Ropinirole Hydrochloride

Ropinirole is a non-ergoline dopamine agonist highly selective for D₂/D₃ receptors, with higher affinity for D₃ than D₂. It is rapidly absorbed orally, has 55% bioavailability, a 6-hour half-life, and is metabolized by CYP1A2. In early Parkinson’s disease, ropinirole monotherapy significantly improves motor symptoms and activities of daily living compared to placebo, with efficacy comparable to levodopa but with markedly lower risk of dyskinesias (20% vs 45% after 5 years). Long-term studies show sustained benefit over 10 years. Compared to bromocriptine, ropinirole demonstrates better motor outcomes and tolerability. A neuroprotective effect is suggested by slower striatal dopamine loss on PET imaging. Unlike ergoline agonists, ropinirole is not associated with cardiac valve fibrosis or retroperitoneal fibrosis. Ropinirole is also effective in restless legs syndrome at low doses, significantly improving symptoms, sleep quality, and periodic leg movements.

Ropinirole-loaded PLGA nanoparticles were developed to improve brain delivery for Parkinson’s disease. The optimized formulation (8 mg ropinirole, 50 mg PLGA 502) achieved 74.8% encapsulation efficiency, particle size below 155 nm, zeta potential -14.25 mV, and zero-order in vitro release for 5 days. In a rotenone-induced rat model of Parkinson’s disease, ropinirole-loaded NPs were compared to free ropinirole in saline. Behavioral tests (catalepsy, akinesia, rotarod, swim test) showed that NP-treated animals significantly outperformed those receiving free ropinirole, with results similar to healthy controls by day 36. Histological analysis revealed that NPs prevented rotenone-induced neuronal loss in the substantia nigra pars compacta (Nissl staining), reduced reactive astrogliosis (GFAP), and restored tyrosine hydroxylase expression. The nanocarrier enabled intermittent dosing while achieving superior neuroprotection compared to daily free drug.

Fig. 1 Microphotographs of formulation NPRP-3. (Barcia E.; et al. 2017)