Preparation of desmopressin-containing liposomes for intranasal delivery

Chitosan-coated liposome with lysozyme-responsive properties for on-demand release of levofloxacin

As an anti-infection antibiotic delivery route, a drug-controlled release system based on a specific condition stimulus response can enhance drug stability and bioavailability, reduce antibiotic resistance, achieve on-demand release and improve targeting and utilization efficiency. In this study, chitosan-coated liposomes containing levofloxacin (Lef@Lip@CS) were prepared with lysozyme in body fluids serving as an intelligent "switch" to enable accurate delivery of antibiotics through the catalytic degradation ability of chitosan. Good liposome encapsulation efficacy (64.89 ± 1.86 %) and loading capacity (5.28 ± 0.18 %) were achieved. The controlled-release behavior and morphological characterization before and after enzymatic hydrolysis confirmed that the levofloxacin release rate depended on the lysozyme concentration and the degrees of deacetylation of chitosan. In vitro bacteriostatic experiments showed significant differences in the effects of Lef@Lip@CS before and after enzyme addition, with 6-h inhibition rate of 72.46 % and 100 %, and biofilm removal rates of 51 % and 71 %, respectively. These findings show that chitosan-coated liposomes are a feasible drug delivery system responsive to lysozyme stimulation.

An overview of in vitro and in vivo techniques for characterization of intranasal protein and peptide formulations for brain targeting

The surge in neurological disorders necessitates innovative strategies for delivering active pharmaceutical ingredients to the brain. The non-invasive intranasal route has emerged as a promising approach to optimize drug delivery to the central nervous system by circumventing the blood-brain barrier. While the intranasal approach offers numerous advantages, the lack of a standardized protocol for drug testing poses challenges to both in vitro and in vivo studies, limiting the accurate interpretation of nasal drug delivery and pharmacokinetic data. This review explores the in vitro experimental assays employed by the pharmaceutical industry to test intranasal formulation. The focus lies on understanding the diverse techniques used to characterize the intranasal delivery of drugs targeting the brain. Parameters such as drug release, droplet size measurement, plume geometry, deposition in the nasal cavity, aerodynamic performance and mucoadhesiveness are scrutinized for their role in evaluating the performance of nasal drug products. The review further discusses the methodology for in vivo characterization in detail, which is essential in evaluating and refining drug efficacy through the nose-to-brain pathway. Animal models are indispensable for pre-clinical drug testing, offering valuable insights into absorption efficacy and potential variables affecting formulation safety. The insights presented aim to guide future research in intranasal drug delivery for neurological disorders, ensuring more accurate predictions of therapeutic efficacy in clinical contexts.

A comprehensive review of advanced nasal delivery: Specially insulin and calcitonin

Peptide drugs through nasal mucous membrane, such as insulin and calcitonin have been widely used in the medical field. There are always two sides to a coin. One side, intranasal drug delivery can imitate the secretion pattern in human body, having advantages of physiological structure and convenient use. Another side, the low permeability of nasal mucosa, protease environment and clearance effect of nasal cilia hinder the intranasal absorption of peptide drugs. Researchers have taken multiple means to achieve faster therapeutic concentration, lower management dose, and fewer side effects for better nasal preparations. To improve the peptide drugs absorption, various strategies had been explored via the nasal mucosa route. In this paper, we reviewed the achievements of 18 peptide drugs in the past decade about the perspectives of the efficacy, mechanism of enhancing intranasal absorption and safety. The most studies were insulin and calcitonin. As a result, absorption enhancers, nanoparticles (NPs) and bio-adhesive system are the most widely used. Among them, chitosan (CS), cell penetrating peptides (CPPs), tight junction modulators (TJMs), soft NPs and gel/hydrogel are the most promising strategies. Moreover, two or three strategies can be combined to prepare drug vectors. In addition, spray freeze dried (SFD), self-emulsifying nano-system (SEN), and intelligent glucose reaction drug delivery system are new research directions in the future.

Formulation and characterization of lamotrigine nasal insert targeted brain for enhanced epilepsy treatment

Lamotrigine. (LMT) is a triazine drug has an antiepileptic effect but with low water solubility, dissolution rate and thus therapeutic effect. Spanlastics are nano-vesicular carriers' act as site-specific drug delivery system. Intranasal route could direct the drug from nose to brain and provide a faster and more specific therapeutic effect. Therefore, this study aimed to upload lamotrigine onto nano-vesicles using spanlastic nasal insert delivery for effective epilepsy treatment via overcoming lamotrigine's low solubility and improving its bioavailability. Lamtrigine-loaded nano-spanlastic vesicles were prepared by ethanol injection method. To study different formulation factor's effect on formulations characters; particle size (PS), Zeta potential (ZP), polydispersity index (PDI), entrapment efficiency percentage (EE%) and LMT released amount after 6 h (Q6h); 2^1 and 3^1 full factorial designs were employed. Optimized formula was loaded in lyophilized nasal inserts formulation which were characterized for LMT release and mucoadhesion. Pharmacokinetics studies in plasma and brain were performed on rats to investigate drug targeting efficiency. The optimal nano-spanlastic formulation (F4; containing equal Span 60 amount (100 mg) and edge activator; Tween 80) exhibited nano PS (174.2 nm), high EE% (92.75%), and Q6h > 80%. The prepared nasal inserts (S4) containing 100 mg HPMC has a higher mucoadhesive force (9319.5 dyne/cm²) and dissolution rate (> 80% within 10 min) for rapid in vivo bio-distribution. In vivo studies showed considerable improvement brain and plasma's rate and extent absorption after intranasal administration indicating a high brain targeting efficiency. The results achieved indicate that nano-spanlastic nasal-inserts offer a promising LMT brain targeting in order to maximize its antiepileptic effect.

Preclinical Assessment of IgY Antibodies Against Recombinant SARS-CoV-2 RBD Protein for Prophylaxis and Post-Infection Treatment of COVID-19

Within the framework of the current COVID-19 pandemic, there is a race against time to find therapies for the outbreak to be controlled. Since vaccines are still tedious to develop and partially available for low-income countries, passive immunity based on egg-yolk antibodies (IgY) is presented as a suitable approach to preclude potential death of infected patients, based on its high specificity/avidity/production yield, cost-effective manufacture, and ease of administration. In the present study, IgY antibodies against a recombinant RBD protein of SARS-CoV-2 were produced in specific-pathogen-free chickens and purified from eggs using a biocompatible method. In vitro immunoreactivity was tested, finding high recognition and neutralization values. Safety was also demonstrated prior to efficacy evaluation, in which body weight, kinematics, and histopathological assessments of hamsters challenged with SARS-CoV-2 were performed, showing a protective effect administering IgY intranasally both as a prophylactic treatment or a post-infection treatment. The results of this study showed that intranasally delivered IgY has the potential to both aid in prevention and in overcoming COVID-19 infection, which should be very useful to control the advance of the current pandemic and the associated mortality.

Levonorgestrel Microneedle Array Patch for Sustained Release Contraception: Formulation, Optimization and In Vivo Characterization

Background: The goal of this work was to develop a levonorgestrel liposome-loaded microneedle array patch for contraception. Methods: Levonorgestrel-loaded liposome was formulated by a solvent injection technique, characterized, and studied. Results: The formulated liposomes were characterized for particle size (147 ± 8 nm), polydispersity index (0.207 ± 0.03), zeta potential (−23 ± 4.25 mV), drug loading (18 ± 3.22%) and entrapment efficiency (85 ± 4.34%). A cryo high-resolution transmission electron microscopy and cryo field emission gun scanning electron microscopy study showed spherical shaped particles with a smooth surface. The in vitro drug release and in vivo pharmacokinetic study showed sustained behaviour of Levonorgestrel for 28 days. Conclusion: The levonorgestrel liposome-loaded microneedle array patch showed better contraception than the drug-loaded microneedle array patch.

Nose-to-brain/spinal cord delivery kinetics of liposomes with different surface properties

The administration of liposomes via nose-to-brain delivery is expected to become a strategy for efficient drug delivery to the central nervous system. Efficient nose-to-brain delivery and the kinetics of drugs administered in this manner depend on the properties of liposomes. However, there is a lack of basic knowledge of which liposomes are suitable for this purpose. Here, a qualitative study of intranasally administered liposomes (positively charged, neutral, and negatively charged, with or without polyethylene glycol [PEG] modification; particle size <100 nm) was performed to elucidate their dynamics in the brain and spinal cord. Additionally, a quantitative investigation was performed to ascertain their distribution in each part of the brain and spinal cord. The effects of liposome surface charge and PEG modification on the kinetics and distribution post intranasal administration were investigated via two experiments. Qualitative evaluation was performed via ex vivo observation after intranasal administration of fluorescently labeled liposomes. Neutral PEG-modified liposomes were distributed throughout the brain and spinal cord 60 min after administration, and the fluorescence intensity increased with time. By contrast, non-PEG-modified neutral liposomes showed particularly strong fluorescence in the olfactory bulb, and the fluorescence was localized in the anterior part of the brain. Positively charged liposomes showed low fluorescence around the lateral part of the brain and lumbar spinal cord 60 min after administration. Low fluorescence was observed in the whole brain and spinal cord, with strong fluorescence being observed in the olfactory bulb after 120 min of administration. Negatively charged liposomes showed no fluorescence at 60 min after administration, but low fluorescence was observed throughout the brain and spinal cord 120 min after administration. We quantified the radioactivity in the brain and spinal cord after intranasal administration of radioisotope-labeled liposomes. Neutral liposomes showed the highest distribution by area under the drug concentration-time curve (AUC_(60-120)) in the brain and spinal cord compared to other liposomes. Compared with negatively charged liposomes, positively charged liposomes had a higher distribution in the olfactory bulb and forebrain, while negatively charged liposomes had a higher distribution in the hindbrain and bulbospinal tract cord. In addition, the distribution of PEG-modified neutral liposomes in the brain and spinal cord was significantly enhanced compared to that of non-PEG-modified neutral liposomes after 90 min of intranasal administration. These results indicate that surface charge and PEG modification strongly affect the efficiency of nose-to-brain delivery kinetics, and that PEG-modified neutral liposomes are excellent carriers for drug delivery to a wide area of the brain and spinal cord.

Nanotherapeutics for Nose-to-Brain Drug Delivery: An Approach to Bypass the Blood Brain Barrier

Treatment of neurodegenerative diseases or other central nervous system (CNS) disorders has always been a significant challenge. The nature of the blood-brain barrier (BBB) limits the penetration of therapeutic molecules to the brain after oral or parenteral administration, which, in combination with hepatic metabolism and drug elimination and inactivation during its journey in the systemic circulation, decreases the efficacy of the treatment, requires high drug doses and often induces adverse side effects. Nose-to-brain drug delivery allows the direct transport of therapeutic molecules by bypassing the BBB and increases drug concentration in the brain. The present review describes mechanisms of nose-to-brain drug delivery and discusses recent advances in this area with especial emphasis on nanotechnology-based approaches.

Development and Evaluation of in-situ Nasal Gel Formulations of Nanosized Transferosomal Sumatriptan: Design, Optimization, in vitro and in vivo Evaluation

Background

Sumatriptan succinate (SUT) is a potent drug used for relieving or ending migraine and cluster headaches. SUT bioavailability is low (15%) when it is taken orally owing to its gastric breakdown and bloodstream before reaching the target arteries.

Aim

The aim of the study was to enhance SUT bioavailability through developing an intranasal transferosomal mucoadhesive gel.

Methods

SUT-loaded nanotransferosomes were prepared by thin film hydration method and characterized for various parameters such as vesicle diameter, percent entrapment efficiency (%EE), in vitro release and ex vivo permeation studies. The in-situ gels were prepared using various ratios of poloxamer 407, poloxamer 188, and carrageenan and characterized for gelation temperature, mucoadhesive strength, and rheological properties.

Results

The prepared transferosomes exhibited percent entrapment efficiencies (%EE) of 40.41±3.02 to 77.47±2.85%, mean diameters of 97.25 to 245.01 nm, sustained drug release over 6 hours, and acceptable ex vivo permeation findings. The optimum formulae were incorporated into poloxamer 407 and poloxamer 188-based thermosensitive in-situ gel using carrageenan as a mucoadhesive polymer. Pharmacokinetic evaluation showed that the prepared in-situ gel of SUT-loaded nano-transferosomes gave enhanced bioavailability, 4.09-fold, as compared to oral drug solution.

Conclusion

Based on enhancing the bioavailability and sustaining the drug release, it can be concluded that the in-situ gel of SUT-loaded nano-transferosomes were developed as a promising non-invasive drug delivery system for treating migraine.

Recent Advances and Novel Approaches for Nose to Brain Drug Delivery for Treatment of Migraine

Background:

Nasal drug delivery has been used since ancient times for therapeutic and recreational purposes. For the last decades, nasal drug delivery has been extended for drug delivery to the brain. Therefore, it is important to understand the several physiological and physicochemical factors of the nose for brain drug delivery.

Objective:

A major highlight of the present review article is the several aspects of the nose to brain delivery for migraine treatment. This review will help to understand different factors which are needed to be considered for intra-nasal formulations to achieve the desired therapeutic effects.

Method:

There are different drug delivery routes available for migraine treatment. Nasal route of administration may be optimal for migraine treatment which has better drug concentration in the brain. These approaches may be associated with limiting the adverse effects of drug therapeutics.

Results:

A list of total FDA approved approaches has been provided. Novel approaches used for drug targeting to get maximum drug concentration in the brain have been highlighted. Several novel drug delivery approaches such as nanoparticle, nanoemulsion, microspheres, etc. have been reported and better therapeutic effects have been observed. Among the novel approaches, some of them are currently under either Phase II or Phase III development but may prove to offer better clinical effects. These approaches would become the alternate choice for migraine treatment with patients experiencing symptoms consistent with gastrointestinal dysfunction associated with migraine.

Conclusion:

Intra-nasal administration of drugs for migraine treatment may offer an interesting alternative for achieving therapeutic effects of drugs which are comparable to the parenteral route. Nasal drug delivery can be an alternative route of drug administration for migraine treatment to achieve better bioavailability.

Lamotrigine encapsulated intra-nasal nanoliposome formulation for epilepsy treatment: Formulation design, characterization and nasal toxicity study

The purpose of this study was to develop lamotrigine nanoliposomes (LTG-NLs) for the treatment in seizures. The formulation was prepared using thin film hydration and rehydration method using the phospholipon 90 G, cholesterol and tween 80 as main ingredients. The nanoliposomes were optimized by plucket burman design (PBD) and response surface methodology (RSM) optimization techniques. The optimized LTGNLopt was further characterized for surface morphology, in-vitro release, stability study, confocal laser scanning microscopic (CLSM) study and naso toxicity study. The results showed that LTGNLopt shown nano size with high entrapment and drug release. The ex-vivo permeation study and confocal laser microscopy study confirmed the enhancement in permeation across the goat nasal mucosa. From the study, it was concluded that the independent variables used to optimize the NLs shown significant effect on the dependent variables and consider effective lipid carrier system for intranasal delivery.

Electrosteric stealth Rivastigmine loaded liposomes for brain targeting: preparation, characterization, ex vivo, bio-distribution and in vivo pharmacokinetic studies

Being one of the highly effective drugs in treatment of Alzheimer's disease, Rivastigmine brain targeting is highly demandable, therefore liposomal dispersion of Rivastigmine was prepared containing 2 mol% PEG-DSPE added to Lecithin, Didecyldimethyl ammonium bromide (DDAB), Tween 80 in 1:0.02:0.25 molar ratio. A major challenge during the preparation of liposomes is maintaining a stable formulation, therefore the aim of our study was to increase liposomal stability by addition of DDAB to give an electrostatic stability and PEG-DSPE to increase stability by steric hindrance, yielding what we called an electrosteric stealth (ESS) liposomes. A medium nano-sized liposome (478 ± 4.94 nm) with a nearly neutral zeta potential (ZP, -8 ± 0.2 mV) and an entrapment efficiency percentage of 48 ± 6.22 was prepared. Stability studies showed no major alteration after three months storage period concerning particle size, polydispersity index, ZP, entrapment efficiency and in vitro release study confirming the successful formation of a stable liposomes. No histopathological alteration was recorded for ESS liposomes of the sheep nasal mucosa. While ESS liposomes showed higher % of drug permeating through the sheep nasal mucosa (48.6%) than the drug solution (28.7%). On completing the in vivo pharmacokinetic studies of 36 rabbits showed 424.2% relative bioavailability of the mean plasma levels of the formula ESS compared to that of RHT intranasal solution and 486% relative bioavailability of the mean brain levels.

Effect of surface charge on the brain delivery of nanostructured lipid carriers in situ gels via the nasal route

The aim of this study was to investigate the influence of the nanocarrier surface charge on brain delivery of a model hydrophilic drug via the nasal route. Anionic and cationic nanostructured lipid carriers (NLCs) were prepared and optimized for their particle size and zeta potential. The optimum particles were incorporated in poloxamer in situ gels and their in vivo behavior was studied in the plasma and brain after administration to rats. Optimum anionic and cationic NLCs of size <200 nm and absolute zeta potential value of ≈ 34 mV were obtained. Toxicity study revealed mild to moderate reversible inflammation of the nasal epithelium in rats treated with the anionic NLCs (A7), and destruction of the lining mucosal nasal epithelium in rats treated with the cationic NLCs (C7L). The absolute bioavailability of both drug loaded anionic and cationic NLCs in situ gels was enhanced compared to that of the intranasal solution (IN) of the drug with values of 44% and 77.3%, respectively. Cationic NLCs in situ gel showed a non significant higher Cmax (maximum concentration) in the brain compared to the anionic NLCs in situ gel. Anionic NLCs in situ gel gave highest drug targeting efficiency in the brain (DTE%) with a value of 158.5 which is nearly 1.2 times that of the cationic NLCs in situ gel.

Drug development of intranasally delivered peptides

Intranasal drug delivery has attracted increasing attention as a noninvasive route of administration for therapeutic proteins and peptides. The delivery of therapeutic peptides through the nasal route provides an alternative to intravenous or subcutaneous injections. This review highlights the drug-development considerations unique to nasal therapeutics and discusses some of the factors and strategies that affect and can improve nasal absorption of peptides. The selectivity and good safety profile typical of peptide therapeutics, along with the dose limitation for intranasal administration, can provide challenges in drug development. Therefore, nasal peptide therapeutics often require special considerations in the nonclinical safety evaluations, such as determining drug exposure in the context of the maximum feasible dose in order to adequately prepare nasal products for clinical studies.

Nanocarrier possibilities for functional targeting of bioactive peptides and proteins: state-of-the-art

This review attempts to provide an updated compilation of studies reported in the literature pertaining to production of nanocarriers encasing peptides and/or proteins, in a way that helps the reader direct a bibliographic search and develop an integrated perspective of the subject. Highlights are given to bioactive proteins and peptides, with a special focus on those from dairy sources (including physicochemical characteristics and properties, and biopharmaceutical application possibilities of e.g. lactoferrin and glycomacropeptide), as well as to nanocarrier functional targeting. Features associated with micro- and (multiple) nanoemulsions, micellar systems, liposomes and solid lipid nanoparticles, together with biopharmaceutical considerations, are presented in the text in a systematic fashion.

Improved transnasal transport and brain uptake of tizanidine HCl-loaded thiolated chitosan nanoparticles for alleviation of pain

The aim of this study was to prepare and characterize thiolated chitosan (TC) nanoparticles (NPs) of tizanidine HCl (TZ) and to evaluate its transport across monolayer of RPMI 2650 cells (Human nasal septum carcinoma cell line) followed by assessment of their pharmacokinetic and pharmacodynamic attributes, after intranasal (i.n.) administration. Chitosan was thiolated by carbodiimide method and thiolation was confirmed qualitatively and quantitatively. NPs were prepared using ionotropic gelation and evaluated for mucoadhesion using sheep nasal mucosa for drug permeation and cytotoxicity using monolayer of RPMI 2650 cells. Drug biodistribution was evaluated after technetium-99m labeling, visualized using gamma camera, and evaluated pharmacodynamically by measuring antinociceptive activity in mice. High mucoadhesion and permeation of drug were observed for TC NPs with least toxicity to nasal epithelial cells. Brain uptake and antinociceptive effect of the drug were significantly enhanced after thiolation of chitosan. This concludes that TC NPs, after i.n. administration, show significant increase in the mucoadhesion, reduction in cytotoxicity, enhanced permeation across cells monolayer, higher TZ brain uptake, and considerable increase in antinociceptive activity of TZ in mice. These features make TC an interesting polymer for demonstrating appreciable improvement of transnasal permeation of hydrophilic drugs, such as TZ, known to have limited permeation across blood-brain barrier.

Nasal delivery of high molecular weight drugs

Nasal drug delivery may be used for either local or systemic effects. Low molecular weight drugs with are rapidly absorbed through nasal mucosa. The main reasons for this are the high permeability, fairly wide absorption area, porous and thin endothelial basement membrane of the nasal epithelium. Despite the many advantages of the nasal route, limitations such as the high molecular weight (HMW) of drugs may impede drug absorption through the nasal mucosa. Recent studies have focused particularly on the nasal application of HMW therapeutic agents such as peptide-protein drugs and vaccines intended for systemic effects. Due to their hydrophilic structure, the nasal bioavailability of peptide and protein drugs is normally less than 1%. Besides their weak mucosal membrane permeability and enzymatic degradation in nasal mucosa, these drugs are rapidly cleared from the nasal cavity after administration because of mucociliary clearance. There are many approaches for increasing the residence time of drug formulations in the nasal cavity resulting in enhanced drug absorption. In this review article, nasal route and transport mechanisms across the nasal mucosa will be briefly presented. In the second part, current studies regarding the nasal application of macromolecular drugs and vaccines with nano- and micro-particulate carrier systems will be summarised.

Preparation of ergoloid mesylate submicron emulsions for enhancing nasal absorption and reducing nasal ciliotoxicity

The aim of this investigation was to prepare ergoloid mesylate submicron emulsions (EMSEs) for enhancing nasal absorption of drug and reducing nasal ciliotoxicity. Following intranasal administrations of EMSE and ergoloid mesylate solution (EMS) and intravenous administration of EMS to rats separately at the dose of 2 mg kg(-1), the levels of EM in blood and the cerebrospinal fluid (CSF) were evaluated by microdialysis method. The nasal ciliotoxicity was evaluated by using in situ toad palate model. The absolute bioavailability and the AUC in the CSF following intranasal administration of EMSE (56.3 +/- 5.3%, AUC(CSF) 28,594 +/- 5680 ng ml(-1) min) were statistically higher than those after intranasal administration of EMS (47.4 +/- 3.5%, AUC(CSF) 19,870 +/- 2247 ng ml(-1) min). No significant difference was found for the value of the brain drug direct transport percentage (DTP%) or the drug targeting efficiency (DTE) between the group receiving EMSE and the group receiving EMS. In conclusion, EMSE exhibited higher nasal absorption of EM in rats and significantly lower nasal ciliotoxicity whereas no greater brain-targeting efficiency in comparison with EMS.

Acyclovir liposomes for intranasal systemic delivery: development and pharmacokinetics evaluation

Intranasal route is one of the most attractive routes for distributing drugs to systemic circulation. Liposomes are used as biocompatible carriers to improve delivery properties across nasal mucosa. The objective of the present study was to formulate acyclovir liposomes and partition into poly-N-vinyl-2-pyrrolidone. Entrapment efficiency showed that multilamellar and unilamellar liposomes were 43.2% +/- 0.83 and 21% +/- 1.01, respectively. The bioavailability of acyclovir from nasal mucoadhesive gel was 60.72% compared with intravenous route. The use of liposomes acyclovir and mucoadhesive gel not only promoted the prolonged contact between the drug and the absorptive sites in the nasal cavity, but also facilitated direct absorption through the nasal mucosa.

A study of rivastigmine liposomes for delivery into the brain through intranasal route

The present study is mainly aimed at delivering a drug into the brain via the intranasal route using a liposomal formulation. For this purpose, rivastigmine, which is used in the management of Alzheimer's disease, was selected as a model drug. Conventional liposomes were formulated by the lipid layer hydration method using cholesterol and soya lecithin as lipid components. The concentration of rivastigmine in brain and plasma after intranasal liposomes, free drug and per oral administration was studied in rat models. A significantly higher level of drug was found in the brain with intranasal liposomes of rivastigmine compared to the intranasal free drug and the oral route. Intranasal liposomes had a longer half-life in the brain than intranasally or orally administered free drug. Delivering rivastigmine liposomes through the intranasal route for the treatment of Alzheimer's disease might be a new approach to the management of this condition.

Thiomers in noninvasive polypeptide delivery: in vitro and in vivo characterization of a polycarbophil-cysteine/glutathione gel formulation for human growth hormone

This study was aimed at investigating the potential of a new polycarbophil-cysteine (PCP-Cys)/glutathione (GSH) gel formulation to enhance the permeation of the model drug human growth hormone (hGH) across nasal mucosa in vitro and in vivo. The aqueous nasal gel contained PCP-Cys, GSH, and hGH in a final concentration of 0.3%, 0.5%, and 0.6% (m/v), respectively. In vitro permeation studies were performed in Ussing chambers on freshly excised bovine nasal mucosa using fluorescence-labeled dextran (molecular mass: 4.3 kDa; FD-4) and hGH (FITC-hGH). The release profile of FITC-hGH from the gel formulation and an unmodified PCP control formulation was determined. Furthermore, in vivo studies in rats were performed comparing the PCP-Cys/GSH/hGH gel with PCP/hGH control gel and physiological saline. The permeation of FD-4 and FITC-hGH across the nasal mucosa was improved two-fold and three-fold, respectively, in the presence of PCP-Cys/GSH. The PCP-Cys/GSH/hGH gel and the PCP/hGH control gel showed the same biphasic and matrix-controlled drug release. The nasal administration of the PCP-Cys/GSH/hGH gel formulation to rats resulted in a significantly increased and prolonged hGH plasma concentration-time profile versus unmodified PCP gel and physiological saline. According to these results, PCP-Cys gels might represent a promising new strategy for systemic nasal polypeptide delivery.

In vitro evaluation of intestinal absorption of desmopressin using drug-delivery systems based on superporous hydrogels

The aim of this study was to investigate and modify the potential of drug-delivery systems based on superporous hydrogel (SPH) for improving the intestinal transport of the peptide drug desmopressin in vitro. The swelling properties and mechanical strength of SPHs were studied. The release profile of desmopressin was investigated by changing the composition of excipients in the formulations. Subsequently, the ability of the SPH-based drug-delivery systems to enhance the transport of desmopressin across porcine intestine was performed in vitro. The swelling properties and mechanical strength of SPHs were affected by the addition of the disintregrant AcDiSol. This disintregrant reduced the swelling ratio to 10% and the time to 80% swelling was retarded by 3-5 min in comparison to the negative control. AcDiSol increased the mechanical strength, according to the increasing of penetration pressure value, the pressure that the punch can penetrate the gel, of the SPHs. The transport of desmopressin across the intestinal mucosa in vitro was enhanced four- and six-fold by applying SPH, with AcDiSol, in the absence and presence of the additional absorption enhancer trimethyl chitosan chloride, respectively, in comparison to the negative control. It is concluded that drug-delivery systems based on SPHs are promising for enhancing the intestinal absorption of desmopressin.

Stability of desmopressin loaded in liposomes

Desmopressin-containing liposome formulations have been developed for intranasal administration previously. Positively charged liposomes were found to be an efficient delivery system for desmopressin. In this study, stability of the loaded desmopressin in positively charged liposomes was further investigated. Comparison of the stability of desmopressin in solution and liposomes was made. Degradation of desmopressin was shown to follow a pseudo-first-order reaction. Degradation of desmopressin in both solution and liposomes demonstrated the same kinetic behavior and exhibited no significant difference in half-lives. Similar v-shape pH-rate profile was found for desmopressin degradation in solution and liposomes. At pH 4.0, the inflection point of the v-shape pH-rate curve, the reaction rate of desmopressin was lowest and the stability was greatest. The stability of lipid ingredients of dioleoylphosphatidylcholine (DOPC), cholesterol (C), and stearylamine (S) in the liposome dispersion at pH 4.0 was studied. Results demonstrated that DOPC, C, and S were relatively stable in the liposome structure when formulated with desmopressin. The degradation of desmopressin in solution and liposomes in the presence of alpha-chymotrypsin was investigated. A longer half-life for desmopressin in liposomes than in solution was observed. It was suggested that desmopressin was protected by the liposomes against alpha-chymotrypsin digestion.

Stroke, dementia, and drug delivery

Stroke and dementia represent a major health burden for elderly subjects as they are associated with significant morbidity and mortality. The rates of stroke and dementia are progressively increasing due to the ageing population in most westernized countries. Therefore, both these conditions represent a major therapeutic target. However, the therapeutic options available for the management of stroke and dementia remain largely unsatisfactory, the main reason being the difficulty in transferring the results obtained in animal and in vitro studies to the clinical setting. This review focuses on the recent advances in pathophysiology and treatment of these conditions and future directions for research. Moreover, the technique of functional magnetic resonance imaging is discussed in detail as a tool to assess the effects of therapeutic agents on the central nervous system and monitor the progression of diseases. Finally, an overview of the issue of drug delivery into the central nervous system is presented.

Neuroprotective peptide drug delivery and development: potential new therapeutics

Alzheimer's disease and related neurodegenerative disorders are prevalent among the elderly and might be considered as the plague of the 21st century. It is thus imperative to find cures for these conditions. The use of nerve growth factor proteins as neuroprotective therapeutics is limited by their hindered mobility through the blood-brain barrier. Peptides provide an attractive alternative. However, do peptide derivatives retain the activity of the entire protein? Are they stable? Would peptides cross the blood-brain barrier and what are the potential side effects? Examples are put forth to strengthen our opinion that peptides are important candidates for future drug development.