Use of indacaterol for the treatment of COPD: a pharmacokinetic evaluation

Application of nano- and micro-particle-based approaches for selected bronchodilators in management of asthma

Asthma is a chronic inflammatory condition that affects the airways, posing a substantial health threat to a large number of people worldwide. Bronchodilators effectively alleviate symptoms of airway obstruction by inducing relaxation of the smooth muscles in the airways, thereby reducing breathlessness and enhancing overall quality of life. The drug targeting to lungs poses significant challenges; however, this issue can be resolved by employing nano- and micro-particles drug delivery systems. This review provides brief insights about underlying mechanisms of asthma, including the role of several inflammatory mediators that contribute to the development and progression of this disease. This article provides an overview of the physicochemical features, pharmacokinetics, and mechanism of action of particular groups of bronchodilators, including sympathomimetics, PDE-4 inhibitors (phosphodiesterase-4 inhibitors), methylxanthines, and anticholinergics. This study presents a detailed summary of the most recent developments in incorporation of bronchodilators in nano- and micro-particle-based delivery systems which include solid lipid nanoparticles, bilosomes, novasomes, liposomes, polymeric nano- and micro-particles. Specifically, it focuses on breakthroughs in the categories of sympathomimetics, methylxanthines, PDE-4 inhibitors, and anticholinergics. These medications have the ability to specifically target alveolar macrophages, leading to a higher concentration of pharmaceuticals in the lung tissues.

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.

Pharmacokinetic considerations surrounding triple therapy for uncontrolled asthma

INTRODUCTION

Solid pharmacological rationale and clinical evidence support the use of a combination of an inhaled corticosteroid (ICS), a long-acting β2-agonist, and a long-acting muscarinic antagonist in severe asthma, which clinically results in increased lung function, improved symptoms, and decreased exacerbation rates.

AREAS COVERED

We examined the pharmacokinetic issues associated with triple therapy for uncontrolled asthma. We considered the pharmacokinetic characteristics of the three drug classes, the role of inhalers in influencing their pharmacokinetic behavior, and the impact of severe asthma on the pharmacokinetics of inhaled drugs.

EXPERT OPINION

The pharmacokinetics of ICSs and bronchodilators are not affected to a great extent by severe asthma, according to a detailed review of the currently accessible literature. Compared to healthy people, patients with severe asthma show only minor variations in a few pharmacokinetic characteristics, which are unlikely to have therapeutic significance and do not require particular attention. However, the difficulty of obtaining pharmacokinetic profiles of the three drugs included in a triple therapy suggests that the clinical response should be followed over time, which can be considered a good surrogate indicator of whether the drugs have reached sufficient concentrations in the lung to exert a valid pharmacological action.

Prediction of pharmacokinetic parameters of inhaled indacaterol formulation in healthy volunteers using physiologically-based pharmacokinetic (PBPK) model

BACKGROUND

Inhaled formulations are the first choices for treating asthma and chronic obstructive pulmonary disease (COPD), attracting the increasing investment and development in the pharmaceutical industry. Both the equivalence of local and systemic exposures need to be considered when assessing the equivalence of generic inhaled drugs, which has become a dilemma in the development of generic inhaled drugs. There is an urgent need for reliable methods such as physiologically-based pharmacokinetic (PBPK) model to assist in the development of inhaled drugs.

METHOD

To test the strategy that in silico simulation is an effective tool in developing inhaled products and further assessing their clinically feasibility, a long-acting beta2-adrenergic agonists indacaterol, which was referred as the first-line therapy for patient with COPD, was selected as a tool drug. The PBPK model was established and the predicted plasma concentration curve was obtained by inputting the physicochemical properties of indacaterol and adjusting model parameters. The accuracy of simulation was verified by an alignment with the actual data. The main factor affecting PK in vivo was investigated by parameter sensitivity analysis. The biological equivalent size of indacaterol was investigated by virtual bioequivalence analysis.

RESULTS

The models of indacaterol after intravenous and oral administration were established and confirmed, and used as a background for PBPK model of inhaled administration. All those models showed favorable stability and applicability. Appropriate lung deposition was generated in the PBPK model, and the predicted plasma profile of indacaterol was consistent with the clinical actual observation values. Particle size is the most important factor affecting the PK of indacaterol in vivo. Furthermore, virtual bioequivalence simulation exhibited statistically comparable results between the particle size fluctuates in the range of 3.5-6.5 μm and baseline levels (D90 = 5 μm).

CONCLUSIONS

The PBPK model can simulate the pharmacokinetics and lung deposition of indacaterol, which will be a powerful tool to assist the development of inhaled drugs.

Effects of (a Combination of) the Beta2-Adrenoceptor Agonist Indacaterol and the Muscarinic Receptor Antagonist Glycopyrrolate on Intrapulmonary Airway Constriction

Expression of bronchodilatory β₂-adrenoceptors and bronchoconstrictive muscarinic M₃-receptors alter with airway size. In COPD, (a combination of) β₂-agonists and muscarinic M₃-antagonists (anticholinergics) are used as bronchodilators. We studied whether differential receptor expression in large and small airways affects the response to β₂-agonists and anticholinergics in COPD. Bronchoprotection by indacaterol (β₂-agonist) and glycopyrrolate (anticholinergic) against methacholine- and EFS-induced constrictions of large and small airways was measured in guinea pig and human lung slices using video-assisted microscopy. In guinea pig lung slices, glycopyrrolate (1, 3 and 10 nM) concentration-dependently protected against methacholine- and EFS-induced constrictions, with no differences between large and small intrapulmonary airways. Indacaterol (0.01, 0.1, 1 and 10 μM) also provided concentration-dependent protection, which was greater in large airways against methacholine and in small airways against EFS. Indacaterol (10 μM) and glycopyrrolate (10 nM) normalized small airway hyperresponsiveness in COPD lung slices. Synergy of low indacaterol (10 nM) and glycopyrrolate (1 nM) concentrations was greater in LPS-challenged guinea pigs (COPD model) compared to saline-challenged controls. In conclusion, glycopyrrolate similarly protects large and small airways, whereas the protective effect of indacaterol in the small, but not the large, airways depends on the contractile stimulus used. Moreover, findings in a guinea pig model indicate that the synergistic bronchoprotective effect of indacaterol and glycopyrrolate is enhanced in COPD.

Drivers of absolute systemic bioavailability after oral pulmonary inhalation in humans

There are few studies in humans dealing with the relationship between physico-chemical properties of drugs and their systemic bioavailability after administration via oral inhalation route (Fpulm). Getting further insight in the determinants of Fpulm after oral pulmonary inhalation could be of value for drugs considered for a systemic delivery as a result of poor oral bioavailability, as well as for drugs considered for a local delivery to anticipate their undesirable systemic effects. To better delineate the parameters influencing the systemic delivery after oral pulmonary inhalation in humans, we studied the influence of physico-chemical and permeability properties obtained in silico on the rate and extent of Fpulm in a series of 77 compounds with or without marketing approval for pulmonary delivery, and intended either for local or for systemic delivery. Principal component analysis (PCA) showed mainly that Fpulm was positively correlated with Papp and negatively correlated with %TPSA, without a significant influence of solubility and ionization fraction, and no apparent link with lipophilicity and drug size parameters. As a result of the small sample set, the performance of the different models as predictive of Fpulm were quite average with random forest algorithm displaying the best performance. As a whole, the different models captured between 50 and 60% of the variability with a prediction error of less than 20%. Tmax data suggested a significant positive influence of lipophilicity on absorption rate while charge apparently had no influence. A significant linear relationship between Cmax and dose (R² = "0.79) highlighted that Cmax was primarily dependent on dose and absorption rate and could be used to estimate Cmax in humans for new inhaled drugs.

Chirality of β2-agonists. An overview of pharmacological activity, stereoselective analysis, and synthesis

β2-Agonists (β2-adrenergic agonists, bronchodilatants, and sympathomimetic drugs) are a group of drugs that are mainly used in asthma and obstructive pulmonary diseases. In practice, the substances used to contain one or more stereogenic centers in their structure and their enantiomers exhibit different pharmacological properties. In terms of bronchodilatory activity, (R)-enantiomers showed higher activity. The investigation of stereoselectivity in action and disposition of chiral drugs together with the preparation of pure enantiomer drugs calls for efficient stereoselective analytical methods. The overview focuses on the stereoselectivity in pharmacodynamics and pharmacokinetics of β2-agonists and summarizes the stereoselective analytical methods for the enantioseparation of racemic beta-agonists (HPLC, LC-MS, GC, TLC, CE). Some methods of the stereoselective synthesis for β2-agonists preparation are also presented.

Bioequivalence studies of inhaled indacaterol maleate in healthy Chinese volunteers under gastrointestinal non-blocking or blocking with concomitant charcoal administration

BACKGROUND

Indacaterol is one of the long-acting beta₂-adrenergic agonists, referred as first-line monotherapy for Chronic obstructive pulmonary disease since 2011. Generic products are encouraged to benefit the large COPD patients in China, in which can provide more choices association with reduced cost and improve the quality of patient life.

OBJECTIVE

The three-part study consists of two independent cohorts of thirty-six subjects, aimed to evaluate the bioequivalence (BE) of two indacaterol formulations in gastrointestinal (GI) absorption charcoal-block or non-block conditions. One pilot study performed in six healthy subjects to determine the blocking effect of a new charcoal-based regimen on GI absorption after orally inhalation of indacaterol.

METHODS

Two BE studies were conducted with a randomized, open-label, 2-period crossover design in two independent 36-healthy-subject cohorts, equivalence in systemic and lung deposition was assessed after inhalation of a single dose of 150 μg indacaterol (test or reference formulation) alone or concomitant administration of charcoal. The charcoal-based regimen was improved by optimizing the dose and number of doses, and its blocking efficacy against GI absorption was assessed in a pilot study. Six healthy subjects received 9 g charcoal 10 min before, immediately after and 2 h after indacaterol (3 g/100 ml water × 3 times). Blood collected at predetermined time points up to 72 h. Plasma indacaterol concentrations were determined using HPLC-MS/MS. Pharmacokinetics parameters were calculated with non-compartment analysis. Equivalences were concluded if the 90% confidence interval (CI) for test: reference of C_max and AUC_0-t fell within the limits of 0.8-1.25.

RESULTS

Indacaterol was undetectable in plasma samples in pilot study. The T/R ratio of the geometric mean C_max and AUC_0-t was 109.9% (90% CI, 106.1-113.8%) and 104.8% (90% CI, 101.5-108.1%) for charcoal-block subjects and 105.4% (90% CI, 99.8% ~ 111.3%), and 101.0% (90% CI, 97.7%-104.4%) for non-block subjects. No serious adverse events were reported.

CONCLUSIONS

The results showed that 150 μg indacaterol (+/- 9 g charcoal) was well tolerated in all subjects. The two formulations are bioequivalent in terms of the rate and absorption both in charcoal-block and non-block conditions. The improved charcoal-based regimen demonstrated to be effective and fully blockade of GI absorption of indacaterol.

Assessing the viability of long-acting β2-agonists in paediatric asthma patients: a pharmacokinetic/pharmacodynamic perspective

INTRODUCTION

Long-acting β₂-agonists (LABAs) combined with inhaled corticosteroids (ICSs) are still commonly prescribed to asthmatic children. Unfortunately, pediatric LABA use is based primarily on data from adults, despite the fact that children are not simply small adults and the magnitude of changes in dose exposure and/or exposure response may not be solely reflected by differences in body weight. Areas covered: The differences in pharmacokinetics (PK) and pharmacodynamics (PD) of LABAs are described and discussed with reference children and adults. Expert opinion: Data on the PK behavior of LABAs is very limited and there is almost no data on once-daily LABAs available in the pediatric population. We do not believe that this is due to a fundamental lack of information because therapeutic response and adverse effects are more useful for the optimization of β₂-agonist treatment than measurement of plasma drug concentrations per se. Nevertheless, population PK-PD studies in children are needed according to the European rules in order to define rational, patient-tailored dosing schemes. Population PK-PD modeling and simulation using non-linear mixed effect modeling should be considered as the preferred tool to develop effective and safe dosing regimens for children because they present an opportunity to analyze sparse and unbalanced datasets, thereby minimizing the burden for each child.

Indacaterol for the treatment of chronic obstructive pulmonary disease

INTRODUCTION

The need for a rapid onset of action and a long duration of the broncholytic effect is the likely reason for the development of new long-acting β2-agonists (LABAs) that are fast acting and have true 24 h duration of action. Indacaterol is the archetype of once-daily LABAs and already marketed as a maintenance therapy in patients with moderate to severe chronic obstructive pulmonary disease (COPD).

AREAS COVERED

Meta-analyses of published data or pooled analyses of primary data provide good insight into the clinical role of indacaterol in COPD.

EXPERT OPINION

The choice of the once-daily bronchodilator to start treatment in a patient with COPD mainly depends on the outcome of interest. Indacaterol is more effective than tiotropium if we consider symptoms or health-related quality of life as the primary outcome. Moreover, in symptomatic patient indacaterol should be preferred to tiotropium because of its rapid onset of action. By contrast, tiotropium appears to be more effective than indacaterol if exacerbations are the expected primary outcome. However, as indacaterol/glycopyrronium fixed-dose combination (QVA149) shows superior efficacy compared to glycopyrronium and tiotropium in patients with moderate to severe COPD, a fundamental question regarding the use of indacaterol that requires clarification is whether it is preferable to start immediately with QVA149 rather than using indacaterol alone.