Inhaled drugs and the lung

Summers, Quentin

doi:10.1111/j.1365-2222.1991.tb01657.x

Cited by 35 publications

(13 citation statements)

References 83 publications

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“…The factors that determine the deposition of aerosols in the airways are [73]: the number and size of the droplets delivered to the mouth, air temperature and relative humidity, airways geometry and breathing pattern. Due to oropharyngeal deposition the actual dose that enters the lungs can only be estimated.…”

Section: Aerosol Generationmentioning

confidence: 99%

Standardized challenge testing with pharmacological, physical and sensitizing stimuli in adults

Sterk

Fabbri

Quanjer

et al. 1993

European Respiratory Journal

851

556

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Section: Aerosol Generationmentioning

confidence: 99%

Standardized challenge testing with pharmacological, physical and sensitizing stimuli in adults

Sterk

Fabbri

Quanjer

et al. 1993

European Respiratory Journal

851

556

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“…The particle size in the aerosol is reduced as evaporation of the propellant occurs [1][2][3]. Also, larger particles are preferentially deposited on the walls of the spacer.…”

mentioning

confidence: 98%

Lung deposition of budesonide from a pressurized metered-dose inhaler attached to a spacer

Thorsson¹,

Edsbäcker²

1998

Eur Respir J

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In the treatment of asthma, inhaled formulations are commonly used to direct drugs to the lungs. The inhaled drug is deposited either in the upper respiratory tract or in the lungs. Exhaled drug generally constitutes a negligible part of the dose. The fraction deposited extrapulmonarily is eventually swallowed and absorbed from the gastrointestinal (GI) tract and will thus contribute to the systemic availability of the inhaled drug.Spacer devices between the actuator and the mouth are used to overcome the problem of co-ordinating actuation and inhalation from a pressurized metered-dose inhaler (pMDI). The particle size in the aerosol is reduced as evaporation of the propellant occurs [1][2][3]. Also, larger particles are preferentially deposited on the walls of the spacer. An increased fraction of small particles means that deposition in the oropharynx is decreased. In addition, lung deposition may be increased due to the fact that the velocity of the aerosol cloud is reduced before inhalation.The Nebuhaler® is a large-volume (750 mL) spacer intended for pMDIs of budesonide and terbutaline sulphate. Studies with 99m Tc-labelled Teflon™ particles, using γ-scintigraphic imaging techniques, have shown that the lung deposition, in asthmatic patients with airflow obstruction, increased from approximately 9% of the metered dose with a pMDI alone, to 21% after a single puff and 15% after multiple puffs when the pMDI was attached to a Nebuhaler® [4]. The lung deposition of 99m Tc-labelled terbutaline sulphate from a pMDI with a Nebuhaler® was 32% compared with 11% from a pMDI alone [5].Scintigraphic imaging is a commonly used technique to determine lung deposition after inhalation. Lung deposition can also be determined from urinary excretion of intact drug, provided that the contribution of orally deposited and subsequently swallowed drug can be accounted for, and that the drug is not metabolized in the lung [6]. One approach to accounting for swallowed drug is to prevent GI absorption by using concomitant oral administration of activated charcoal [7]. Another approach is to calculate the lung deposition from the systemic availability after inhalation by subtracting the estimated oral contribution [7].Budesonide is a potent glucocorticosteroid effective in the treatment of asthma. When given by inhalation, its antiasthmatic effect may be explained by a local pulmonary action [8]. No oxidative or reductive metabolism of budesonide has been noted in human lung homogenates [9]. The drug is rapidly and extensively absorbed [10]. Pharmacokinetic studies, performed in healthy subjects and asthmatic children, have shown that budesonide undergoes a high first-pass metabolism and has a low systemic availability (about 10%) after oral dosing [10,11]. Inhaled budesonide undergoes a rapid systemic uptake, with a time of maximum concentration of about 20 min. The systemic availability was found to be 26% from a pMDI and 38% Lung deposition of budesonide from a pressurized metered-dose inhaler attached to a spacer. L. Thorsson, S. E...

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“…Epithelium and Tight Junctions Underlying the mucus layer, airway epithelial cells form a tight ciliated barrier connected by tight junctions that blocks fluid flow and control the transport of ions and solutes through the intercellular space [141]. The permeation of hydrophilic substances of high molecular weight and ionic species is limited [142], with the molecular weight cutoff of the tight junctions of alveolar type I cells at 0.6 nm [143].…”

Section: Barriers To Airway Delivery Of Biologicsmentioning

confidence: 99%

Routes of Delivery for Biological Drug Products

Irvine¹,

Su²,

Kwong³

2013

Pharmaceutical Sciences Encyclopedia

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Unlike conventional small‐molecule drugs, many of which can be formulated effectively with excipients to avoid degradation in the stomach and which exhibit reasonably efficient uptake through the gastrointestinal tract, biological drugs may exhibit lower stability and a greater sensitivity to enzymatic degradation, making oral delivery problematic. Thus, the majority of biologics are currently administered through subcutaneous/intramuscular injection or via intravenous infusion. Recent advances in delivery of traditional biologics include methods to increase the acceptable volume of drug solutions that can be administered subcutaneously.In addition, a number of alternative routes of administration for biologic drug products are being intensively investigated at the preclinical and clinical stages, such as intranasal, pulmonary, transcutaneous, and other routes, with some first examples of products recently licensed.This chapter will review current methods in use for marketed biologics and advanced approaches undergoing clinical testing.

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Inhaled drugs and the lung

Cited by 35 publications

References 83 publications

Standardized challenge testing with pharmacological, physical and sensitizing stimuli in adults

Standardized challenge testing with pharmacological, physical and sensitizing stimuli in adults

Lung deposition of budesonide from a pressurized metered-dose inhaler attached to a spacer

Routes of Delivery for Biological Drug Products

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