferring pramipexole. Plasma half-life is approximately 6 hours; metabolism is via CYP1A2. Approved for Parkinson disease and restless legs syndrome. Comparable efficacy and tolerability to pramipexole in head-to-head studies, with similar impulse control disorder risk. Used as an alternative reference non-ergot dopamine agonist.

Mechanism of action

Non-ergot D2/D3 dopamine receptor agonist (approximately balanced D2/D3 affinity). Mechanism comparable to pramipexole.

Reported research dose ranges

Clinical 0.25 to 24 mg in the published literature or ER. Rodent studies 0.1 to 3 mg/kg.

References

Eden RJ, et al. Preclinical pharmacology of ropinirole. Pharmacol Toxicol 1991.
Brooks DJ. Dopamine agonists: their role in the treatment of Parkinson's disease. J Neurol Neurosurg Psychiatry 2000.
Stocchi F, et al. A randomized, double-blind, placebo-controlled study of dopamine agonists in advanced Parkinson disease. Mov Disord 2002.

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KDC-MN-317

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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Ropinirole

Abstract

Mechanism of action

Reported research dose ranges

References

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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