Nano and Microemulsions for the Treatment of Depressive and Anxiety Disorders: An Efficient Approach to Improve Solubility, Brain Bioavailability and Therapeutic Efficacy

Abstract

Most drugs used for the treatment of depression, anxiety and related disorders have low absorption, high metabolism, low brain targeting and/or low water solubility, which can make it hard to formulate them at high strength and can also lead to decreased bioavailability. Incorporating these drugs into nanometric emulsions can solve these issues. Hence, the aim of the present review was to assess the potential of nano and micro emulsions for the delivery of antidepressant and anxiolytic drugs. The results from several studies showed that nanometric emulsions were able to increase drug strength up to 20,270-fold (compared to aqueous solubility). Moreover, in general, the formulations showed droplet size, polydispersity index, zeta potential, viscosity, osmolality, pH, in vitro drug release and ex vivo drug permeation as adequate for the intended effect and administration route. In vivo animal pharmacokinetic experiments showed that nanometric emulsions improved systemic drug bioavailability and/or brain targeting, and in vivo pharmacodynamic studies showed that they had antidepressant and/or anxiolytic effects, also being apparently safe. Hence, the current review provides proof of the potential of nano and microemulsions for improving solubilization and increasing the overall bioavailability of antidepressant and/or anxiolytic drugs, providing evidence of a possible useful strategy for future therapies.

Nanosystems, Drug Molecule Functionalization and Intranasal Delivery: An Update on the Most Promising Strategies for Increasing the Therapeutic Efficacy of Antidepressant and Anxiolytic Drugs

“…In terms of nanosystems that are meant to be administered by the IN route, these are designed to provide a longer residence time in the nasal cavity, overcome nasal mucociliary clearance, and facilitate rapid drug transport across the nasal mucosa. Independently of the intended administration route, there are several types of nanosystems ( Figure 4 ), with the main being: polymeric nanoparticles (NP), which are divided into nanocapsules and nanospheres; lipid nanoparticles, namely solid lipid nanoparticles and nanostructured lipid carriers; liposomes; nanometric emulsions, such as nanoemulsions and microemulsions; and nanoemulgels [ 20 , 38 , 39 , 40 , 41 ].…”

“…Similar to microemulsions, they also have an oil phase, an aqueous phase, and a surfactant. However, the latter is usually present in smaller quantities [ 21 , 38 , 41 ].…”

Nanosystems for Brain Targeting of Antipsychotic Drugs: An Update on the Most Promising Nanocarriers for Increased Bioavailability and Therapeutic Efficacy

“…They are usually either biphasic, being oil-in-water or water-in-oil in nature, or triphasic, being water-in-oil-in-water or oil-in-water-in-oil dispersions. Surfactants and cosurfactants are added to these formulations in order to reduce their thermodynamic instability, interfacial tension and, in turn, droplet coalescence, with the amount and type being important factors in the formation of a stable nanoemulsion [ 71 , 72 , 73 , 74 ]. Additionally, under specific circumstances, there might be a need to increase the viscosity of these nanosystems, for example, in intranasal delivery, in order to allow for a longer residence time of the formulation in the nasal cavity, consequently leading to increased drug absorption.…”

Formulation, Characterization, and Evaluation of β-Cyclodextrin Functionalized Hypericin Loaded Nanocarriers

“…Various therapies of depression include multiple drug classes such as monoamino oxidase inhibitors, selective serotonin reuptake inhibitors, and tricyclic antidepressants. Such drugs have been effectively absorbed from the gastrointestinal tract (GIT) but undergo an extensive first-pass metabolism that will be a reason for poor oral bioavailability of less than 50%. − …”