Pressurised metered dose inhalers

Liquid instillation and nebulised aerosols are the most common methods for pulmonary administration to experimental animals [22, 54, 109, 134], The use of pressurised metered dose inhaler (pMDIs) and dry powder inhaler (DPIs) in preclinical studies is limited by the need for formulation development, which often cannot be performed in early drug discovery due to short supply of test materials. A number of alternative techniques for intra-tracheal administration of coarse sprays and powder formulations have been described [9, 15, 21, 36, 71, 80, 99, 138],... 

Farr, S.J., Rowe, A.M., Rubsamen, R., and Taylor, G., Aerosol deposition in the human lung following administration from a microprocessor controlled pressurised metered dose inhaler. Thorax, 50 639-644 (1995). 

Ram FS, Brocklebank DM, Muers M, et al. Pressurised metered-dose inhalers versus all other handheld inhalers devices to deliver bronchodilators for chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2002 CD002170. 

Patients who have difficulty in coordination with inhalers can use a spacer device. These remove the need for coordination between actuation of a pressurised metered dose inhaler and inhalation. The spacer device reduces the velocity of the aerosol and subsequent impaction on the oropharynx. In addition, the device allows more time for evaporation of the propellant so that a larger proportion of the particles can be inhaled and deposited in the lungs. The size of the spacer is important, the larger spacers with a one-way valve (Nebuhaler, Volumatic) being most effective. Spacer devices are particularly useful for patients with poor inhalation technique, for children, for patients requiring higher doses, for nocturnal asthma, and for patients who have poor coordination. 

Dhillon, S., and Keating, G. M. (2006), Beclometasone dipropionate/formoterol In an HFA-propelled pressurised metered-dose inhaler, Drugs, 66,1475-1483. 

Hallworth, G.W. The formulation and evaluation of pressurised metered dose inhalers. In Drug Delivery to the Respiratory Tract, Ganderton, D., Jones, T., Eds. Ellis Horwood Chichester, UK, 1987 87-118. 

Atkins, P.J. Barker, N.P. Mathisen, D. The design and development of inhalation drug delivery systems. In Pharmaceutical Inhalation Pressurised Metered-Dose Inhaler Technology, Hickey, A.J., Ed. Marcel Dekker, Inc. New York, 1992. 

Raoult s law is important because it allows the calculation of vapour pressure from a knowledge of the composition of the solution. The requirement of the Montreal Protocol in 1989 for the replacement of chlorofluorocarbon (CFG) propellants in pressurised metered-dose inhalers with hydrofluoroalkanes (HFAs), because of the ozone-depleting... 

This method could either be used as a one-step process for the preparation of protein or peptide suspension for pressurised metered dose inhaler or the suspension could be poured into a flask and rotated at room temperature until the propellant evaporates. The powder derived from this could be used for the preparation of a dry powder for inhalation, which makes this technique versatile. 

In pressurised metered dose inhaler (pMDI) technology, CFC propellants are being replaced with the ozone-friendly hydrofluoroalkanes (HFA)-134a and -227. In pMDI drug delivery systems, the drugs are formulated as a suspension or as a solution, depending on the solubility of... 

Riker Laboratories, now 3M Healthcare, invented the pressurised metered dose inhaler (MDI) in 1955 when they combined the atomising power of CFCs and a metering valve design. The great majority of valves still use this basic retention valve principle, and hence pressurised MDIs (pMDIs) are all similar in appearance and operation when used with a standard actuator in the normal press and breathe manner. 

Both corticosteroids and bronchodilator therapy should routinely be delivered by a pressurised metered dose inhaler (pMDI) and spacer system, with a facemask where necessary in infants, toddlers and children under 5 years of age. 

Baroody FM. Anatomy and physiology. In Naclerio RM, Durham SR, Mygind N, eds. Rhinitis Mechanisms and Management. New York Marcel Dekker, 1999 1-22. Berg E. In vitro properties of pressurised metered dose inhalers with and without spacer devices. J Aerosol Med 1995 8 S3-S11. 

Liljas B, Stahl E, Pauwels RA. Cost-effectiveness analysis of a dry powder inhaler (Turbuhaler) versus a pressurised metered dose inhaler in patients with asthma. Pharmacoeconomics 1997 12 267-277. 

Zainudin BMZ, Biddiscombe M, Tolfree SEJ, Short M, Spiro SG. Deposition patterns of salbutamol inhaled from a pressurised metered dose inhaler, as a dry powder, and as a nebulised solution. Thorax 1990 45 469-473. 

Clarke JG, Farr SJ, Wicks SR. Technetium-99m labelling of suspension type pressurised metered dose inhalers comprising various drug/surfactant combinations. Int J Pharm 1992 80 R1-R5. 

Thorsson L, Edsbacker S. Lung deposition froma pressurised metered dose inhaler attached to a spacer. Eur Respir J 1998 12 1340-1345. 

Newman S, Steed K, Hooper G, Kallen A, Borgstrom L. Comparison of gamma scintigraphy and pharmacokinetic technique for assessing pulmonary deposition of terbutaline sulphate delivered by pressurised metered dose inhaler. Pharm Res 1995 12 231-266. 

Jackson L, Stahl E, Holgate ST. Terbutaline via a pressurised metered dose inhaler (pMDI) and Turbuhaler in highly reactive asthmatic patients. Eur Respir J 1994 7 1598-1601. 

Sehroos O, Lofroos AB, Pietinalho A, Riska H. Comparison of terbutaline and placebo from a pressurised metered dose inhaler and a dry powder inhaler in a subgroup of patients with asthma. Thorax 1994 49 1228-1230. 

Hardy J, Jasuja A, Frier M, Perkins A. A small volume spacer for use with a breath-operated pressurised metered dose inhaler. Int J Pharm 1996 142 129-133. 

Newman S, Clark A, Talace N, Clarke S. Lung deposition of 5 mg of Intal from a pressurised metered dose inhaler assessed by radiotracer technique. Int J Pharm 1991 74 203-208. 

The European Pharmacopeia lists four different devices to enable administration to the lungs, namely nebulisers, pressurised metered dose inhalers (pMDls), non-pressurised metered-dose inhalers (MDls) and dry powder inhalers (DPls) [7]. Aerosolisation is based on nebulisation or atomisation for the three devices using aqueous solutions or suspensions and dedicated to dry powder dispersion for DPls as addressed in this project [1, 7]. 

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