The novel application of chitosan for the intranasal delivery of insulin

The findings of this project have added to the pool of information reported in the literature regarding the application of the nasal route for the delivery of insulin and other peptide drugs. The preliminary studies reported in this project were apparently the first studies performed to investigate the potential use of chitosan in nasal delivery systems. Nasal delivery systems were investigated in rat and sheep models. The efficacy of chitosan as a nasal absorption enhancer for insulin was compared to that of several other compounds which had been reported in the literature to enhance nasasl [i.e. nasal] drug absorption. Erythrocyte haemolysis studies were also performed to evaluate the membrane damaging effects of the various compounds tested. The grade of chitosan predominantly used was a medium viscosity glutamate salt (MVCSN) which was 82% deacetylated and had a molecular weight of about 162,000. Other grades of chitosan of similar degree of deacetylation were also investigated for comparison with MVCSN (low viscosity grades of chitosan glutamate (LVCSN) and lactate (CSN lactate), medium viscosity chitosan hydrochloride (CSN HC1) and high viscosity chitosan base (HVCSN)). The efficacy of chitosan in enhancing the nasal absorption of both insulin and salmon calcitonin, used as an alternative peptide, was demonstrated in rat and sheep models. Nasal insulin delivery systems were extensively investigated in rat and sheep models. In the rat model, insulin / LVCSN formulations at pH -4 were more effective than formulations at pH -7 in enhancing intranasal insulin absorption which was assessed indirectly from the degree of hypoglycaemia following dose administration. The reduced absorption in the latter formulation which was in the form of a suspension was attributed to complex formation between insulin and LVCSN. In the rat model, the absorption enhancing efficacy of MVCSN was second only to that of LPC. This was encouraging in view of the severe membrane damaging effects that LPC solutions have been shown to cause. In contrast, chitosan solutions have been shown to be relatively non-toxic to biomembranes. In the sheep model, a formulation incorporating MVCSN was much more effective than a formulation containing LPC in promoting nasal insulin absorption. These differences were attributed to the animal models used to investigate nasal absorption. The degree of nasal absorption enhancement was improved by increasing the solution concentration of MVCSN until an optimal concentration was attained (approximately 0.5% and 0.35% in rat and sheep models, respectively). Further evaluation of nasal insulin / chitosan formulations in sheep, suggested that the formulation concentration of chitosan was important for its absorption enhancing efficacy and at optimal chitosan concentration nasal insulin absorption was limited by the dose concentration of insulin. In both rat and sheep models, the nasal administration of hypotonic or isotonic formulations of insulin with chitosan did not influence the degree of nasal absorption enhancement attained. However, in rats, a hypertonic formulation was shown to further improve nasal insulin absorption which was attributed to the combined effects of the chitosan and the increased tonicity of the formulation on the nasal membrane. The grade of chitosan used in the nasal absorption studies appeared to influence the degree of absorption enhancement obtained. In the rat model there was no difference in the absorption enhancing efficacy of CSN lactate and MVCSN although the performance of HVCSN was marginally reduced. In contrast, in the sheep model, MVCSN was more effective than LVCSN and CSN lacate in enhancing nasal insulin absorption although there was no difference in the performance of MVCSN and CSN HCL. In studies in the rat, MVCSN was shown to have a transient effect on the permeability of the nasal mucosa to insulin which lasted about 30 minutes. This supports the claims that chitosan is non-damaging to the nasal mucosa. Erythrocyte haemolysis studies showed that MVCSN was non-damaging to rat erythrocyte membranes at concentrations which were higher than the concentrations used in nasal absorption studies. This was encouraging since the other compounds investigated for comparison with chitosan in this project were shown to be potent haemolytic agents at concentrations which were much lower than the concentrations which were effective for nasal absorption enhancement. MVCSN was less damaging to erythrocyte membranes than the other grades of chitosan tested. This project demonstrated that chitosan enhanced the nasal absorption of insulin in rat and sheep models. In the sheep model the bioavailability of nasal insulin, relative to the subcutaneous route, was generally less than 5%. However, the hypoglycaemia which followed nasal insulin / chitosan dose administration was encouraging and a similar degree of efficacy in humans could be feasible for the therapeutic application of nasal insulin

The novel application of chitosan for the intranasal delivery of insulin

The findings of this project have added to the pool of information reported in the literature regarding the application of the nasal route for the delivery of insulin and other peptide drugs. The preliminary studies reported in this project were apparently the first studies performed to investigate the potential use of chitosan in nasal delivery systems. Nasal delivery systems were investigated in rat and sheep models. The efficacy of chitosan as a nasal absorption enhancer for insulin was compared to that of several other compounds which had been reported in the literature to enhance nasasl [i.e. nasal] drug absorption. Erythrocyte haemolysis studies were also performed to evaluate the membrane damaging effects of the various compounds tested. The grade of chitosan predominantly used was a medium viscosity glutamate salt (MVCSN) which was 82% deacetylated and had a molecular weight of about 162,000. Other grades of chitosan of similar degree of deacetylation were also investigated for comparison with MVCSN (low viscosity grades of chitosan glutamate (LVCSN) and lactate (CSN lactate), medium viscosity chitosan hydrochloride (CSN HC1) and high viscosity chitosan base (HVCSN)). The efficacy of chitosan in enhancing the nasal absorption of both insulin and salmon calcitonin, used as an alternative peptide, was demonstrated in rat and sheep models. Nasal insulin delivery systems were extensively investigated in rat and sheep models. In the rat model, insulin / LVCSN formulations at pH -4 were more effective than formulations at pH -7 in enhancing intranasal insulin absorption which was assessed indirectly from the degree of hypoglycaemia following dose administration. The reduced absorption in the latter formulation which was in the form of a suspension was attributed to complex formation between insulin and LVCSN. In the rat model, the absorption enhancing efficacy of MVCSN was second only to that of LPC. This was encouraging in view of the severe membrane damaging effects that LPC solutions have been shown to cause. In contrast, chitosan solutions have been shown to be relatively non-toxic to biomembranes. In the sheep model, a formulation incorporating MVCSN was much more effective than a formulation containing LPC in promoting nasal insulin absorption. These differences were attributed to the animal models used to investigate nasal absorption. The degree of nasal absorption enhancement was improved by increasing the solution concentration of MVCSN until an optimal concentration was attained (approximately 0.5% and 0.35% in rat and sheep models, respectively). Further evaluation of nasal insulin / chitosan formulations in sheep, suggested that the formulation concentration of chitosan was important for its absorption enhancing efficacy and at optimal chitosan concentration nasal insulin absorption was limited by the dose concentration of insulin. In both rat and sheep models, the nasal administration of hypotonic or isotonic formulations of insulin with chitosan did not influence the degree of nasal absorption enhancement attained. However, in rats, a hypertonic formulation was shown to further improve nasal insulin absorption which was attributed to the combined effects of the chitosan and the increased tonicity of the formulation on the nasal membrane. The grade of chitosan used in the nasal absorption studies appeared to influence the degree of absorption enhancement obtained. In the rat model there was no difference in the absorption enhancing efficacy of CSN lactate and MVCSN although the performance of HVCSN was marginally reduced. In contrast, in the sheep model, MVCSN was more effective than LVCSN and CSN lacate in enhancing nasal insulin absorption although there was no difference in the performance of MVCSN and CSN HCL. In studies in the rat, MVCSN was shown to have a transient effect on the permeability of the nasal mucosa to insulin which lasted about 30 minutes. This supports the claims that chitosan is non-damaging to the nasal mucosa. Erythrocyte haemolysis studies showed that MVCSN was non-damaging to rat erythrocyte membranes at concentrations which were higher than the concentrations used in nasal absorption studies. This was encouraging since the other compounds investigated for comparison with chitosan in this project were shown to be potent haemolytic agents at concentrations which were much lower than the concentrations which were effective for nasal absorption enhancement. MVCSN was less damaging to erythrocyte membranes than the other grades of chitosan tested. This project demonstrated that chitosan enhanced the nasal absorption of insulin in rat and sheep models. In the sheep model the bioavailability of nasal insulin, relative to the subcutaneous route, was generally less than 5%. However, the hypoglycaemia which followed nasal insulin / chitosan dose administration was encouraging and a similar degree of efficacy in humans could be feasible for the therapeutic application of nasal insulin

Nasal Administration and Plasma Pharmacokinetics of Parathyroid Hormone Peptide PTH 1-34 for the Treatment of Osteoporosis

Nasal delivery of large peptides such as parathyroid 1-34 (PTH 1-34) can benefit from a permeation enhancer to promote absorption across the nasal mucosa into the bloodstream. Previously, we have published an encouraging bioavailability (78%), relative to subbcutaneous injection in a small animal preclinical model, for a liquid nasal spray formulation containing the permeation enhancer polyethylene glycol (15)-hydroxystearate (Solutol® HS15). We report here the plasma pharmacokinetics of PTH 1-34 in healthy human volunteers receiving the liquid nasal spray formulation containing Solutol® HS15. For comparison, data for a commercially manufactured teriparatide formulation delivered via subcutaneous injection pen are also presented. Tc-99m-DTPA gamma scintigraphy monitored the deposition of the nasal spray in the nasal cavity and clearance via the inferior meatus and nasopharynx. The 50% clearance time was 17.8 min (minimum 10.9, maximum 74.3 min). For PTH 1-34, mean plasma Cmax of 5 pg/mL and 253 pg/mL were obtained for the nasal spray and subcutaneous injection respectively; relative bioavailability of the nasal spray was 1%. Subsequently, we investigated the pharmacokinetics of the liquid nasal spray formulation as well as a dry powder nasal formulation also containing Solutol® HS15 in a crossover study in an established ovine model. In this preclinical model, the relative bioavailability of liquid and powder nasal formulations was 1.4% and 1.0% respectively. The absolute bioavailability of subcutaneously administered PTH 1-34 (mean 77%, range 55–108%) in sheep was in agreement with published human data for teriparatide (up to 95%). These findings have important implications in the search for alternative routes of administration of peptides for the treatment of osteoporosis, and in terms of improving translation from animal models to humans

Intranasal H5N1 vaccines, adjuvanted with chitosan derivatives, protect ferrets against highly pathogenic influenza intranasal and intratracheal challenge

We investigated the protective efficacy of two intranasal chitosan (CSN and TM-CSN) adjuvanted H5N1 Influenza vaccines against highly pathogenic avian Influenza (HPAI) intratracheal and intranasal challenge in a ferret model. Six groups of 6 ferrets were intranasally vaccinated twice, 21 days apart, with either placebo, antigen alone, CSN adjuvanted antigen, or TM-CSN adjuvanted antigen. Homologous and intra-subtypic antibody cross-reacting responses were assessed. Ferrets were inoculated intratracheally (all treatments) or intranasally (CSN adjuvanted and placebo treatments only) with clade 1 HPAI A/Vietnam/1194/2004 (H5N1) virus 28 days after the second vaccination and subsequently monitored for morbidity and mortality outcomes. Clinical signs were assessed and nasal as well as throat swabs were taken daily for virology. Samples of lung tissue, nasal turbinates, brain, and olfactory bulb were analysed for the presence of virus and examined for histolopathological findings. In contrast to animals vaccinated with antigen alone, the CSN and TM-CSN adjuvanted vaccines induced high levels of antibodies, protected ferrets from death, reduced viral replication and abrogated disease after intratracheal challenge, and in the case of CSN after intranasal challenge. In particular, the TM-CSN adjuvanted vaccine was highly effective at eliciting protective immunity from intratrache

LEARN: A multi-centre, cross-sectional evaluation of Urology teaching in UK medical schools

OBJECTIVE: To evaluate the status of UK undergraduate urology teaching against the British Association of Urological Surgeons (BAUS) Undergraduate Syllabus for Urology. Secondary objectives included evaluating the type and quantity of teaching provided, the reported performance rate of General Medical Council (GMC)-mandated urological procedures, and the proportion of undergraduates considering urology as a career. MATERIALS AND METHODS: LEARN was a national multicentre cross-sectional study. Year 2 to Year 5 medical students and FY1 doctors were invited to complete a survey between 3rd October and 20th December 2020, retrospectively assessing the urology teaching received to date. Results are reported according to the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). RESULTS: 7,063/8,346 (84.6%) responses from all 39 UK medical schools were included; 1,127/7,063 (16.0%) were from Foundation Year (FY) 1 doctors, who reported that the most frequently taught topics in undergraduate training were on urinary tract infection (96.5%), acute kidney injury (95.9%) and haematuria (94.4%). The most infrequently taught topics were male urinary incontinence (59.4%), male infertility (52.4%) and erectile dysfunction (43.8%). Male and female catheterisation on patients as undergraduates was performed by 92.1% and 73.0% of FY1 doctors respectively, and 16.9% had considered a career in urology. Theory based teaching was mainly prevalent in the early years of medical school, with clinical skills teaching, and clinical placements in the later years of medical school. 20.1% of FY1 doctors reported no undergraduate clinical attachment in urology. CONCLUSION: LEARN is the largest ever evaluation of undergraduate urology teaching. In the UK, teaching seemed satisfactory as evaluated by the BAUS undergraduate syllabus. However, many students report having no clinical attachments in Urology and some newly qualified doctors report never having inserted a catheter, which is a GMC mandated requirement. We recommend a greater emphasis on undergraduate clinical exposure to urology and stricter adherence to GMC mandated procedures