吸入给药的剂型选择和等效性验证

目前临床常用吸入给药的剂型包括定量吸入气雾剂（metered dose inhaler，MDI）、吸入粉雾剂／干粉吸入剂（Dry powder inhaler，DPI）和吸入喷雾剂（Nebulizer），这3种吸入给药剂型各有特点。如何正确选择所研发的药物的剂型，如何正确验证相同制剂间是否等效有其特殊性。本文结合吸入给药的药物吸收特点、各剂型特点及国外有关考虑，重点探讨了如何正确选择所研发的药物的剂型及如何正确验证相同制剂间是否等效。     

影响干粉吸入剂肺沉积的制剂因素

干粉吸入剂的制剂因素包括药物粉末的处方组成、给药装置类型等,是影响药物肺沉积的主要因素。文中按照药物处方组成将干粉吸入剂分成无载体、药物-载体、药物-添加剂、药物-载体-添加剂4种类型,并分别对其影响肺沉积的制剂因素进行了分析。     

影响干粉吸入剂雾化和沉积性能的制剂因素

干粉吸入剂是近年来肺部给药制剂研发的热点。随着微粉化技术不断成熟,新型给药装置日益涌现,干粉吸入剂的应用范围越来越广。本文从微粉化的药物、载体和干粉吸入器等3个方面综述了干粉吸入剂的处方组成,并重点介绍了影响药物粉末雾化和沉积性能的几个关键因素。     

中国吸入制剂的研发现状及工业化前景

肺部给药系统简介 肺部给药系统是指药物以溶液、混悬液或固体粉末的形式,通过一定的给药装置,经口腔吸入至呼吸道深部。肺部给药的剂型一般包括定量吸入气雾剂（pMDI）、干粉吸入剂（DPI）、喷雾剂（吸入溶液,Inhalation solution,IS）。雾滴或颗粒大小有特殊要求。     

肺部吸入给药制剂及临床应用

目的:分析和综述肺吸入制剂的分类、现状及其临床用药。方法:收集国内外发表出版的相关论文及专著,对肺部吸入给药的特点及临床药物制剂进行了分析总结。结果与结论:肺部吸入给药是防治哮喘、慢性阻塞性肺病等呼吸道疾病的首选给药方式。常见的吸入给药制剂包括定量吸入气雾剂、干粉吸入剂和雾化吸入剂,所用药物主要为β2受体激动剂、抗胆碱药物、吸入性糖皮质激素及复方药物等。     

常用吸入剂的正确使用方法

<正>吸入给药可以增加局部药物浓度,减少全身性的药物吸收,从而提高疗效,减少不良反应。吸入给药的药动学与口服给药不同,肺部沉积率是比较不同吸入给药制剂的常用指标。吸入药物的肺部沉积量远小于药物的标示量。一小部分药物残留于给药装置或消散在空气中;一部分沉积在口腔,随漱     

肺部吸入制剂评价方法研究进展

肺部吸入制剂在治疗肺炎、哮喘、慢性阻塞性肺病（COPD）等肺部疾病中的应用广泛。肺部吸入制剂主要包括吸入气雾剂、干粉吸入剂、吸入喷雾剂和吸入溶液,其体外评价方法主要包括递送剂量及递送剂量均一性,空气动力学粒径分布,喷雾模式和喷雾形态;体内评价方法主要包括药动学研究与放射性核素成像。就肺部吸入制剂的体内外评价方法的研究进展进行综述。     

肺内吸入给药治疗哮喘和慢性阻塞性肺病研究进展

哮喘和慢性阻塞性肺疾病(COPD)是最常见的呼吸道疾病之一,全球分别有3 亿和2.1 亿患者。肺部吸入给药是治疗和管理哮喘、COPD 等呼吸道疾病的首选给药方式,而患者的依从性与该类制剂的疗效优劣有密切关系。综述现在已经上市的肺部吸入给药治疗哮喘和慢性阻塞性肺疾病的主要剂型和药品,以及雾化吸入剂、定量吸入剂和干粉吸入剂对患者依从性的影响,并认为提高患者依从性需要反复提供给患者个性化用药和正确使用给药装置的指导。     

载药纳米粒在干粉吸入剂中的应用

本文分析了载药纳米粒在干粉吸入剂上缺乏商业吸引力的原因,以及与常规干粉吸入剂相比存在的优势;介绍了纳米粒-载体复合物、大粒径中空纳米粒聚集体两种干粉吸入剂的制备方法及形成机制。由于纳米粒干粉吸入制剂具备优良的分散性能和肺沉积性能,并同时拥有纳米粒作为药物载体的独特性能,使其在干粉吸入剂上具有强大的优势和广阔的发展空间。     

吸入装置的演变过程及研究进展

吸入装置通过不同的气溶胶发生原理,结合相应的药物形态形成了现有的药械组合式吸入制剂,目前已广泛应用于吸入治疗领域。但在临床使用过程中也逐渐暴露出一些问题,如患者使用压力定量吸入气雾剂(pressurized metered-dose inhaler,pMDI)时协调性不够,使用干粉吸入剂(dry powder inhaler,DPI)时吸力不足,患者使用依从性差等。新型吸入装置致力于通过装置性能的改善弥补吸入装置目前存在的缺点,并结合智能化和云端管理扩展功能等,提高患者的使用依从性,从而进一步提高临床治疗效果。     

Clinical perspectives on pulmonary systemic and macromolecular delivery

The large epithelial surface area, the high organ vascularization, the thin nature of the alveolar epithelium and the immense capacity for solute exchange are factors that led the lung to serve as an ideal administration route for the application of drugs for treatment of systemic disorders. However, the deposition behaviour of aerosol particles in the respiratory tract depends on a number of physical (e.g. properties of the particle), chemical (e.g. properties of the drug) and physiological (e.g. breathing pattern, pulmonary diseases) factors. If these are not considered, it will not be possible to deposit a reproducible and sufficient amount of drug in a predefined lung region by means of aerosol inhalation. The lack of consideration of such issues led to many problems in inhalation drug therapy for many years mainly because physiological background of aerosol inhalation was not fully understood. However, over the last 20 years, there has been considerable progress in aerosol research and in the understanding of the underlying mechanisms of particle inhalation and pulmonary particle deposition. As a consequence, an increasing number of studies have been performed for the lung administration of drugs using a variety of different inhalation techniques. This review describes the physical and in part some of the physiological requirements that need to be considered for the optimization of pulmonary drug delivery to target certain lung regions.     

Pulmonary Deposition and Clinical Response of99mTc-Labelled Salbutamol Delivered from a Novel Multiple Dose Powder Inhaler

Pulmonary deposition of ^99mTc-labelled sulbutamol was determined after delivery from a novel multiple dose powder inhaler (Easyhaler^®). The clinical efficacy of the inhalation powder, evaluated simultaneously with gamma camera detection, was compared with that obtained after drug delivery from a metered dose inhaler-spacer combination. The study was performed as an open, non-randomized cross-over trial. A single dose of radiolabelled inhalation powder was inhaled on the first and the inhalation aerosol, as control, on the second study day. Sulbutamol sulphate was labelled with ^99mtechnetium, and the inhalation powder was formulated by mixing radioactive drug particles with carrier material. Aerodynamic properties of the radiolabelled inhalation powder were similar to those of the unlabelled salbutamol powder. Delivered dose from the breath-actuated powder inhaler was adjusted to be equal to two puffs from a conventional aerosol actuator with a short plastic mouthpiece. Twelve non-smoking asthmatic patients participated in the trial. The mean pulmonary deposition of 24% was obtained after drug delivery from Easyhaler^® powder inhaler. Clinical efficacy of the medications was similar in terms of area under the FEV₁ curve, maximum FEV₁ and the improvement ratio. Thus it can be suggested that powder delivery from Easyhaler^® powder inhaler and the aerosol delivery through the spacer are equally effective.     

Pulmonary drug delivery from the Taifun dry powder inhaler is relatively independent of the patient's inspiratory effort.

The Taifun dry powder inhaler (Leiras OY, Turku, Finland) is a breath-actuated, multidose device, each metered dose containing 200 micrograms of budesonide. A two-way randomized crossover gamma scintigraphic study was performed in 10 asthmatic patients to determine the in vivo deposition pattern of budesonide inhaled from the Taifun. In vitro radiolabelling validation studies demonstrated that the radiolabel could be used as an accurate marker to assess in vivo drug deposition. Patients used either maximal inspiratory effort (targeted peak inhalation flow 30 L/min) or submaximal inspiratory effort (targeted peak inhalation flow 15 L/min) on each study day. Mean (S.D.) whole lung deposition (% of metered dose) was 34.3 (5.8)% and 29.6 (5.9)% for the two inhalation flows. The intersubject coefficient of variation in lung deposition was less than 20% on both study days. Drug was deposited uniformly across the central, intermediate, and peripheral lung regions for maximal and submaximal inspiratory efforts. The study suggests that the Taifun is a superior drug delivery device compared with many other inhalers, in terms of the amount of drug deposited in the lungs, the reproducibility of the lung dose, and the relative flow--independence of lung deposition.     

Novolizer: how does it fit into inhalation therapy?

Inhalation therapy is the preferred route of administration of anti-asthmatic drugs to the lungs. However, the vast majority of patients cannot use their inhalers correctly, particularly pressurised metered dose inhalers (pMDIs). The actual proportion of patients who do not use their inhalers correctly may even be under-estimated as GPs tend to over-estimate correct inhalation technique. Dry powder inhalers (DPIs) have many advantages over pMDIs. Unlike pMDIs, they are environmentally-friendly, contain no propellant gases and, more importantly, they are breath-activated, so that the patient does not need to coordinate actuation of the inhaler with inspiration. Three key parameters for correct inhaler use should be considered when evaluating existing or future DPI devices and especially when choosing the appropriate device for the patient: (1) usability, (2) particle size distribution of the emitted drug and (3) intrinsic airflow resistance of the device. The Novolizer is a breath-activated, multidose, refillable DPI. It is easy to use correctly, has multiple feedback and control mechanisms which guide the patient through the correct inhalation manoeuvre. In addition, the Novolizer has an intelligent dose counter, which resets only after a correct inhalation and may help to monitor patient compliance. The Novolizer has a comparable or better lung deposition than the Turbuhaler at similar or higher peak inspiratory flow (PIF) rates. A flow trigger valve system ensures a clinically effective fine particle fraction (FPF) and sufficient drug delivery, which is important for a good lung deposition. The FPF produced through the Novolizer is also relatively independent of flow rate and the device shows better reproducibility of metering and delivery performance compared to the Turbuhaler. The low-to-medium airflow resistance means that the Novolizer is easy for patients to use correctly. Even children, patients with severe asthma and patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) have no problems to generate the trigger inspiratory flow rate required to activate the Novolizer. The Novolizer uses an advanced DPI technology and may improve patient compliance.     

Clinical pharmacokinetics of inhaled budesonide

The corticosteroid budesonide is a 1:1 racemic mixture of 2 epimers, (22R)- and (22S)-, and is available in 3 different inhaled formulations for the management of asthma: a pressurised metered dose inhaler (pMDI), a dry powder inhaler (DPI) and a solution for nebulised therapy. Inhaled corticosteroids such as budesonide reach the systemic circulation either by direct absorption through the lungs (a route that is much more important than previously recognised) or via gastrointestinal absorption of drug that is inadvertently swallowed. Although the pharmacokinetics of budesonide have been extensively investigated following oral and intravenous administration, relatively few studies have defined the systemic disposition of budesonide after inhalation. Drug deposition in the lungs depends on the inhaler device: 15% of the metered dose of budesonide reached the lung with a pMDI compared with 32% with a breath-actuated DPI. In patients with asthma (n = 38) receiving different doses of budesonide by DPI (Turbuhaler), the pharmacokinetic parameters peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) were dose-dependent after both single dose and repeat dose (3 weeks) administration: time to Cmax (tmax) was short (0.28 to 0.40 hours) and the elimination half-life approximately 3 hours. Both AUC and Cmax were linearly related to budesonide dose. In a small group of healthy male volunteers (n = 9), the pharmacokinetics of budesonide 1,600 microg twice daily via pMDI were assessed on the fifth day of administration. Mean model-independent parameters for (22R)-budesonide were as follows: Cmax 1.8 microg/L, tmax 0.46 hours, elimination half-life 2.3 hours and oral clearance 163 L/h, and there were no enantiomer-specific differences in drug disposition. Budesonide undergoes fatty acid conjugation within the lung, but very limited pharmacokinetic data are available to define the pulmonary absorption characteristics. There is evidence from a population analysis that the pulmonary absorption of budesonide is prolonged and shows wide interindividual variation. Further pharmacokinetic studies are required to define the time-course of budesonide absorption through the lung in specific patient groups, and to investigate the effect of new inhaler devices (especially chlorofluorocarbon-free pMDIs) on the pharmacokinetic profile and systemic drug exposure.     

Comparison of Gamma Scintigraphy and a Pharmacokinetic Technique for Assessing Pulmonary Deposition of Terbutaline Sulphate Delivered by Pressurized Metered Dose Inhaler

A comparison has been made of pulmonary deposition of terbutaline sulphate from a pressurized metered dose inhaler (pMDI), measured in 8 healthy male subjects by gamma scintigraphy and by a pharmacokinetic (charcoal-block) method, involving drug recovery in urine. Measurements were carried out with a pMDI at slow (27 1/min) and fast (151 1/min) inhaled flows and with Nebuhaler^® large volume spacer device (average inhaled flow 171/min). Overall, the two methods did not differ significantly in their estimates of whole lung deposition, although values obtained by gamma scintigraphy exceeded those from the charcoal-block method for the pMDI with fast inhalation. The regional distribution of drug within the lungs and deposition in the oropharynx could be assessed by gamma scintigraphy, but not by the charcoal-block method. It is concluded that either method may be used to assess whole lung deposition of terbutaline sulphate from pMDIs, both with and without a spacer, although each method has its own inherent advantages and disadvantages.     

Effect of an external resistance to airflow on the inspiratory flow curve

Inhalation is a convenient way to deliver drugs to the respiratory tract in the treatment of respiratory diseases. For dry powder inhalers (DPI's), the principle of operation is to use the patient-generated inspiratory flow as energy source for emptying of the dose system and the delivery of fine drug particles into the respiratory tract. Resistance to airflow of the inhaler device is a major determinant for the inspiratory flow profile through the dry powder inhaler that can be generated by the patient. Therefore, resistance to airflow is one of the design parameters for DPI's, that could be used to control the inspiratory flow profile, and is one of the parameters to optimise particle deposition in the airways. In this study the effect of resistance to airflow on different parameters of the inspiratory flow curves as generated by healthy subjects, asthmatics and COPD patients was determined. As a result of increased resistance to airflow, the peak inspiratory flow (PIF), the flow increase rate (FIR) and the inhaled volume to reach PIF is decreased. On the other hand, the total inhalation time as well as the 80% dwell time is increased. In general, tuning of the resistance to airflow in the design of a dry powder inhaler may improve the drug deposition in the respiratory tract.     

Intrapulmonary distribution of deposited particles.

Inhalation drug delivery for both topical and systemic treatments has many advantages over oral, intravenous, or subcutaneous drug delivery. Because some drugs should be deposited within the bronchial tree and others should deposit within the respiratory zone of the lung, it should be possible to determine and influence the preferential site of drug deposition to develop efficient inhalation therapy strategies. In this article, a method that allows estimation of the longitudinal distribution of deposited particles in the lungs of individual subjects is introduced. From the photometrically measured deposition of monodisperse di-2-ethylhexyl sebacate (DEHS) droplets, the longitudinal distribution of deposited particles (i.e., the number of particles that are deposited in a certain lung volume element) can be assessed. In this study in four healthy volunteers the distribution of deposited particles was assessed for different airflow rates, tidal volumes (VTS), and particle sizes. The results showed that there are considerable differences in the longitudinal distribution of deposited particles between subjects and that the distribution is strongly dependent on particle size: if particle size is increased, the site of particle deposition is shifted proximally. Particles with diameters greater than approximately 5 microns cannot penetrate to a volumetric lung depth (VP) greater than approximately 600 cm3 even if the VT is increased. Airflow rate has a minor effect on the distribution of deposited particles, but if airflow rate increases, the site of particle deposition is slightly shifted peripherally. This method can be used to investigate individual patterns of drug deposition in human lungs noninvasively and to develop and optimize inhalation strategies for inhalation drug delivery.     

Lactose characteristics and the generation of the aerosol

The delivery efficiency of dry-powder products for inhalation is dependent upon the drug formulation, the inhaler device, and the inhalation technique. Dry powder formulations are generally produced by mixing the micronised drug particles with larger carrier particles. These carrier particles are commonly lactose. The aerosol performance of a powder is highly dependent on the lactose characteristics, such as particle size distribution and shape and surface properties. Because lactose is the main component in these formulations, its selection is a crucial determinant of drug deposition into the lung, as interparticle forces may be affected by the carrier-particle properties. Therefore, the purpose of this article is to review the various grades of lactose, their production, and the methods of their characterisation. The origin of their adhesive and cohesive forces and their influence on aerosol generation are described, and the impact of the physicochemical properties of lactose on carrier-drug dispersion is discussed in detail.