Respirable powders

The respirable powders of a DPI cannot be characterized adequately by single-particle studies alone bulk properties must also be assessed since they contribute to ease of manufacture and affect system performance. Primary bulk properties include particle size, particle size distribution, bulk density, and surface area. These properties, along with particle electrostatics, shape, surface morphology, etc., affect secondary bulk-powder characteristics such as powder fiow, handling, consolidation, and dispersibility. 

Bulk powder density, porosity, and consolidation rate are used as characteristics of powder structure and ease of flow. These properties are typically more difficult to determine for fine respirable powders than... 

Matinkhoo S, Lynch KH, Dennis JJ, Finlay WH, Vehring R. Spray-dried respirable powders containing bacteriophages for the treatment of pulmonary infections. / Pharm Sci. 100 (12) 5197-5205, 2011. 

Vandenheuvel, D., Singh, A., Vandersteegen, K., Klumpp, J., Lavigne, R., Van Den Mooter, G., 2013. Feasibility of spray drying bacteriophages into respirable powders to combat pulmonary bacterial infections. Eur. J. Pharm. Biopharm. 84, 578-582. 

Exposure limits for siHcon carbide and powders of zirconium compounds (including zirconium dioxide) have been estabHshed by ACGIH. TLV—TWA s are 10 mg/m and 5 mg/m, respectively. OSHA guidelines for zirconium compounds call for a PEL of 5 mg/m. There are no exposure limits for siHcon nitride powder, but pmdent practice suggests a TLV—TWA of 0.1 mg/m. The soHd ceramics present no apparent health hazard. In machining such ceramics, however, care should be taken to prevent inhalation of respirable particles in amounts in excess of estabHshed limits. Disposal should be in approved landfills the materials are inert and should pose no danger to the environment. 

Mg(OH)2 powder is classified by OSHA as a nuisance dust. ACGIH categorizes the powder form as particulates not otherwise classified. Exposure limits are as follows (108) ACGIH 10 mg/m , OSHA 5 mg/m (respirable), and 15 mg/m (total). Magnesium hydroxide is reported in the EPA TSCA inventory (109). 

It is good practice to keep concentrations of airborne nickel in any chemical form as low as possible and certainly below the relevant standard. Local exhaust ventilation is the preferred method, particularly for powders, but personal respirator protection may be employed where necessary. In the United States, the Occupational Safety and Health Administration (OSHA) personal exposure limit (PEL) for all forms of nickel except nickel carbonyl is 1 mg/m. The ACGIH TLVs are respectively 1 mg/m for Ni metal, insoluble compounds, and fume and dust from nickel sulfide roasting, and 0.1 mg/m for soluble nickel compounds. The ACGIH is considering whether to lower the TLVs for all forms of nickel to 0.05 mg/m, based on nonmalignant respiratory effects in experimental animals. 

Potassium [7440-09-7] K, is the third, element ia the aLkaU metal series. The name designation for the element is derived from potash, a potassium mineral the symbol from the German name kalium, which comes from the Arabic qili, a plant. The ashes of these plants al qili) were the historical source of potash for preparing fertilisers (qv) or gun powder. Potassium ions, essential to plants and animals, play a key role in carbohydrate metaboHsm in plants. In animals, potassium ions promote glycolysis, Hpolysis, tissue respiration, and the synthesis of proteins (qv) and acetylcholine. Potassium ions are also beheved to function in regulating blood pressure. 

During machining operations, eye protection is recommended during grinding operations, NIOSH-approved respirators for metal fumes and dust are recommended (177). Fine powder of Co is known to cause dermatitis and pulmonary disorders in humans. Most manufacturers supply safety information with their products (178). These should be followed strictly for the welfare of the personnel on the shop floor. 

Quartz on filter media in a clay matrix is also available from NIST. The SRM 2679a is certified for quartz at three levels 30.8, 80.2 and 202.7 [xg/filter respectively. Respirable silica in powder form is also issued by NIST SRMs 1878a and 1879a are crystalline silica materials with particles in the respirable range and they are intended for use in X-ray diffraction and infrared spectroscopy. 

The molecular structure of arsphenamin is a typical representative of a thermotropic mesogen. With its symmetrical arrangement of the atoms the same holds for disodium cromoglycate, DNCG [20], which forms both thermotropic liquid crystals and lyotropic mesophases in the presence of water. Micronized DNCG powder applied to the mucosa of the nose or the bronchi absorbs water from the high relative humidity of the respiration tract and is first transformed into a lyotropic mesophase and then into a solution depending on the amount of water available. 

The stability of a suspension-emulsion of benzimidazole in oil was evaluated by quantifying the fractions of polymorphs A, B, and C as soon as prepared and after one year using a calibration model developed using pure polymorph samples [233]. The concentrations of mannitol in its amorphous form and each of three polymorphs were determined within 5% mass fraction, relative to salmon calcitonin [234]. The powders all were sized for delivery by respiration, less than 5 tan. 

R. Vehring, Red-excitation dispersive Raman spectroscopy is a snitable techniqne for solid-state analysis of respirable pharmaceutical powders, Appl. Spectrosc., 59, 286-292 (2005). 

Adhesive mixtures require large carrier crystals to improve the handhng properties of the powders. Dispersion of the small drng particles over the larger carrier material should assure dose uniformity. However, the small dmg particles shonld be removed from the carrier material dnring inhalation, to render an aerosol clond of respirable particles. If the particles remain on the carrier, month or throat deposition of the drng will occur, which might decrease therapeutic efficacy or cause serious side-effects. 

Petersson, G., and Wiren, J. E. (1980), The brochodilator response from inhaled terbu-taline is influenced by the mass of small particles A study on a dry powder inhaler (Turbuhaler), Eur. Respir. 2, 253-256. 

In an attempt to increase the amount of particles retained in the lungs, large porous particles with low density (p < 0.1 g/cm2) have been designed (Edwards et al. 1997). The particles were composed of 50% lactide and 50% glycolide. Porous and nonporous particles loaded with testosterone were aerosolized into a cascade impactor system from a dry powder inhaler (DPI) and the respirable fraction was measured. Nonporous particles (d = 3.5 pm, p = 0.8 g/cm3) exhibited a respirable fraction of 20.5 3.5%, whereas 50 + 10% of porous particles (d = 8.5 pm, p = 0.1 g/cm3) were respirable, even though the aerodynamic diameter of the two particle types were nearly identical. Porous particles as a consequence of their large size and low mass density can... 

Ganderton D. Generation of respirable clouds from coarse powder aggregates. J Biopharma Sci 1992 3 101-105. 

It is good practice to keep concentrations of airborne nickel in any chemical form as low as possible and certainly below the relevant standard. Local exhaust ventilation is the preferred method, particularly for powders, but personal respirator protection may be employed. 

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