Development, characterization and application of in situ gel systems for intranasal delivery of tacrine

Nanosystems for targeted drug Delivery: Innovations and challenges in overcoming the Blood-Brain barrier for neurodegenerative disease and cancer therapy

The evolution of sophisticated nanosystems has revolutionized biomedicine, notably in treating neurodegenerative diseases and cancer. These systems show potential in delivering medication precisely to affected tissues, improving treatment effectiveness while minimizing side effects. Nevertheless, a major hurdle in targeted drug delivery is breaching the blood-brain barrier (BBB), a selective shield separating the bloodstream from the brain and spinal cord. The tight junctions between endothelial cells in brain capillaries create a formidable physical barrier, alongside efflux transporters that expel harmful molecules. This presents a notable challenge for brain drug delivery. Nanosystems present distinct advantages in overcoming BBB challenges, offering enhanced drug efficacy, reduced side effects, improved stability, and controlled release. Despite their promise, challenges persist, such as the BBB's regional variability hindering uniform drug distribution. Efflux transporters can also limit therapeutic agent efficacy, while nanosystem toxicity necessitates rigorous safety evaluations. Understanding the long-term impact of nanomaterials on the brain remains crucial. Additionally, addressing nanosystem scalability, cost-effectiveness, and safety profiles is vital for widespread clinical implementation. This review delves into the advancements and obstacles of advanced nanosystems in targeted drug delivery for neurodegenerative diseases and cancer therapy, with a focus on overcoming the BBB.

Development of synergistic antifungal in situ gel of miconazole nitrate loaded microemulsion as a novel approach to treat vaginal candidiasis

Limited solubility is the main cause of the low local availability of anti-candidiasis drug, miconazole nitrate (MN). The study's objective was to develop and characterize microemulsion (ME) based temperature-triggered in situ gel of MN for intravaginal administration to enhance local availability and antifungal activity. The solubility of MN was initially studied in different oils, surfactants, and co-surfactants. Then, pseudo-ternary phase diagrams were constructed to select the best ratio of various components. The ME formulations were characterized by thermodynamic study, droplet size, polydispersity index (PDI), viscosity, and in-vitro antifungal mean inhibition zone (MIZ). Selected MEs were incorporated into different in situ gel bases using a combination of two thermosensitive polymers (poloxamer (PLX) 407 and 188), with 0.6% of hydroxypropyl methylcellulose (HPMC K4M) and gellan gum (GG) as mucoadhesive polymer. ME-based gels (MG) were investigated for gelation temperature, gelation time, viscosity, spreadability, mucoadhesive strength, in vitro release profile, and MIZ test. Furthermore, the optimum MG was assessed for in vivo animal irritation test and FESEM investigation. Tea tree oil, lavender oil, tween 80, and propylene glycol (PG) were chosen for ME preparation for the optimal formulation; formulation ME7 and ME10 were chosen. After incorporation of the selected formulation into a mixture of P407 and P188 (18:2% w/w) with 0.6% mucoadhesive polymer, the resultant MG formulation (MG1) revealed optimum gelation temperature (33 ± 0.01℃) and appropriate viscosity with enhanced sustained release (98%) and retention through sheep vaginal mucosa, MG1 exhibited a better MIZ compared to the 2% MN gel formulation and the marketed MN product, and no rabbit vagina irritation. In conclusion, the miconazole nitrate-loaded MG-based formula sustained the duration of action and better antifungal activity than the marketed miconazole nitrate formulation.

Recent advances in the natural product analogues for the treatment of neurodegenerative diseases

Neurodegenerative diseases (NDs) represent a hallmark of numerous incapacitating and untreatable conditions, the incidence of which is escalating swiftly, exemplified by Alzheimer's disease and Parkinson's disease. There is an urgent necessity to create pharmaceuticals that exhibit high efficacy and minimal toxicity in order to address these debilitating diseases. The structural complexity and diversity of natural products confer upon them a broad spectrum of biological activities, thereby significantly contributing to the history of drug discovery. Nevertheless, natural products present challenges in drug discovery, including time-consuming separation processes, low content, low bioavailability, and other related issues. To address these challenges, numerous analogs of natural products have been synthesized. This methodology enables the rapid synthesis of analogs of natural products with the potential to serve as lead compounds for drug development, thereby paving the way for the discovery of novel pharmaceuticals. This paper provides a summary of 127 synthetic analogues featuring various natural product structures, including flavonoids, alkaloids, coumarins, phenylpropanoids, terpenoids, polyphenols, and amides. The compounds are categorized based on their efficacy in treating various diseases. Furthermore, this article delves into the structure-activity relationship (SAR) of certain analogues, offering a thorough point of reference for the systematic development of pharmaceuticals aimed at addressing neurodegenerative conditions.

Assembly of In-Situ Gel Containing Nano-Spanlastics of an Angiotensin II Inhibitor as a Novel Epitome for Hypertension Management: Factorial Design Optimization, In-vitro Gauging, Pharmacokinetics, and Pharmacodynamics Appraisal

More than 1 billion people worldwide suffer from hypertension; therefore, hypertension management has been categorized as a global health priority. Losartan potassium (LP) is an antihypertensive drug with a limited oral bioavailability of about 33% since it undergoes the initial metabolic cycle. Thus, nasal administration is a unique route to overcome first-pass metabolism. The investigation focused on the potential effects of LP-loaded spanlastic vesicles (SNVs) on LP pharmacodynamics and pharmacokinetic parameters, utilizing a thin-film hydration methodology established on a 3122 full factorial design. Entrapment efficiency (EE%) ranged from 39.8 ± 3.87.8 to 83.8 ± 2.92% for LP-SNVs. Vesicle size (VS) varied from 205.5 ± 6.5.10 to 445.1 ± 13.52 nm, and the percentage of LP released after 8 h (Q8h) ranged from 30.8 ± 3.10 to 68.8 ± 1.45%. LP permeated through the nasal mucosa during 24 h and flocculated from 194.1 ± 4.90 to 435.3 ± 13.53 µg/cm2. After twenty-four hours, the optimal LP-SNVs in-situ gel showed 2.35 times more permeation through the nasal mucosa than the LP solution. It also lowered systolic blood pressure, so it is thought to be better than the reference formulation in terms of pharmacodynamics. The pharmacokinetics studies demonstrated that the intranasal LP-SNVs gel boosted its bioavailability approximately 6.36 times compared to the oral LP solution. Our research showed that intranasal LP-SNVs could be a good nanoplatform because they are well-tolerated and have possible pharmacokinetics and pharmacodynamics.

In-depth Mechanism, Challenges, and Opportunities of Delivering Therapeutics in Brain Using Intranasal Route

Central nervous system-related disorders have become a continuing threat to human life and the current statistic indicates an increasing trend of such disorders worldwide. The primary therapeutic challenge, despite the availability of therapies for these disorders, is to sustain the drug's effective concentration in the brain while limiting its accumulation in non-targeted areas. This is attributed to the presence of the blood-brain barrier and first-pass metabolism which limits the transportation of drugs to the brain irrespective of popular and conventional routes of drug administration. Therefore, there is a demand to practice alternative routes for predictable drug delivery using advanced drug delivery carriers to overcome the said obstacles. Recent research attracted attention to intranasal-to-brain drug delivery for promising targeting therapeutics in the brain. This review emphasizes the mechanisms to deliver therapeutics via different pathways for nose-to-brain drug delivery with recent advancements in delivery and formulation aspects. Concurrently, for the benefit of future studies, the difficulties in administering medications by intranasal pathway have also been highlighted.

Formulation development and evaluation of nasal in situ gel of promethazine hydrochloride

OBJECTIVE

The present work aims to develop mucoadhesive thermosensitive nasal in situ gel for Promethazine hydrochloride using quality by design (QbD) approach. It can reduce nasal mucociliary clearance (MCC) and increase residence of the drug on nasal mucosa. This might increase drug absorption to improve bioavailability of the drug as compared to oral dosage form.

SIGNIFICANCE

Promethazine hydrochloride is an antiemetic drug administered by oral, parenteral and rectal routes. These routes have poor patient compliance or low bioavailability. Nasal route is a better alternative as it has large surface area, high drug absorption rate and no first pass effect. Its only limitation is short drug retention time due to MCC. By formulating a mucoadhesive in situ gel, the MCC can be reduced, and drug absorption will be prolonged. Thus, improving bioavailability.

METHOD

In-situ gel was prepared by cold method having material attributes as concentration of Poloxamer 407 (X1) as gelling agent and hydroxypropyl methyl cellulose K4M (X2) as mucoadhesive agent. Critical Quality Attributes (CQA) were gelation temperature, mucoadhesive force and ex-vivo diffusion. Central composite design (CCD) was adopted for optimization.

RESULT

Optimized formulation satisfied all the CQA significant for nasal administration. Moreover, the formulation was found to be stable in accelerated stability studies for 3 months.

CONCLUSION

It can be concluded that since the drug can easily permeate through nasal mucosa and can gain access directly in the brain without undergoing first pass metabolism along with increased residence due to mucoadhesion, mucoadhesive in situ gel has potential to increase drug bioavailability.

The prescription design and key properties of nasal gel for CNS drug delivery: A review

Central nervous system (CNS) diseases are among the major health problems. However, blood-brain barrier (BBB) makes traditional oral and intravenous delivery of CNS drugs inefficient. The unique direct connection between the nose and the brain makes nasal administration a great potential advantage in CNS drugs delivery. However, nasal mucociliary clearance (NMCC) limits the development of drug delivery systems. Appropriate nasal gel viscosity alleviates NMCC to a certain extent, gels based on gellan gum, chitosan, carbomer, cellulose and poloxamer have been widely reported. However, nasal gel formulation design and key properties for alleviating NMCC have not been clearly discussed. This article summarizes gel formulations of different polymers in existing nasal gel systems, and attempts to provide a basis for researchers to conduct in-depth research on the key characteristics of gel matrix against NMCC.

Development and Assessment of Acyclovir Gel Plaster Containing Sponge Spicules

Acyclovir is an acyclic purine nucleoside analog that is highly effective in inhibiting the herpes simplex virus. However, topical acyclovir has poor efficacy because of its low skin permeability. This study aimed to develop an acyclovir gel plaster containing sponge spicules (AGP-SS) to achieve synergistic improvements in skin absorption and deposition of acyclovir. The process of preparing the gel plaster was optimized by orthogonal experiments, while the composition of the formulation was optimized using the Plackett-Burman and Box-Behnken experimental designs. The selected formula was tested for physical properties, in vitro release, stability, ex vivo permeation, skin irritation, and pharmacokinetics. The optimized formulation exhibited good physical characteristics. In vitro release and ex vivo permeation studies showed that acyclovir release from AGP-SS was dominated by diffusion with significantly higher skin permeation (20.00 ± 1.07 μg/cm2) than that of the controls (p < 0.05). Dermatopharmacokinetic analyses revealed that the maximum concentration (78.74 ± 11.12 μg/g), area under the curve (1091.81 ± 29.05 μg/g/h) and relative bioavailability (197.12) of AGP-SS were higher than those of the controls. Therefore, gel plaster containing sponge spicules show potential for development as transdermal delivery systems to achieve higher skin absorption and deposition of acyclovir, especially in deep skin layers.

Tailoring Risperidone-Loaded Glycethosomal In Situ Gels Using Box-Behnken Design for Treatment of Schizophrenia-Induced Rats via Intranasal Route

Schizophrenic patients often face challenges with adherence to oral regimens. The study aimed to highlight the potentiality of intranasal ethanol/glycerin-containing lipid-nanovesicles (glycethosomes) incorporated into in situ gels for sustaining anti-psychotic risperidone (RS) release. The Box-Behnken Design (BBD) was followed for in vitro characterization. Glycethosomal-based in situ gels were examined by physical, ex vivo, and in vivo investigations. The ethanol impact on minimizing the vesicle size (VS) and enhancing the zeta potential (ZP) and entrapment efficiency (EE%) of nanovesicles was observed. Glycerin displayed positive action on increasing VS and ZP of nanovesicles, but reduced their EE%. After incorporation into various mucoadhesive agent-enriched poloxamer 407 (P407) in situ gels, the optimized gel containing 20% P407 and 1% hydroxypropyl methyl cellulose-K4M (HPMC-K4M) at a 4:1 gel/glycethosomes ratio showed low viscosity and high spreadability with acceptable pH, gel strength, and mucoadhesive strength ranges. The ethanol/glycerin mixture demonstrated a desirable ex vivo skin permeability of RS through the nasal mucosa. By pharmacokinetic analysis, the optimized gel showed eight-fold and three-fold greater increases in RS bioavailability than the control gel and marketed tablet, respectively. Following biochemical assessments of schizophrenia-induced rats, the optimized gel boosted the neuroprotective, anti-oxidant, and anti-inflammatory action of RS in comparison to other tested preparations. Collectively, the intranasal RS-loaded glycethosomal gel offered a potential substitute to oral therapy for schizophrenic patients.

Thermo-Responsive Sol-Gel-Based Nano-Carriers Containing Terbinafine HCl: Formulation, In Vitro and Ex Vivo Characterization, and Antifungal Activity

The current research aims to create a sol-gel-based nanocarrier containing terbinafine formulated for transdermal delivery of the drug into the skin. Sol-gel-based nanocarriers were prepared via the cold method using poloxamer-188, poloxamer-407, and distilled water. The prepared formulation was examined for pH, gelation temperature, Fourier transform infrared spectrophotometer (FTIR) analysis, thermal stability analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis, zeta potential, and anti-microbial activity. The in-vitro drug release study of F1 was found to be 94%, which showed greater drug release as compared to F2 and F3. The pH of the formulation was found to be within the range applicable to the skin. The gelation temperature was detected at 28 °C. The SEM images of formulations have spotted various particles well-segregated from each other. Analysis of formulations showed a mean globule size diameter of 428 nm, zeta potential values of 0.04 mV, refractive index (1.329), and viscosity (5.94 cP). FTIR analysis confirmed various functional groups' presence in the prepared formulation. Thermal analysis has confirmed the stability of the drug within the prepared formulation. The growth of inhibition was found to be 79.2% in 60 min, which revealed that the prepared formulation has shown good permeation from the membrane. Hence, the sol-gel-based nanocarrier formulation of terbinafine was successfully developed and evaluated.

Quality by design-based optimization of in situ ionic-sensitive gels of amoxicillin-loaded bovine serum albumin nanoparticles for enhanced local nasal delivery

A recommended first-line acute bacterial rhinosinusitis (ABR) treatment regimen includes a high dose of orally administered amoxicillin, despite its frequent systemic adverse reactions coupled with poor oral bioavailability. Therefore, to overcome these issues, nasal administration of amoxicillin might become a potential approach for treating ABR locally. The present study aimed to develop a suitable carrier system for improved local nasal delivery of amoxicillin employing the combination of albumin nanoparticles and gellan gum, an ionic-sensitive polymer, under the Quality by Design methodology framework. The application of albumin nanocarrier for local nasal antibiotic therapy means a novel approach by hindering the nasal absorption of the drug through embedding into an in situ gelling matrix, further prolonging the drug release in the nasal cavity. The developed formulations were characterized, including mucoadhesive properties, in vitro drug release and antibacterial activities. Based on the results, 0.3 % w/v gellan gum concentration was selected as the optimal in situ gelling matrix. Essentially, each formulation adequately inhibited the growth of five common nasal pathogens in ABR. In conclusion, the preparation of albumin-based nanoparticles integrated with in situ ionic-sensitive polymer provides promising ability as nanocarrier systems for delivering amoxicillin intranasally for local antibiotic therapy.

Lamotrigine-Loaded Poloxamer-Based Thermo-Responsive Sol-Gel: Formulation, In Vitro Assessment, Ex Vivo Permeation, and Toxicology Study

The present study aimed to prepare, characterize, and evaluate a thermo-responsive sol-gel for intranasal delivery of lamotrigine (LTG), which was designed for sustained drug delivery to treat epilepsy. LTG sol-gel was prepared using the cold method by changing the concentrations of poloxamer 407 and poloxamer 188, which were used as thermo-reversible polymers. The optimized formulations of sol-gel were analyzed for clarity, pH, viscosity, gelation temperature, gelation time, spreadability, drug content, in vitro drug release studies, ex vivo permeation studies, and in vivo toxicological studies. FTIR, XRD, and DSC were performed to determine the thermal stability of the drug and polymers. The prepared formulations had a clear appearance in sol form; they were liquid at room temperature and became gel at temperatures between 31 °C and 36 °C. The pH was within the range of the nasal pH, between 6.2 and 6.4. The drug content was found to be between 92% and 94%. In vitro drug release studies indicated that the formulations released up to 92% of the drug within 24 h. The FTIR, DSC, and XRD analyses showed no interaction between the drug and the polymer. A short-term stability study indicated that the formulation was stable at room temperature and at 4-8 °C. There was a slight increase in viscosity at room temperature, which may be due to the evaporation of the vehicle. A histological study indicated that there were no signs of toxicity seen in vital organs, such as the brain, kidney, liver, heart, and spleen. It can be concluded from the above results that the prepared intranasal sol-gel for the delivery of LTG is safe for direct nose-to-brain delivery to overcome the first-pass effect and thus enhance bioavailability. It can be considered an effective alternative to conventional drug delivery for the treatment of epilepsy.

Transnasal-brain delivery of nanomedicines for neurodegenerative diseases

Neurodegenerative diseases (NDs) have become a serious global health problem as the population ages. Traditionally, treatment strategies for NDs have included oral and intravenous administration; however, the blood–brain barrier (BBB) can prevent drugs from reaching the brain, rendering the treatment incomplete and the effect unsatisfactory. Additionally, the prolonged or excessive use of drugs that can cross the BBB can damage liver and kidney function. Recent studies have shown that nose-to-brain drug delivery can noninvasively bypass the BBB, allowing drugs to enter the brain through the olfactory or trigeminal nerve pathways; additionally, nanoparticle carriers can enhance drug delivery. This review introduces drug carrier nanoparticles for nose-to-brain delivery systems, compares the advantages and disadvantages of different nanoparticles, and discusses the factors influencing nose-to-brain nanomedicine delivery and enhancement strategies. We also summarize nose-to-brain delivery and nanomedicines for treating NDs, the current challenges of this approach, and the future promise of nanomedicine-based ND treatment.

Numerical Optimization of Prednisolone-Tacrolimus Loaded Ultraflexible Transethosomes for Transdermal Delivery Enhancement; Box-Behnken Design, Evaluation, Optimization, and Pharmacokinetic Study

The aim of the present study is to formulate highly permeable carriers (i.e., transethosomes) for enhancing the delivery of prednisolone combined with tacrolimus for both topical and systemic pathological conditions. A Box-Behnken experimental design was implemented in this research. Three independent variables: surfactant concentration (X1), ethanol concentration (X2), and tacrolimus concentration (X3) were adopted in the design while three responses: entrapment efficiency (Y1), vesicle size (Y2), and zeta potential (Y3) were investigated. By applying design analysis, one optimum formulation was chosen to be incorporated into topical gel formulation. The optimized transethosomal gel formula was characterized in terms of pH, drug content, and spreadability. The gel formula was challenged in terms of its anti-inflammatory effect and pharmacokinetics against oral prednisolone suspension and topical prednisolone-tacrolimus gel. The optimized transethosomal gel achieved the highest rate of rat hind paw edema reduction (98.34%) and highest pharmacokinetics parameters (Cmax 133.266 ± 6.469 µg/mL; AUC_0-∞ 538.922 ± 49.052 µg·h/mL), which indicated better performance of the formulated gel.

In-situ Gels for Brain Delivery: Breaching the Barriers

The blood-brain barrier (BBB) regulates blood and chemical exchange in the central nervous system. It is made up of brain parenchyma capillary endothelial cells. It separates the interstitial cerebrospinal fluid from the circulation and limits brain drug entry. Peptides, antibodies, and even tiny hydrophilic biomolecules cannot flow across the BBB due to their semi-permeability. It protects the brain from poisons, chemicals, and pathogens, and blood cells penetrate brain tissue. BBB-facilitated carrier molecules allow selective permeability of nutrients such as D-glucose, L-lactic acid, L-phenylalanine, L-arginine, and hormones, especially steroid hormones. Brain barriers prevent drug molecules from entering, making medication delivery difficult. Drugs can reach specific brain regions through the nasal cavity, making it a preferred route. The in-situ gels are mucoadhesive, which extends their stay in the nasal cavity, allows them to penetrate deep and makes them a dependable way of transporting numerous medications, including peptides and proteins, straight into the central nervous system. This approach holds great potential for neurological therapy as they deliver drugs directly to the central nervous system, with less interference and better drug release control. The brain affects daily life by processing sensory stimuli, controlling movement and behaviour, and sustaining mental, emotional, and cognitive functioning. Unlike systemic routes, the nasal mucosa is extensively vascularized and directly contacts olfactory sensory neurons. Compared to the systemic circulation, this improves brain bioavailability of medications. Drugs can be delivered to the brain using in-situ gel formulations safely and efficiently, with a greater therapeutic impact than with traditional techniques.

Drug delivery to the brain via the nasal route of administration: exploration of key targets and major consideration factors

Background

Cranial nerve-related diseases such as brain tumors, Alzheimer's disease, and epilepsy are serious diseases that continue to threaten human. Brain-related diseases are increasing worldwide, including in the United States and Korea, and these increases are closely related to the exposure to harmful substances and excessive stress caused by rapid industrialization and environmental pollution. Drug delivery to the brain is very important for the effective prevention and treatment of brain-related diseases. However, due to the presence of the blood-brain barrier and the extensive first-pass metabolism effect, the general routes of administration such as oral and intravenous routes have limitations in drug delivery to the brain. Therefore, as an alternative, the nasal-brain drug delivery route is attracting attention as a route for effective drug delivery to the brain.

Areas covered

This review includes physiological factors, advantages, limitations, current application status, especially in clinical applications, and the necessary factors for consideration in formulation development related to nasal-brain drug delivery.

Expert opinion

The nasal-brain drug delivery route has the advantage of enhancing drug delivery to the brain locally, mainly through the olfactory route rather than the systemic circulation. The nasal-brain lymphatic system has recently attracted attention, and it has been implied that the delivery of anticancer drugs to the brain nervous system is possible effectively. However, there are limitations such as low drug permeability, as well as nasal mucosa and the mucociliary system, as obstacles in nasal-brain drug delivery. Therefore, to overcome the limitations of nasal-brain drug delivery, the use of nanocarriers and mucoadhesive agents is being attempted. However, very few drugs have been officially approved for clinical application via the nasal-brain drug delivery route. This is probably because the understanding of and related studies on nasal-brain drug delivery are limited. In this review, we tried to explore the major considerations and target factors in drug delivery through the nasal-brain route based on physiological knowledge and formulation research information. This will help to provide a mechanistic understanding of drug delivery through the nasal-brain route and bring us one step closer to developing effective formulations and drugs in consideration of the key factors for nasal-brain drug delivery.

Development of Thermoresponsive-Gel-Matrix-Embedded Amoxicillin Trihydrate-Loaded Bovine Serum Albumin Nanoparticles for Local Intranasal Therapy

A high dose of amoxicillin is recommended as the first-line therapy for acute bacterial rhinosinusitis (ABR). However, oral administration of amoxicillin is connected to many adverse reactions coupled with moderate bioavailability (~60%). Therefore, this study aimed to develop a topical nasal preparation of amoxicillin, employing a thermoresponsive nanogel system to increase nasal residence time and prolong drug release. Rheological investigations revealed that formulations containing 21−23% w/w Poloxamer 407 (P407) were in accordance with the requirement of nasal administration (gelling temperature ~35 °C). The average hydrodynamic diameter (<200 nm), pH (6.7−6.9), and hypertonic osmolality (611−663 mOsmol/L) of the in situ gelling nasal nanogel appeared as suitable characteristics for local rhinosinusitis treatment. Moreover, taking into account the mucoadhesive strength and drug release studies, the 21% w/w P407 could be considered as an optimized concentration for effective nasal delivery. Antibacterial activity studies showed that the ability of amoxicillin-loaded in situ gelling nasal nanogel to inhibit bacterial growth (five common ABR pathogens) preserved its effectiveness in comparison to 1 mg/mL amoxicillin aqueous solution as a positive control. Altogether, the developed amoxicillin-loaded in situ gelling thermoresponsive nasal nanogel can be a potential candidate for local antibiotic therapy in the nasal cavity.

Thermoreversible Carbamazepine In Situ Gel for Intranasal Delivery: Development and In Vitro, Ex Vivo Evaluation

Over the past decade, intranasal (IN) delivery has been gaining attention as an alternative approach to conventional drug delivery routes targeting the brain. Carbamazepine (CBZ) is available as an orally ingestible formulation. The present study aims to develop a thermoreversible in situ gelling system for delivering CBZ via IN route. A cold method of synthesis has been used to tailor and optimize the thermoreversible gel composition, using poloxamer 407 (P407) (15-20% w/v) and iota carrageenan (ɩ-Cg) (0.15-0.25% w/v). The developed in situ gel showed gelation temperatures (28-33°C), pH (4.5-6.5), rheological properties (pseudoplastic, shear thinning), and mucoadhesive strength (1755.78-2495.05 dyne/cm²). The in vitro release study has shown sustained release behavior (24 h) for gel, containing significant retardation of CBZ release. The release kinetics fit to the Korsmeyer-Peppas model, suggesting the non-Fickian diffusion type controlled release behavior. Ex vivo permeation through goat nasal mucosa showed sustained release from the gel containing 18% P407 with the highest cumulative drug permeated (243.94 µg/cm²) and a permeation flux of 10.16 µg/cm²/h. After treatment with CBZ in situ gel, the barrier function of nasal mucosa remained unaffected. Permeation through goat nasal mucosa using in situ gel has demonstrated a harmless nasal delivery, which can provide a new dimension to deliver CBZ directly to the brain bypassing the blood-brain barrier.

A Comprehensive Review of Cross-Linked Gels as Vehicles for Drug Delivery to Treat Central Nervous System Disorders

Gels are attractive candidates for drug delivery because they are easily producible while offering sustained and/or controlled drug release through various mechanisms by releasing the therapeutic agent at the site of action or absorption. Gels can be classified based on various characteristics including the nature of solvents used during preparation and the method of cross-linking. The development of novel gel systems for local or systemic drug delivery in a sustained, controlled, and targetable manner has been at the epitome of recent advances in drug delivery systems. Cross-linked gels can be modified by altering their polymer composition and content for pharmaceutical and biomedical applications. These modifications have resulted in the development of stimuli-responsive and functionalized dosage forms that offer many advantages for effective dosing of drugs for Central Nervous System (CNS) conditions. In this review, the literature concerning recent advances in cross-linked gels for drug delivery to the CNS are explored. Injectable and non-injectable formulations intended for the treatment of diseases of the CNS together with the impact of recent advances in cross-linked gels on studies involving CNS drug delivery are discussed.

Nose-to-brain drug delivery for the treatment of Alzheimer's Disease: Current advancements and challenges

INTRODUCTION

The irreversible destruction of neurons, progressive loss of memory and cognitive behavior, high cost of therapy, and impact on society desire a better, effective, and affordable treatment of AD. The nose-to-brain drug delivery approach holds a great potential to access the brain without any hindrance of BBB and result in higher bioavailability thus better therapeutic efficacy of anti-AD drugs.

AREAS COVERED

The present review article highlighted the current facts and worldwide statistics of AD and its detailed etiology. Followed by barriers to brain delivery, nose-to-brain delivery, their limitations, and amalgamation with various novel carrier systems. We have emphasized recent advancements in nose-to-brain delivery using mucoadhesive, stimuli-responsive carriers, polymeric nanoparticles, lipid nanoparticles, protein/peptide delivery for treatment of AD.

EXPERT OPINION

The available therapies are symptomatic, mitigate the symptoms of AD at the initial stages. In this lieu, nose-to-brain delivery has the ability to overcome these limitations and increase drug bioavailability in the brain. Various novel strategies including stimuli-responsive systems, nanoparticles, etc. enhance the nasal drug permeation, protects the drug, and enhance its therapeutic potency. Although, successful preclinical data does not assure the clinical success of the therapy and hence exhaustive clinical investigations are needed to make the therapy available for patients.

Intranasal delivery of Clozapine using nanoemulsion-based in-situ gels: An approach for bioavailability enhancement

Limited solubility and hepatic first-pass metabolism are the main causes of low bioavailability of anti-schizophrenic drug, Clozapine (CZP). The objective of the study was to develop and validate nanoemulsion (NE) based in-situ gel of CZP for intranasal administration as an approach for bioavailability enhancement. Solubility of CZP was initially investigated in different oils, surfactants and co-surfactants, then pseudoternary phase diagrams were constructed to select the optimized ratio of oil, surfactant and co-surfactant. Clear and transparent NE formulations were characterized in terms of droplet size, viscosity, solubilization capacity, transmission electron microscopy, in-vitro drug release and compatibility studies. Selected NEs were incorporated into different in-situ gel bases using combination of two thermosensitive polymers; Pluronic® F-127 (PF127) and F-68 (PF68). NE-based gels (NG) were investigated for gelation temperature, viscosity, gel strength, spreadability and stability. Moreover, selected NGs were evaluated for ex-vivo permeation, mucoadhesive strength and nasal ciliotoxicity. Peppermint oil, tween 80 and transcutol P were chosen for NE preparation owing to their maximum CZP solubilization. Clear NE points extrapolated from tween 80:transcutol P (1:1) phase diagram and passed dispersibility and stability tests, demonstrated globule size of 67.99 to 354.96 nm and zeta potential of −12.4 to −3.11 mV with enhanced in-vitro CZP release (>90% in some formulations). After incorporation of the selected N3 and N9 formulations of oil:Smix of 1:7 and 2:7, respectively to a mixture of PF127 and PF68 (20:2% w/w), the resultant NG formulations exhibited optimum gelation temperature and viscosity with enhanced CZP permeation and retention through sheep nasal mucosa. Ciliotoxicity examinations of the optimum NGs displayed no inflammation or damage of the lining epithelium and the underlying cells of the nasal mucosa. In conclusion, NE-based gels may be a promising dosage form of CZP for schizophrenia treatment.

Chitosan/Pluronic F127 Thermosensitive Hydrogel as an Injectable Dexamethasone Delivery Carrier

Intra-articular administration of anti-inflammatory drugs is a strategy that allows localized action on damaged articular cartilage and reduces the side effects associated with systemic drug administration. The objective of this work is to prepare injectable thermosensitive hydrogels for the long-term application of dexamethasone. The hydrogels were prepared by mixing chitosan (CS) and Pluronic-F127 (PF) physically. In addition, tripolyphosphate (TPP) was used as a crosslinking agent. Chitosan added to the mix increased the gel time compared to the pluronic gel alone. The incorporation of TPP into the material modified the morphology of the hydrogels formed. Subsequently, MTS and Live/Dead® experiments were performed to investigate the toxicity of hydrogels against human chondrocytes. The in vitro releases of dexamethasone (DMT) from CS-PF and CS-PF-TPP gels had an initial burst and took more time than that from the PF hydrogel. In vivo studies showed that hydrogels retained the fluorescent compound longer in the joint than when administered in PBS alone. These results suggest that the CS-PF and CS-PF-TPP hydrogels loaded with DMT could be a promising drug delivery platform for the treatment of osteoarthritis.

Drug Delivery Systems and Strategies to Overcome the Barriers of Brain

The transport of drugs to the central nervous system is the most challenging task for conventional drug delivery systems. Reduced permeability of drugs through the blood-brain barrier is a major hurdle in delivering drugs to the brain. Hence, various strategies for improving drug delivery through the blood-brain barrier are currently being explored. Novel drug delivery systems (NDDS) offer several advantages, including high chemical and biological stability, suitability for both hydrophobic and hydrophilic drugs, and can be administered through different routes. Furthermore, the conjugation of suitable ligands with these carriers tend to potentiate targeting to the endothelium of the brain and could facilitate the internalization of drugs through endocytosis. Further, the intranasal route has also shown potential, as a promising alternate route, for the delivery of drugs to the brain. This can deliver the drugs directly to the brain through the olfactory pathway. In recent years, several advancements have been made to target and overcome the barriers of the brain. This article deals with a detailed overview of the diverse strategies and delivery systems to overcome the barriers of the brain for effective delivery of drugs.

Formulation and Evaluation of Resveratrol Loaded Cubosomal Nanoformulation for Topical Delivery

AIM

The aim of the study was to formulate, characterize, and evaluate the Resveratrol- loaded Cubosomes (RC) for topical application.

BACKGROUND

Resveratrol (RV) is a nutraceutical compound with exciting pharmacological potential in different diseases, including cancers. Many studies on resveratrol have been reported for anti- melanoma activity. Due to its low bioavailability, the therapeutic activities of resveratrol are strongly limited. Hence, an approach with nanotechnology has been made to increase its activity through transdermal drug delivery.

OBJECTIVE

To formulate, characterize, and evaluate the resveratrol-loaded cubosomes (RC). To evaluate Resveratrol-loaded Cubosomal Gel (RC-Gel) for its topical application.

METHODS

RC was formulated by homogenization technique and optimized using a 2-factor 3-level factorial design. Formulated RCs were characterized for particle size, zeta potential, and entrapment efficiency. Optimized RC was evaluated for in vitro release and stability study. Optimized RC was further formulated into cubosomal gel (RC-Gel) using carbopol and evaluated for drug permeation and deposition. Furthermore, developed RC-Gel was evaluated for its topical application using skin irritancy, toxicity, and in vivo local bioavailability studies.

RESULTS

The optimized RC indicated cubic-shaped structure with mean particle size, entrapment efficiency, and zeta potential were 113±2.36 nm, 85.07 ± 0.91%, and -27.40 ± 1.40 mV, respectively. In vitro drug release of optimized RC demonstrated biphasic drug release with the diffusion-controlled release of resveratrol (RV) (87.20 ± 3.91%). The RC-Gel demonstrated better drug permeation and deposition in mice skin layers. The composition of RC-Gel has been proved non-irritant to mice skin. In vivo local bioavailability study depicted the good potential of RC-Gel for skin localization.

CONCLUSION

The RC nanoformulation proposes a promising drug delivery system for melanoma treatment simply through topical application.

Promising Polymeric Drug Carriers for Local Delivery: The Case of in situ Gels

BACKGROUND

At present, the controlled local drug delivery is a very promising approach compared to systemic administration, since it mostly targets the affected tissue. In fact, various drug carriers for local delivery have been prepared with improved therapeutic efficacy.

OBJECTIVE

in situ polymer gels are drug delivery systems that not only present liquid characteristics before their administration in body, but once they are administered, form gels due to gelation. Their gelation mechanism is due to factors such as pH alteration, temperature change, ion activation or ultraviolet irradiation. in situ gels offer various advantages compared to conventional formulations due to their ability to release drugs in a sustainable and controllable manner. Most importantly, in situ gels can be used in local drug delivery applications for various diseases.

METHODS

This review includes the basic knowledge and theory of in situ gels as well as their various applications according to their administration route.

RESULTS

Various natural, semisynthetic, and synthetic polymers can produce in situ polymeric gels. For example, natural polysaccharides such as alginic acid, chitosan, gellan gum, carrageenan etc. have been utilized as in situ gels for topical delivery. Besides the polysaccharides, poloxamers, poly(Nisopropylacrylamide), poly(ethyleneoxide)/ (lactic-co-glycolic acid), and thermosensitive liposome systems can be applied as in situ gels. In most cases, in situ polymeric gels could be applied via various administration routes such as oral, vaginal, ocular, intranasal and injectable.

CONCLUSION

To conclude, it can be revealed that in situ gels could be a promising alternative carrier for both chronic and immediate diseases.

Intranasal drug delivery for treatment of Alzheimer's disease

The Alzheimer's disease is a neurodegenerative condition with severe consequences interfering with patient quality of life. It is characterized as a progressive and irreversible brain disorder hampering memory and thinking, affecting the capacity to perform daily tasks leading to physical and cognitive incapacitation. The conventional treatment occurs by the oral route, but it presents relevant drawbacks such as low bioavailability, fast metabolism, limited brain exposure, and undesirable side effects. The intranasal route has been proposed as a promising alternative to deliver drugs and improve the Alzheimer's disease treatment. Still, there is not a clear alternative delivery system available in the market with advantageous bioavailability and safety. The aim of this review is to perform an overview on the strategies for drug intranasal delivery for Alzheimer's disease treatment. The advantages and disadvantages of this delivery route and the delivery systems developed so far are discussed. A special focus is given on the use of permeation enhancers, the types of intranasal drug delivery devices, as well as possible toxicity concerns.

Design and Application in Delivery System of Intranasal Antidepressants

One of the major reasons why depressed patients fail their treatment course is the existence of the blood-brain barrier (BBB), which prevents drugs from being delivered to the central nervous system (CNS). In recent years, nasal drug delivery has achieved better systemic bioavailability and activity in low doses in antidepressant treatment. In this review, we focused on the latest strategies for delivery carriers (or formation) of intranasal antidepressants. We began this review with an overview of the nasal drug delivery systems, including nasal drug delivery route, absorption mechanism, advantages, and limitations in the nasal drug delivery route. Next, we introduced the development of nasal drug delivery devices, such as powder devices, liquid-based devices, and so on. Finally, intranasal delivery carriers of antidepressants in clinical studies, including nanogels, nanostructured lipid, liposomes nanoparticles, nanoemulsions/microemulsion, were summarized. Moreover, challenges and future perspectives on recent progress of intranasal delivery carriers in antidepressant treatments were discussed.

Connecting the dots in drug delivery: A tour d'horizon of chitosan-based nanocarriers system

One of the most promising pharmaceutical research areas is developing advanced delivery systems for controlled and sustained drug release. The drug delivery system (DDS) can be designed to strengthen the pharmacological and therapeutic characteristics of different medicines. Natural polymers have resolved numerous commencing hurdles, which hindered the clinical implementation of traditional DDS. The naturally derived polymers furnish various advantages such as biodegradability, biocompatibility, inexpensiveness, easy availability, and biologically identifiable moieties, which endorse cellular activity in contrast to synthetic polymers. Among them, chitosan has recently been in the spotlight for devising safe and efficient DDSs due to its superior properties such as minimal toxicity, bio-adhesion, stability, biodegradability, and biocompatibility. The primary amino group in chitosan shows exceptional qualities such as the rate of drug release, anti-microbial properties, the ability to cross-link with various polymers, and macrophage activation. This review intends to provide a glimpse into different practical utilization of chitosan as a drug carrier. The first segment of the review will give cognizance into the source of extraction and chitosan's remarkable properties. Further, we have endeavored to provide recent literature pertaining to chitosan applications in various drug delivery systems via different administration routes along with current patented chitosan formulations.

Nanoparticlized System: Promising Approach for the Management of Alzheimer's Disease through Intranasal Delivery

Alzheimer's disease (AD) is a neurodegenerative brain problem and responsible for causing dementia in aged people. AD has become most common neurological disease in the elderly population worldwide and its treatment remains still challengeable. Therefore, there is a need of an efficient drug delivery system which can deliver the drug to the target site. Nasal drug delivery has been used since prehistoric times for the treatment of neurological disorders like Alzheimer's disease (AD). For delivering drug to the brain, blood brain barrier (BBB) is a major rate limiting factor for the drugs. The desired drug concentration could not be achieved through the conventional drug delivery system. Thus, nanocarrier based drug delivery systems are promising for delivering drug to brain. Nasal route is a most convenient for targeting drug to the brain. Several factors and mechanisms need to be considered for an effective delivery of drug to the brain particularly AD. Various nanoparticlized systems such as nanoparticles, liposomes, exosomes, phytosomes, nanoemulsion, nanosphere, etc. have been recognized as an effective drug delivery system for the management of AD. These nanocarriers have been proven with improved permeability as well as bioavailability of the anti-Alzheimer's drugs. Some novel drug delivery systems of anti-Alzheimer drugs are under investigation of different phase of clinical trials. Present article highlights on the nanotechnology based intranasal drug delivery system for the treatment of Alzheimer's disease. Furthermore, consequences of AD, transportation mechanism, clinical updates and recent patents on nose to brain delivery for AD have been discussed.

Nano Carrier Drug Delivery Systems for the Treatment of Neuropsychiatric Disorders: Advantages and Limitations

Neuropsychiatric diseases are one of the main causes of disability, affecting millions of people. Various drugs are used for its treatment, although no effective therapy has been found yet. The blood brain barrier (BBB) significantly complicates drugs delivery to the target cells in the brain tissues. One of the problem-solving methods is the usage of nanocontainer systems. In this review we summarized the data about nanoparticles drug delivery systems and their application for the treatment of neuropsychiatric disorders. Firstly, we described and characterized types of nanocarriers: inorganic nanoparticles, polymeric and lipid nanocarriers, their advantages and disadvantages. We discussed ways to interact with nerve tissue and methods of BBB penetration. We provided a summary of nanotechnology-based pharmacotherapy of schizophrenia, bipolar disorder, depression, anxiety disorder and Alzheimer's disease, where development of nanocontainer drugs derives the most active. We described various experimental drugs for the treatment of Alzheimer's disease that include vector nanocontainers targeted on β-amyloid or tau-protein. Integrally, nanoparticles can substantially improve the drug delivery as its implication can increase BBB permeability, the pharmacodynamics and bioavailability of applied drugs. Thus, nanotechnology is anticipated to overcome the limitations of existing pharmacotherapy of psychiatric disorders and to effectively combine various treatment modalities in that direction.

Nose-to-brain delivery of teriflunomide-loaded lipid-based carbopol-gellan gum nanogel for glioma: Pharmacological and in vitro cytotoxicity studies

The research work was intended to formulate teriflunomide (TFM) loaded nano lipid-based (TNLC) carbopol-gellan gum in situ gel (TNLCGHG) and to investigate its therapeutic efficacy against glioma, a brain and spine tumor. Nanoformulation was developed using gellan gum and carbopol 974P as gelling and mucoadhesive agents, respectively, Glyceryl di-behenate and Glyceryl mono-linoleate blend as lipids, and Gelucire 44/14: water blend as surfactant system. Globule size, PDI, zeta potential, encapsulation efficiency, mucoadhesive strength, and nasal permeation were found to be 117.80 nm, 0.56, -21.86 mV, 81.16%, 4.80 g, and 904 μg/cm², respectively. Anticancer efficacy of TFM-loaded nano lipid-based carbopol-gellan gum in situ gel (TNLCGHG) was determined in human U-87MG glioma cell line. IC₅₀ was found 7.0 μg/mL for TNLCGHG, 4.8 μg/mL for pure TFM, and 78.5 μg/mL for TNLC, which approve the superiority of surfactant along with gellan gum as permeation enhancer. Brain C_max for technetium (^99mTC) labeled intranasal (i.n.) ^99mTC-TNLCGHG was found 2-folds higher than ^99mTC-TNLC (i.n.) and ^99mTC-TNLC intravenous (i.v.) because the TNLCGHG formulation contains surfactant with natural gelling polymers, which promisingly improved drug permeability. Finally, this research revealed encouraging outcomes and successfully developed intranasal TNLCGHG nanoformulation as a novel tool for safe delivery of TFM in glioma patients.

Liquid Crystalline Nanoparticles for Nasal Delivery of Rosuvastatin: Implications on Therapeutic Efficacy in Management of Epilepsy

In the present study we investigated the protective role of intranasal rosuvastatin liquid crystalline nanoparticles (Ros-LCNPs) against pentylenetetrazole (PTZ) induced seizures, increasing current electroshock (ICES) induced seizures, and PTZ-induced status epilepticus. From the dose titration study, it was evident that intranasal rosuvastatin (ROS), at lower dose, was more effective than oral and intraperitoneal ROS. The Ros-LCNPs equivalent to 5 mg/kg ROS were developed by hydrotrope method using glyceryl monooleate (GMO) as lipid phase. The high resolution TEM revealed that the formed Ros-LCNPs were cubic shaped and multivesicular with mean size of 219.15 ± 8.14 nm. The Ros-LCNPs showed entrapment efficiency of 70.30 ± 1.84% and release was found to be biphasic following Korsmeyer–Peppas kinetics. Intranasal Ros-LCNPs (5 mg/kg) showed significant increase in latency to PTZ-induced seizures and ICES seizure threshold compared to control and intranasal ROS solution. Additionally, intranasal Ros-LCNPs provided effective protection against PTZ-induced status epilepticus. No impairment in cognitive functions was observed following intranasal Ros-LCNPs. The results suggested that Ros-LCNPs could be an effective and promising therapeutics for the epilepsy management.

Design, Characterization, and Application of a pH-Triggered In Situ Gel for Ocular Delivery of Vinpocetine

We developed a pH-triggered in situ gel (ISG) for ocular delivery of vinpocetine to achieve systemic absorption and a brain-targeting effect in rats. Carbopol acted as a gelling agent combined with hydroxypropyl methylcellulose (HPMC) as a viscosity-enhancing agent. The concentration of Carbopol (0.2%, w/v) and HPMC (1.5%, w/v) was optimized for the ISG system. The optimized formulation was evaluated for studies on release in vitro, rheology, differential scanning calorimetry, ocular irritation, residence time, and in vivo pharmacokinetics. The vinpocetine ISG stayed longer in rabbit eyes than vinpocetine ointment. In vivo pharmacokinetics showed that compared with vinpocetine ointment, vinpocetine ISG attained a peak plasma concentration and area under the curve that was 1-2 folds greater in rat plasma. The Drug Targeting Index (DTI) was 1.06 and 1.26 for vinpocetine ointment and vinpocetine ISG, respectively, after ocular administration, showing that vinpocetine ISG had better distribution in rat brain. These results revealed that a pH-triggered ISG system via ocular administration could be an alternative approach compared with traditional ophthalmic formulations.

Stimuli-responsive In situ gelling system for nose-to-brain drug delivery

The diagnosis and treatment of neurological ailments always remain an utmost challenge for research fraternity due to the presence of BBB. The intranasal route appeared as an attractive and alternative route for brain targeting of therapeutics without the intrusion of BBB and GI exposure. This route directly and effectively delivers the therapeutics to different regions of the brain via olfactory and trigeminal nerve pathways. However, shorter drug retention time and mucociliary clearance curtail the efficiency of the intranasal route. The in situ mucoadhesive gel overthrow the limitations of direct nose-to-brain delivery by not only enhancing nasal residence time but also minimizing the mucociliary clearance and enzymatic degradation. This delivery system further improves the nasal absorption as well as bioavailability of drugs in the brain. The in situ mucoadhesive gel is a controlled and sustained release system that facilitates the absorption of various proteins, peptides and other larger lipophilic and hydrophilic moieties. Owing to multiple benefits, in situ gelling system has been widely explored to target the brain via nasal route. However, very few review works are reported which explains the application of in situ nasal gel for brain delivery of CNS acting moieties. Hence, in this piece of work, we have initially discussed the global statistics of neurological disorders reported by WHO and other reputed organizations, nasal anatomy, mechanism and challenges of nose-to-brain drug delivery. The work mainly focused on the use of different stimuli-responsive polymers, specifically thermoresponsive, pH-responsive, and ion triggered systems for the development of an effective and controlled dosage form, i.e., in situ nasal gel for brain targeting of bioactives. We have also highlighted the origin, structure, nature and phase transition behavior of the smart polymers found suitable for nasal administration, including poloxamer, chitosan, EHEC, xyloglucan, Carbopol, gellan gum and DGG along with their application in the treatment of neurological disorders. The article is aimed to gather all the information of the past 10 years related to the development and application of stimuli-responsive in situ nasal gel for brain drug delivery.

Primary Studies on Construction and Evaluation of Ion-Sensitive in situ Gel Loaded with Paeonol-Solid Lipid Nanoparticles for Intranasal Drug Delivery

BACKGROUND

Paeonol (PAE) is a potential central neuroprotective agent with poor water solubility and rapid metabolism in vivo. The key to improve the clinical application of PAE in the treatment of neurodegenerative diseases is to improve the brain delivery of it. The purpose of this study was to construct a paeonol-solid lipid nanoparticles-in situ gel (PAE-SLNs-ISG) drug delivery system based on nose-brain transport pathway.

MATERIALS AND METHODS

In this study, the stability of PAE in simulated biological samples was studied firstly in order to clarify the reasons for low oral bioavailability. Paeonol-solid lipid nanoparticles (PAE-SLNs) were prepared by high-temperature emulsification-low-temperature curing combined with ultrasound. The PAE-SLNs-ISG drug delivery system was constructed, and related formulation optimization, preparation characterization, cell evaluation and in vivo evaluation were performed.

RESULTS

The metabolic mechanism of PAE incubated in the liver microsomes metabolic system was in accordance with the first-order kinetics, and the half-life was 0.23 h. PAE-SLNs were polyhedral or spherical particles with good dispersion and the particle size was 166.79 nm ± 2.92 nm. PAE-SLNs-ISG solution was a Newtonian fluid with a viscosity of 44.36 mPa · S ± 2.89 mPa · S. The viscosity of PAE-SLNs-ISG gel was 1542.19 mPa · S ± 19.30 mPa · S, and the rheological evaluation showed that the gel was a non-Newtonian pseudoplastic fluid with shear thinning, thixotropy and yield value. The release mechanism of PAE from PAE-SLNs was drug diffusion; the release mechanism of PAE from PAE-SLNs-ISG was a synergistic effect of skeleton erosion and drug diffusion. The cell viabilities of PAE-SLNs and PAE-SLNs-ISG in the concentration range of 0.001 µg/mL to 10 µg/mL were higher than 90%, showing a low level of cytotoxicity. The geometric mean fluorescent intensities of RPMI 2650 cells incubated with fluorescein isothiocyanate-solid lipid nanoparticles (FITC-SLNs) for 1 h, 4 h and 6 h were 1841 ± 24, 2261 ± 27 and 2757 ± 22, respectively. Cyanine7 NHS ester-solid lipid nanoparticles-in situ gel (Cy7-SLNs-ISG) accumulated effectively in the brain area after administration through the olfactory area, and the fluorescence response was observed in olfactory bulb, cerebellum and striatum.

CONCLUSION

SLNs-ISG nose-brain drug delivery system can effectively deliver SLNs to brain regions, and it is a potentially effective strategy to realize the brain region delivery of PAE.

Formulation strategies to modulate drug release from poloxamer based in situ gelling systems

Introduction: Poloxamer based in situ gelling systems offer numerous advantages in drug delivery; however, their application as prolonged-release delivery platforms is limited mainly due to their weak mechanical properties and the interconnected aqueous network causing fast gel erosion and drug diffusion.Area covered: The focus of this review is to provide an insightful discussion on the formulation strategies that can be employed to sustain/prolong the drug release from poloxamer based in situ gelling systems. The review also outlines the formulation factors, influencing drug release from these systems.Expert opinion: The nature, composition, and concentration of poloxamers are the most critical factors in defining the rate of drug release from an in situ gelling matrix. Hydrophobic gel matrices have compact micellar arrangements resulting in slow diffusion and erosion. Depending on the intended clinical application, gel characteristics can be modulated, either by physical blending or by chemical crosslinking with additive materials, to slow release and improve residence time at the administration site. Incorporating drug-loaded particles into poloxamer gels sustains drug release by creating multiple rate-limiting release barriers. Chemical modification of poloxamers appears to be a promising strategy to obtain prolonged sustained release for parenteral application without compromising the rheological properties of the formulation.

Mucoadhesive thermoreversible formulation of metoclopramide for rectal administration: a promising strategy for potential management of chemotherapy-induced nausea and vomiting

The study aimed to investigate the feasibility of incorporation of metoclopramide hydrochloride (MCP HCl) in mucoadhesive thermoreversible liquid suppository (MCP HCl_-LS) to bypass the first-pass metabolism and maximize its efficacy to be a promising substitute for parenteral therapy. MCP HCl_-LS was formulated using Pluronic (PF127/PF68) and hydroxypropylmethylcellulose (HPMC) and in vitro evaluated through their gelation temperature, gel strength (GS), mucoadhesive force, and in vitro release studies. Also, the MCP HCl_-LS was evaluated for its rheological behavior and examined for rectal mucosal integrity after administration. The results revealed that the MCP HCl_-LS; composed of PF127/PF68/HPMC (20/7/0.5% w/w) was in the liquid state at room temperature, experienced gelation at 30.23 °C, with suitable GS of 28.66 s and rectal retention force of 43.03 × 10² dyne/cm². The pharmacokinetic data showed that the MCP HCl_-LS exhibited a significant increase (p < 0.05) in AUC_0-480 (219.688 vs 172.333 ng.h.mL^-1 of the marketed) and 1.3-fold increase in relative bioavailability compared to Primperan^® suppository, indicating that LS formula bypassed the first-pass metabolism. Moreover, MCP HCl_-LS did not cause any morphological harm to the rectal tissues suggested that the developed formulation was safe and could be a potentially useful alternative drug carrier for rectal delivery of MCP HCl in patients experiencing chemotherapy-induced nausea and vomiting.

Current Limitations in the Treatment of Parkinson's and Alzheimer's Diseases: State-of-the-Art and Future Perspective of Polymeric Carriers

Alzheimer's and Parkinson's diseases are the most common neurodegenerative diseases worldwide and their incidence is increasing due to the aging population. At the moment, the available therapies are not disease modifying and have several limitations, some of which are discussed in this review. One of the main limitations of these treatments is the low concentration that drugs reach in the central nervous system after systemic administration. Indeed, the presence of biological barriers, particularly the blood-brain barrier (BBB), hinders the effective drug delivery to the brain, reducing the potential benefit coming from the administration of the medication. In this review, the mechanisms of transport across the BBB and new methods to improve drug passage across the BBB are discussed. These methods include non-invasive solutions such as intranasal and intravitreal administration, and the use of nanotechnology solutions based on polymeric carriers when the drug is intravenously injected, orally taken for intestine adsorption or delivered through the dermal mucosa. Also, it provides an analysis of more invasive solutions that include intracranially injected hydrogels and implanted devices for local drug delivery. Efforts in finding new therapeutic drugs blocking neurodegenerative disease progression or reverting their course should be coupled with efforts addressed to efficient drug delivery systems. Hence, new pharmacology discoveries together with advancements in nanotechnologies and biomaterials for regenerative medicine are required to effectively counteract neurodegenerative diseases.

Superiority of TPGS-loaded micelles in the brain delivery of vinpocetine via administration of thermosensitive intranasal gel

Background: Vinpocetine (VPN) is a synthetic derivative of the Vinca minor alkaloids. The drug is characterized by a short half-life, limited water solubility and high hepatic first-pass effect. The objective was to develop different lipid-based nanocarriers (NCs) loaded into a thermosensitive in situ gelling (ISG) system to improve VPN bioavailability and brain targeting via intranasal (IN) delivery. Methods:  Different lipid-based NCs were developed and characterized for vesicle size, zeta potential, VPN entrapment efficiency (EE) and morphological characterization using transmission electron microscope (TEM). The prepared NCs were loaded into ISG formulations and characterized for their mucoadhesive properties. Ex-vivo permeation and histological study of the nasal mucosa were conducted. Pharmacokinetic and brain tissue distribution were investigated and compared to a marketed VPN product following administration of a single dose to rats. Results: VPN-D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) micelles nano-formulation showed the smallest particle size, highest EE among the studied NCs. TEM images revealed an almost spherical shape for all the prepared NCs. Among the NCs studied, VPN-loaded TPGS micelles demonstrated the highest percent cumulative VPN ex vivo permeation. All the prepared ISG formulations revealed the presence of mucoadhesive properties and showed no signs of inflammation or necrosis upon histological examination. Rats administered IN VPN-loaded TPGS-micelles ISG showed superior VPN concentration in the brain tissue and significant high relative bioavailability when compared to that received raw VPN-loaded ISG and marketed drug oral tablets. VPN-D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) micelles nano-formulation showed the smallest particle size, highest EE among the studied NCs. TEM images revealed an almost spherical shape for all the prepared NCs. Among the NCs studied, VPN-loaded TPGS micelles demonstrated the highest percent cumulative VPN ex vivo permeation. All the prepared ISG formulations revealed the presence of mucoadhesive properties and showed no signs of inflammation or necrosis upon histological examination. Rats administered IN VPN-loaded TPGS-micelles ISG showed superior VPN concentration in the brain tissue and significant high relative bioavailability when compared to that received raw VPN-loaded ISG and marketed drug oral tablets. Conclusion: VPN-loaded TPGS-micelles ISG formulation is a successful brain drug delivery system with enhanced bioavailability for drugs with poor bioavailability and those that are frequently administered.

Buspirone Hydrochloride Loaded In Situ Nanovesicular Gel as an Anxiolytic Nasal Drug Delivery System: In Vitro and Animal Studies

Nasal nanovesicular gels of buspirone hydrochloride (BH) were prepared and characterized aiming for sustained delivery and enhancing bioavailability. Buspirone hydrochloride has low bioavailability of about 4% after oral administration due to first pass metabolism. Buspirone hydrochloride nanovesicles were formulated by thin film hydration method (TFH). The selected nanovesicular formulation was incorporated into two types of in situ gels (pH-induced and thermoreversible) using carbopol 974P and poloxamer 407 (P407), respectively, together with different mucoadhesive polymers. The in situ gels were examined for pH, gelling capability, viscosity, content uniformity, mucoadhesiveness, and in vitro drug release. The ex vivo permeation performance of the in situ gel formulations that showed the most sustained release was also assessed. The in vivo study was done by the determination of BH blood level in albino rabbits after nasal administration. Results revealed that nanovesicles prepared using Span 60 and cholesterol in a ratio of 80:20 showed the highest EE% (70.57 ± 1.00%). The ex vivo permeation data confirmed higher permeability figures for carbopol formulation in comparison to poloxamer formulations. The in vivo study data showed an increase of 3.26 times in BH bioavailability when formulated into the carbopol nanovesicular in situ gel relative to control (nasal drug solution).