الفهرس 
History of Inhalation TherapyOnly 14 pages are availabe for public view
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Abstract
Inhalation therapy has revolutionized the treatment of several respiratory diseases including obstructive airway diseases. This form of therapy refers to delivery of the drug directly into the lower airways for either topical or systemic effect (Khilnani and Banga, 2008).
Ancient man discovered the therapeutic material by trials and observation. In that he used many plants, minerals and organic materials for the treatment of his body troubles. Credit goes to ancient Egypt for the first use of inhalation therapy for the treatment of the oral, pharyngeal and chest troubles (El Gammal, 1994).
Advantages of inhalation include: (i) Delivers medication directly to the lungs; (ii) small amounts of drug suffice to prevent or treat symptoms (iii) adverse reactions are usually much less than those produced by systemic administration and (iv) there is a rapid and predictable onset of action.
The primary disadvantage of the inhalant route when compared to the systemic route is that some drugs have decreased therapeutic effect by this route (Harvey and Hamby, 2002).
Pharmaceutical aerosols have been used as important drug carriers to the body for decades. Pulmonary delivery of bronchodilators, mucolytics, anticholinergics, and steroids is widely accepted in clinical practice. As drug carriers, aerosols remain unquestionably the most effective mode for treating patients with asthma and some of systemic disease. In general, however, the lung remains underutilized for systemic administration of drugs compared to the oral and injectable delivery routes. This is unfortunate and is largely a result of the human lung being a complex organ with significant perceived safety risks compared to nonconventional routes of administration (Scheuch et al., 2006).
The use of the inhalant route allows easy accessibility to the respiratory tract because antiasthma drugs and other medications can be directly administered to their sites of action in the lungs (Godfery and BarYishay, 1993).
Recently, there are numbers of medications take by inhalation for systemic treatment such as hormones (insulin, calcitonin,oxytocin and growth hormones),different interleukins ,heparin (unfractionated and low molecular weight heparin (LMWH)),cyclosporine in lung transplantion (Newman and Chan, 2008).
The major aerosol systems used to deliver medication directly to the lung including metered dose inhalers (MDIs), dry powder inhalers (DPIs), and nebulizers. In addition to asthma, chronic bronchitis, and emphysema, the value of lung aerosol medications for cystic fibrosis (CF) and pulmonary infections, The possible role provides an overview of delivery devices, including nebulizers, pressurized MDIs(pMDIs), and DPIs (Atkins, 2002).
The effectiveness of an inhaled therapeutic depends on how much of the drug is able to navigate through the upper airway and into the lung, and how well the distribution of the drug matches the location of the target. The deposition efficiency of aerosols in the lungs is related to numerous variables, including aerosol characteristics, drug formulation, patient variables, and the interface between the delivery device and the patient (Geller, 2009).
The most important aerosol characteristics are the size and size distribution of the particles, and the velocity at which they travel. The upper airway is a very effective filter for particulates. Particles less than 5 µm in size have the highest probability of bypassing the upper airway and entering the lower airways. Large particles and those with higher velocity will likely impact on the upper airway and not be able to make the bend around the throat (Ratjen, 2009).
Future research should continue to focus on fundamental aspects related to drug inhalation. The influence of various factors like disease progression, aerosol behaviour in the lung and patient related factors on the deposited dose should be mapped. The use of monodisperse par¬ticles for inhalation in a research environment with lung deposition imaged using scintigraphy, is expected to increase our understanding of critical parameters regarding inhaler and inhala¬tion parameters (Newman and Chan, 2008).