Intensive therapy with inhaled insulin via the AERx insulin diabetes management system: a 12-week proof-of-concept trial in patients with type 2 diabetes

Non-invasive routes for insulin administration: current state and perspectives

Diabetes mellitus is a chronic disease that usually requires multiple insulin injections to achieve adequate glycaemic control. This represents a major cause of reduced compliance to treatment. Consequently, other routes for insulin administration have been explored. During recent years, much progress in the development of inhaled insulin has been made. Inhaled insulin has shown favourable properties, such as a rapid onset of action, improved bioavailability and good tolerability; thereby providing satisfaction and ease of administration. However, long-term safety of inhaled insulin needs to be assessed, and the cost would be higher than injectable insulin. Nasal, oral and transdermal insulins are undergoing early phases of pharmacological development. The purpose of this review is to describe the latest developments in the area of non-invasive routes for insulin delivery.

Inhalation of Human Insulin Is Associated with Improved Insulin Action Compared with Subcutaneous Injection and Endogenous Secretion in Dogs

This study compared the effects of endogenous (portal) insulin secretion versus peripheral insulin administration with subcutaneous or inhaled human insulin [INH; Exubera, insulin human (rDNA origin) inhalation powder] on glucose disposal in fasted dogs. In the control group, glucose was infused into the portal vein (Endo; n = 6). In two other groups, glucose was infused portally, whereas insulin was administered peripherally by inhalation (n = 13) or s.c. injection (n = 6) with somatostatin and basal glucagon. In the Endo group, over the first 3 h, the arterial insulin concentration was twice that of the peripheral groups, whereas hepatic sinusoidal insulin levels were half as much. Although net hepatic glucose uptake was greatest in the Endo group, the peripheral groups demonstrated larger increases in nonhepatic glucose uptake so that total glucose disposal was greater in the latter groups. Compared with s.c. insulin action, glucose excursions were smaller and shorter, and insulin action was at least twice as great after INH. Thus, at the glucose dose and insulin levels chosen, peripheral insulin delivery was associated with greater whole-body glucose disposal than endogenous (portal) insulin secretion. INH administration resulted in increased insulin sensitivity in nonhepatic but not in hepatic tissues compared with s.c. delivery.

Inhaled insulin as adjunctive therapy in subjects with type 2 diabetes failing oral agents: a controlled proof-of-concept study

AIM

This controlled proof-of-concept study investigated inhaled insulin (INH) as adjunctive therapy to existing oral antidiabetic agents in subjects with type 2 diabetes.

METHODS

Twenty-four subjects with type 2 diabetes [19 men and 5 women, 56.1 +/- 6.6 years, body mass index 32.7 +/- 4.2 kg/m(2), glycosylated haemoglobin (HbA1c) 8.4 +/- 0.8% (mean +/- s.d.)] inadequately controlled by metformin and/or sulfonylureas were randomized to receive additional therapy with either INH administered preprandially using a metered-dose inhaler (MDI), or insulin glargine (GLA) injected subcutaneously at bedtime for 4 weeks. Both inhaled and injected insulin doses were titrated to predefined blood glucose (BG) targets.

RESULTS

INH and GLA improved metabolic control to a similar extent. Mean daily BG decreased by 2.8 mmol/l in the INH group (p < 0.001) and by 2.4 mmol/l in the GLA group (p < 0.001). Accordingly, fasting BG (-2.7 vs. -3.6 mmol/l for INH vs. GLA), preprandial- and 2-h postprandial BG, HbA1c (-1.23 vs. -1.05%), body weight (-1.9 vs. -2.3 kg) and serum fructosamine were similarly and significantly reduced in both groups (p < 0.05). Triglycerides decreased significantly with INH (-1.15 micromol/l; p < 0.001) but not with GLA [-0.52 micromol/l; not significant (NS)]. Incidence rates of adverse events did not differ significantly, and there were no indications of respiratory tract irritation.

CONCLUSIONS

In subjects with type 2 diabetes inadequately controlled by oral agents, preprandial administration of INH delivered by a MDI provided a comparable metabolic control to bedtime GLA and did not show any safety concerns during a 4-week treatment. These results warrant a more extensive investigation of preprandial treatment with INH in longer term studies.

Diabetes therapy trials with inhaled insulin

Administration of insulin by inhalation was first attempted > 50 years ago. At that time, little was known concerning effective delivery systems and insulin formulations. The recent development of pulmonary delivery systems for the administration of insulin is driven by the reluctance of patients and their providers to initiate insulin earlier in the course of Type 2 diabetes, the desire to reduce the number of daily insulin injections for both Type 1 and 2 patients, and the recent emphasis on intensified glycaemic control including postprandial glycaemic control. The deep lung is a unique mucosal tissue having a surface area of > 100 m2 and is readily accessible both to the external environment and to drug delivery, provided that appropriate conditions are met. There have been four mid- to late-phase pulmonary insulin programmes using modern inhalation devices that will be reported in this paper. The programmes differ in the choice of delivery systems, the formulations of insulin and reported bioavailability, pharmacokinetic and glucodynamic profiles and adverse events. However, all systems successfully deliver insulin to the deep lung and biological effectiveness compares favourably with injected subcutaneous insulins.

Role of inhaled human insulin in the management of Type 1 and 2 diabetes

Inhaled human insulin (Exubera^®) has been approved by the FDA and other regulatory bodies for treatment in Type 1 and 2 diabetes in the USA. It is the first alternative to injectable insulin since the discovery of the insulin compound to treat diabetes. This article will review results of recent clinical studies that support the therapeutic efficacy and safety of inhalable insulin for use in patients with diabetes. The pharmacological profile of inhaled insulin with particular reference to inhaled human insulin and the potential to influence diabetes care is also discussed.

Inhaled insulin: new technology, new possibilities

The prevalence of diabetes is reaching epidemic proportions with an increasing need for new therapies. Several new therapies are in development and amongst these is inhaled insulin. Inhaled insulin is a novel way of delivering insulin and has been shown to have an efficacy comparable to subcutaneous insulin in patients with both type 1 and type 2 diabetes. Several inhaled insulin delivery systems are currently in development and the first of these, Exubera has recently been granted license in Europe and in the USA. In this article we review the efficacy and safety profile of Exubera and discuss its potential place in the management of diabetes.

Nanoscale analysis of protein and peptide absorption: insulin absorption using complexation and pH-sensitive hydrogels as delivery vehicles

Recent advances in the discovery and delivery of drugs to cure chronic diseases are achieved by combination of intelligent material design with advances in nanotechnology. Since many drugs act as protagonists or antagonists to different chemicals in the body, a delivery system that can respond to the concentrations of certain molecules in the body is invaluable. For this purpose, intelligent therapeutics or "smart drug delivery" calls for the design of the newest generation of sensitive materials based on molecular recognition. Biomimetic polymeric networks can be prepared by designing interactions between the building blocks of biocompatible networks and the desired specific ligands and by stabilizing these interactions by a three-dimensional structure. These structures are at the same time flexible enough to allow for diffusion of solvent and ligand into and out of the networks. Synthetic networks that can be designed to recognize and bind biologically significant molecules are of great importance and influence a number of emerging technologies. These synthetic materials can be used as unique systems or incorporated into existing drug delivery technologies that can aid in the removal or delivery of biomolecules and restore the natural profiles of compounds in the body.

Efficacy and safety of preprandial human insulin inhalation powder versus injectable insulin in patients with type 1 diabetes

AIMS/HYPOTHESIS

The efficacy and safety of human insulin inhalation powder (HIIP) plus insulin glargine were compared to subcutaneously injected insulin (SC insulin) plus insulin glargine in patients with type 1 diabetes.

METHODS

This was a randomised, open-label crossover study in which one group of patients received preprandial HIIP plus insulin glargine for 12 weeks, followed by the same duration with preprandial SC insulin (lispro or regular) plus insulin glargine. Another group of patients received the reverse treatment sequence. The trial was designed as a non-inferiority comparison of the two treatments for effect on HbA(1c); blood glucose levels were also monitored. Safety assessments included adverse event reporting and hypoglycaemic events.

RESULTS

HbA(1c) at endpoint was 7.95+/-0.12% for the HIIP treatment and 8.06+/-0.12% for the SC insulin treatment; mean changes from baseline to endpoint were -0.08 and 0.00%, respectively, (p=NS). The upper limit of the 95% CI of mean difference in HbA(1c) between the two treatments was 0.02%, indicating that HIIP was not inferior relative to SC insulin, as measured against the pre-defined margin of 0.3%. Fasting blood glucose was significantly lower for HIIP treatment (8.09+/-0.33 mmol/l; n=117) than for SC insulin treatment (9.05+/-0.33 mmol/l; n=111) (p=0.01). Safety profiles were comparable between the two treatments. The rate of any hypoglycaemia (least-squares mean adjusted for 30 days+/-SE) was 8.9+/-0.7 and 8.2+/-0.8 for HIIP and SC insulin treatments, respectively, (p=0.29). The rate of nocturnal hypoglycaemia was greater for HIIP (4.2+/-0.4) than for SC insulin (2.7+/-0.4; p<0.001).

CONCLUSIONS/INTERPRETATION

HIIP was similar in efficacy to SC insulin for glycaemic control in type 1 diabetes mellitus. The two treatments had comparable safety profiles.

Inhaled insulin: recent advances in the therapy of Type 1 and 2 diabetes

There are promising data in the field of inhaled insulin. This article describes the current devices being developed for insulin delivery via inhalation. Encouraging advanced clinical data are available in Type 1 diabetes, where inhaled insulin is used in conjunction with basal insulin. Moreover, patients with Type 2 diabetes who have failed oral therapy show improved control when inhaled insulin therapy is initiated. Safety data show that cough is the most common side effect. Pulmonary function tests have shown some changes in carbon monoxide diffusion in the lung. Further studies are needed to clarify the significance of this finding. Inhaled insulin appears to be a non-invasive, well-tolerated and -liked modality of treatment, with potential in both Type 1 and 2 diabetes.

Dose response of inhaled dry-powder insulin and dose equivalence to subcutaneous insulin lispro

OBJECTIVE

To determine the pharmacokinetic (PK) and glucodynamic (GD) dose response of human insulin inhalation powder (HIIP) delivered via AIR particle technology and dose equivalence to subcutaneous (SC) insulin lispro.

RESEARCH DESIGN AND METHODS

Twenty healthy, nonsmoking, male or female subjects (aged 29.6 +/- 6.9 years, BMI 23.2 +/- 2.3 kg/m2, means +/- SD) with normal forced vital capacity and forced expiratory volume were enrolled in an open-label, randomized, seven-period, euglycemic glucose clamp, cross-over trial. Each subject received up to four single doses of HIIP (2.6, 3.6, 5.2, or 7.8 mg) and three doses of SC lispro (6, 12, or 18 units) from 5 to 18 days apart.

RESULTS

HIIP demonstrated a similar rapid onset but an extended time exposure and a prolonged duration of effect (late t(50%) 412 vs. 236 min, P < 0.001) compared with SC lispro. The HIIP versus SC lispro doses of 2.6 mg vs. 6 units, 5.2 mg vs. 12 units, and 7.8 mg vs. 18 units achieved similar PK area under the serum immunoreactive insulin (IRI) concentration-versus-time curve from time zero until the serum IRI concentrations returned to the predose baseline value [AUC(0-t')] and GD (G(tot)) responses. The median insulin (t(max)) was not different between HIIP and SC lispro (45 min for both), although the median time of return to baseline for PK was apparently longer for HIIP compared with SC lispro (480 vs. 360 min). Relative bioavailability and relative biopotency of HIIP were consistent across doses (8 and 9%).

CONCLUSIONS

While the time-action profile was longer for HIIP than for SC lispro, both treatments showed rapid initial absorption and similar overall PK exposure and GD effect. HIIP was as well tolerated as SC lispro, thereby offering a promising alternative to injectable insulin therapy.

Insulin Therapy: Current Alternatives

In normal humans, blood glucose and insulin are maintained within a narrow range despite wide variations in physical activity and dietary intake. At present, reproducing this pattern is an impossible task in type 1 diabetes and extremely difficult in type 2 DM. New approaches using novel insulin analogs and routes of administration, attempting to replicate physiological insulin secretion in diabetic patients, are improving the profiles of glucose levels and, thus, the quality of life. Ultra-short-acting insulin analogues and ultra-long-acting analogues are being used for prandial and basal effects with better results, lower prevalence of hypoglycemia, and, hopefully, fewer chronic complications. Non-invasive routes of administration are being developed. The most promising appears to be inhaled insulin according to studies demonstrating excellent control, apparently without significant side effects, although in relatively short-term trials. Longer-term studies to assure the safety are still necessary before recommending its extended use. This is an extensive, up-to-date review of recent advances in insulin therapy.

New strategies in insulin treatment: analogues and noninvasive routes of administration

Abstract Recent years have seen the development of alternatives to human insulin for the treatment of diabetes. Both rapid-acting and long-acting analogues are available. Alternative routes of insulin administration are emerging. The present review briefly summarizes the present knowledge on insulin analogues and alternative administration routes.

Novel pharmacologic agents for type 2 diabetes

After many decades of relative therapeutic stagnation since the initial discovery of insulin, followed by some modifications on its structure and only having sulfonylureas and biguanides for many years, the last decade has seen a surge in new therapeutic options for the management of diabetes. The results of the United Kingdom Prospective Diabetes Study and Kumamoto study indicate the need for aggressive glycemic control and the slow inexorable clinical deterioration associated with type 2 diabetes overtime. The propensity for weight gain and hypoglycemia are the two major limitations that subcutaneous insulin and sulfonylureas have been particularly prone to. The newer antidiabetic medications and those on the horizon attempt to address these limitations. GLP-1 agonists and the DPP-IV inhibitors exploit the innate incretin system to improve glycemia while promoting satiety and weight management. Like GLP-1 related compounds, pramlintide offers the potential to address postprandial hyperglucagonemia associated with type 2 diabetes only limited by the multiple injections and gastrointestinal side effects. The glitazars offer the hope ofa new approach to diabetes care addressing not just glycemia, but dyslipidemia and other components of the metabolic syndrome, though the side effect profile remains a major unknown. The INGAP peptide represents the holy grail of diabetes care as it offers the potential of a new paradigm: that of islet regeneration and potential for a cure. But at this stage, with no human data available, it remains highly speculative. Beyond these and other novel agents being developed to meet the challenge of the worldwide epidemic of diabetes, the central place of insulin in diabetes care cannot be forgotten. In view of this the continued efforts of improvement in insulin delivery, kinetics and action have spurred such innovations as the various inhaled insulins and new insulin analogues. There is cause for guarded optimism and excitement about the years ahead. There is reason to expect that despite the growing burden of diabetes worldwide, we will be better equipped to manage it and its comorbidities and prevent its onset and possibly even cure it.

Inhaled Insulins

The inhalation of insulin was conceptualized by the mid-1920s, but the first successful testing of inhaled insulin occurred in the mid-1990s. The lung has proven to be an organ well capable of absorbing insulin in a reproducible and dose-dependent manner. At present, two concepts of pulmonary insulin delivery at relatively advanced stages of development have been investigated in several published studies. The first involves the Exubera device, a system consisting of a formulation of insulin in a dry and amorphous powder, which is then packaged into blisters. A special delivery system generates a pulse of compressed air, which causes the insulin to form a white fog in a transparent reservoir that can be inhaled by deep breathing. The second approach is the AERx insulin Diabetes Management System, which uses an aqueous formulation of insulin, delivered as an aerosol generated by a special, microprocessor-controlled, inhalation device. This device is capable of monitoring the patient's inspiratory flow and guiding the inhalation by a microelectronic feedback system. The therapeutic efficacy and safety of these inhaled insulins seem comparable to those of subcutaneous insulin regimens; however, inhaled insulins do not appear to achieve significantly better glycemic control. Several other concepts for the pulmonary delivery of insulin are also being developed. With the incidence of diabetes mellitus, especially type 2 diabetes, dramatically increasing worldwide, patients with type 2 diabetes appear to be an important target group for new modalities of insulin delivery. In this group, the onset of insulin treatment is frequently delayed due to the fear of self-injection, preventing effective glycemic control. Patient acceptance of inhaled insulins is excellent and no serious adverse effects have been observed to date. Further advantages of inhaled insulins are the more rapid onset of insulin action and a mitigation of postprandial glucose excursions. However, there are some open questions. The most important concerns the possible long-term effects of insulin inhalation on the lung, as insulin is known to have growth-promoting properties. Thus far, there are no observations of the effects of inhaled insulin on lung structure and function that extend beyond 10 years. In patients with pulmonary disease, the smaller cumulative alveolar surface may cause problems in absorption, and in smokers the action of inhaled insulin has been shown to be stronger and with a faster onset. Furthermore, treatment with inhaled insulin requires larger doses of insulin compared with the subcutaneous route of insulin administration to achieve the same systemic effect, and the costs of this therapy could therefore be significantly higher than the costs of present insulin therapies.

Trends in the technology-driven development of new inhalation devices

Inhalation technology diverges rapidly along various lines. A variety of technological solutions are currently under development to overcome the many problems related to adequate aerosol generation both for dry powder inhalation systems and for liquid inhalation systems. Many of the improvements are related to the fine particle fraction in the generated aerosol, particularly its dependency on the patients' inspiratory flow profile and the velocity of the aerosol.:

Compliance with inhaled insulin treatment using the AERx iDMS Insulin Diabetes Management System

OBJECTIVE

The AERx Insulin Diabetes Management System [AERx iDMS, jointly developed by Novo Nordisk (Bagsvaerd, Denmark) and Aradigm Corp. (Hayward, CA)] provides insulin by pulmonary administration. This investigation was designed as a pilot trial to demonstrate the ability of patients to use the electronic device to deliver mealtime inhaled insulin doses and explore the impact on compliance.

METHODS

AERx iDMS was evaluated in a substudy of a 12-week, multicenter open trial by adult patients with type 2 diabetes previously on any insulin regimen. The device was used for dosing fast-acting human insulin immediately before main meals, in combination with bedtime NPH insulin. The AERx iDMS device recorded the date and time of each insulin inhalation, insulin units used, and inhalation technique during aerosol delivery. Compliance was defined as the percentage of prescribed doses taken during the treatment period, dose timing, and the efficiency of dosing technique.

RESULTS

Insulin dosing for 49 patients (age 59.1 +/- 7.7 years) using AERx iDMS was monitored for 78.9 +/- 10 days (range, 41-94 days) with 226 +/- 35 doses (range, 122-272 doses). Patients inhaled on average 2.9 +/- 0.3 doses of insulin daily, taking an average of 11.8 +/- 5.6 units per dose. Compliance with the prescribed regimen was 94.3 +/- 9.1% (range, 45-100%). Overall, 4.2 +/- 9.5% of prescribed doses were omitted. Hemoglobin A1c decreased 0.77 +/- 0.96% from baseline to the end of the study. Inhalation technique was excellent, with 97% of patients experiencing fewer than five inadequate doses.

CONCLUSIONS

Excellent compliance with AERx iDMS dosing, timing, and inhalation technique showed that the device was well accepted by patients. The electronic monitoring feature could be used as an educational tool to help patients and clinicians manage insulin dosing.

Efficacy and safety of inhaled insulin (exubera) compared with subcutaneous insulin therapy in patients with type 2 diabetes: results of a 6-month, randomized, comparative trial

OBJECTIVE

Glycemic control using inhaled, dry-powder insulin plus a single injection of long-acting insulin was compared with a conventional regimen in patients with type 2 diabetes, which was previously managed with at least two daily insulin injections.

RESEARCH DESIGN AND METHODS

Patients were randomized to 6 months' treatment with either premeal inhaled insulin plus a bedtime dose of Ultralente (n = 149) or at least two daily injections of subcutaneous insulin (mixed regular/NPH insulin; n = 150). The primary efficacy end point was the change in HbA1c from baseline to the end of study.

RESULTS

HbA1c decreased similarly in the inhaled (-0.7%) and subcutaneous (-0.6%) insulin groups (adjusted treatment group difference: -0.07%, 95% CI -0.32 to 0.17). HbA1c < 7.0% was achieved in more patients receiving inhaled (46.9%) than subcutaneous (31.7%) insulin (odds ratio 2.27, 95% CI 1.24-4.14). Overall hypoglycemia (events per subject-month) was slightly lower in the inhaled (1.4 events) than in the subcutaneous (1.6 events) insulin group (risk ratio 0.89, 95% CI 0.82-0.97), with no difference in severe events. Other adverse events, with the exception of increased cough in the inhaled insulin group, were similar. No difference in pulmonary function testing was seen. Further studies are underway to assess tolerability in the longer term. Insulin antibody binding increased more in the inhaled insulin group. Treatment satisfaction was greater in the inhaled insulin group.

CONCLUSIONS

Inhaled insulin appears to be effective, well tolerated, and well accepted in patients with type 2 diabetes and provides glycemic control comparable to a conventional subcutaneous regimen.

Waiting to inhale: noninjectable insulin, are we there yet?

Subcutaneous injection has been the only route of insulin administration for patients with type 1 or type 2 diabetes for the past 80 years. Although research and development in this time has improved the insulin treatments themselves, it is only now that alternative routes of insulin administration are becoming viable. Many avenues of insulin administration have been explored, including oral, buccal, and pulmonary routes. However, these methods of noninvasive insulin delivery are not free from difficulties and only preliminary data are available for oral insulin pills and buccal insulin sprays. The most promising alternative route of delivery appears to be inhaled insulin and two devices are already in phase III testing. Nevertheless, inhaled insulin devices will still have to overcome some problems and recent studies show that these challenges are currently being confronted. It appears that years of research into noninvasive methods of insulin administration are close to fruition and this review outlines the most recent findings in this area.

Intrasubject variability of inhaled insulin in type 1 diabetes: a comparison with subcutaneous insulin

We compared intrasubject variability of insulin and glucose profiles after a standardized meal between insulin inhaled via the AERx insulin Diabetes Management System (AERx iDMS, Aradigm Corp., Hayward, CA) and given as a subcutaneous injection. In this single-center, parallel, randomized, open-labeled trial, 17 male, non-smoking patients with type 1 diabetes (mean age, 27.7 years; body mass index, 23.4 kg/m(2)) received a fixed, individualized dose of human insulin, on four treatment days followed by an individualized breakfast, administered either by inhalation via AERx iDMS (n = 9) or by subcutaneous injection. Serum insulin and serum glucose levels were determined at regular intervals for 6 h postdose. Intrasubject variability was expressed as coefficient of variation. No statistically significant differences in intrasubject variability were observed between the treatments for the areas under the insulin curves for 0-6 h [27% vs. 19% (inhaled insulin vs. subcutaneous)] and areas under the glucose curves 0-6 h (30% vs. 23%). Intrasubject variability values for insulin half-life, terminal elimination rate constant, and mean residence time were significantly less in the inhaled insulin group compared with the subcutaneous insulin group (P = 0.01-0.02). Only one potentially trial product-related adverse event (an audible wheeze) was reported, and no clinically relevant changes in pulmonary function were detected. The intrasubject variability was comparable between patients receiving inhaled insulin and subcutaneous insulin, thereby confirming the reproducibility of administering insulin via AERx iDMS. Inhaled insulin was well tolerated and is a feasible alternative to subcutaneous insulin in patients with type 1 diabetes.