3rd meeting of young researchers at UP 1 - IJUP - Universidade do ...

Near infrared spectroscopy: a tool for diagnosing physical
properties of pharmaceutical powders
A. Cruz 1 , M. Sarraguça 1 , H. Amaral 2 , P. Costa 2 and J. Lopes 1
1 REQUIMTE, Serviço de Química-Física, Faculdade de Farmácia, Universidade do Porto, Portugal
2 Serviço de Tecnologia Farmacêutica, Faculdade de Farmácia, Universidade do Porto, Portugal
Pharmaceutical powders are described as heterogeneous systems with different physical and/or
chemical composition with a range of particle size between a few micrometers to about a
millimetre [1]. The powder flow behaviour is a key factor in a series of unit operations such as
blending, compression, filling, transportation, and in scale-up operations [2]. Flowing
properties of powdered solids depend strongly on their particle size and shape. Several
techniques have been used to determine particle size distribution depending on the level of
accuracy and precision to be reached [3]. Sieving is the simplest method to determine the
particle size distribution. Samples are processed through a series of sieves of variable sieve
opening sizes and the fraction of powder retained on each sieve recipient is weighted.
However, this method is time consuming and needs specific equipment. Near infrared (NIR)
spectra are affected by chemical and physical properties of powders, including particle size
distributions [3]. To establish the potential of near infrared spectroscopy (NIRS) to determine
the particle size distribution of pharmaceutical powders in a rapid and easy manner, blended
powders based on paracetamol as the pharmaceutical active ingredient (API) were produced
and analysed using the sieving method. Powders were also analysed by NIRS. The identified
particle size distribution was modelled from the NIR spectra using partial least squares (PLS)
and results were analysed in terms of figures of merit.
In a previous work, the flow properties angle of repose and bulk densities were successfully
estimated using NIRS [4]. In this work, the latter were modelled from the NIR spectra and
particle size distribution using PLS. The analysis of model results allowed the determination of
the relative importance of NIRS and particle size distribution for modelling the important
pharmaceutical physical properties angle of repose and bulk densities.
References:
[1] Navaneethan, C.V., Missaghi, S., and Fassihi, R., (2005), Application of Powder Rheometer to
Determine Powder Flow Properties and Lubrication Efficiency of Pharmaceutical Particulate Systems,
Aaps Pharmscitech, 6, article 49.
[2] Rasanen, E., Antikainen, O., and Yliruusi, J., (2003), A New Method to predict Flowability using a
Micro Fluid Bed, Aaps Pharmscitech, 4, 418-424.
[3] Blanco, M and Peguero, A.,(2008), An Expeditious Method for Determining Particle Size
Distribution by Near Infrared Spectroscopy: Comparison of PLS2 and ANN Models, Talanta, 77, 647-
651.
[4] Sarraguça, M., Cruz, A., Soares, S., Amaral, H., Costa, P., Lopes, J., Determination of Physical
Properties of Pharmaceutical Powders, (submitted).
3 rd meeting of young researchers at UP 351