Thiel Charles G
3M Drug Delivery Systems, St Paul, Minnesota 55144-1000, USA.
J Aerosol Med. 2002 Winter;15(4):369-78. doi: 10.1089/08942680260473443.
At present, cascade impactors are the instruments of choice for measuring the particle size distribution of aerosol present in the complex discharge from pharmaceutical inhalers. The distribution of drug captured in the cascade impactor may be most usefully represented by the lognormal distribution. Only two parameters must be extracted from the analysis of cascade impactor data in order to describe the distribution. These two parameters are the mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD). A cumulative version of the lognormal curve or more frequently, a linearized version of the cumulative curve called a "log probability plot," is used as a surrogate for the lognormal curve. The probability plot has great appeal since a lognormal distribution yields a straight line on log probability paper. One may easily determine the apparent MMAD and GSD from this linear plot. However, when one plots a lognormal curve, using the MMAD and GSD derived from a log probability plot, over a histogram constructed from cascade impactor data, an obvious mismatch is frequently seen. In order to derive parameters that more truly reflect the impactor data, a computer program, which uses nonlinear regression to derive an MMAD and GSD for the lognormal curve, has been written. It is presented here.
目前，多级冲击采样器是测量药物吸入器复杂排放物中气溶胶粒径分布的首选仪器。多级冲击采样器中捕获的药物分布最有用的表示方式可能是对数正态分布。为了描述这种分布，只需从多级冲击采样器数据分析中提取两个参数。这两个参数是质量中值空气动力学直径（MMAD）和几何标准差（GSD）。对数正态曲线的累积形式，或者更常见的是累积曲线的线性化形式，即所谓的“对数概率图”，被用作对数正态曲线的替代。概率图很有吸引力，因为对数正态分布在对数概率纸上会产生一条直线。人们可以很容易地从这个线性图中确定表观MMAD和GSD。然而，当人们使用从对数概率图得出的MMAD和GSD绘制对数正态曲线，并将其覆盖在由多级冲击采样器数据构建的直方图上时，经常会看到明显的不匹配。为了得出更能真实反映冲击采样器数据的参数，已经编写了一个计算机程序，该程序使用非线性回归来推导对数正态曲线的MMAD和GSD。在此展示该程序。
