《药剂学》课程双语教学方法建设的工作进展

Particle size and analysis
typical particle size of granules: 4- to 12- sieve Granules fall within the range of 12- to 20- sieve
are sometimes used in tablet making.
d1: density of the particle in g/ml d2: density of the liquid in g/ml g=gravitational constant=980.7 cm·sec-2
η＝the viscosity of the medium in poises, i.e., g·cm-1·sec-1 (poise) in cgs units
Chapter 3 Powders and granules
2007.1.14
Definition of powders
Connotation(涵义) 1, the physical form of a material a dry substance composed of finely divided particles The use of powdered substances in the preparation of other dosage forms is extensive. For example, a. tablets and capsules; b. liquid dosage forms (solutions or suspensions); c. ointments and creams.
d a v %1 r e 0 at0 s v ai i e z 2 n 1 .2 e 9 e 0 3 d 0 .0 2 29 m 2m 3
Angle of repose（休止角）
The angle of repose is a parameter used to estimate the flowability of a powder.
The purpose of particle size analysis in pharmacy is to obtain quantitative data on the size, size distribution, and shapes of drug and nondrug components to be used in pharmaceutical formulations
Incidentally, the water at 20 ℃ has a viscosity of approximately one centipoises (0.01 poise).
1 g·cm-1·sec-1 = 1 p = 100 cp =0.1Pa·s 1 cp =1 mPa·s
On micromeritics (微粒学,粉粒学)
chemical and pharmaceutical processing
The requirements for the material of solid dosage form
Mixing thoroughly Flowability Filling property
efficient production of a finished dosage form
The chemical and physical features of solid
materials used in the preparation of
pharmaceutical products
1. morphology (形态学) 2. purity (纯度) 3. solubility (溶解度) 4. stability (稳定性) 5. particle size (粒径) 6. uniformity (均一性) 7. compatibility (相容性) with any other formulation components
Particle size and analysis
Particle size can influence a variety of important factors:
• Dissolution rate (particle size↓→ surface area↑) • Suspendability(混悬性) (suspensions; 0.5-10 μm) • Uniform distribution to ensure dose-to-dose content
0.2 to 500 μm laser scattering 0.02 to 2000 μm photon correlation spectrum • Laser Holography 1.4 to 100 μm provide information of shape • Cascade impaction (级联撞击) A combination of the above methods and others is often preferred to provide greater assurance of size and shape parameters.
Particle size and analysis
Stokes’ law/relation 1
v22rd1d2gD 2d1d2g
9η
1η8
D
18v
d1 d2
g
2
v: velocity of the sedimentation in cm/sec
r: particle radius in cm
D: particle diameter in cm
Micromeritics is the science of small particles; a particle is any unit of matter having defined physical dimensions.
Micromeritics includes a number of characteristics including particle size, particle size distribution, particle shape, angle of repose(休止角), porosity(空隙 率), true volume(真实体积), bulk volume(总体积、松容积), apparent density(松密度) and bulkiness(膨松度) .
“nd”
750 1750 8550 15400 10400 ∑nd=36850
particle size
determined by sieving method
Seive number
20/40 40/60 60/80 80/100 100/120
Arithmetic mean opening (mm)
and ophthalmic(眼科) preparations; 50-100 μm)
Particle size and analysis
The methods used for the determination of particle size • Sieving 40 to 9500 μm • Microscopy 0.2 to 100 μm provide information of shape • Sedimentation rate 0.8 to 300 μm • Light energy diffraction or light scattering
uniformity (powders, granules and tablets) • Penetrability (inhalers; 1-5 μm, deposition deep in the
respiratory tract) • Nongrittiness(无砂砾感) (dermal ointments, creams,
A reduction in a powder’s particle size increases the number of particles and the powder’s total surface area.
particle size
determined by microscopic method
θ
h
tangenθt h r
r
Powders with low angles of repose will flow freely and powders with high angles of repose will flow poorly.
A number of factors, including shape and size, determine the flowability of powders. Shape: Spherical particles flow better than needles. Size: Very fine particles do not flow as freely as large particles.
Connotation 2, a type of pharmaceutical preparation a medicated powder intended for internal (i.e., oral powder) or external (i.e., topical powder) use The use of medicated powders per se in therapeutics is limited
size group of counted
particles/μm
40-60 60-80 80-100 100-120 120-140
Middle value μm “d”
Number of particles pergrou “n”5015
70
25
90
95
110
140
130
80
∑n=355
dav nnd3365855100.83
Definition of granules
Granules are prepared agglomerates of powdered materials, and may be used per se for the medicinal value of their content or they may be used for pharmaceutical purposes, as in tableting.
分法）, and is related to the proportion of powder that is capable of passing through the opening of standardized sieves of varying dimensions in a specified time period under shaking.
0.630 0.335 0.214 0.163 0.137
Weight retained (G)
15.5 25.8 48.3 15.6 3.5 108.7
% Retained
14.3 23.7 44.4 14.3 3.3 100.0
%Retained× Mean opening
9.009 7.939 9.502 2.330 0.452 29.232
and optimum therapeutic efficacy
Particle size and analysis
The particle size gradation in USP • Very coarse（最粗粉） • Coarse（粗粉） • Moderately coarse（中粉） • Fine（细粉） • Very fine（最细粉） This gradation system is based on sieving method（筛