Inhaled drugs and the lung

Inhaled Chemotherapy

Cytotoxic chemotherapy remains the cornerstone of treatment for patients diagnosed with advanced stage cancers and is an important component in the multi-disciplinary treatment of several early stage cancers. In the majority of patients with cancer, cytotoxic chemotherapy is administered intravenously and in some instances by oral administration. Systemic administration of cytotoxic chemotherapy is well known to cause adverse effects, which can be severe and debilitating. Regional therapy with cytotoxic agents has the potential to reduce the extent of systemic exposure to the drug and reduce the risk of systemic adverse effects. Regional chemotherapy has been successfully employed in the treatment of certain solid tumors such as hepatocellular carcinoma. However, regional chemotherapy has not been commonly utilized for treatment of lung tumors. Inhaled cytotoxic chemotherapy has the potential to become an effective regional therapy for both primary lung cancer and metastases to the lung from other primary tumors. Aerosol administration of chemotherapy could potentially avoid some of the adverse effects seen with systemic therapy. In addition, some chemotherapeutic agents when administered as an aerosol are absorbed directly into the arterial circulation and have therapeutic effects at extrapulmonary sites. Aerosol administration of several different chemotherapeutic agents is currently under evaluation either in the preclinical setting or in early phase human trials. Some of these studies have shown that inhaled chemotherapy is feasible and effective in treating lung tumors. In this chapter, we review the published studies and ongoing trials on inhaled chemotherapy to better understand the current status of this field of cancer treatment.

Pharmacokinetics-On-a-Chip: In Vitro Microphysiological Models for Emulating of Drugs ADME

Despite many ongoing efforts across the full spectrum of pharmaceutical and biotech industries, drug development is still a costly undertaking that involves a high risk of failure during clinical trials. Animal models played vital roles in understanding the mechanism of human diseases. However, the use of these models has been a subject of heated debate, particularly due to ethical matters and the inevitable pathophysiological differences between animals and humans. Current in vitro models lack the sufficient functionality and predictivity of human pharmacokinetics and toxicity, therefore, are not capable to fully replace animal models. The recent development of micro-physiological systems has shown great potential as indispensable tools for recapitulating key physiological parameters of humans and providing in vitro methods for predicting the pharmacokinetics and pharmacodynamics in humans. Integration of Absorption, Distribution, Metabolism, and Excretion (ADME) processes within one close in vitro system is a paramount development that would meet important unmet pharmaceutical industry needs. In this review paper, synthesis of the ADME-centered organ-on-a-chip technology is systemically presented from what is achieved to what needs to be done, emphasizing the requirements of in vitro models that meet industrial needs in terms of the structure and functions.

Newer approaches and novel drugs for inhalational therapy for pulmonary arterial hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by remodeling of small pulmonary arteries leading to increased pulmonary arterial pressure. Existing treatments acts to normalize vascular tone via three signaling pathways: the prostacyclin, the endothelin-1, and the nitric oxide. Although over the past 20 years, there has been considerable progress in terms of treatments for PAH, the disease still remains incurable with a disappointing prognosis.Areas covered: This review summarizes the pathophysiology of PAH, the advantages and disadvantages of the inhalation route, and assess the relative advantages various inhaled therapies for PAH. The recent studies concerning the development of controlled-release drug delivery systems loaded with available anti-PAH drugs have also been summarized.Expert opinion: The main obstacles of current pharmacotherapies of PAH are their short half-life, stability, and formulations, resulting in reducing the efficacy and increasing systemic side effects and unknown pathogenesis of PAH. The pulmonary route has been proposed for delivering anti-PAH drugs to overcome the shortcomings. However, the application of approved inhaled anti-PAH drugs is limited. Inhalational delivery of controlled-release nanoformulations can overcome these restrictions. Extensive studies are required to develop safe and effective drug delivery systems for PAH patients.

Inhaled Cisplatin for NSCLC: Facts and Results

Although we have new diagnostic tools for non-small cell lung cancer, diagnosis is still made in advanced stages of the disease. However, novel treatments are being introduced in the market and new ones are being developed. Targeted therapies and immunotherapy have brought about a bloom in the treatment of non-small cell lung cancer. Still we have to find ways to administer drugs in a more efficient and safe method. In the current review, we will focus on the administration of inhaled cisplatin based on published data.

Vectors for inhaled gene therapy in lung cancer. Application for nano oncology and safety of bio nanotechnology

Novel aerosol therapeutic modalities have been investigated for lung cancer. Inhaled gene therapy has presented safety and effectiveness previously in cystic fibrosis. However, safety concerns have been raised regarding the safety of non-viral vectors for inhaled gene therapy in lung cancer, and therefore small steps have been made towards this multifunctional treatment modality. During the last decade, numerous new nanocomplexes have been created and investigated as a safe gene delivery nano-vehicle. These formulations are multifunctional; they can be used as either local therapy or carrier for an effective inhaled gene therapy for lung cancer. Herein, we present current and future perspectives of nanocomplexes for inhaled gene therapy treatment in lung cancer.

Deposition of inhaled particles in the lungs

Inhaled medication is the first-line treatment of diseases such as asthma or chronic obstructive pulmonary disease. Its effectiveness is related to the amount of drug deposited beyond the oropharyngeal region, the place where the deposit occurs and its distribution (uniform or not). It is also important to consider the size of the inhaled particles, the breathing conditions, the geometry of the airways and the mucociliary clearance mechanisms. Currently, mathematical models are being applied to describe the deposition of inhaled drugs based on the size of the particles, the inspiratory flow and the anatomical distribution of the bronchial tree. The deposition of particles in the small airways gets maximum attention from pharmaceutical companies and is of great interest as it is related with a better control in patients receiving these drugs.

Inhaled chemotherapy in lung cancer: future concept of nanomedicine

Regional chemotherapy was first used for lung cancer 30 years ago. Since then, new methods of drug delivery and pharmaceuticals have been investigated in vitro, and in animals and humans. An extensive review of drug delivery systems, pharmaceuticals, patient monitoring, methods of enhancing inhaled drug deposition, safety and efficacy, and also additional applications of inhaled chemotherapy and its advantages and disadvantages are presented. Regional chemotherapy to the lung parenchyma for lung cancer is feasible and efficient. Safety depends on the chemotherapy agent delivered to the lungs and is dose-dependent and time-dependent. Further evaluation is needed to provide data regarding early lung cancer stages, and whether regional chemotherapy can be used as neoadjuvant or adjuvant treatment. Finally, inhaled chemotherapy could one day be administered at home with fewer systemic adverse effects.

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.

Pulmonary drug delivery. Part I: physiological factors affecting therapeutic effectiveness of aerosolized medications

As the end organ for the treatment of local diseases or as the route of administration for systemic therapies, the lung is a very attractive target for drug delivery. It provides direct access to disease in the treatment of respiratory diseases, while providing an enormous surface area and a relatively low enzymatic, controlled environment for systemic absorption of medications. As a major port of entry, the lung has evolved to prevent the invasion of unwanted airborne particles from entering into the body. Airway geometry, humidity, mucociliary clearance and alveolar macrophages play a vital role in maintaining the sterility of the lung and consequently are barriers to the therapeutic effectiveness of inhaled medications. In addition, a drug's efficacy may be affected by where in the respiratory tract it is deposited, its delivered dose and the disease it may be trying to treat.

Development of inhalational agents for oncologic use

Because regional chemotherapy has been useful in treatment and palliation of many cancer types, the concept of delivering drugs by inhalation for the treatment of cancers in the lung is attractive. Much higher local drug exposure can be achieved with total doses considerably lower than those required for systemic administration, resulting in lower exposure of nonrespiratory tract tissues to potentially toxic drugs. Regional delivery of chemotherapy to the respiratory tract has been shown to have activity in preclinical and clinical studies. Technical improvements in delivery methods have now made it possible to conduct trials of inhalational agents, both to treat cancers affecting the respiratory tract and to deliver other drugs used in cancer patients. This review discusses the rationale of drug delivery by the inhalational route, its technical challenges, preclinical and clinical experiences, limitations, and promise.

Comparative study of budesonide as a nebulized suspension vs pressurized metered-dose inhaler in adult asthmatics

The study objective was to compare the effect of budesonide administered as a nebulized suspension as compared to a spray with a spacer in adult asthmatics. In a double-blind, double-dummy crossover study, 26 adult patients with moderately severe unstable asthma were randomized to three 4-week treatment periods with budesonide 0.8 mg b.i.d. administered by a pressurized metered-dose inhaler (pMDI) with spacer (Nebuhaler) and budesonide 1 mg and 4 mg b.i.d. administered by a Pari Inhalier Boy jet nebulizer. The nebulizer was activated only during inspiration. The total mass output was similar from the two devices but their fraction of small particles differed by a factor of 2 in favour of pMDI. Effect was evaluated from daily home measurements of peak expiratory flow (PEF), need of beta 2-agonist and symptom scores. Plasma cortisol and budesonide levels were measured in a subgroup of 10 patients. A consistent trend showed the nebulizer treatment to be at least as efficient as the pMDI plus spacer treatment. In actual fact, the apparent order of effect was: 4 mg nebulized suspension treatment > or = 1 mg nebulized suspension treatment > or = 0.8 mg pMDI with spacer treatment. Plasma budesonide and plasma cortisol also exhibited dose-related levels independent of device. The adverse effects reported appeared to be related to the dose rather than delivery device. Accordingly, the effect was related to total mass output, rather than to the small particle fraction of the budesonide aerosol. These results attest to the efficiency of jet-nebulized budesonide suspension, and indicate nebulized budesonide to be equipotent to standard budesonide therapy delivered by pMDI with Nebuhaler, provided nebulization is synchronized with inspiration and no loss of aerosol occurs during expiration.

Pharmacokinetic optimisation of asthma treatment

Asthma is generally managed with bronchodilator therapy and/or anti-inflammatory drugs. Guidelines now advocate selection of drugs and pharmaceutical formulations (long-acting vs short-acting, inhaled vs systemic) on the basis of disease severity. Theophylline has a narrow therapeutic margin. Clearance is highly variable and plasma concentrations should be monitored to avoid the occurrence of plasma concentration-related adverse effects. The rate of absorption of theophylline differs depending on the sustained release formulation administered. Some products do not provide sufficient plasma drug concentrations for therapeutic efficacy over a 12-hour period, particularly in patients with high clearance rates (e.g. children and patients who smoke). Administration of drugs via inhalation offers several advantages over systemic routes of administration (e.g. adverse effects are decreased). Inhalation is now advocated as first-line therapy. Aerosol medications available for the treatment of asthma are beta 2-agonist (including the newer long-acting agents such as salmeterol), corticosteroids, anticholinergic drugs, sodium cromoglycate (cromolyn sodium) and nedocromil. To reach the airways, aerosolised particles should be 1 to 5 microns in diameter. Particles of this size can be produced by nebuliser for continuous administration or by metered-dose inhaler and drug powder inhaler for unit dose medication. For efficient use of the metered-dose inhaler, slow inhalation and actuation must be coordinated. However, efficacy and convenience can be improved when spacer devices are used. Furthermore, spacer devices lessen the oropharyngeal adverse effects of inhaled corticosteroids. Dry powder inhalers are more easily used by children and elderly patients than metered-dose inhalers. Regardless of the device used, a maximum of 10% of the inhaled dose reaches the airways. The rest of the dose is swallowed and absorbed through the gastrointestinal tract. Most inhaled drugs have low oral bioavailability, either because of a high first-pass metabolism (beta 2-agonists and glucocorticoids) or because of lack of absorption (sodium cromoglycate). Sulphation of beta 2-agonists occurs in the wall of the gastrointestinal tract and extensive metabolism of inhaled corticosteroids occurs in the liver. Low bioavailability of the swallowed fraction contributes to reduced adverse effects. The pharmacokinetic properties of an inhaled drug are of interest. The fraction of the dose absorbed through the lung has the same disposition characteristics as an intravenous dose, and the swallowed fraction has the same disposition as an orally administered dose. However, for many drugs, pharmacokinetic data after inhalation are limited and cannot be used as a criteria for selection of therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

The quantitative distribution of nebulized antibiotic in the lung in cystic fibrosis

Nebulized antibiotic therapy in cystic fibrosis is an established procedure. The present study was designed to quantitate deposition, and assess its relation to the disease state. Twenty seven children and young adults with cystic fibrosis (mean 11.6 years, range 4-23 years, 12 females) were studied to establish the quantity and pattern of deposition of nebulized tobramycin in the respiratory tract. A single (120 mg) dose of nebulized 99 m technetium-labelled tobramycin was administered, and imaged with a gamma-camera. The mean penetration index (which compares the distribution of 81 m-Krypton gas with Tc-radioaerosol) was also used to measure peripheral deposition efficiency. The aerosol mass median diameter (MMAD) for the compressor-nebulizer system used was 5.3 u, measured with the Malvern Mastersizer. Serial sputum samples were fluroimmunoassayed for tobramycin in nine patients. A mean of 8.0 (SEM 1.0) mg tobramycin reached the lungs. There was no relationship between the total pulmonary deposition and indices of pulmonary damage in cystic fibrosis. Sixteen percent of the lung tobramycin reached the periphery. The greater the lung damage as indicated by FEV1 and Chrispin-Norman scores, the smaller the proportion of pulmonary tobramycin that reached the periphery. The mean penetration index increased with increase in the FRC, but bore no relation to other respiratory function tests or to chest X-ray scores. Sputum tobramycin concentrations reached levels bactericidal for Pseudomonas aeruginosa. Airway obstruction and damage affected the proportion of pulmonary tobramycin reaching the periphery. The proportion of tobramycin reaching the lungs was small and variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Delivery of micronized budesonide suspension by metered dose inhaler and jet nebulizer into a neonatal ventilator circuit

We compared the delivery of a micronized suspension of budesonide by a metered dose inhaler (MDI) with two different spacers (Aerochamber and Aerovent) and by two jet nebulizers (MAD2 and Ultravent) to a ventilated neonatal test-lung using a standard neonatal ventilator circuit. The combination of MDI and Aerochamber was significantly better at delivering budesonide to a filter in front of the test lung (14.2% of aerosolized dose) than were either the MDI and Aerovent (3.6%) or the Ultravent or MAD2 jet nebulizers (0.02% and 0.68% of initial reservoir dose). Of the droplets emerging from the MDI, Aerochamber, and ET tube, 18% of the initial dose was in droplets less than 4.7 microns. Assuming that the test-lung model accurately reflects in vivo deposition, the combination of MDI and Aerochamber appears to be an extremely effective way of delivering budesonide aerosol to ventilated newborn infants.

Delivery of therapeutic aerosols to intubated babies

Delivery of drug aerosols to the lungs of ventilated neonates by metered dose inhaler and spacer (Aerochamber) and ultrasonic nebuliser (Pentasonic) was assessed using sodium cromoglycate. The mean proportion of a known intratracheal dose of sodium cromoglycate excreted in the urine of four intubated infants was 37.5%. After assuming that 38% of the sodium cromoglycate aerosol reaching the neonatal lung will be excreted in the urine, three puffs (15 mg) delivered by metered dose inhaler and spacer resulted in a pulmonary dose of 258 micrograms (1.7%, n = 7). A dose of 20 mg (4 ml) sodium cromoglycate ultrasonically nebulised over five minutes into the inspiratory limb of a standard ventilator circuit produced a pulmonary dose of 257 micrograms (1.3%, n = 7). Of two in vitro lung models assessed, a combination of filter and neonatal test lung was superior to a multistage impactor in estimating the in vivo pulmonary sodium cromoglycate dose delivered by metered dose inhaler and spacer (243 micrograms v 1740 micrograms).