The aim of this study was to develop and characterise an intranasal delivery system for amantadine (AMT). Optimal formulations (F) consisted of a thermosensitive polymer Pluronic ® 127 (P127) and either carboxy methyl cellulose (CMC) or chitosan (CS) which demonstrated gel-transition at nasal cavity temperatures (34 °C ± 1 °C). Rheologically, the loss tangent (Tan δ) confirmed a three-stage gelation phenomena at 34 °C ± 1 °C and nonNewtonian behaviour. Storage of FCMC and FCS at 4 °C for 8 weeks resulted in repeatable release profiles at 34 °C when sampled, with a Fickian mechanism earlier on but moving towards anomalous transport by week 8. Polymers (P127, CMC and CS) demonstrated no significant cellular toxicity to human nasal epithelial cells up to 4 mg/mL and up to 1 mM for AMT (IC50: 4.5 mM ± 0.05 mM). FCMC and FCS demonstrated slower release across an in-vitro human nasal airway model (43-44 % vs 79 % ± 4.58 % for AMT). Using a human nasal cast model, deposition into the olfactory regions (potential nose-to-brain) was demonstrated upon nozzle insertion (5 mm) whereas tilting of the head forward (15°) resulted in greater deposition in the bulk of the nasal cavity.
KEYWORDSParkinson's disease; rheology; nasal; RPMI 2650; nose to brain; thermoresponsive; 3 INTRODUCTION Parkinson's disease (PD) is an ageing associated progressive neurological disorder and affects 1.5 % of the population over 65-years of age 1 , with age-adjusted prevalence rates thought to be around 150 per 100,000 with a suggested mean onset in the 70's 1 . Ageing is the largest single risk factor for the development of PD and the pathogenesis of PD is composed of a range of events leading towards neuronal apoptosis, primarily of degradation of dopamine neurones in the sustantia nigra. The mainstay of clinical drug therapy focuses on increases the levels of dopamine (DA) in the brain, with oral dosing of levodopa being the most commonly used to pharmacological intervention treatment to reverse the symptoms of PD. It is also common to use adjunct therapies in conjunction with levodopa, such as the weak NMDA-type receptor antagonist amantadine, which can aid in blocking dopamine reuptake.