Development and validation of rapid and sensitive LC methods with PDA and fluorescence detection for determination of piribedil in rat plasma and brain tissues and their pharmacokinetic application

Lipid nanoparticles strategies to modify pharmacokinetics of central nervous system targeting drugs: Crossing or circumventing the blood-brain barrier (BBB) to manage neurological disorders

The main limitation to the success of central nervous system (CNS) therapies lies in the difficulty for drugs to cross the blood-brain barrier (BBB) and reach the brain. Regarding its structure and enzymatic complexity, crossing the BBB is a challenge, although several alternatives have been identified. For instance, the use of drugs encapsulated in lipid nanoparticles has been described as one of the most efficient approaches to bypass the BBB, as they allow the passage of drugs through this barrier, improving brain bioavailability. In particular, solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been a focus of research related to drug delivery to the brain. These systems provide protection of lipophilic drugs, improved delivery and bioavailability, having a major impact on treatments outcomes. In addition, the use of lipid nanoparticles administered via routes that transport drugs directly into the brain seems a promising solution to avoid the difficulties in crossing the BBB. For instance, the nose-to-brain route has gained considerable interest, as it has shown efficacy in 3D human nasal models and in animal models. This review addresses the state of the art on the use of lipid nanoparticles to modify the pharmacokinetics of drugs employed in the management of neurological disorders. A description of the structural components of the BBB, the role of the neurovascular unit and limitations for drugs to entry into the CNS is first addressed, along with the developments to increase drug delivery to the brain, with a special focus on lipid nanoparticles. In addition, the obstacle of BBB complexity in the creation of new effective drugs for the treatment of the most prevalent neurological disorders is also addressed. Finally, the proposed strategies for lipid nanoparticles to reach the CNS, crossing or circumventing the BBB, are described. Although promising results have been reported, especially with the nose-to-brain route, they are still ongoing to assess its real efficacy in vivo in the management of neurological disorders.

Simple and rapid LC-MS/MS method for determination of Piribedil in human plasma

A sensitive, simple, and fast LC-MS/MS method of analysis was developed and validated for the determination of piribedil in human plasma. Piribedil was extracted by protein precipitation using acetonitrile and separated on C18 Phenomenex Gemini column (150 × 4.6mm, 5 µm) using isocratic elution of 75% of ammonium acetate buffer (10 mM) and 25% acetonitrile at a flow rate of 1 ml.min-1 over 5 min run time. Piribedil and d8-Piribedil, as internal standard, were detected and quantified in positive ion mode via MRM at m/z 299/135 and 307/135 for piribedil and d8–piribedil, respectively. The suggested method for piribedil was validated according to FDA and EMA guidelines. The standard calibration curve was linear over the concentration range of 3.4–5952 pg.ml-1. The intra-day precision was 2.45–9.94% and accuracy 92.78–99.97%. The inter-day precision was 2.14–5.47% and accuracy 95.73–101.99%. The recovery of analyte and IS was 96.94% and 111.18%, respectively. piribedil in plasma was stable at benchtop (short term) for 24 h, in autosampler tray for 48 h, in instrumentation room for 24 h (post-preparative), after 5 freeze-thaw cycles (–70 °C), and 11 days in the freezer (–70 °C). The validated method was successfully applied to a bioequivalence study of piribedil formulations involving 15 healthy Jordanian volunteers.

Design and evaluation of thermo-responsive nasal in situ gelling system dispersed with piribedil loaded lecithin-chitosan hybrid nanoparticles for improved brain availability

Piribedil (PBD) is a compound that has shown efficacy in clinical trials to treat motor and non-motor symptoms of Parkinson's disease. However, drug delivery issues like low oral bioavailability, high dosing frequency (3-5 tablets/day), gastrointestinal side-effects reduced the clinical use of PBD. In this work, we have developed lecithin-chitosan hybrid nanoparticles (PBD-LCNs) to improve the direct nose to brain uptake of PBD. PBD-LCNs were optimized using hybrid design approach based on DoE. The mean particle size and drug loading of PBD-LCNs were 147 nm, and 12%, respectively. The PBD-LCNs showed good stability and were found to be nearly spherical in shape. Further, the optimized LCNs were loaded in methylcellulose thermo-responsive in situ gel (PBD-LCN-ISG) to overcome rapid mucociliary clearance upon intranasal administration. Plasma and brain pharmacokinetic studies in rats showed that PBD-LCN-ISG increased the relative bioavailability of PBD in brain (AUC_brain) by about 6.4-folds and reduced the (C_max)_plasma by 3.7-folds when compared to plain intranasal suspension of PBD (PBD-Susp). Further, PBD-Susp showed limited direct nose to brain uptake with DTP values less than 0, while the optimized PBD-LCNs showed DTP value of 56% indicating efficient direct nose to brain uptake. Overall, the development of nanoformulations significantly improved the direct nose to brain uptake of PBD.

Design, optimization and pharmacokinetic evaluation of Piribedil loaded solid lipid nanoparticles dispersed in nasal in situ gelling system for effective management of Parkinson's disease

Piribedil (PBD) is an anti-Parkinson's drug that gained interest recently due to its unique pharmacological profile. But its clinical use is severely limited by drug delivery issues like high dosing frequency (up to 5 tablets/day), low oral bioavailability (<10%), severe GI side-effects, etc. In this work, we have developed solid lipid nanoparticles (PBD-SLNs) to access the nose to brain pathways for direct uptake of PBD. PBD-SLNs were optimized using design of experiments approach to a mean particle size of 358 nm, and drug loading of 15%. The optimized PBD-SLNs were found to be nearly spherical in shape and showed good stability. Further, the SLNs were loaded in thermoresponsive Methyl Cellulose in situ gel (PBD-SLN-ISG) to delay mucociliary clearance upon intranasal administration in rats. Intranasal administration at the olfactory region was achieved with a cannula-microtip setup. In vivo pharmacokinetic studies showed that PBD-SLN-ISG increased the PBD (AUC)_brain by about 4-folds and reduced the (C_max)_plasma by 2.3-folds when compared to plain intranasal suspension of PBD (PBD-Susp). Further, PBD-Susp showed limited direct nose to brain uptake with direct transport percentage (DTP) values less than 0, while the optimized PBD-SLN-ISG showed DTP value of 27% indicating efficient direct nose to brain uptake.

Piribedil loaded thermo-responsive nasal in situ gelling system for enhanced delivery to the brain: formulation optimization, physical characterization, and in vitro and in vivo evaluation

Methyl cellulose (MC) based nasal in situ gels were developed to enhance the brain delivery of piribedil (PBD), an anti-Parkinson's drug. Different grades of MC and several solutes (NaCl, KCl, Na.Citrate, STPP, PEG-6000, sucrose, etc.) were screened to formulate thermo-responsive nasal in situ gelling systems. Formulations were evaluated for their sol-gel transition temperature and time, rheological behaviour, in vitro drug release, mucociliary clearance (MCC), ex vivo nasal toxicity, and in vivo brain availability studies in Wistar rats. Intranasal (i.n.) administration was carried out using a cannula-microtip setup to deliver PBD at the olfactory region of the nose. The concentration and viscosity grade of MC and also the concentration and type of solute used were found to affect the rheological behaviour of the formulations. Among the solutes tested, NaCl was found to be effective for formulating MC in situ gels. The developed in situ gels significantly delayed the MCC of PBD from the site of administration when compared with conventional suspension (p < 0.05). Further, formulations with higher gel strength showed lower in vitro drug release rate and longer intranasal residence (delayed MCC) (p < 0.05). The absolute brain availability (brain AUC_0-t) of PBD increased to 35.92% with i.n. delivery when compared to 4.71% with oral administration. Overall, it can be concluded that intranasal delivery of PBD is advantageous when compared to the currently practiced oral therapy. Graphical abstract.