The effect of smoking cessation and subsequent resumption on absorption of inhaled insulin

The Pharmacokinetics of Inhaled Drugs

The pharmacokinetic (PK) profile of a drug after inhalation may differ quite markedly from that seen after dosing by other routes of administration. Drugs may be administered to the lung to elicit a local action or as a portal for systemic delivery of the drug to its site of action elsewhere in the body. Some knowledge of PK is important for both locally- and systemically-acting drugs. For a systemically-acting drug, the plasma concentration-time profile shares some similarities with drug given by the oral or intravenous routes, since the plasma concentrations (after the distribution phase) will be in equilibrium with concentrations at the site of action. For a locally-acting drug, however, the plasma concentrations reflect its fate after it has been absorbed and removed from the airways, and not what is available to its site of action in the lung. Consequently, those typical PK parameters which are determined from plasma concentration measurements, e.g., area under the curve (AUC), Cmax, tmax and post-peak t1/2 may provide information on the deposition and absorption of drugs from the lung; however, the information from these parameters becomes more complicated to decipher for those drugs which are locally-acting in the lung. Additionally, the plasma concentration profile for both locally- and systemically-acting drugs will not only reflect drug absorbed from the lung but also that absorbed from the gastrointestinal (GI) tract from the portion of the dose which is swallowed. This absorption from the GI tract adds a further complication to the interpretation of plasma concentrations, particularly for locally-acting drugs. The influence of physiological and pathological factors needs to be considered in the absorption of some inhaled drugs. The absorption of some hydrophilic drugs is influenced by the inspiratory maneuver used during initial inhalation of the drug, and at later times after deposition. Similarly, the effects of smoking have been shown to increase lung permeability and increase the absorption of certain hydrophilic drugs. The effects of different disease states of the lung have less defined influences on absorption into the systemic circulation.

Seeing what is behind the smokescreen: A systematic review of methodological aspects of smoking interaction studies over the last three decades and implications for future clinical trials

Smoking drug interaction studies represent a common approach for the clinical investigation of CYP1A2 induction. Despite this important role, they remain an "orphan topic" in the existing regulatory framework of drug interaction studies, and important methodological aspects remain unaddressed. The University of Washington Drug Interaction Database (DIDB) was used to systematically review the published literature on dedicated smoking pharmacokinetic interaction studies in healthy subjects (1990 to 2021, inclusive). Various methodological aspects of identified studies were reviewed. A total of 51 studies met all inclusion criteria and were included in the analysis. Our review revealed that methods applied in smoking interaction studies are heterogeneous and often fall short of established methodological standards of other interaction trials. Methodological deficiencies included incomplete description of study populations, poor definition and lack of objective confirmation of smoker and nonsmoker characteristics, under-representation of female subjects, small sample sizes, frequent lack of statistical sample size planning, frequent lack of use of existing markers of nicotine exposure and CYP1A2 activity measurements, and frequent lack of control of extrinsic CYP1A2 inducing or inhibiting factors. The frequent quality issues in the assessment and reporting of smoking interaction trials identified in this review call for a concerted effort in this area, if the results of these studies are meant to be followed by actionable decisions on dose optimization, when needed, for the effects of smoking on CYP1A2 victim drugs in smokers.

A Review of the Impact of Smoking on Inhaled Insulin: Would You Stop Smoking if Insulin Can Be Inhaled?

High prevalence of diabetes and the need for tight glycemic control have been well established. With the invention of inhaled insulin, an alternate route has been explored and shows great promise. Inhaled insulin shows a similar physiologic response to subcutaneous insulin, with a faster onset of action, making it suitable for post-prandial hyperglycemia. This comes as a great relief, especially to those who are hesitant to use multiple injections in a day. Many factors affect insulin absorption, including device, particle size, airway patency. Another essential factor is smoking, which is prevalent among people with diabetes, as is in the non-diabetic population. Smoking increases the absorption of inhaled insulin, but it is not a straight fact, since acute smoking, passive smoking, chronic smoking - all have different effects on inhaled insulin. Furthermore, inhaled insulin is also affected by lung diseases. Most studies that have been conducted have included limited populations, thus questioning their generalisability. The studies from inception till 2020 have shown increased permeability of epithelial with acute smoking, change of epithelial layer back to normal after few weeks of smoking cessation, and reverting to chronic smoker levels with just one to two days of start in smoking. Data also suggests that smoking causes a reduction in insulin sensitivity, which could compensate for its increased absorption. Nicotine causes a decrease in the absorption of subcutaneous insulin, but its effect has not been seen on inhaled insulin. More studies, including diabetic smoker patients, need to be performed to give a specific set of variables. This would also add another reason to encourage smokers to quit smoking.

SIRT1 is required for mitochondrial biogenesis reprogramming in hypoxic human pulmonary arteriolar smooth muscle cells

Although recent studies have reported that mitochondria are putative oxygen sensors underlying hypoxic pulmonary vasoconstriction, little is known concerning the sirtuin 1 (SIRT1)-mediated mitochondrial biogenesis regulatory program in pulmonary arteriolar smooth muscle cells (PASMCs) during hypoxia/reoxygenation (H/R). We investigated the epigenetic regulatory mechanism of mitochondrial biogenesis and function in human PASMCs during H/R. Human PASMCs were exposed to hypoxia of 24–48 h and reoxygenation of 24–48 h. The expression of SIRT1 was reduced in a time-dependent manner. Mitochondrial transcription factor A (TFAM) expression was increased during hypoxia and decreased during reoxygenation, while the release of TFAM was increased in a time-dependent manner. Lentiviral overexpression of SIRT1 preserved SIRT3 deacetylase activity in human PASMCs exposed to H/R. Knockdown of PGC-1α suppressed the effect of SIRT1 on SIRT3 activity. Knockdown of SIRT3 abrogated SIRT1-mediated deacetylation of cyclophilin D (CyPD). Notably, knockdown of SIRT3 or PGC-1α suppressed the incremental effect of SIRT1 on mitochondrial TFAM, mitochondrial DNA (mtDNA) content and cellular ATP levels. Importantly, polydatin restored SIRT1 levels in human PASMCs exposed to H/R. Knockdown of SIRT1 suppressed the effect of polydatin on mitochondrial TFAM, mtDNA content and cellular ATP levels. In conclusion, SIRT1 expression is decreased in human PASMCs during H/R. TFAM expression in mitochondria is reduced and the release of TFAM is increased by H/R. PGC-1α/SIRT3/CyPD mediates the protective effect of SIRT1 on expression and release of TFAM and mitochondrial biogenesis and function. Polydatin improves mitochondrial biogenesis and function by enhancing SIRT1 expression in hypoxic human PASMCs.

Review: Inhaled insulin: overcoming barriers to insulin therapy?

nhaled insulin is a new route of insulin delivery that can be used in the treatment of type 1 and type 2 diabetes. It offers an alternative and additional means of insulin administration, and has been received with particular satisfaction by patients who dislike injections. Trials indicate that inhaled insulin can be used effectively for pre-meal bolus intensification of treatment. Pre-meal inhaled insulin with Exubera® has shown faster absorption and similar duration of action to regular subcutaneous insulin with an overall similar glucodynamic effect. Although bioavailability is lower, mainly due to losses in the upper airways, this is compensated for by dose. The commonest side effect reported with inhaled insulin, as with subcutaneous insulin, was hypoglycaemia, almost a quarter of patients noted a cough which settled with continued treatment. Increased antibody titres and changes in lung function return to normal on discontinuation of inhaled insulin. Quality of life scores indicate patient preference for inhaled versus injected insulin, thus increased choice may improve adherence to treatment regimens. However, true cost:benefit analyses have to be undertaken as do studies in children, smokers and people with respiratory conditions, e.g. asthma.

Effect of smoking on the pharmacokinetics of inhaled loxapine

Background:

Loxapine inhalation powder delivered by a hand-held device as a thermally generated aerosol (ADASUVE) was recently approved in the United States and European Union for use in the acute treatment of agitation in patients with bipolar disorder or schizophrenia. As smokers comprise a large subpopulation of these patients, and many antipsychotic drugs require dose adjustments for smokers, the objective of this study was to compare the pharmacokinetics of inhaled loxapine administered to smokers and nonsmokers.

Methods:

Pharmacokinetics and sedation pharmacodynamics using a visual analog scale were studied in 35 male and female adult subjects (18 nonsmokers and 17 smokers) following a single dose of 10 mg of inhaled loxapine. Blood samples were drawn at predose, 30 seconds, 1, 2, 3, 10, 30, and 60 minutes, and 2, 6, 12, and 24 hours after dosing. Loxapine and 8-OH-loxapine were analyzed using reverse-phase liquid chromatography coupled with a tandem mass spectrometer. Pharmacokinetic parameters assessed included C_max, T_max, AUC_inf, and T_1/2 for loxapine and 8-OH-loxapine. Geometric mean ratios (GMRs) were determined for smokers to nonsmokers.

Results:

Loxapine C_max was similar in smokers and nonsmokers with a GMR of 99.0%. The median loxapine T_max was 1.88 and 1.01 minutes for nonsmokers and smokers, respectively. Loxapine AUC_inf and AUC_last values in nonsmokers were comparable with smokers (GMRs of 85.3% and 86.7%, respectively). A slight decrease in the observed mean terminal half-life values was observed for smokers (6.52 hours for smokers and 7.30 hours for nonsmokers).

Conclusions:

Sedation profiles and visual analog scale scores at each time point were similar for nonsmokers and smokers. It was concluded that inhaled loxapine does not require dosage adjustment based on smoking behavior.

Technosphere insulin (Afrezza): a new, inhaled prandial insulin

OBJECTIVE

To review the pharmacology, pharmacokinetics, safety, and efficacy of Technosphere insulin (TI), a new inhaled insulin product.

DATA SOURCES

Searches were conducted in PubMed/MEDLINE, Scientific Citation Index, and abstracts from both the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) meetings from 2005 to August 2014, utilizing the search terms Afrezza, Technosphere, Afresa, and inhaled insulin. References were reviewed to identify additional sources.

STUDY SELECTION AND DATA EXTRACTION

Studies with adequate sample sizes, evaluating clinically relevant end points were included.

DATA SYNTHESIS

TI is approved by the Food and Drug Administration as a bolus insulin to treat patients with type 1 and type 2 diabetes. Its glucose-lowering properties are less than that of rapid-acting insulins, but it does demonstrate less hypoglycemia. TI's kinetics make it the fastest absorbed of any insulin available, although its overall onset of action appears similar to insulin lispro. It represents an alternative to bolus injections but would likely be used concomitantly with injected basal insulin. Major adverse effects are respiratory in nature, with cough being the most prominent. There is a small decrease in the forced expiratory volume in 1 s (FEV1) with TI; this appears to be consistent, nonprogressive, and reversible. Patients using TI must receive pulmonary function tests periodically throughout therapy. TI is contraindicated in patients with chronic lung disease and should be used with caution in patients who smoke.

CONCLUSION

TI is a novel inhaled insulin that provides prandial coverage to patients with diabetes, representing an alternative to bolus insulin injections.

Further experimentation of inhaled; LANTUS, ACTRAPID and HUMULIN with todays' production systems

BACKGROUND

Several aerosol production systems have been used for aerosol insulin production. However; since the first studies several new models of jet-nebulizers and ultrasound nebulizers have been introduced in the market.

MATERIALS AND METHODS

Three different models of jet-nebulizers (different brands, same properties) and three different ultrasound nebulizers (different brands, same properties). Six residual cups (2 small ≤ 6 ml and 3 large ≤ 8 ml) were used for the jet-nebulizers. The ultrasound nebulizers were used with their facemasks or with their inlets which were included in the purchase package.

RESULTS

Ultrasound nebulizers; LANTUS produces by far the lowest mean droplets (2.44) half the size of the other two drugs (4.43=4.97). GIMA nebulizer is the most efficient producing one third of the droplet size of SHIMED and one second of EASYNEB (2.06<3.15<6.62). Finally, the 4 ml loading concentration is more suitable for supporting the production of smaller droplets (3.65<4.24). Drugs and nebulizers act interactively yielding very large droplets when ACTRAPID and HUMULIN are administered in joint with SHIMED nebulizer (9.59=7.72). Jet-nebulizers; HUMULIN again is the least preferred insulin since it hardly reaches the low but equal performance of others at the loading level of 6 ml. Residual cups E and B produce uniquely lower mean droplets at loading level 6.

CONCLUSIONS

Ultrasound nebulizers; the best suggested combination should be LANTUS insulin, GIMA nebulizer administered at loading dose of 4 ml jet-nebulizers. A global review can give the best combination: the lowest mean droplets are produced when the drugs LANTUS (mostly) and ACTRAPID are administered, applying the SUNMIST nebulizer in concert with residual cup B at loading levels of 6 ml.

Inhaled biopharmaceutical drug development: nonclinical considerations and case studies

Biopharmaceuticals are complex molecules often manufactured from living systems and their specificity and novelty holds great promise for the treatment of chronic diseases for which there are currently no cures. The inhalation route of biopharmaceutical drug delivery is attractive because the large surface area of the lung, and close proximity of the alveolar and vascular systems, maximizes the potential for drug delivery to the lung and/or systemic circulation. In addition, costs of delivery to the patient are potentially much reduced, in comparison with parental administration, since inhalation is non-invasive and likely to promote patient compliance. However, in comparison with small molecule drug development, developing an inhaled biopharmaceutical that is effective and safe for human use is associated with many challenges. This review considers some general principles of drug delivery to lung and issues associated with the translation of proof of concept studies to toxicology safety studies (e.g. aerosol generation, species selection, exaggerated pharmacology, and immunogenicity). This review also presents a summary of nonclinical and clinical data from inhaled biopharmaceuticals which are either marketed for human use or in Phase II clinical trials (e.g. DNase, insulin, human growth hormone, vaccines, therapeutic plasmid DNA complexes).

Effect of cigarette smoke extract on insulin transport in alveolar epithelial cell line A549

BACKGROUND

The main purpose of this study was to evaluate the effect of cigarette smoke extract (CSE) on insulin transport in alveolar epithelial cells.

METHODS

We first examined the effect of CSE pretreatment on cell viability, mRNA expression, and lamellar body structures in A549 cells. Then the effect of CSE pretreatment on FITC-insulin transport was examined.

RESULTS

When A549 cells were treated with 30 μg/ml of CSE for 48 h, the expression of some mRNAs abundantly expressed in type II alveolar epithelial cells such as surfactant protein B was significantly increased. Lamellar bodylike structures became more evident with CSE treatment. FITC-insulin uptake from the apical side and subsequent efflux to the basal side was enhanced by CSE treatment in A549 cells. The enhancing effect of CSE on FITC-insulin uptake was concentration-dependent and reversible. A concentration-dependent enhancing effect of CSE on FITC-insulin uptake was also observed in normal, primary cultured alveolar type II epithelial cells isolated from rats.

CONCLUSIONS

Treatment of A549 cells by CSE may direct the cells to a more type II-like phenotype. In accordance with this observation, FITC-insulin uptake was enhanced by CSE treatment. These results may partly explain the higher insulin absorption from the lung in smokers than in nonsmokers.

Chronic obstructive pulmonary disease and glucose metabolism: a bitter sweet symphony

Chronic obstructive pulmonary disease, metabolic syndrome and diabetes mellitus are common and underdiagnosed medical conditions. It was predicted that chronic obstructive pulmonary disease will be the third leading cause of death worldwide by 2020. The healthcare burden of this disease is even greater if we consider the significant impact of chronic obstructive pulmonary disease on the cardiovascular morbidity and mortality. Chronic obstructive pulmonary disease may be considered as a novel risk factor for new onset type 2 diabetes mellitus via multiple pathophysiological alterations such as: inflammation and oxidative stress, insulin resistance, weight gain and alterations in metabolism of adipokines. On the other hand, diabetes may act as an independent factor, negatively affecting pulmonary structure and function. Diabetes is associated with an increased risk of pulmonary infections, disease exacerbations and worsened COPD outcomes. On the top of that, coexistent OSA may increase the risk for type 2 DM in some individuals. The current scientific data necessitate a greater outlook on chronic obstructive pulmonary disease and chronic obstructive pulmonary disease may be viewed as a risk factor for the new onset type 2 diabetes mellitus. Conversely, both types of diabetes mellitus should be viewed as strong contributing factors for the development of obstructive lung disease. Such approach can potentially improve the outcomes and medical control for both conditions, and, thus, decrease the healthcare burden of these major medical problems.

Can inhaled insulin be used for the treatment of diabetes mellitus?

Reluctance to start and adequately titrate subcutaneous insulin are major reasons why many patients with diabetes mellitus are insufficiently metabolically controlled. Pulmonary insulin administration has the advantage over subcutaneous insulin in that it is noninvasive, seems better accepted by the diabetic population and exerts equal efficacy in terms of glycemic control. As such, inhaled insulin has the potential to increase the diabetic (Type 2) patient's willingness to commence and adhere to insulin therapy. Inhaled insulin's short duration of action makes it suitable for prandial administration provided that basal insulin requirements are met by residual b-cell function, or by supplemental long-acting subcutaneous insulin. In clinical trials, inhaled insulin is comparable to short-acting subcutaneous insulin with regard to efficacy and hypoglycemic risk. Adverse effects associated with inhaled insulin include dry cough, which tends to diminish over time, a slight drop in pulmonary function that does not progress and is reversible in most patients if treatment is discontinued, and increased insulin antibody formation, albeit without clinical sequelae. Long-term safety remains an issue for a product intended to be used chronically for many years. Exubera((R)) was thus far the only inhaled insulin product to receive approval in the USA and Europe for use in adults with Type 1 or Type 2 diabetes, but was recently withdrawn from the market. At present it is unclear how this decision will affect programs from other companies with inhaled insulin products under development.

The endocrine effects of nicotine and cigarette smoke

With a current prevalence of approximately 20%, smoking continues to impact negatively upon health. Tobacco or nicotine use influences the endocrine system, with important clinical implications. In this review we critically evaluate the literature concerning the impact of nicotine as well as tobacco use on several parameters of the endocrine system and on glucose and lipid homeostasis. Emphasis is on the effect of smoking on diabetes mellitus and obesity and the consequences of smoking cessation on these disorders. Understanding the effects of nicotine and cigarettes on the endocrine system and how these changes contribute to the pathogenesis of various endocrine diseases will allow for targeted therapies and more effective approaches for smoking cessation.

Comparative pharmacoscintigraphic and pharmacokinetic evaluation of two new formulations of inhaled insulin in type 1 diabetic patients

In this open, single-dose study, we compared the lung deposition and bioavailability of two newly developed insulin formulations for pulmonary delivery. Twelve type 1 diabetic patients were administered the two insulin products (2 U/kg b.w.), which had been radiolabelled with (99m)Tc. The formulations were either microparticles of insulin without excipients (F1) or lipid-coated insulin microparticles (F2). Lung deposition was assessed by γ-scintigraphy imaging performed immediately after administration. Bioavailability was evaluated by quantifying serum insulin levels over a period of 6 h. Lung deposition was found to be 50 ± 9% and 24 ± 8% for the F1 and F2 formulations, respectively. The insulin AUC₀₋₃₆₀ ratio of F1/F2 was 188%, which was consistent with scintigraphic imaging. The concordance between imaging and biological results suggests that the lower bioavailability of F2 is due to its lower lung deposition and not to a reduced absorption into the blood stream. Additional in vitro experiments indicated that the lower performance of F2 was most probably related to a lower disaggregation efficiency of the powder when administered at a sub-optimal flow rate. The two formulations showed interesting pharmacokinetic profiles (T(max) of 26 and 16 min for F1 and F2, respectively) that mimic the physiological insulin secretion pattern. The bioavailability of the developed formulations was within the range of other DPI insulin formulations that have reached the final stages of clinical development.

Inhaled insulin: too soon to be forgotten?

Inhalation is a potentially viable route of administration for numerous agents. In diabetes mellitus, the need for frequent injections to achieve ideal glycemic control remains a significant limitation for initiating and complying with insulin therapy in a large number of patients. To overcome this barrier, inhaled insulin was developed. The inhalation form of regular human insulin has been tested and administered in a large number of trials. Respiratory capacity was evaluated in patients with normal lung parenchyma in whom inhaled insulin was administered without complications. However, issues like cost, bulky device, fear for lung safety, and the small number of studies in subjects with underlying respiratory disease prevented widespread use of this new mode of delivery. In the present review, we will suggest a number of methods that could be applied in this form of administration to maximize drug absorption and fully exploit the advantages of this route of administration.

A Review of Inhaled Technosphere Insulin

Objective:

To review the pharmacology, pharmacokinetics, efficacy, safety, and clinical use of Technosphere insulin.

Data Sources:

A MEDLINE search (1966–March 2010) was conducted for English-language articles using the terms AFREZZA, AFRESA, Technosphere insulin, pulmonary insulin, and inhaled insulin. Abstracts from the American Diabetes Association and European Association for the Study of Diabetes annual meetings, presented in 2004, 2005, 2006, 2007, 2008, and 2009 were also searched for relevant data.

Study Selection and Data Extraction:

English-language articles pertinent to the pharmacology, pharmacokinetics, efficacy, and safety of Technosphere insulin were reviewed.

Data Synthesis:

Technosphere insulin is an inhaled insulin product with a pharmacokinetic profile suitable to meet prandial insulin needs in patients with diabetes. Technosphere insulin has demonstrated efficacy in terms of postprandial and overall glycemic control, with efficacy and safety outcomes maintained for up to 4 years in one study. The overall tolerability profile for Technosphere insulin in clinical trials published to date has demonstrated a relatively low risk of hypoglycemia and weight gain when compared with subcutaneous mealtime insulins. Clinical trials to date have demonstrated safety in terms of pulmonary function, and the absorption of Technosphere insulin is not significantly altered in patients with chronic obstructive pulmonary disease or in those who smoke.

Conclusions:

The Technosphere delivery system allows for the rapid absorption of Technosphere insulin via the lung, making this product a potential option for prandial insulin coverage in both type 1 and type 2 diabetes. The device to administer the insulin is well designed, small, and easy to use. Technosphere inhaled insulin may provide a useful treatment option for patients resistant to or fearful of initiating prandial insulin injections.

Inhaled insulin: overview of a novel route of insulin administration

Diabetes is a chronic disease characterized by inadequate insulin secretion with resulting hyperglycemia. Diabetes complications include both microvascular and macrovascular disease, both of which are affected by optimal diabetes control. Many individuals with diabetes rely on subcutaneous insulin administration by injection or continuous infusion to control glucose levels. Novel routes of insulin administration are an area of interest in the diabetes field, given that insulin injection therapy is burdensome for many patients. This review will discuss pulmonary delivery of insulin via inhalation. The safety of inhaled insulin as well as the efficacy in comparison to subcutaneous insulin in the various populations with diabetes are covered. In addition, the experience and pitfalls that face the development and marketing of inhaled insulin are discussed.

Glycemic control with preprandial versus basal insulin in patients with type 2 diabetes mellitus poorly controlled by oral antidiabetes agents

OBJECTIVE

This study was designed to compare glycemic control (glycated hemoglobin [A1C] level) with either once-daily basal insulin (BI) (insulin glargine) or preprandial insulin (PPI) (Exubera) [insulin human (recombinant DNA origin)] inhalation powder, Pfizer Inc., New York, NY) in patients with type 2 diabetes mellitus (T2DM) poorly controlled on at least two oral antidiabetes agents (OADs).

METHODS

This was a 26-week, open-label, parallel-group, randomized study where 257 patients (mean A1C 8.6%) on OAD treatment for > or = 3 months were treated with either BI (n = 122) or PPI (n = 135). Based on self-monitored blood glucose levels, PPI dose was adjusted before each major meal, whereas BI dose was titrated in the morning or before bedtime. Prestudy OADs were continued, but doses could be modified.

RESULTS

At 26 weeks, change from baseline in A1C was greater with PPI (-1.7 vs. -1.4%, P = 0.0389). Numerically, more patients achieved A1C <6.5% (28% vs. 19%) and A1C <7.0% (63% vs. 55%) with PPI compared with BI. PPI had lower postmeal glucose increments, but higher prebreakfast glucose and weight gain (1.1kg), than BI. Mild or moderate hypoglycemic events were more frequent with PPI (6.2 vs. 2.9 events/months), but nocturnal hypoglycemic events were less frequent (22% vs. 30%).

CONCLUSIONS

PPI improved postprandial glucose and A1C levels significantly more than BI. More patients achieved A1C targets with PPI, at the expense of more hypoglycemia and body weight gain. These results illustrate the potential benefits and detriments of prandial insulin supplementation in patients with T2DM poorly controlled on OADs alone.

Cigarette smoking, smoking cessation, and diabetes

There is evidence for increased risk of developing type 2 diabetes among cigarette smokers. In addition, smoking-associated health risks can exacerbate major conditions that precede or accompany diabetes, such as cardiovascular and kidney diseases. Smoking cessation can result in weight gain and a short-term worsening of some diabetic symptoms that may deter smokers with diabetes from attempting to quit. Additionally, there is limited evidence regarding the efficacy/safety of smoking cessation pharmacotherapies in this population and the general effects of smoking cessation, particularly for type 1 diabetes. Smoking cessation in diabetes therefore remains a highly relevant subject for further research.

Inhaled insulin is associated with prolonged enhancement of glucose disposal in muscle and liver in the canine

Diabetic patients treated with inhaled insulin exhibit reduced fasting plasma glucose levels. In dogs, insulin action in muscle is enhanced for as long as 3 h after insulin inhalation. This study was designed to determine whether this effect lasts for a prolonged duration such that it could explain the effect observed in diabetic patients. Human insulin was administered via inhalation (Exubera; n = 9) or infusion (Humulin R; n = 9) in dogs using an infusion algorithm that yielded matched plasma insulin kinetics between the two groups. Somatostatin was infused to prevent insulin secretion, and glucagon was infused to replace basal plasma levels of the hormone. Glucose was infused into the portal vein at 4 mg/kg/min and into a peripheral vein to maintain the arterial plasma glucose level at 160 mg/dl. Arterial and hepatic sinusoidal insulin and glucose levels were virtually identical in the two groups. Notwithstanding, glucose utilization was greater when insulin was administered by inhalation. At its peak, the peripheral glucose infusion rate was 4 mg/kg/min greater in the inhalation group, and a 50% difference between groups persisted over 8 h. Inhalation of insulin caused a greater increase in nonhepatic glucose uptake in the first 3 h after inhalation; thereafter, net hepatic glucose uptake was greater. Inhalation of insulin was associated with greater than expected (based on insulin levels) glucose disposal. This may explain the reduced fasting glucose concentrations observed in humans after administration of certain inhaled insulin formulations compared with subcutaneous insulin.

Acute passive cigarette smoke exposure and inhaled human insulin (Exubera) pharmacokinetics

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Active cigarette smoking is associated with increased permeability of the pulmonary alveolar epithelium, resulting in faster absorption of inhaled drugs such as Exubera (EXU). Absorption of EXU is increased approximately twice to four times as much in chronic smokers compared with nonsmokers. The rate of clearance of radioaerosols such as technetium-labelled diethylenetriamine penta-acetic acid is decreased in response to passive smoke exposure.

WHAT THIS STUDY ADDS

Passive smoke exposure causes a decrease in lung permeability, an effect opposite to that of active smoking. Acute passive smoke exposure results in a decrease in EXU bioavailability and does not create a risk of hypoglycaemia. These results are consistent with previous studies of radioaerosol lung clearance. AIMS Relative to nonsmokers, the bioavailability of inhaled human insulin (Exubera(R); EXU) is markedly increased in chronic smokers. The pharmacokinetics of EXU following passive cigarette smoke exposure is unknown. METHODS In an open-label, crossover study, healthy nonsmoking volunteers received two treatments in randomized sequence separated by a 2-week wash-out: (i) EXU 3 mg with no passive smoke exposure and (ii) EXU 3 mg after passive smoke exposure (atmospheric nicotine levels 75-125 mug m(-3)) for 2 h. Blood samples were obtained at prespecified times up to 6 h after EXU administration.

RESULTS

Twenty-seven subjects completed both study periods. Mean plasma insulin AUC(0-360) decreased by 17% [ratio 83%, 95% confidence interval (CI) 68.8, 99.5] and mean C(max) by 29% (ratio 71%, 95% CI 59.8, 83.1) after passive cigarette smoke exposure. The median (range) t(max) was 60 min (20-120 min) and 75 min (20-360 min) in the EXU with no exposure and EXU passive exposure groups, respectively. EXU was well tolerated.

CONCLUSIONS

Unlike active chronic smoking, acute passive cigarette smoke exposure modestly decreases EXU bioavailability and thus should not increase hypoglycaemia risk. These results are consistent with those from published literature involving technetium-labelled diethylenetriamine penta-acetic acid and suggest that passive cigarette smoke exposure causes an acute decrease in lung permeability vs. active smoking, which causes an increase in permeability.

[Inhaled insulin. General characteristics. Repercussion on lung function]

Inhaled insulin satisfies the unsuccessful search for non-injectable insulin pathways for the chronic treatment of diabetes. Its use will allow insulin-dependent patients to even receive a single daily injection of basal insulin or early insulinization in patients with type 2 diabetes and poor glycemic control, many of whom maintain the treatment with oral antidiabetics due to aversion to the subcutaneous route (sc). Current data indicate that this insulin is at least as effective as the sc in regards to glucose control. However, clinical experience will clarify its true efficacy and the presence of possible side effects in the long term, especially on the lung function. In this sense, it has been observed that inhaled insulin leads a non-significant small decrease in forced expiratory volume in one second (FEV1). This appears early and does not progress during the first 2 years of treatment, being reversible after its withdrawal.

Inhaled insulin

Inhaled insulin has attractive pharmacodynamic properties with a fast onset of action which should lead to improved postprandial blood glucose concentrations. Comparisons with regular subcutaneous (sc) insulin in clinical studies, however, showed lower fasting blood glucose concentrations. Overall, clinical efficacy of inhaled insulin was comparable to that of regular sc insulin. Treatment with inhaled insulin was safe and well tolerated, with slight and reversible changes in lung function parameters and a rise in insulin antibodies (not associated with any clinical or safety parameters) as main adverse effects. Treatment satisfaction in open-label studies was higher with inhaled than with sc insulin, indicating that inhaled insulin might help to overcome one of the major hurdles of diabetes therapy, i.e. a timely initiation of insulin therapy. The first inhaled insulin formulation was approved in the US and Europe in January 2006, but some countries granted reimbursement only for selected patients, or did not reimburse treatment with inhaled insulin at all because of the high treatment costs. These are due to the rather low bioavailability of approximately 8-15%. Therefore, further research is needed to improve the bioavailability of inhaled insulin: e.g. through optimization of the inhaler, the insulin formulation, or the inhalation technique. In view of the potential for further improvement, inhaled insulin may become a very attractive alternative to sc insulin, in particular in patients in whom insulin therapy has to be initiated and/or intensified.

Effects of smoking cessation, acute re-exposure and nicotine replacement in smokers on AIR inhaled insulin pharmacokinetics and glucodynamics

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

* Only one other study (Becker et al.) has reported on the influence of smoking cessation and smoking resumption on inhaled insulin pharmacokinetics and glucodynamics, concluding that the rapid changes associated with smoking resumption carry the risk for hypoglycaemia and thus should not be used by active smokers.

WHAT THIS STUDY ADDS

* This is the first euglycaemic clamp study on the impact of smoking cessation, acute smoking re-exposure and nicotine replacement on AIR((R)) inhaled insulin pharmacokinetics and glucodynamics. * We demonstrate clinically and statistically significant shifts in glucodynamic response to acute re-exposure to a single cigarette, leading us to conclude that active smokers should be advised against inhaled insulin therapy until smoking abstinence is stable. * Additionally, these results are also the first to demonstrate an apparent independent effect of nicotine replacement therapy on insulin exposure and glucodynamic response.

AIMS

To explore the effects of smoking cessation and acute smoking re-exposure on the pharmacokinetic (PK) and glucodynamic (GD) profiles of AIR inhaled insulin (AIR Insulin) with or without nicotine replacement therapy (NRT).

METHODS

Nondiabetic smokers (n = 24) with normal pulmonary function completed a two-phase (four-period), open-label, randomized euglycaemic clamp study. During the initial study phase, subjects underwent glucose clamps following AIR Insulin dosing, shortly after smoking, 8-12 h after smoking, or following subcutaneous insulin lispro shortly after smoking. AIR Insulin PK and GD were again assessed during and after a 4-week smoking-cessation period with or without NRT. In the last study period, subjects smoked one cigarette shortly before final AIR Insulin dosing and glucose clamp, to study the effect of acute smoking re-exposure on inhaled insulin PK and GD.

RESULTS

Compared with the preceding active smoking phase, the administration of AIR Insulin in nondiabetic subjects undergoing a 4-week period of smoking abstinence resulted in a decrease in PK and GD of approximately 25% (P = 0.008 for both), an effect which was greater in subjects using NRT. Following rechallenge with a single cigarette (without NRT), GD response to AIR Insulin increased significantly (P = 0.006) towards precessation levels, relative to smoking abstinence. In subjects using NRT, however, the increase in GD was less pronounced.

CONCLUSION

Smoking, smoking cessation and acute re-exposure with a single cigarette are associated with clinically significant alterations in AIR Insulin pharmacokinetics and glucodynamics. AIR Insulin should not be used by smokers or those at risk for recidivism.

The effect of exercise on the absorption of inhaled human insulin via the AERx insulin diabetes management system in people with type 1 diabetes

OBJECTIVE

This study investigated the effect of moderate exercise on the absorption of inhaled insulin via the AERx insulin diabetes management system (iDMS).

RESEARCH DESIGN AND METHODS

In this randomized, open-label, four-period, crossover, glucose clamp study 23 nonsmoking subjects with type 1 diabetes received a dose of 0.19 units/kg inhaled human insulin followed in random order by either 1) no exercise (NOEX group) or 30 min exercise starting, 2) 30 min after dosing (EX30), 3) 120 min after dosing (EX120), or 4) 240 min after dosing (EX240).

RESULTS

Exercise changed the shape of the free plasma insulin curves, but compared with the NOEX group the area under the curve for free plasma insulin (AUC(ins)) for the first 2 h after the start of exercise was unchanged for EX30 and EX240, while it was 15% decreased for EX120 (P < 0.01). The overall insulin absorption during 6 and 10 h after dosing was 13% decreased for EX30 (P < 0.005), 11% decreased for EX120 (P < 0.01), and unchanged for EX240. Exercise did not influence the maximum insulin concentration (Cmax), while the time to Cmax was 22 min earlier for EX30 (P = 0.04). The AUC for the glucose infusion rate (AUC(GIR)) for 2 h after the start of exercise increased by 58% for EX30, 45% for EX120, and 71% for EX240 (all P < 0.02) compared with the NOEX group.

CONCLUSIONS

Thirty minutes of moderate exercise led to unchanged or decreased absorption of inhaled insulin via AERx iDMS and faster Cmax for early exercise. Thus, patients using AERx iDMS can adjust insulin dose as usual independent of time of exercise, but they should be aware of the faster effect if exercising early after dosing.

Selection and education of patients for inhaled insulin

Inhaled insulin is a recent advance in insulin delivery that promises to be an effective alternative to subcutaneous insulin. Several insulin delivery systems are currently in development and the first of these has been approved for clinical use. Inhaled insulin offers greater flexibility and convenience for patients with diabetes and may be particularly useful in those who are reluctant to initiate or intensify insulin treatment. Although promising, potential concerns remain regarding its long-term effects on lungs. Also, excluding certain groups of patients such as smokers and those with respiratory illnesses will restrict its use at present. Lack of familiarity with the technology, especially relating to dose adjustments and inhaler device, is also likely to present fresh challenges. But, careful selection of patients, education, and continued support from health professionals is vital to ensure success with this new technology.

Drug interactions with smoking

PURPOSE

The mechanisms for drug interactions with smoking and clinically significant pharmacokinetic and pharmacodynamic drug interactions with smoking are reviewed.

SUMMARY

Polycyclic aromatic hydrocarbons (PAHs) are some of the major lung carcinogens found in tobacco smoke. PAHs are potent inducers of the hepatic cytochrome P-450 (CYP) isoenzymes 1A1, 1A2, and, possibly, 2E1. After a person quits smoking, an important consideration is how quickly the induction of CYP1A2 dissipates. The primary pharmacokinetic interactions with smoking occur with drugs that are CYP1A2 substrates, such as caffeine, clozapine, fluvoxamine, olanzapine, tacrine, and theophylline. Inhaled insulin's pharmacokinetic profile is significantly affected, peaking faster and reaching higher concentrations in smokers compared with nonsmokers, achieving significantly faster onset and higher insulin levels. The primary pharmacodynamic drug interactions with smoking are hormonal contraceptives and inhaled corticosteroids. The most clinically significant interaction occurs with combined hormonal contraceptives. The use of hormonal contraceptives of any kind in women who are 35 years or older and smoke 15 or more cigarettes daily is considered contraindicated because of the increased risk of serious cardiovascular adverse effects. The efficacy of inhaled corticosteroids may be reduced in patients with asthma who smoke.

CONCLUSION

Numerous drug interactions exist with smoking. Therefore, smokers taking a medication that interacts with smoking may require higher dosages than nonsmokers. Conversely, upon smoking cessation, smokers may require a reduction in the dosage of an interacting medication.

AIR inhaled insulin in subjects with chronic obstructive pulmonary disease: pharmacokinetics, glucodynamics, safety, and tolerability

OBJECTIVE

In this open-label, randomized, crossover study, pharmacokinetic and glucodynamic responses were compared in healthy subjects versus subjects with moderate chronic obstructive pulmonary disease (COPD), following administration of 12 units equivalent AIR inhaled insulin versus 12 units subcutaneous insulin lispro.

RESEARCH DESIGN AND METHODS

Three nonsmoking groups (n = 15 each)--healthy subjects (baseline mean +/- SD age 38 +/- 13 years, forced expiratory volume in 1 s [FEV1] 4.06 +/- 1.04 l), subjects with chronic bronchitis (aged 53 +/- 9 years, FEV1 2.14 +/- 0.60 l), and subjects with pulmonary emphysema (aged 58 +/- 6 years, FEV1 1.67 +/- 0.61 l)--were randomly assigned to one of three treatment sequences. Three euglycemic glucose clamp procedures were performed.

RESULTS

In subjects with chronic bronchitis and emphysema, AIR inhaled insulin administration resulted in reduced insulin exposure (area under the serum insulin concentration curve from time zero until time of return to baseline [AUC(0-t')]) (55.7%, P = 0.13 and 78.5%, P < 0.001, respectively) and reduced total insulin effect (total glucose infusion rate) (60.4%, P < 0.01 and 67.1%, P < 0.01, respectively) relative to healthy subjects. Subcutaneous insulin lispro administration resulted in similar responses across study groups for insulin exposure and metabolic effect. Intrasubject pharmacokinetic and glucodynamic variability ranged from 17 to 52% across groups. No significant differences were shown for pre- and postclamp pulmonary function tests. During clamps, FEV1 and forced vital capacity declined modestly in both COPD groups, with no difference between AIR insulin and subcutaneous insulin lispro.

CONCLUSIONS

Short-term exposure to AIR inhaled insulin was well tolerated by COPD subjects, showing similar time-exposure and time-action profiles, but with reduced insulin absorption and metabolic effect compared with healthy subjects. Further clinical evaluation is warranted in patients with comorbid diabetes and COPD.

Inhaled insulin: a clinical perspective with emphasis on EXUBERA®

There is a Type 2 diabetes epidemic; however, unfortunately, even though insulin is an effective therapy, it is mostly used late and as a last resort. Type 1 diabetics find it difficult to administer extra insulin injections when needed owing to the inconvenience and, although most cope well, many dislike injecting themselves so frequently. The newly approved EXUBERA^® inhaled insulin should help counteract the resistance of patients and physicians in instituting insulin in the Type 2 diabetic, and the Type 1 diabetic can take more than 1000 fewer injections per year, making their diabetes easier to live with. Pulmonary function tests have demonstrated clinically insignificant changes after years of monitoring. The increases of insulin antibodies found in those who use inhaled insulin have not affected diabetes control. Side effects of inhaled insulin are insignificantly different from injectable insulin except for a couple of mild coughs after an inhalation, which decrease quickly with time. The two dosage forms of EXUBERA insulin are 1 and 3 mg (equivalent to approximately 3 and 8 U of U-100 insulin, respectively), are adaptable to most regimens for both types of diabetes, and inhaled insulin is preferred by a significant majority of patients. Inhaled insulin should be cost effective if it allows earlier institution in the Type 2 diabetic thus improving diabetic control and lowering the expensive complications of diabetes.

The impact of large tidal volume ventilation on the absorption of inhaled insulin in rabbits

Previous studies have shown that ventilation patterns affect absorption of inhaled compounds. Thus, the aim of this study was to investigate the effect of large tidal volume ventilation (LTVV) on the absorption of inhaled insulin in rabbits. Mechanically ventilated rabbits were given human insulin via a nebuliser system, and plasma insulin was measured for the following 120min. Ventilation was adjusted to (1) normal tidal volume ventilation (NTVV) for the entire period after dosing (NTVV group), to (2) LTVV for the entire period after dosing (LTVV group), to (3) NTVV except for 15min LTVV immediately after dosing (Early LTVV group), or to (4) NTVV except for 15min LTVV starting at 60min after dosing (late LTVV group). Insulin absorption (AUC(ins(0-120min))) was increased by 149% for the LTVV group compared to NTVV group (p<0.01) with increased maximal insulin concentration (106%, p=0.03). The Early LTVV group showed a changed absorption profile. For the late LTVV group an increase in insulin levels was observed after the LTVV period (not significant compared to the NTVV group). These data could potentially have implications for patients using inhaled insulin in situations where a change in breathing pattern is seen, such as exercise.

Inhaled insulin (Exubera): Combining efficacy and convenience

The pulmonary route, due to its rich vascularity, large surface area and immunotolerant characteristics, may be an ideal target for drug delivery. Although the inhaled route has been used to deliver drugs used in the management of respiratory disorders, success with peptide delivery has been limited by poor bioavailability. Recent advances in technology have overcome these barriers and have enabled new delivery devices to be developed. Insulin is the first peptide to be delivered successfully by this route and the first of the inhaled insulin delivery devices (Exubera) has now been approved for clinical use. In clinical trials it has been shown to be effective, apparently safe and a preferred alternative to subcutaneously injected meal-time insulin. This new technology offers great convenience to patients needing insulin treatment. While it will considerably reduce the number of injections needed by people with type 1 and type 2 diabetes, it should also encourage more patients to start insulin treatment earlier. The potential benefits from improved adherence and better glycaemic control with this insulin are also significant.

Alternatives routes of insulin delivery

Optimal glycaemic control is necessary to prevent diabetes-related complications. An intensive treatment, which could mimic physiological insulin secretion, would be the best one. However subcutaneous insulin treatment is not physiologic and represents a heavy burden for patients with type 1 and type 2 diabetes mellitus. Consequently, more acceptable, at least as effective, alternative routes of insulin delivery have been developed over the past years. Up to now, only pulmonary administration of insulin (inhaled insulin) has become a feasible alternative to cover mealtime insulin requirements and one of the various administration systems was recently approved for clinical use in Europe and the United States. But, due to advances in technology, other routes, such as transdermal or oral (buccal and intestinal) insulin administration, could become feasible in a near future, and they could be combined together to offer non-invasive, efficacious and more physiological way of insulin administration to patients with diabetes.

Inhaled human insulin ((insulin human [rDNA origin]) Inhalation Powder) in diabetes mellitus

Inhaled human insulin ((insulin human [rDNA origin]) Inhalation Powder) is a prandial insulin approved in the EU and the US for the treatment of adults with diabetes. Its glycaemic control is comparable to subcutaneous insulin in Type 1 and 2 diabetes, and has superior efficacy versus oral antidiabetic agents in Type 2 diabetes. Hypoglycaemia and mild-to-moderate cough are the main side effects. The treatment group differences in pulmonary function occur early, and are small, nonprogressive for up to 2 years and reversible following discontinuation. Patient-reported outcomes data displays higher diabetes treatment satisfaction, improvements in some quality-of-life scores, and treatment preference with inhaled human insulin versus traditional means. Availability of inhaled insulin may increase insulin acceptance and thus improve glycaemic control in patients with diabetes.

Inhaled human insulin (Exubera): a review of its use in adult patients with diabetes mellitus

Inhaled human insulin (Exubera) (insulin human [rDNA origin]) Inhalation Powder) has recently been approved in the European Union and the US for preprandial use in adult patients with diabetes mellitus. This formulation of insulin has a more rapid onset, but similar duration, of glucose-lowering activity compared with subcutaneously administered regular human insulin. Preprandial inhaled human insulin provided glycaemic control that was comparable to preprandial subcutaneous regular insulin when added to long- or intermediate-acting subcutaneous basal insulin in patients with type 1 diabetes mellitus. Inhaled human insulin is also effective when administered alone, when combined with oral antihyperglycaemic therapy, or when combined with basal subcutaneous insulin in patients with type 2 diabetes mellitus. Comparable rates of hypoglycaemia occurred in patients treated with inhaled human insulin and in those treated with subcutaneous regular human insulin. Patients treated with inhaled human insulin demonstrated a greater decline in pulmonary function (forced expiratory volume in 1 second [FEV(1)], carbon monoxide diffusing capacity [DL(CO)]) than patients treated with comparator antihyperglycaemic agents; the mean difference between the treatment groups that favoured the comparators was noted within the first several weeks of treatment, and did not change over a 2-year treatment period. This agent has also been associated with significant improvements in some quality-of-life and treatment satisfaction scores, especially when compared with subcutaneous mealtime insulin regimens. Inhaled human insulin is an effective and well tolerated formulation suitable for preprandial use in combination with basal subcutaneous insulin in patients with type 1 diabetes. It is also well tolerated and effective in patients with type 2 diabetes when administered alone, when combined with oral antihyperglycaemic therapy, or when combined with basal subcutaneous insulin.

Will availability of inhaled human insulin (Exubera) improve management of type 2 diabetes? The design of the Real World trial

Background

Common deterrents to insulin therapy for both physicians and patients are the complexity and burden of daily injections. In January 2006, the first inhaled human insulin (INH, Exubera^® (insulinhuman [rDNA origin])InhalationPowder) was approved for use in adult patients with type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM) in the United States and European Union. Results from the INH clinical trial program have shown comparable efficacy of INH to subcutaneous (SC) insulin and superior efficacy versus oral antidiabetic agents; thus providing effective glycemic control in adult patients with T2DM without the requirement for preprandial injections. However, because subjects in those trials were randomized to either INH or an alternative, the studies could not estimate the effect of INH on patient acceptance of insulin therapy. Therefore, traditional study designs cannot provide answers to important and practical questions regarding real world effectiveness, which is influenced by psychological and other access barriers.

Methods

To overcome these limitations, the Real World Trial was designed to estimate the effect of the availability of INH as a treatment option for glycemic control. A total of approximately 700 patients from Canada, France, Germany, Italy, Spain, United Kingdom, and the United States with T2DM poorly controlled by oral agent therapy will be randomized to two different treatment settings. Patients and clinicians in both groups (A & B) may choose from all licensed therapies for diabetes including SC insulin delivered by pens; INH will be an additional treatment option only available in Group A. The Real World Trial (Protocol A2171018) has been registered with ClincalTrials.gov, registration id NCT00134147.

Results

The primary outcome for the trial will be the difference in mean glycosylated hemoglobin (HbA_1c) at 6 months between groups. The design was based on a preceding feasibility study examining the theoretical effects of inhaled insulin availability on treatment choice in 779 patients. In that study, patients were three times more likely to choose insulin therapy when inhaled insulin was available.

Conclusion

Innovations in study designs may provide an opportunity to reveal unbiased answers to important treatment questions that are more relevant to prescribers, funding agencies, and healthcare policymakers.

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.

Upper airway obstruction and craniofacial morphology

Otolaryngologists are being asked with increasing frequency to assess adequacy of the upper airway and to treat upper airway obstructive problems in orthodontic patients. The incentive has been provided by recent studies that purport to relate upper airway obstruction to dental and craniomorphologic changes. It is hypothesized that prolonged oral respiration during critical growth periods in children initiates a sequence of events that commonly results in dental and skeletal changes. In the chronic mouth-breather excessive molar tooth eruption is almost a constant feature, causing a clockwise rotation of the growing mandible, with a disproportional increase in anterior lower vertical face height. Such increases in anterior lower vertical face height are often associated with retrognathia and open bites. Low tongue posture seen with oral respiration impedes the lateral expansion and anterior development of the maxilla. Otolaryngologists have the ability to objectively and accurately assess upper airway patency. Rhinometric assessment before and after application of topical nasal decongestant, in conjunction with clinical examination, provides valuable information regarding upper airway patency and the cause of any existing obstructive pathologic condition. Studies should be designed carefully to control the numerous variables that have an impact on the growing face of a young child so that meaningful data can be obtained in our own field regarding this challenging topic.