MicromeriticsFrom Wikipedia, the free encyclopedia Jump to: navigation, search This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. The talk page may contain suggestions. (September 2007) Micromeritics is the science and technology of small particles. The knowledge and control of the size of particles is of importance in pharmacy and materials science. The size, and hence the surface area of a particle, can be related to the physical, chemical and pharmacologic properties of drugs. Clinically, the particle size of a drug can affect its release from dosage forms that are administered orally, parenterally, rectally and topically. The successful formulation of suspensions, emulsions and tablets; both physical stability and pharmacologic response also depends on the particle size achieved in the product.[1][2][3][4] Contents [hide] • • 1 Origin 2 Applications ○ ○ ○ ○ 2.1 Release and dissolution 2.2 Absorption and drug action 2.3 Physical stability 2.4 Dose uniformity • 3 References [edit] Origin The term was created by J. M. DallaValle in his book Micromeritics: the technology of fine particles. It was derived from the Greek word for small and part. The size range which he covered in the book was from 10−1 to 105 micrometers. Anything smaller than this but bigger than a molecule were referred to at the time as colloids but are now often referred to as nanoparticles. Applications included soil physics, mineral physics, chemical engineering, geology, and hydrology. Characteristics discussed included particle size and shape, packing, electrical, optical, chemical and surface science.[5] [edit] Applications [edit] Release and dissolution Particle size and surface area influence the release of a drug from a dosage form that is administered orally, rectally parenterally and topically. Higher surface area brings about intimate contact of the drug with the dissolution fluids in vivo and increases the drug solubility and dissolution. [edit] Absorption and drug action pp.Particle size and surface area influence the drug absorption and subsequently the therapeutic action.com/Library. Ga: Micromeritics Instrument Corp. ^ Carstensen. faster the absorption and hence quicker and greater the drug action. ^ Martin. Dekker. ISBN 096567830x. The distribution of particles should be uniform in terms of number and weight. ISBN 0-8247-9372-2. Pa: Technomic Pub. Martin's physical pharmacy and pharmaceutical sciences: physical chemical and biopharmaceutical principles in the pharmaceutical sciences. better the physical stability of the dosage form owing to the Brownian motion of the particles in the dispersion.e. Jens Thurø (1993). (1995). 533–560. (1997). 4. New York: Pitman publishing Micromeretics The science and technology of small particles is called micromeretics. p. The smallest particles are found in Colloids while the largest particles of interest to the pharmaceutical industry are those used in making tablets and capsules. Norcross.. . Paul W. ^ Brittain. 3. Pharmaceutical principles of solid dosage forms. H. the particle size in a formulation. Clyde. J. Physical characterization of pharmaceutical solids. influence the physical stability of the suspensions and emulsions. Micromeritics: the technology of fine particles. ^ Dallavalle. [edit] Dose uniformity Good flow properties of granules and powders are important in the manufacturing of tablets and capsules. Smaller the size of the particle. M. New York: M.aspx. Webb. G. http://micromeritics. Phila: Lippincott Williams and Wilkins. Alfred N. ^ Orr. Patrick J Sinko (2006). 2. (1943). Analytical methods in fine particle technology. ISBN 0-87762-955-2. 211. [edit] Physical stability Micromeritic properties of a particle. p. [edit] References 1. ISBN 078175027X. Lancaster. i. The table below gives some indication as to the relationship between particle size and examples of which products might contain that size particle. (Ansel page 167) Particles of different size behave differently and are evaluated differently. 5. 254. Higher the dissolution. and f is a frequency index.data from microscopic measurements Sn M N n n . Statistical Diameters pC fS T F 1U 0 A L N 2A 0 A S N 3A 0 A V N 1O 1 A L L 1I 2 A L S 1S 3 A L W Calculation of Statistical Diameters .) I have also included a second table with an example of some data collected on a sample of powder.In the area of tablet and capsule manufacture control of the particle size and the nature of the distribution of particle size in the mixture is essential if we wish to achieve the necessary flow properties and mixing characteristics. or harmonic mean diameter. Edmundson has derived a general equation for the average particle size whether it be an arithmetic. p is an index related to the size of the particle. Too many small particles will not allow the powder to mix well or flow through the tablet and capsule manufacturing equipment. d = {(SUMndp+f)/(SUMndf)}1/p Where n is the number of particles in a size range. (The pharmaceutical uses of each of the possible values of "p" and "f" in different situations are also included in the table below. Particle Size Determination Rarely do we have a powder that is not a collection of particles of different sizes. d is the average diameter of the particles in that range. Please remember that when we discuss a pharmaceutical powder it is normally a mixture of chemicals ( the active drug and excipients) not just a pure chemical. It is therefore important to know both the average particle size and shape and the distribution of the particle size range in the powder. geometric. Angle of repose . d = SquareRoot {[18Viscosity h]/[(rho .2 .This uses a modification of stokes law.Andreasen Apparatus .True and Apparent .rho)gt]} Other properties of powders that are important Porosity .1 1 0 11 1 1 1 11 1 2 3 6 26 2 5 1 2 23 2 1 4 1 32 3 8 2 8 32 3 5 1 7 S1 1 2 6 Edmondson value for p = 1 and f = 2 is 2.Elastic vs plastic deformation . As long as each subsequent sample of the powder is evaluated in the same way we can make predictions as to its performance in the equipment and in use.How do we measure it?? Compressability .what is the difference?? Flowability .. All have some uses but none are perfect.why is this information useful?? Density .57 There are several other methods for evaluating the powder sample based on its particle size distribution.which one is needed in tablet manufacture?? Top of Form . Methods for determining Particle Size Optical Microscope Sieving Sedimentation . Stability: Some drugs are more stable in dry powder form and their activity is reduced in solution form. The merits and demerits of fine particles as dosage forms are given below: Advantages of fine powder as dosage form: 1. Flexibility or activity: In powder form.partner-pub-14214 ISO-8859-1 Search jeepakistan. all quantity of a drug becomes active but in tablet or capsule form all quantity of drug is not active and small quantity is excreted out as inactive drug for example. . in powder form if we take 100 mg drug then all of 100 mg will be active while in 500 mg tablet 350 or 400 mg drug will be activated and remaining will be excreted out. 2. 2010 Micromeritics Micromeritics is the study of finer particles which are smaller in size. drugs in powder form are completely hydrolyzed where as in tablets form it may be possibility that no total drug is hydrolyzed. Rapid therapeutic effect: The effect of a tablet or capsule is given below: If drug is already available in powder form then it is rapidly absorbed and show rapid therapeutic effect than tablets. Ease of administration: In powder form smaller surface area of drug particles can be easily administered but in tablets form there is a difficulty to swallow it. April 29. 3.blogsp Bottom of Form Thursday. Moreover. 4. Prevention due to acidity: Some drugs become inactive due to acidity in stomach pH. These are used mostly on small scale. So we take them in enteric coating to prevent from acidity instead of taking in powder form. Efflorescent. Mechanical size reduction Manual size reduction: It can be done by one of the following methods or their combination.Disadvantages of fine powder as dosage form: 1. 1. This method is used for those materials which are elastic in nature. There are various methods of size reduction. 2. Compression: By applying pressure larger molecules can be broken down into smaller pieces. 1. so we take them in tablets or in capsule forms for preventing them. deliquescent or hygroscopic in nature and we can not use them in powder form. Their bitter taste is masked by coating. 2. Cutting: In this method. 3. Manual Size reduction 2. Bitter in taste: Some drugs are bitter in taste and we take them in tablet or in capsule form instead of powder form. Comminution: It is a process by which we can reduce the size of a substance. sharp blades or knives are used to cut a material into small particles. Deliquescent and hygroscopic: Some drugs become efflorescent. . 3. 6. In this you will get fine paste. After mixing. spatula and glass slabs are used. If we hit large particle with heavy mass or hit heavy mass with stationary large particle. ether. 5. Pulverization by intervention: In this method. Trituration is also used for mixing of two or more substances. large particles are broken by heavy mass. Substances are used: oil. it can be powdered easily and these substances evaporate. Impaction: In this method. chloroform. This process is often used to incorporate the solid substances into dermatological and ophthalmic preparations. levigation continue for this purpose. mortar and pestle. solid substance is reduced to a fine powder by means of triturating the solid with a suitable solvent which is easily removed at the end for example camphor is difficult to reduce in size because as it reduces in size. large particles are crushed down into small pieces between two opposite moving surfaces. 4. In this size of substance is reduced to finer state by triturating the substance with few drops of liquid in which it is insoluble. Here different types of mortar and pestles can be used. Attrition: In this method. It cohere with each other but when few drops of alcohol. Trituration: Grinding of solid into powder is done by continuous stirring or rubbing the particle in mortar with pestle. 7. water. glycerine and alcohol. Mechanical method: . Levigation: It is also called as wet grinding. the large particle is broken into pieces. different sieves are arranged together. . when material is put over the sieves and sieves are shaken. colloidal mill etc. we can get 50-5000micrometer.On large scale. In this method. As different mills are used to reduce the particle size hence it is also known as milling. 4. Fine: All particles pass through sieve number 60 and not more than 40% through sieve number 80. 2. Moderately coarse: All particles pass through sieve number 40 and not more than 40% pass through sieve number 80. Various mills are ball mill. We get finest powder at the last while the remaining material is present in above sieves which entrap them according to size of their holes. Very coarse: All particles pass through sieve number 8 and not more than 20% through sieve number 60. size reduction is carried out mostly by using different kinds of mills which have capacity of producing powder of wide range of particle size. Coarse: All particles pass through sieve number 20 and not more than 40% through sieve number 60. Grading of powders: 1. Seiving method: This is the most common applicable method. Methods used to determine the size: The following methods are used to determine the size of particles and to separate them: 1. 3. By this method. So in this way size of powder is determined. 5. Very fine: All particles pass through sieve number 80 and there is no limit for greater finest. hammer mill. 8. Elutriation method: This method is used for the separation of different sized particles of the powder. In case of suspension.2. The advantage of this method is that we can measure the size of particle directly. very small particles result in formation of cake and very large particles settles quickly but we should have to form loose cake because it redisperse upon shaking. Stability of some drugs increase in powder form and decrease in solution form. which helps in solution formation and bioavailability increases. 4.e. Multiple Choice Questions (MCQs) from Micromeritics in Pharmaceutics . 3. By microscopy: We can measure the size of particles of powder by microscope. Rate of drying is enhanced. larger sedimented particles are taken out by the tube from the bottom and remaining are the fine particles. The particles whose size ranges from 1-25 micron can be measured under microscope. Mixing is easier and uniform. Powdered drugs are easily administered than solid dosage forms. The apparatus used in this method is called as Andreasen apparatus. Stability of emulsion is increased by decreasing the size of globules. The larger particles settle down rapidly while smaller particles take sometime to settle down. 9. if particle size is reduced. 4. When a prepared slide of material is examined under microscope then the microscope has a micrometer by which we can determine the size of particles. 2. 7. So. Size reduction increases the surface area of drugs. How much time is taken to settle down the particles of powder from dispersion medium. Importance of particle size in pharmacy: 1. paste and creams can be improved. 3. 6. 5. Physical appearance of ointments. Rate of absorption will be greater when the particle size is small. Sedimentation method: This method is based on sedimentation time i. Which is smallest.1. Particle size can be reduced by. (a) Micrometer (b) Millimeter (c) Nanometer . Particle size. Sedimentation rate can be decreased by …………. (a) Mortar and pestle (b) Sieve (c) Grinder (d) Both a and c --------------4. Increase the particle size increase will be.. Is the science and technology of small particles. (a)Absorption (b) Distribution (c) Both a and b (d) None of above ----------------3. ……………. (a) Increase (b) Decrease (c) Unchanged (d) None of above ------------------5. (a) Nanotechnology (b) Micromeritics (c) Molecular Chemistry (d) None of above -----------------2. 4. 2. 5. 3. Micromeritics. Nanometer --------------Further Reading: Micromeritics. DOSAGE FORM PHARMACEUTICS. None of above. Decrease.(d) Catharometer -----------------Answers to Multiple Choice Questions (MCQs) from Micromeritics in Pharmaceutics 1. Both a and c. PHARMACEUTICS POSTED BY JEEPAKISTAN AT 12:40 AM .: The technology of fine particles Tutorial Pharmacy Textbook of Pharmaceutics Remington: The Science and Practice of Pharmacy (Remington the Science and Practice of Pharmacy) British Pharmacopoeia 2010 USP NF 2009 (United States Pharmacopeia/National Formulary) LABELS: DISPENSING.