Micromeritics
{{Short description|Science and technology of small particles}}
Micromeritics is the science of the behavior of particulate materials smaller than 75 μm.{{Cite journal |last=Singh |first=Amarjit |last2=Dhami |first2=Harish Singh |last3=Sinha |first3=Manoj Kumar |last4=Kumar |first4=Ravi |date=2022 |title=Evaluation and comparison of mineralogical, micromeritics and rheological properties of waste machining chips, coal fly ash particulates with metal and ceramic powders |url=https://linkinghub.elsevier.com/retrieve/pii/S0032591022005848 |journal=Powder Technology |language=en |volume=408 |pages=117696 |doi=10.1016/j.powtec.2022.117696|url-access=subscription }} It is thus the study of the fundamental and derived properties of individual as well as a collection of particles. Micromeritics involves materials with larger particles than nanoparticles where they are smaller than 0.1 μm.
The knowledge and control of the size of particles has importance in pharmacy and materials science. The size, and hence the surface area of a particle, can be related to the physical, chemical and pharmacological 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 pharmacological response also depends on the particle size achieved in the product.{{cite book |author=Brittain |first=H. G. |title=Physical characterization of pharmaceutical solids |journal=Pharmaceutical Research |publisher=M. Dekker |year=1995 |isbn=0-8247-9372-2 |volume=08 |location=New York |pages=963–73 |doi=10.1023/a:1015888520352 |pmid=1924166 |issue=8 |s2cid=38179603}}{{cite book |author=Carstensen, Jens Thurø |title=Pharmaceutical principles of solid dosage forms |url=https://archive.org/details/pharmaceuticalpr0000cars |url-access=registration |publisher=Technomic Pub |location=Lancaster, Pa |year=1993 |page=[https://archive.org/details/pharmaceuticalpr0000cars/page/211 211] |isbn=0-87762-955-2}}{{cite book |author1=Martin |first=Alfred N. |title=Martin's physical pharmacy and pharmaceutical sciences: physical chemical and biopharmaceutical principles in the pharmaceutical sciences |author2=Sinko |first2=Patrick J. |date= |publisher=Lippincott Williams and Wilkins |year=2006 |isbn=0-7817-5027-X |location=Phila |pages=533–560}}{{cite book |author=Orr |first=Clyde |url=http://micromeritics.com/Library.aspx |title=Analytical methods in fine particle technology |author2=Webb |first2=Paul W. |publisher=Micromeritics Instrument Corp |year=1997 |isbn=0-9656783-0-X |location=Norcross, Ga}}
Origin
The term was coined by Joseph Marius DallaValle in his book Micromeritics: The Technology of Fine Particles (1948).{{Cite book |last1=Valle |first1=Joseph Marius Dalla |url=https://books.google.com/books?id=lQAhAAAAMAAJ |title=Micromeritics: The Technology of Fine Particles |date=1948 |publisher=Pitman Publishing Corporation |isbn=9780598902719 |oclc=1016195333}} It was derived from the Greek words {{langx|el|μικρο|micro}} meaning "small" and {{langx|el|μέρος|méros}} meaning "part".{{Cite web |title=Definition of MICROMERITICS |url=https://www.merriam-webster.com/dictionary/micromeritics#:~:text=etymology,ics |access-date=2023-01-15 |website=www.merriam-webster.com |language=en}} The size range which he covered in the book was from 100 nm to 100 mm. Anything smaller than this but bigger than a molecule was referred to at the time as a colloid but is now often referred to as a nanoparticle.
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.
Applications
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=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.
=Absorption and drug action=
Particle size and surface area influence the drug absorption and subsequently the therapeutic action. The higher the dissolution, the faster the absorption and hence the quicker and greater the drug action.
=Physical stability=
Micromeritic properties of a particle, i.e. the particle size in a formulation, influence the physical stability of the suspensions and emulsions. The smaller the size of the particle, the better the physical stability of the dosage form owing to the Brownian motion of the particles in the dispersion.