Statistical optimization of insulin-loaded Pluronic F-127 gels for buccal delivery of basal insulin

Advances in buccal and oral delivery of insulin

Diabetes mellitus is a metabolic endocrine disease characterized by chronic hyperglycemia with disturbances in metabolic processes, such as those related to carbohydrates, fat, and protein. There are two main types of this disease: type 1 diabetes (T1D) and type 2 diabetes (T2D). Insulin therapy is pivotal to the management of diabetes. Over the last two decades, many routes of administration, including nasal, pulmonary, rectal, transdermal, buccal, and ocular, have been investigated. Nevertheless, subcutaneous parenteral administration is still the most common route for insulin therapy. To overcome poor bioavailability and the barriers to oral insulin absorption, novel approaches in the field of oral drug delivery and administration have been brought about by the coalescence of different branches of nanoscience and nanotechnology, such as nanomedicine, nano-biochemistry, and nano-pharmacy. Novel drug delivery systems, including nanoparticles, nano-platforms, and nanocarriers, have been suggested. The objective of this review is to provide an update on the various promising approaches that have been explored and evaluated for the safe and efficient oral and buccal administration of insulin.

The impact of chemical engineering and technological advances on managing diabetes: present and future concepts

Monitoring blood glucose levels for diabetic patients is critical to achieve tight glycaemic control. As none of the current antidiabetic treatments restore lost functional β-cell mass in diabetic patients, insulin injections and the use of insulin pumps are most widely used in the management of glycaemia. The use of advanced and intelligent chemical engineering, together with the incorporation of micro- and nanotechnological-based processes have lately revolutionized diabetic management. The start of this concept goes back to 1974 with the description of an electrode that repeatedly measures the level of blood glucose and triggers insulin release from an infusion pump to enter the blood stream from a small reservoir upon need. Next to the insulin pumps, other drug delivery routes, including nasal, transdermal and buccal, are currently investigated. These processes necessitate competences from chemists, engineers-alike and innovative views of pharmacologists and diabetologists. Engineered micro and nanostructures hold a unique potential when it comes to drug delivery applications required for the treatment of diabetic patients. As the technical aspects of chemistry, biology and informatics on medicine are expanding fast, time has come to step back and to evaluate the impact of technology-driven chemistry on diabetics and how the bridges from research laboratories to market products are established. In this review, the large variety of therapeutic approaches proposed in the last five years for diabetic patients are discussed in an applied context. A survey of the state of the art of closed-loop insulin delivery strategies in response to blood glucose level fluctuation is provided together with insights into the emerging key technologies for diagnosis and drug development. Chemical engineering strategies centered on preserving and regenerating functional pancreatic β-cell mass are evoked in addition as they represent a permanent solution for diabetic patients.

Sublingual insulin administration: application of hydroxypropyl beta-cyclodextrin and poloxamer188 as permeation enhancers

The objective of this investigation is to investigate the feasibility of sublingual insulin administration. Insulin solutions formulated with permeation enhancers (HPβCD/poloxamer 188) and their in-vitro and in-vivo performances were evaluated. Thereafter, insulin fast-dissolving film was further developed to have similar properties, upon dissolving the film, of the optimized insulin solution. In-vitro performance was evaluated via effect of HPβCD and/or poloxamer 188 concentration across cellulose acetate membrane and porcine esophagus. In-vivo performance was evaluated via pharmacodynamic and pharmacokinetic profiles of insulin solution administered. Cumulative amounts of insulin permeated at 60 min formulated with HPβCD (5%), poloxamer 188 (0.5%), and their combination were 1.31, 3.23, and 4.99 IU/cm², respectively, indicating an additive effect of combination of HPβCD and poloxamer 188. Insulin-induced hypoglycemic effect was observed for insulin solutions with combination of HPβCD and poloxamer 188 after sublingual administration to Sprague-Dawley rats. Microscopic evaluation of porcine oesophageal tissue indicates that HPβCD and poloxamer 188 are safe. Furthermore, the cumulative amount permeated across cellulose acetate membrane at 30 min was 1.13 and 1.00 IU/cm² for insulin solution and fast-dissolving film, respectively, demonstrating to be similar. In conclusion, the use of HPβCD/poloxamer 188 is feasible for the development of sublingual insulin solutions/films.

Pluronic® F127-mediated control of insulin release rates from NPH microcrystals and blood glucose depression in STZ-induced diabetic rats

Introduction: Neutral protamine Hagedorn (NPH) insulin is an intermediate-acting basal insulin with a long history of clinical use, consisting native human insulin. Its rather undesirable action profile, characterized by a peak release within a few hours, followed by insufficient insulin delivery upon a single subcutaneous (s.c.) dose, is well-documented. This may have been caused by the inherent microcrystal structure involving the basic peptide protamine, as well as the presence of tissue enzyme activities that readily act on protamine at the injection site. This issue may be circumvented by utilizing thermosensitive, erodible Pluronic F127 (PF127) to modulate the kinetics of insulin release from NPH over a period of 24 hours in which the hydrogel is completely eroded.

Methods: Previously, we have shown that insulin release rates in vitro from NPH/PF127 formulations (0-25% PF127) markedly reduced the initial insulin release, especially in the presence of enzyme activity that selectively degraded protamine at 1-5 U/mL. Insulin release over the course of 20 hours was better modulated in the presence of increasing PF127 content. In this study, the insulin formulations (0, 20, and 25% PF127) were administered s.c. (4 U/kg) to streptozotocin (STZ)-induced diabetic rats and blood glucose levels were monitored over 24 hours.

Results: In vivo blood glucose depression profiles in STZ-induced diabetic rats exhibited a similar pattern of control to in vitro data at the single s.c. dose of 4 U/kg, apparently extending the duration of action of NPH over a 24-hour period in the presence of PF127.

Conclusion: Our findings suggest that the undesirable kinetics of insulin release from NPH is significantly influenced by tissue enzyme activity and that the presence of PF127 provided a timely modulation of insulin release from NPH microcrystals in the STZ-induced diabetic rat model.

Insulin Release from NPH Insulin-Loaded Pluronic® F127 Hydrogel in the Presence of Simulated Tissue Enzyme Activity

Background: Despite the widespread use of newer basal insulins, Natural Protamine Hagedorn (NPH) insulin still represents a well-established basal formulation with its long history of use, featuring the native form of human insulin. However, NPH insulin exhibits an undesirable peak within hours after a single subcutaneous (s.c.) injection, which may lead to hypoglycemia followed by insufficient basal insulin delivery. This may be attributed to the s.c. enzyme activities degrading the protamine in NPH microcrystals. Methods: A thermogelling block copolymer Pluronic® F127 (PF127) was utilized as a protective carrier for NPH microcrystals and as a modulator for insulin release from NPH. NPH insulin-loaded PF127 gel was prepared with varying concentrations of the polymer (15–25%) under mild conditions. The formulations were characterized for their gelling temperature, morphology, gel erosion, and in vitro insulin release, with trypsin concentrations up to 5 U/mL. Results: Scanning electron microscopy (SEM) showed that the integrity of NPH microcrystals was maintained after preparation. The burst release of insulin from NPH was significantly attenuated over the course of ~16h in the presence of PF127 with or without enzyme activity. Conclusion: NPH-PF127 successfully resisted the acceleration of NPH crystal dissolution and insulin release in vitro in the presence of protamine-degrading enzyme activity, warranting further testing.

Nanoparticles integrating natural and synthetic polymers for in vivo insulin delivery

The aims of the current study were to develop insulin-loaded nanoparticles comprised of various polymers at different compositions, and to evaluate their ability to lower blood glucose levels in diabetic rats following subcutaneous and oral administrations. Several combinations of natural and synthetic polymers have been utilized for preparation of nanoparticles including, chitosan, alginate, albumin and Pluronic. Nanosized (170 nm-800 nm) spherical particles of high encapsulation efficiency (15-52%) have been prepared. Composition and ratios between the integrated polymers played a pivotal role in determining size, zeta potential, and in vivo hypoglycemic activity of particles. After subcutaneous and oral administration in diabetic rats, some of the insulin-loaded nanoparticles were able to induce much higher hypoglycemic effect as compared to the unloaded free insulin. For instance, subcutaneous injection of nanoparticles comprised of chitosan combined with sodium tripolyphosphate, Pluronic or alginate/calcium chloride, resulted in comparable hypoglycemic effects to free insulin, at two-fold lower dose. Nanoparticles were well-tolerated after oral administration in rats, as evidenced by by measuring levels of alanine aminotransferase, aspartate aminotransferases, albumin, creatinine and urea. This study indicates that characteristics and delivery efficiency of nanomaterials can be controlled via utilizing several natural/synthetic polymers and by fine-tuning of combination ratio between polymers.

Stability of a novel Lidocaine, Adrenaline and Tetracaine sterile thermosensitive gel: A ready-to-use formulation

BACKGROUND

Superficial wounds that require suturing are often the reason children visit the Paediatric Emergency Department. Suturing is usually accompanied by perilesional administration of lidocaine, a local anaesthetic drug that improves pain tolerance. In paediatric patients, this approach has a low compliance because lidocaine has to be injected, which in children generates fear and anxiety, a sterile anaesthetic gel could improve the child compliance.

OBJECTIVE

To develop a sterile and stable sterile gel capable of remaining in place over time for topical anaesthesia.

METHOD

Different formulations were analysed by HPLC, by UV and fluorimetric detection. Two different sterilisation methods were tested.

MAIN OUTCOME

To maintain the original stability of the gel also after sterilisation process.

RESULTS

Four different gels were prepared and analysed; the most stable gel lasts over 3 months with a degradation less than 10%.

CONCLUSION

The use of Poloxamer 407 guarantees stability of the preparation, showing a reduction in oxidative reaction, and gives the gel the right texture for application to a bleeding wound.

Thermogelling properties of purified poloxamer 407

Poloxamers are triblock copolymers with a center block of hydrophobic polypropylene oxide (PPO) flanked by two hydrophilic polyethyleneoxide (PEO) blocks. Among this family of copolymers, poloxamer 407 is a non-ionic surfactant with reversible gelation properties above a particular polymer concentration and a particular temperature. Easy preparation of poloxamer 407 based sterile injectable formulations have made this copolymer a good candidate for drug delivery, specifically when controlled release of the drug is required. Previously, the applications of compendial poloxamer 407 preparations were demonstrated; however, low viscosity, poor elasticity, and sol-to-gel transition temperature (T_sol-gel) over a wide temperature range were observed. A purification process was introduced to eliminate impurities and low molecular weight copolymer molecules from the compendial poloxamer 407 resulting in higher viscosity values with T_sol-gel in a narrow temperature range. Here, poloxamer 407 was purified based on the proposed process and the rheological and analytical evaluation of the purified poloxamer 407 was conducted and compared to unpurified, compendial poloxamer 407. Then, the impact of poloxamer 407 concentration on gel formation was evaluated. For drug delivery applications, the effect of relevant buffer salts and the effect of addition of ethanol to the poloxamer 407 solutions were rheologically evaluated.

Controlled release effervescent buccal discs of buspirone hydrochloride: in vitro and in vivo evaluation studies

In the present study controlled release effervescent buccal discs of buspirone hydrochloride (BS) were designed using HPMC as rate controlling and bioadhesive polymer by direct compression method. Sodium bicarbonate and citric acid were used in varying amounts as effervescence forming agents. Carbon dioxide evolved due to reaction of sodium bicarbonate and citric acid was explored for its potential as buccal permeation enhancer. The designed buccal discs were evaluated for physical characteristics and in vitro drug release studies. Bioadhesive behavior of designed buccal discs was assessed using texture analyzer. In vivo animal studies were performed in rabbits to study bioavailability of BS in the designed buccal discs and to establish permeation enhancement ability of carbon dioxide. It was observed that effervescent buccal discs have faster drug release compared to non-effervescent buccal discs in vitro and effervescent buccal discs demonstrated significant increase in bioavailability of drug when compared to non-effervescent formulation. Hence, effervescent buccal discs can be used as an alternative to improve the drug permeation resulting in better bioavailability. However, the amount of acid and base used for generation of carbon dioxide should be selected with care as this may damage the integrity of bioadhesive dosage form.

Oral transmucosal drug delivery--current status and future prospects

Oral transmucosal drug delivery (OTDD) dosage forms have been available since the 1980s. In contrast to the number of actives currently delivered locally to the oral cavity, the number delivered as buccal or sublingual formulations remains relatively low. This is surprising in view of the advantages associated with OTDD, compared with conventional oral drug delivery. This review examines a number of aspects related to OTDD including the anatomy of the oral cavity, models currently used to study OTDD, as well as commercially available formulations and emerging technologies. The limitations of current methodologies to study OTDD are considered as well as recent publications and new approaches which have advanced our understanding of this route of drug delivery.

Thermosensitive periodontal sol of ciprofloxacin hydrochloride and serratiopeptidase: Pharmaceutical and mechanical analysis

AIM

The aim of the present work was to explore the development of a dual-controlled release periodontal system of a potent broad spectrum first-generation fluoroquinolone, ciprofloxacin, and the anti-inflammatory enzyme serratiopeptidase (STP).

MATERIALS AND METHODS

Based on 3(2) full factorial design, thermoreversible periodontal sols capable of controlled dual delivery of ciprofloxacin hydrochloride and STP were designed using pluronic F127 and carbopol 934P as thermosensitive gelling polymers. Sol gel transition characteristics, %cumulative drug release at 48(th) h and exvivo mucoadhesive strength were designated as dependent responses. The sols were mucoadhesive, syringeable, and inverted into gels at simulated periodontal cavity temperature.

RESULTS

F9 with optimal drug release was identified as the best formulation. Extra design check point generated using Design Expert software 8.02 (Stat-Ease, USA) validated the experimental design. Textural analysis revealed that the developed sols were syringeable and spreadable enough for periodontal treatment so it can be expected that hardness and compressibility of sols would pose no problem during clinical application. The in vitro release behavior exhibited controlled release of both cipro HCl and STP (>90% release).

CONCLUSION

A dual-controlled release thermoreversible periodontal sol of ciproflaxin and STP was successfully developed. Incorporation of STP as anti-inflammatory agent has the potential of developing a therapeutically efficacious system of cipro HCl for treatment of periodontal inflammatory anaerobic infections.

IL-1Ra and its delivery strategies: inserting the association in perspective

Interleukin-1 receptor antagonist (IL-1Ra) is a naturally occurring anti-inflammatory antagonist of interleukin-1 family of pro-inflammatory cytokines. The broad spectrum anti-inflammatory effects of IL-1Ra have been investigated against various auto-immune diseases such as diabetes mellitus, rheumatoid arthritis. Despite of its outstanding broad spectrum anti-inflammatory effects, IL-1Ra has short biological half-life (4-6 h) and to cope with this problem, up till now, many delivery strategies have been applied either to extend the half-life and/or prolong the steady-state sustained release of IL-1Ra from its target site. Here in our present paper, we have provided an overview of all approaches attempted to prolong the duration of therapeutic effects of IL-1Ra either by fusing IL-1Ra using fusion protein technology to extend the half-life and/or development of new dosage forms using various biodegradable polymers to prolong its steady-state sustained release at the site of administration. These approaches have been characterized by their intended impact on either in vitro release characteristics and/or pharmacokinetic and pharmacodynamic parameters of IL-1Ra. We have also compared these delivery strategies with each other on the basis of bioactivity of IL-1Ra after fusion with fusion protein partner and/or encapsulation with biodegradable polymer.

Sustained delivery of IL-1Ra from PF127-gel reduces hyperglycemia in diabetic GK-rats

Interleukin-1beta (IL-1β) is a major cause for induction of various inflammatory mechanisms that are decisively involved to provoke pathogenesis of type 2 diabetes mellitus (T2DM). Interleukin-1 receptor antagonist (IL-1Ra) a naturally occurring anti-inflammatory antagonist of IL-1β has been recently approved for treatment of T2DM but due to its short half-life, higher doses and frequent dosing intervals are required. Pluronic F-127 (PF127) has previously shown to prolong the release of various proteinous drugs and their serum half-lives. Subsequently, in our previous work, we developed a new dosage form of IL-1Ra using PF127 and investigated its in-vitro and in-vivo effects. Here in present work, we have extended this approach using diabetic Goto-kakizaki (GK) rats. We administered IL-1Ra loaded in PF127 gel subcutaneously for one month into GK rats. IL-1Ra loaded in PF127 gel exhibited a sustained and prolonged hypoglycemic effects on treated animals. Intraperitoneal glucose tolerance test (IPGTT) results showed that IL-1Ra loaded in PF127 gel increased glucose tolerance along with increased insulin sensitivity and β-cell’s secretory function in treated rats. Moreover, significant reduction in pro-insulin/insulin ratio, lipid profiles and interleukin 6 (IL-6) were also observed. Immunohistochemical analysis showed slight macrophages infiltration in pancreatic islets. Histochemical analysis revealed no PF127-induced alteration in the normal physiology of skin and kidney of treated animals. Hence, we concluded that IL-1Ra loaded in PF127 gel has potential to exhibit broad spectrum anti-inflammatory effects alleviating the symptoms of T2DM.