Solid dosage forms Flashcards
What is an oral dosage form?
Medicinal products in the solid form to be administered in the mouth and absorbed by the GI system or oral cavity
What are tablets?
A solid preparation manufactured by compressing uniform volumes of particles which contain a single dose of one of more active ingredients and excipients.
What are capsules?
solid preperations with either hard or soft shell gelatine capsules containing a single dose of API
What classifications of powders?
size:
- >1000um = coarse
- >100<1000um = intermediate
- >5<100um = fine
- <5um = ultra fine
Shape:
- Spherical - good flow
- acicular - poor flow
Density:
More dense - heavier (better)
Less dense - lighter
What are light techniques used to measure particle size
- Microscopy: easy, multiple samples needed, only useful for particles visiable to naked eye
- SEM ot TEM (scanning/ transmission electron microscopy): ultrafine range of particles. Can observe surface texture
- Laser light difraction
- Proton correlation spectroscopy
What sieving techniques are used to determine particle size?
- Sieving: sample placed on top of stack of seives and aggitated. Smaller particles that sieve apeture pass through onto next mesh.
- Air jet sieving: Using pulses of air and vacuum to push and pull particles off and onto a screen. Particles which pas through are transferred onto a larger apeture screen and the process repeated.
- Inertial impacation: used for inhalation products
What alternaive methods can be used to measure particle size?
- Time of flight measurement: TIme of passage between 2 laser beams
- Electrical stream sensing zone method: Monitors charge of electricsl signal which occurs as a particle passes through an orfice
- Sedimentation method: Using stokes law and reynolds number to determine particle size based on time take to settle in a fluid of known viscosity
What is particle size analysis the equivalvent sphere?
Make an equivalent sphere if particle not spherical to measure it. Equivalent sphere of length and volume of particle
What are the 2 types of methods of powder sampling?
Dynamic: take proportion of sample when in motion (better). Take several samples at varrying times
Static: Take sample when product at rest
Important to take whole sample at one time
What is adhesion and what is cohesion?
Adhesion: 2 chemically disimilar materials stick together
Cohesion: 2 chemically similar materials stick together
What are examples of cohesive and adhesive forces?
- Van der Waals: decrease as particle size increases
- mechanical forces: When particles become interlocked due to shape and roughness
- Frictional forces: electrical forces caused by friction between particles
- Capillary forces: from adsorbed liquid on the surface of a particle
When will a powder flow?
When an external force is applied by will resist stressed below a limiting value.
Depends upon forces resisting flow e.g. adhesion/ cohesion and forces promoting flow e.g. gravity and applied stress
What techniques are used to measue powder flow?
- Angle of repsonse
- bulk density
- critical orfice diameter
(See powders and granulation for more depth)
Why are all medicines mixtures?
- Due to small quantities of the drug
Or
- Poor processing characteristics of the drug
Or
- Special characteristics requirements of the medicine
What does mixing and segregation mean?
Blending
Demixing
