Nanoemulsions for Intranasal Delivery of Riluzole to Improve Brain Bioavailability: Formulation Development and Pharmacokinetic Studies.

BACKGROUND: Amyotrophic Lateral Sclerosis (ALS), a motor neuron disease (MND), is a progressive neurodegenerative disorder characterized by the deterioration of both upper and lower motor neurons. Only one drug (riluzole) has been approved for the treatment of ALS. Riluzole is a BCS class II drug having 60% absolute bioavailability. It is a substrate of P-glycoprotein and BBB restricts its entry in brain. OBJECTIVE: This investigation was aimed to develop O/W nanoemulsion system of riluzole to improve its brain bioavailability. METHODS: Riluzole loaded nanoemulsion was prepared by phase titration method. It was consisting of 3% w/w Sefsol 218, 28.3% w/w Tween 80:Carbitol (1:1) and 68.7% w/w water. It was characterized for drop size, drop size distribution, transmittance, viscosity, pH, zeta potential, conductivity and nasal ciliotoxicity study. Thermodynamic stability and room temperature stability of prepared nanoemulsion formulation were evaluated. Pharmacokinetic and brain uptake study was carried out using albino rats (wistar) post intranasal and oral administration. RESULTS: Riluzole loaded nanoemulsion was having a drop size of 23.92±0.52 nm. It was free from nasal ciliotoxicity and stable for three months. Brain uptake of riluzole post intranasal administration of riluzole loaded nanoemulsion was significantly (P <4.10 × 10-6) higher when it was compared with oral administration of riluzole loaded nanoemulsion. CONCLUSION: This study indicates that nanoemulsion of riluzole for intranasal administration could be a promising approach for the treatment of ALS to minimize the dose of riluzole in order to avoid dose related adverse events.

The neuroprotection exerted by memantine, minocycline and lithium, against neurotoxicity of CSF from patients with amyotrophic lateral sclerosis, is antagonized by riluzole.

In a recent study we found that cerebrospinal fluids (CSFs) from amyotrophic lateral sclerosis (ALS) patients caused 20-30% loss of cell viability in primary cultures of rat embryo motor cortex neurons. We also found that the antioxidant resveratrol protected against such damaging effects and that, surprisingly, riluzole antagonized its protecting effects. Here we have extended this study to the interactions of riluzole with 3 other recognized neuroprotective agents, namely memantine, minocycline and lithium. We found: (1) by itself riluzole exerted neurotoxic effects at concentrations of 3-30 µM; this cell damage was similar to that elicited by 30 µM glutamate and a 10% dilution of ALS/CSF; (2) memantine (0.1-30 µM), minocycline (0.03-1 µM) and lithium (1-80 µg/ml) afforded 10-30% protection against ALS/CSF-elicited neurotoxicity, and (3) at 1-10 µM, riluzole antagonized the protection afforded by the 3 agents. These results strongly support the view that at the riluzole concentrations reached in the brain of patients, the neurotoxic effects of this drug could be masking the potential neuroprotective actions of new compounds being tested in clinical trials. Therefore, in the light of the present results, the inclusion of a group of patients free of riluzole treatment may be mandatory in future clinical trials performed in ALS patients with novel neuroprotective compounds.

Multifunctional albumin nanoparticles as combination drug carriers for intra-tumoral chemotherapy.

Current cancer therapies are challenged by weakly soluble drugs and by drug combinations that exhibit non-uniform biodistribution and poor bioavailability. In this study, we have presented a new platform of advanced healthcare materials based on albumin nanoparticles (ANPs) engineered as tumor penetrating, delivery vehicles of combinatorially applied factors to solid tumors. These materials were designed to overcome three sequential key barriers: tissue level transport across solid tumor matrix; uptake kinetics into individual cancer cells; therapeutic resistance to single chemotherapeutic drugs. The ANPs were designed to penetrate deeper into solid tumor matrices using collagenase decoration and evaluated using a three-dimensional multicellular melanoma tumor spheroid model. Collagenase modified ANPs exhibited 1-2 orders of magnitude greater tumor penetration than unmodified ANPs into the spheroid mass after 96 hours, and showed preferential uptake into individual cancer cells for smaller sized ANPs (<100 nm). For enhanced efficacy, collagenase coated ANPs were modified with two therapeutic agents, curcumin and riluzole, with complementary mechanisms of action for combined cell cycle arrest and apoptosis in melanoma. The collagenase coated, drug loaded nanoparticles induced significantly more cell death within 3-D tumor models than the unmodified, dual drug loaded ANP particles and the kinetics of cytotoxicity was further influenced by the ANP size. Thus, multifunctional nanoparticles can be imbued with complementary size and protease activity features that allow them to penetrate solid tumors and deliver combinatorial therapeutic payload with enhanced cancer cytotoxicity but minimal collateral damage to healthy primary cells.

Brain and plasma riluzole pharmacokinetics: effect of minocycline combination.

PURPOSE: amyotrophic lateral sclerosis is a fatal neurodegenerative disease characterized by the loss of motorneurons. The only drug approved is riluzole. Minocycline is an antibiotic with numerous neuroprotective properties. riluzole and minocycline were given to an animal model of ALS and had beneficial effect on the disease. The combination was then tested in humans in phase II and phase III studies with less beneficial effects and a faster decline of the disease in the group treated with minocycline. In a previous study, we showed that riluzole is transported out of the brain by the P-glycoprotein at the blood-brain barrier level. METHODS: in this work, we studied in CF1 mice, the plasmatic and cerebral pharmacokinetics of riluzole combined or not with minocycline. RESULTS: our results showed that the kinetics of riluzole are not linear with dose, but that cerebral AUC0-infinity increase proportionally with plasmatic AUC0-infinity. At the dose of 10 mg/kg, the cerebral AUC0-infinity /plasmatic AUC0-infinity ratio was 4.6 in mdr1a (-/-) mice and 2.4 in mdr1a (+/+) mice. The combination of minocycline (170 mg/kg) and riluzole (10 mg/kg) induced a 2 fold increase in the cerebral AUC0-infinity of riluzole and induced a neuromuscular toxicity in mice. This effect of minocycline was not found at low concentration (10 mg/kg of minocycline). CONCLUSIONS: if our results are confirmed in humans, riluzole cerebral concentrations could be predicted by plasmatic concentrations. Furthermore, the combination of high doses of minocycline with riluzole could induce neurological toxicity that lead to deceiving results in ALS clinical studies.