Intranasal solid lipid nanoparticles for management of pain: A full factorial design approach, characterization & Gamma Scintigraphy

A randomized, double-blind study to compare the efficacy and safety of nalbuphine nasal spray and injectable solution in patients after orthopaedic interventions and traumatological procedures

AIMS

Our previous 3-period crossover study in healthy volunteers comparing the pharmacokinetics of nalbuphine nasal spray Apain with parenteral nalbuphine solution demonstrated high bioavailability of the nasal spray and close similarity of pharmacokinetic profiles after intranasal and intramuscular administration, especially within 30 min postdose. The aim of the present study was a noninferiority assessment of nalbuphine nasal spray vs. intramuscular injection for pain relief in postoperative patients.

METHODS

Ninety orthopaedic and traumatology patients were enrolled in this double-blind, randomized study of the effectiveness and tolerance of a single 10.5 mg dose of nalbuphine nasal spray vs. 10 mg intramuscular injection. The summed pain intensity difference (SPID0-6) calculated using visual analogue scale scores was the primary study endpoint.

RESULTS

Of 90 subjects enrolled, the per-protocol efficacy population comprised 79 patients; 6 patients in the reference group and 5 patients in the test group were excluded due to remedication. The mean values of study endpoints with 95% confidence interval were as follows in reference and test groups, respectively: SPID0-6 = 228.08 (205.73-250.43) vs. 248.73 9 (225.83-271.63), time to pain relief onset = 0.28 h (0.25-0.31) vs. 0.27 h (0.25-0.29), duration of analgesia = 5.55 h (5.17-5.93) vs. 5.51 h (5.10-5.92), area under the curve = 119.30 (91.17-147.43) vs. 99.81 (74.52-107.10). No statistically significant differences were revealed.

CONCLUSION

Nalbuphine nasal spray Apain has been proven to be a safe, noninvasive alternative to intramuscular nalbuphine to relieve severe postoperative pain. Designed for self-administration and dose-adjusting, the noncontrolled opioid analgesic nalbuphine spray can be used for patient-controlled analgesia in out-of-hospital, field and home settings.

In silico and in vitro assessment of an optimized QbD-guided myoinositol and metformin-loaded mucus-penetrating particle-based gel for the amelioration of PCOS

Polycystic ovarian syndrome (PCOS) is a multi-factorial endocrine disorder affecting women of reproductive age. However, its high prevalence and the unsuccessful translation of conventional modalities have made PCOS a pharmaco-therapeutic challenge. In the present study, we explored bi-formulations (comprising metformin-loaded mucus-penetrating nanoparticles, MTF-MPPs, and myoinositol-loaded mucus-penetrating particles, MI-MPPs) incorporated in a carbomer gel tailored for intravaginal administration. For the development and optimization of the MPPs-gel, a QbD (quality by design) approach was employed, including the initial and final risk assessment, central composite design of experts, and method validation. The optimized MTF-MPPs and MI-MPPs possessed an optimum nanometric particle size (195.0 nm and 178.8 nm, respectively) and a PDI of 0.150 and 0.123, respectively, together with a negligible negative zeta potential (-5.19 mV and -6.19 mV, respectively) through the vaginal mucus. It was observed that the MPPs are small and monodisperse with a neutral surface charge. It was observed that the MPPs-gel formulations released approximately 69.86 ± 4.65% of MTF and 67.14 ± 5.74% of MI within 120 h (5 days), which was observed to be sustained unlike MFT-MI-gel with approximately 94.89 ± 4.17% of MTF and 90.91 ± 15% of MI drugs released within 12 h. The confocal microscopy study of rhodamine-loaded MPPs indicated that they possessed a high fluorescence intensity at a depth of 15 μm, while as the penetration trajectory in the vaginal tissue increased to 35 μm, their intensity was reduced, appearing to be more prominent in the blood vessels. The analyzed data of MPPs-gel suggest that the optimized MPPs-gel formulation has potential to reach the targeted area via the uterovaginal mucosa, which has a wide network of blood vessels. Subsequently, in vivo studies were conducted and the results revealed that the proposed MPPs-gel formulation could regulate the estrous cycle of the reproductive system compared to the conventional formulation. Moreover, the formulation significantly reduced the weight of the ovaries compared to the control and conventional vaginal gel. Biochemical estimation showed improved insulin and sex hormone levels. Thus, the obtained data revealed that the deep penetration and deposition of MTF and MI on the targeted area through intravaginal delivery resulted in better therapeutic effects than the conventional vaginal gel. The obtained results confirmed the amelioration of PCOS upon treatment using the prepared MPPs-gel formulation. According to the relevant evaluation studies, it was concluded that MPPs-gel was retained in the vaginal cavity for systemic effects. Also, the sustained and non-irritating therapeutic effect meets the safety aspects. This work serves as a promising strategy for intravaginal drug delivery.

Comparative pharmacokinetics of nalbuphine nasal spray and solution for injection in healthy volunteers

AIMS

Nalbuphine is a synthetic opioid with comparable analgesic activity to morphine but with a better safety profile. Nalbuphine is only available in injectable form due to low oral bioavailability. Nasal nalbuphine spray provides advantages in drug safety, avoids hepatic first-pass metabolism, is non-invasive and is convenient for patient-controlled analgesia by self-administration. This study aimed to evaluate the safety and pharmacokinetics (PK) of the newly developed nalbuphine nasal spray in comparison with a solution for injections.

METHODS

Twenty-four healthy Caucasian volunteers were enrolled in this randomized, open-label, cross-over study. Subjects were administered one of the drugs: nasal spray 7.0 mg/dose, nalbuphine hydrochloride solution for injection 10 mg/dose intravenously (IV) or intramuscularly (IM). High-performance liquid chromatography-tandem mass spectrometry was used to determine nalbuphine concentrations.

RESULTS

A comparison of PK profiles for IV, IM and intranasal (IN) routes of nalbuphine administration revealed a close similarity of absorption phases for nasal spray and IM injection. Differences between the mean Tmax and dose-adjusted Cmax values for nasal spray and IM injection were statistically insignificant. The median values of the elimination rate constants and the terminal elimination half-life following IV, IM and IN nalbuphine administration were similar. The mean absolute bioavailability of the nasal spray equalled 65.04%.

CONCLUSIONS

The similarity of PK parameters of IM-injected nalbuphine solution and the nasal spray allows us to assume the latter is a feasible alternative to intramuscular nalbuphine injections appropriate for self-administration and field environments for managing moderate and severe pain of various aetiologies.

Illuminating Insights: Clinical Study Harnessing Pharmacoscintigraphy for Permeation Study of Radiolabeled Nimesulide Topical Formulation in Healthy Human Volunteers

An alternative to oral administration for the delivery of therapeutic substances is the topical route, which frequently has comparable efficacy but may have a better tolerability profile. Gamma scintigraphy is a noninvasive technique that involves the application of radioactive substances to conduct biodistribution studies of therapeutic substances delivered through various routes. Nimesulide (NSD) was radiolabeled with technetium pertechnetate (Technetium99m [99mTc]) and this radiolabeled drug complex (99mTc-NSD) was used to prepare a topical gel formulation. The permeation of the radiolabeled drug from the topical gel was determined by gamma scintigraphy on human volunteers. The region of interest was calculated for the quantification of permeated radiolabeled drugs. This was observed that the mean percentage permeation of 99mTc-NSD was found to be 0.32 ± 0.22 to 36.37 ± 2.86 at 5 and 240 min. It was demonstrated that gamma scintigraphy may be a noninvasive and reliable technique for the determination of drug permeation through topical routes.

Advanced multifunctional nano-lipid carrier loaded gel for targeted delivery of 5-flurouracil and cannabidiol against non-melanoma skin cancer

Non-melanoma skin cancer is one of the most common malignancies reported around the globe. Current treatment therapies fail to meet the desired therapeutic efficacy due to high degree of drug resistance. Thus, there is prominent demand in advancing the current conventional therapy to achieve desired therapeutic efficacy. To break the bottleneck, nanoparticles have been used as next generation vehicles that facilitate the efficient interaction with the cancer cells. Here, we developed combined therapy of 5-fluorouracil (5-FU) and cannabidiol (CBD)-loaded nanostructured lipid carrier gel (FU-CBD-NLCs gel). The current investigation has been designed to evaluate the safety and efficacy of developed 5-Flurouracil and cannabidiol loaded combinatorial lipid-based nanocarrier (FU-CBD NLCs) gel for the effective treatment of skin cancer. Initially, confocal microscopy study results showed excellent uptake and deposition at epidermal and the dermal layer. Irritation studies performed by IR camera and HET cam shows FU-CBD NLCs was much more tolerated and less irritant compared to conventional treatment. Furthermore, gamma scintigraphy evaluation shows the skin retention behavior of the formulation. Later, in-ovo tumor remission studies were performed, and it was found that prepared FU-CBD NLCs was able to reduce tumor volume significantly compared to conventional formulation. Thus, obtained results disclosed that permeation and disposition of 5-FU and CBD into different layers of the skin FU-CBD NLCs gel could be more potential carrier than conventional gel. Furthermore, prepared formulation showed greater tumor remission, better survival rate, reduction in tumor number, area, and volume with improved biochemical profile. Thus, prepared gel could serve as a promising formulation approach for the skin cancer treatment.

Global research trends of nanotechnology for pain management

Background: Nanotechnology has been increasingly used in healthcare during recent years. However, the systematic evaluation of research on nanotechnology for pain management is lacking. In this study, we employed a bibliometric approach to examine the status of the research and global trends of nanotechnology in relation to pain management. Methods: We selected relevant papers published in the Web of Science Core Collection database between 2013 and 2022 using search terms related to nanotechnology and pain management. Subsequently, the following bibliographic information was collected: publication year, originating country/region, affiliated authors and institutions, published journal, references cited, citation frequency, and keywords. The bibliometric software programs VOSViewer and CiteSpace were employed to obtain bibliometric statistics and perform visual analysis. Results: A total of 2680 papers were retrieved. The number of publications in the field of nanotechnology for pain management has been increasing annually since 2013. China had the highest number of published papers, whereas the United States led in total citations. The Chinese Academy of Sciences was the most prolific institution, while the Tehran University of Medical Sciences had the highest overall citations. Furthermore, De Paula was the most prolific author. Papers associated with nanotechnology for pain management were mainly published in the International Journal of Pharmaceutics, Pharmaceutics, and the International Journal of Nanomedicine. Keyword analysis showed that "in-vitro" and "drug-delivery" appeared most frequently, with the top 10 common keywords comprising nanoparticles, pain, in-vitro, drug-delivery, delivery, release, inflammation, neuropathic pain, formulation, and expression. Lastly, the latest emerging keyword was "electrochemical sensor". Conclusion: Research on applying nanotechnology for pain management is growing steadily. China is the top country in terms of number of publications, with institutions under the Chinese Academy of Sciences making significant contributions to this field. "In-vitro" and "drug-delivery" are the current hotspots in this area, with "electrochemical sensor" as the latest topic at the research forefront. However, national and inter-institutional collaborations should be strengthened to enable patients with pain disorders to benefit from nanotechnology implementation in pain management.

The significance of quercetin-loaded advanced nanoformulations for the management of diabetic wounds

Quercetin is a well-known plant flavanol that exhibits multiple biological activities, including antioxidant, anti-inflammatory and anticancer activities. The role of quercetin in wound healing has been widely explored by a range of researchers in different models. However, the physicochemical properties, such as solubility and permeability, of this compound are low, which ultimately limits its bioavailability on the target site. To overcome these limitations for successful therapy, scientists have developed a range of nanoformulations that provide effective therapeutic potential. In this review, the broad mechanism of quercetin for acute and chronic wounds is covered. A compilation of recent advances on the horizon of wound healing via quercetin is incorporated with several advanced nanoformulations.

Recent Progress of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as Ocular Drug Delivery Platforms

Sufficient ocular bioavailability is often considered a challenge by the researchers, due to the complex structure of the eye and its protective physiological mechanisms. In addition, the low viscosity of the eye drops and the resulting short ocular residence time further contribute to the observed low drug concentration at the target site. Therefore, various drug delivery platforms are being developed to enhance ocular bioavailability, provide controlled and sustained drug release, reduce the number of applications, and maximize therapy outcomes. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) exhibit all these benefits, in addition to being biocompatible, biodegradable, and susceptible to sterilization and scale-up. Furthermore, their successive surface modification contributes to prolonged ocular residence time (by adding cationic compounds), enhanced penetration, and improved performance. The review highlights the salient characteristics of SLNs and NLCs concerning ocular drug delivery, and updates the research progress in this area.

Lyophilized Nasal Inserts of Atomoxetine HCl Solid Lipid Nanoparticles for Brain Targeting as a Treatment of Attention-Deficit/Hyperactivity Disorder (ADHD): A Pharmacokinetics Study on Rats

The study aims to investigate the ability of lyophilized nasal inserts of nanosized atomoxetine HCl solid lipid nanoparticles (ATM-SLNs) to transport atomoxetine (ATM) directly to the brain and overcome the first-pass metabolism. In this case, 16 formulae of (ATM-SLNs) were prepared using hot melt emulsification, stirring and ultrasonication method technique. A full factorial design was established with 2⁴ trials by optimization of four variables; lipid type (Compritol 888 ATO or stearic acid) (X1), lipid to drug ratio [(1:2) or (2:1)] (X2), span 60: Pluronic f127 ratio [(1:3) or (3:1)] (X3) and probe sonication time (five or ten minutes) (X4). The prepared SLNs were characterized for entrapment efficiency (EE%), in-vitro drug release after 30 min (Q30min), particle size (PS), zeta potential (ZP) and polydispersity index (PDI). Design Expert^® software was used to select the optimum two formulae. The morphological examination for the optimum two formulae was carried out using a transmission electron microscope (TEM). Furthermore, eight lyophilized nasal inserts were prepared by using a 2³ full factorial design by optimization of three variables: type of (ATM-SLNs) formula (X1), type of polymer (NOVEON AA1 or HPMC K100m) (X2) and concentration of polymer (X3). They were evaluated for nasal inserts' physicochemical properties. The two optimum inserts were selected by Design Expert^® software. The two optimum insets with the highest desirability values were (S4 and S8). They were subjected to DSC thermal stability study and in-vivo study on rats. They were compared with atomoxetine oral solution, atomoxetine (3 mg/kg, intraperitoneal injection) and the pure atomoxetine solution loaded in lyophilized insert. (ATM-SLNs) showed EE% range of (41.14 mg ± 1.8% to 90.6 mg ± 2.8%), (Q30min%) of (27.11 ± 5.9% to 91.08 ± 0.15%), ZP of (-8.52 ± 0.75 to -28.4 ± 0.212% mV), PS of (320.9 ± 110.81% nm to 936.7 ± 229.6% nm) and PDI of (0.222 ± 0.132% to 0.658 ± 0.03%). Additionally, the two optimum (ATM-SLNs) formulae chosen, i.e., F7 and F9 showed spherical morphology. Nasal inserts had assay of drug content of (82.5 ± 2.5% to 103.94 ± 3.94%), Q15min% of (89.9 ± 6.4% to 100%) and Muco-adhesion strength of (3510.5 ± 140.21 to 9319.5 ± 39.425). DSC results of S4 and S8 showed compatibility of (ATM) with the other excipients. S8 and S4 also showed higher trans-nasal permeation to the brain with brain targeting efficiency of (211.3% and 177.42%, respectively) and drug transport percentages of (52.7% and 43.64%, respectively). To conclude, lyophilized nasal inserts of (ATM-SLNs) enhanced (ATM) trans-nasal drug targeting permeation and brain targeting efficiency.

A calcium and zinc composite alginate hydrogel for pre-hospital hemostasis and wound care

We developed, characterized, and examined the hemostatic potential of sodium alginate-based Ca²⁺ and Zn²⁺ composite hydrogel (SA-CZ). SA-CZ hydrogel showed substantial in-vitro efficacy, as observed by the significant reduction in coagulation time with better blood coagulation index (BCI) and no evident hemolysis in human blood. SA-CZ significantly reduced bleeding time (≈60 %) and mean blood loss (≈65 %) in the tail bleeding and liver incision in the mice hemorrhage model (p ≤ 0.001). SA-CZ also showed enhanced cellular migration (1.58-fold) in-vitro and improved wound closure (≈70 %) as compared with betadine (≈38 %) and saline (≈34 %) at the 7th-day post-wound creation in-vivo (p < 0.005). Subcutaneous implantation and intra-venous gamma-scintigraphy of hydrogel revealed ample body clearance and non-considerable accumulation in any vital organ, proving its non-thromboembolic nature. Overall, SA-CZ showed good biocompatibility along with efficient hemostasis and wound healing qualities, making it suitable as a safe and effective aid for bleeding wounds.

Repositioning of drugs for Parkinson's disease and pharmaceutical nanotechnology tools for their optimization

Parkinson's disease (PD) significantly affects patients' quality of life and represents a high economic burden for health systems. Given the lack of safe and effective treatments for PD, drug repositioning seeks to offer new medication alternatives, reducing research time and costs compared to the traditional drug development strategy. This review aimed to collect evidence of drugs proposed as candidates to be reused in PD and identify those with the potential to be reformulated into nanocarriers to optimize future repositioning trials. We conducted a detailed search in PubMed, Web of Science, and Scopus from January 2015 at the end of 2021, with the descriptors "Parkinson's disease" and "drug repositioning" or "drug repurposing". We identified 28 drugs as potential candidates, and six of them were found in repositioning clinical trials for PD. However, a limitation of many of these drugs to achieve therapeutic success is their inability to cross the blood-brain barrier (BBB), as is the case with nilotinib, which has shown promising outcomes in clinical trials. We suggest reformulating these drugs in biodegradable nanoparticles (NPs) based on lipids and polymers to perform future trials. As a complementary strategy, we propose functionalizing the NPs surface by adding materials to the surface layer. Among other advantages, functionalization can promote efficient crossing through the BBB and improve the affinity of NPs towards certain brain regions. The main parameters to consider for the design of NPs targeting the central nervous system are highlighted, such as size, PDI, morphology, drug load, and Z potential. Finally, current advances in the use of NPs for Parkinson's disease are cited.

Cannabis as a potential compound against various malignancies, legal aspects, advancement by exploiting nanotechnology and clinical trials

Various preclinical and clinical studies exhibited the potential of cannabis against various diseases, including cancer and related pain. Subsequently, many efforts have been made to establish and develop cannabis-related products and make them available as prescription products. Moreover, FDA has already approved some cannabis-related products, and more advancement in this aspect is still going on. However, the approved product of cannabis is in oral dosage form, which exerts various limitations to achieve maximum therapeutic effects. A considerable translation is on a hike to improve bioavailability, and ultimately, the therapeutic efficacy of cannabis by the employment of nanotechnology. Besides the well-known psychotropic effects of cannabis upon the use at high doses, literature has also shown the importance of cannabis and its constituents in minimising the lethality of cancer in the preclinical models. This review discusses the history of cannabis, its legal aspect, safety profile, the mechanism by which cannabis combats with cancer, and the advancement of clinical therapy by exploiting nanotechnology. A brief discussion related to the role of cannabinoid in various cancers has also been incorporated. Lastly, the information regarding completed and ongoing trials have also been elaborated.

Micro- and nanocarriers for pain alleviation

Acute or chronic pain is a major source of impairment in quality of life and affects a substantial part of the population. To date, pain is alleviated by a limited range of treatments with significant toxicity, increased risk of misuse and inconsistent efficacy, owing, in part, to lack of specificity and/or unfavorable pharmacokinetic properties. Thanks to the unique properties of nanoscaled drug carriers, nanomedicine may enhance drug biodistribution and targeting, thus contributing to improved bioavailability and lower off-target toxicity. After a brief overview of the current situation and the main critical issues regarding pain alleviation, this review will examine the most advanced approaches using nanomedicine of each drug class, from the preclinical stage to approved nanomedicines.

Pharmacokinetics and Pharmacodynamics of Intranasal Solid Lipid Nanoparticles and Nanostructured Lipid Carriers for Nose-to-Brain Delivery

Nose-to-brain drug delivery has been of great interest for the treatment of many central nervous system (CNS) diseases and psychiatric disorders over past decades. Several nasally administered formulations have been developed to circumvent the blood-brain barrier and directly deliver drugs to the CNS through the olfactory and trigeminal pathways. However, the nasal mucosa’s drug absorption is insufficient and the volume of the nasal cavity is small, which, in combination, make nose-to-brain drug delivery challenging. These problems could be minimized using formulations based on solid lipid nanoparticles (SLNs) or nanostructured lipid carriers (NLCs), which are effective nose-to-brain drug delivery systems that improve drug bioavailability by increasing drug solubility and permeation, extending drug action, and reducing enzymatic degradation. Various research groups have reported in vivo pharmacokinetics and pharmacodynamics of SLNs and NLCs nose-to-brain delivery systems. This review was undertaken to provide an overview of these studies and highlight research performed on SLN and NLC-based formulations aimed at improving the treatment of CNS diseases such neurodegenerative diseases, epilepsy, and schizophrenia. We discuss the efficacies and brain targeting efficiencies of these formulations based on considerations of their pharmacokinetic parameters and toxicities, point out some gaps in current knowledge, and propose future developmental targets.

Rapid analytical method development and validation for the simultaneous estimation of 5-Fluorouracil and Cannabidiol in plasma and lipid-based nanoformulations

Background:

5-Fluorouracil (5-FU) is a well-established anticancer drug. Several studies have also demonstrated the anticancer potential of Cannabidiol (CBD) against various malignancies, including skin cancer. Reported synergistic effects of this combination fascinate researchers to consider this for the management of skin cancer.

Methods:

A simple and robust HPLC method for simultaneous estimation of 5-FU and CBD at its single wavelength (237 nm) was developed and validated. The separation of these compounds was performed on Waters® HPLC system with Hypersil™ C18 RP-column using methanol and water in gradient flow as mobile phase. The method could effectively quantify the nanogram levels of both analytes simultaneously in plasma spiked samples and various nanoformulations. The analytical performance of the proposed method was validated in terms of various parameters, such as linearity, ruggedness, specificity, and few others.

Results:

5-FU as well as CBD were successfully detected at 237 nm with retention time 1.4 and 1.84 minutes respectively. Calibration curves were found to be linear with R2 values of 0.985 and 0.984 for 5-FU and CBD respectively. The method was linear, precise, specific and robust. Additionally, prepared method successfully employed in determining concentration of both drugs in combitorial nanoformulations.

Conclusion:

The findings show that the developed method was simple, reliable, sensitive and economical. It could be employed for the simultaneous estimation of 5-FU and CBD in various in vitro and in vivo studies.

Recent update on electrospinning and electrospun nanofibers: current trends and their applications

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made in techniques for creating electro-spun and non-electro-spun nanofibers. Nanofibers were the center of attention for industries and researchers due to their simplicity in manufacture and setup. The review discusses a thorough overview of both electrospinning and non-electrospinning processes, including their setup, fabrication process, components, and applications. The review starts with an overview of the field of nanotechnology, the background of electrospinning, the surge in demand for nanofiber production, the materials needed to make nanofibers, and the critical process variables that determine the characteristics of nanofibers. Additionally, the diverse applications of electrospun nanofibers, such as smart mats, catalytic supports, filtration membranes, energy storage/heritage components, electrical devices (batteries), and biomedical scaffolds, are then covered. Further, the review concentrates on the most recent and pertinent developments in nanofibers that are connected to the use of nanofibers, focusing on the most illustrative cases. Finally, challenges and their possible solutions, marketing, and the future prospects of nanofiber development are discussed.

Electrospinning is a versatile and viable technique for generating ultrathin fibers.

Formulation and development of tacrolimus-gellan gum nanoformulation for treatment of dry eye disease

The present study aimed at the development and evaluation of tacrolimus gellan gum nanoparticles (TGNPs) for the effective management of dry eye disease (DED) following topical application. TGNPs were developed by ionotropic gelation between gellan gum and aluminum chloride. Developed TGNPs were nanosized (274.46 ± 8.90 nm) with high % encapsulation efficiency (74.2 ± 2.4%) and loading capacity (36.14 ± 1.7%). The nanosize and spherical morphology of TGNPs was confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Fourier transform infrared spectroscopy (FTIR) revealed no interaction between drug and GG. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) confirms the conversion of crystalline tacrolimus to amorphous post encapsulation in the nanoparticle. TGNPs showed prolonged drug release throughout 12 h and higher pre-corneal retention compared to tacrolimus solution. HET-CAM studies, histopathological evaluation, and Draize test confirmed the safety of the formulation for ocular use. Further, the pharmacodynamic studies using experimental DED in rabbits showed that TGNPs are effective in treating symptoms of DED. In conclusion, topical delivery of TGNPs could hold potential for efficient management of DED.

In Vitro Studies on Nasal Formulations of Nanostructured Lipid Carriers (NLC) and Solid Lipid Nanoparticles (SLN)

The nasal route has been used for many years for the local treatment of nasal diseases. More recently, this route has been gaining momentum, due to the possibility of targeting the central nervous system (CNS) from the nasal cavity, avoiding the blood-brain barrier (BBB). In this area, the use of lipid nanoparticles, such as nanostructured lipid carriers (NLC) and solid lipid nanoparticles (SLN), in nasal formulations has shown promising outcomes on a wide array of indications such as brain diseases, including epilepsy, multiple sclerosis, Alzheimer's disease, Parkinson's disease and gliomas. Herein, the state of the art of the most recent literature available on in vitro studies with nasal formulations of lipid nanoparticles is discussed. Specific in vitro cell culture models are needed to assess the cytotoxicity of nasal formulations and to explore the underlying mechanism(s) of drug transport and absorption across the nasal mucosa. In addition, different studies with 3D nasal casts are reported, showing their ability to predict the drug deposition in the nasal cavity and evaluating the factors that interfere in this process, such as nasal cavity area, type of administration device and angle of application, inspiratory flow, presence of mucoadhesive agents, among others. Notwithstanding, they do not preclude the use of confirmatory in vivo studies, a significant impact on the 3R (replacement, reduction and refinement) principle within the scope of animal experiments is expected. The use of 3D nasal casts to test nasal formulations of lipid nanoparticles is still totally unexplored, to the authors best knowledge, thus constituting a wide open field of research.

Intranasal Administration for Pain: Oxytocin and Other Polypeptides

Pain, particularly chronic pain, remains one of the most debilitating and difficult-to-treat conditions in medicine. Chronic pain is difficult to treat, in part because it is associated with plastic changes in the peripheral and central nervous systems. Polypeptides are linear organic polymers that are highly selective molecules for neurotransmitter and other nervous system receptors sites, including those associated with pain and analgesia, and so have tremendous potential in pain therapeutics. However, delivery of polypeptides to the nervous system is largely limited due to rapid degradation within the peripheral circulation as well as the blood–brain barrier. One strategy that has been shown to be successful in nervous system deposition of polypeptides is intranasal (IN) delivery. In this narrative review, we discuss the delivery of polypeptides to the peripheral and central nervous systems following IN administration. We briefly discuss the mechanism of delivery via the nasal–cerebral pathway. We review recent studies that demonstrate that polypeptides such as oxytocin, delivered IN, not only reach key pain-modulating regions in the nervous system but, in doing so, evoke significant analgesic effects. IN administration of polypeptides has tremendous potential to provide a non-invasive, rapid and effective method of delivery to the nervous system for chronic pain treatment and management.