Micomeritics Flashcards
(39 cards)
a decrease in particle size will…
increase the surface area per unit weight
Recall the reasons for studying Micromeritics?
- It affects dissolution rates
- In inhalation aerosols, particle size is critical to achieve maximum penetration and deposition into the deeper airways of the lungs.
- Drug particle size influences the content uniformity of low dose drugs in solid dosage forms such as tablets and capsules
- Suspensions can be adversely or constructively affected by reduction in particle size.
- Organoleptic properties such as color and the mechanical irritation of topicals applied to diseased or traumatized tissues is a function of particle size.
- Good flowability is essential to ensuring uniform feeding of formulations to high-speed tablet machines & capsule filling machines.
- In mixing, particles of the same size blend more easily & segregation of the particles by size is less of a problem
- With lubricants & glidants, the larger the surface area of the agent, the greater the coating effect and the more effective the agent is.
- In comparison, smaller particles can compact more closely, so the compact is harder and more dense because there are less voids or “air spaces”
since dissolution rate is a surface phenomenon, an increase in surface area will…
increase the dissolution rate
85% of particles >5 are
retained in the upper respiratory tract
90% of particles in the 1-5 range are…
retained in the alveolae
Particles <0.5 are…
exhaled
Particle size reduction…
increases the number of particles per gram
The greater the number of particles per dose the…
lower the variability between dosage units
Suspensions can be adversely or constructively affected by?
a reduction in particle size
How are suspensions constructively affected by a reduction in particle size?
Sedimentation is proportional to the (particle size)^2 ex. stokes law
&&
the large surface area of particles of finely-divided suspended insoluble or poorly soluble drug ensures a high availability for dissolution hence absorption
What is an adverse affect of suspensions being affected by a reduction in particle size?
caking
Organoleptic properties such as color and the mechanical irritation of topical applied to diseased or traumatized tissues is a function of
particle size
A common “rule of thumb” is that particles should pass through a ______ mesh sieve (44 micrometers) to minimize mechanical irritation
325
Good ________ is essential to ensuring uniform feeding of formulations to high-speed tablet machines and capsule filling machines.
flowability
smaller particles with higher “mean surface area per unit weight” do not flow as well as _______________.
larger particles
The ________ the “mean surface area per unit weight” the _____ dominant are surface interaction that interfere with flow.
greater, more
____________ shapes do not flow as well as ________, ________ shapes.
irregular, rounded, smooth
In mixing, particles of the ___________ blend more _______ and segregation of the particles by size is _______ of a problem.
same size, easily, less
Segregation means that __________ & __________ cause the smaller particles to descend in the mass
vibrations & handling
With lubricants and glidants, the _______ the surface area of the agent, the greater the coating effect and the more effective the agent is
larger
In comparison, the ________ particles can compact more closely, so the compact is _____ and more _______ because there are _________ voids or _________
smaller, harder,dense, less, air spaces.
What are the 2 classifications of Micromeritic Properties?
Fundamental & Derived
What are the fundamental basic properties (3)
Particle size, Particle shape, Particle surface area
What is derived from fundamental properties (6)
Porosity, Packing arrangements, Densities of particles, bulkiness, flow properties, compatability
