Pharmaceutical biotechnology II Flashcards
1
Q
What is micromeritirics?
A
Micromeritics is the science and technology of small
particles.
Micromeritics deals with a number of characteristics including
particle size, the size ranges of particles (size distribution), particle
shape, flowability, true volume, bulk volume.
2
Q
Why is particle size important?
A
-Affects the drug’s release
-affects the flows and thus packing properties
-affects the rate of dissolution
3
Q
What is polydisperse
A
particles having a range of sizes
4
Q
Why is higher surface of particles important?
A
A higher surface area allows intimate contact of the drug with the dissolution fluids and increases the drug solubility and
dissolution.
higher the dissolution, the faster is the absorption.
* The smaller the size of the particle, the better is the physical stability of the dosage form.
5
Q
Name the ‘diameters’
A
➢Surface diameter, which is the diameter of a sphere having the same surface
area as the asymmetric particles.
➢Volume diameter, which is the diameter of a sphere having the same volume
as the asymmetric particles.
➢Projected diameter, which is the projected diameter of a sphere having the same observed area as the particle under microscope.
➢Stokes diameter, which is the diameter describing an equivalent sphere undergoing sedimentation at the same rate as the asymmetric particle.
6
Q
Why is it important to determine the flow properties of particles?
A
Powders with different particle sizes have different flows and packing
properties which alter the volumes of powder during each encapsulation or tablet compression.
7
Q
What are the methods used for determining particle size?
A
- Microscopy
- Sieving
- Sedimentation technique
4.Laser light scattering techniques
8
Q
What are the advantages using microscopy to determine particle size?
A
- Each particle is individually examined
- with visualised record
- particle shape can be observed
9
Q
What are the disadvantages using microscopy to determine particle size?
A
- time-consuming
- Equipment cost (EM is expensive)
9
Q
What types of microscopy is used to determine the size of particles and what is the range?
A
- Optical microscopy (0.2-100um)
- Electron microscopy (0.001-5000um)
10
Q
What is the size range for sieving technique?
A
5um - 9mm
11
Q
What are the advantages of sieving to determine particle size?
A
- Easy
- Wide size range
- Inexpensive
12
Q
What are the disadvantages of sieving to determine particle size?
A
- does not provide a high resolution for a sample with narrow size range
- damage in use and cleaning
- elongated and flat particles do not yield reliable results?
13
Q
Describe sedimentation technique to determine size range of particles
A
This method depends on the fact that
the terminal velocity of a particle in a
fluid increases with size.
14
Q
What is the size range for sedimentation technique?
A
0.8-300um
15
Q
State the advantages of using sedimentation technique to determine particle sizes
A
- inexpensive and simple
- accuracy and reproducibility
16
Q
State the disadvantages of using sedimentation technique to determine particle sizes
A
- particles must be completely insoluble
- Must be carried out at low concentrations
- Particle re-aggregation
17
Q
Describe the technique of laser light scattering for determining particle sizes
A
Particles pass through a laser beam and the light scattered by them is collected over a range of angles in the forward direction.
There must be a difference in refractive index
between particles
18
Q
What is the particle size range for laser light scattering technique?
A
10nm - 2000um
19
Q
State the advantages of using laser light scattering technique to determine particle size
A
- fast
- easy to use
- precise and wide range
20
Q
State the disadvantages of using laser light scattering technique to determine particle size
A
- expensive
- Volume measurement, assuming spherical
particles - There must be a difference in refractive index
between particles
21
Q
What is true density and bulk density?
A
True density: the density of a sample which excludes the volume of the pores and voids within the powder sample
Bulk density: the density value which includes the volume of all the pores and voids within the powder sample.
22
Q
What indexes are used to measure flowability of a powder?
A
- Carr’s index (Carr’s compressibility index )
- Hausner ratio
- Angle of repose
23
Q
The better fluidity of a product, the _______________________________________________ .
A
easier it is to spread smoothly and tightly, and thereby obtain a high-quality product.
24
What is the angle of repose dependent on?
Angle of repose is a characteristic related to inter particulate friction or resistance to movement
between particles. When the grains are smooth and rounded, the angle of repose is low. For very
fine and sticky materials the angle of repose is high. Powders with a steep angle of repose may
flow poorly, leading to problems in manufacturing processes such as blending, tablet compression,
and capsule filling.
25
Name the types of oral solid dosage froms
a) Powders & Granules
b) Tablets
c) Capsules
d) Lozenges
26
What kind of dosage forms is powder used in?
tablet, capsules, suspension, cream, ointments
27
What are granules?
Granules are defined as a dosage form composed of dry aggregates of powder particles that may contain one or more APIs, with or without excipients.
28
What methods are used to prepare granules?
1. wet granulation
2. dry granulation
29
Describe the process of wet granulation
1. weighing and blending the ingredients
2. add liquid binder to facilitate adhesion of powder particles
3. Screen damp mass into pellets and granules
4. size the granulation by dry screening.
30
Describe granulation
Granulation is a process by which primary powder particle adhere to form large multi particulate entities called GRANULES
31
What is dry granulation?
Dry granulation converts primary powder particles into granules using the application of pressure without the intermediate use of a liquid.
-avoids heat temperature
32
What are the 2 pieces of equipment necessary for dry granulation?
1. compressing machine
2. milling machine
33
Name the compressing methods
slugging and roller compaction
34
Describe disintegration and dissolution.
Disintegration: the physical process by which a tablet breaks down into fine
particles
Dissolution : the process by which the active ingredient is dissolved in a liquid
35
What properties should tablets possess?
*Should have elegant product identity while being free of defects like chips, cracks, discoloration, and
contamination
* Should have sufficient strength to withstand
mechanical shock during its production packaging,
shipping and dispensing
* Should have the chemical and physical stability to maintain its attributes over time
* The tablet must be able to release the medicinal agents in a predictable and reproducible manner
36
What are the advantages of using tablets as a form of dosage?
* Suitable for large scale production
* Large scale production at lowest cost
* Easy and cheap to package and ship
* Easy to handle
* Light and compact
* Dose precision & least content variability
* Greatest chemical and microbial stability over all oral dosage forms
* Product identification is easy and rapid
37
What are the disadvantages of tablets as a form of dosage?
-Drugs with poor wetting and slow dissolution properties may be difficult to formulate as a table
-Some drugs are difficult to compress
-Difficult to swallow in case of children and unconscious patients
-Drugs with bitter taste, with strong odour, or are sensitive to oxidation may require
encapsulation or coating
38
What are the tablets that could be used for oral cavity as opposed to oral ingestion?
1. Buccal tablet
2. Lozenges
3. sublingual tablet
39
What are compressed tablets and what are the pros of it?
- standard uncoated tablets. The manufacturing process involves compression of granules or powder
* Designed to provide rapid disintegration and hence rapid drug release
40
What are sugar coated tablets?
Conventional tablets that have been coated with a concentrated sugar solution
41
Why are tablets sugar coated?
Primary goal: to produce an elegant and glossy appearance, as well as to mask the bitter taste
42
What are film-coated tablets?
Conventional tablets coated with a layer of polymer or polymer mixture
43
What are the primary functions of film-coated tablets?
– Improve the appearance of conventional tablets
– Control the rate of drug release in certain regions of gastrointestinal tract
44
What are the two types of polymer coating used for film-coated tablets?
* Polymer coating could be easily dissolved in the stomach to allow rapid disintegration and dissolution e.g. hydroxypropyl cellulose
* Polymer coating could be insoluble in the gastrointestinal tract to allow slow diffusion of drug e.g ethylcellulose
45
What polymers should be used in film coated tablets to allow rapid disintegration and dissolution?
-hydroxypropylcellulose
-hydroxypropylmethylcellulose
-Eudragit 100
46
What polymers should be used in film coated tablets to allow slow disintegration and dissolution?
-hydroxyethylcellulose
-Eudragit RS and RL
47
Why is film coating better than sugar coating?
- better mechanical strength and flexibility
-film coating causes little increase in tablet weight
48
What kind of drugs are not suitable for chewable tablets?
foul tasting or bitter drugs
49
When and what are chewable tablets used for?
- for people who have difficulty in swallowing
- large tablet antacids, in which the efficacy depends on particle size
-calcium tablets when intended as phosphate binder
50
What are effervescent tablets?
Designed to disintegrate rapidly when added to aqueous solution, producing a solution or suspension.The rapid disintegration is due to chemical interaction between two compartments
51
State the 'mechanism' of effervescent tablets?
sodium bicarbonate and an organic acid,
typically citric or tartaric acid. When these are solids they will not react with each other but when they dissolve in water they will and carbon dioxide is evolved.
52
State the pro and con of effervescent tablets
pro:
-CO2 facilitates rapid disintegration
-more rapid absorption than conventional tablets
cons:
-may be sensitive to environmental moisture
53
What are multiple compressed tablets?
Usually composed of ≥2 layers
54
Why are multiple compressed tablets used?
1. to separate physically and chemically incompatible ingredients
2. to produce product with repeated action or prolonged action.
55
What are the two types of multiple compressed tablets?
1. multiple-layered (2 or 3 layered)
2. compressed coated (tablet within a tablet)
56
Explain the difference between buccal and sublingual tablets
Buccal tablets: placed between cheek and gum (gingiva)
Sublingual tablet: placed under the tongue
57
What characteristic shall buccal or sublingual tablets have?
shall not stimulate oral mucosa
58
State the advantages of buccal/sublingual tablets
- bypass first pass metabolism
- quick absorption
- quick termination if necessary
- economical
- can be self administered
59
State the disadvantages of buccal/sublingual tablets
- not given in large quantity
- irritate oral mucosa
- bitter taste
-few drugs are absorbed
60
Describe lozenges
* Intended to disintegrate or dissolve slowly in the mouth
* They are harder than ordinary tablets so they will slowly dissolve or disintegrate
* Contains one or more medicaments usually in a flavored, sweetened base
61
What are lozenges often used for?
for localised effects in the mouth
62
What are modified release tablets?
Modified-release drug product is used to describe products that alter the timing
and/or the rate of release of the drug substance.
63
What are modified release drugs also called?
- prolonged-release
- sustained release (SR)
- extended release (EL)
- extended release (EX)
- controlled release (CR
64
Modified release (MR)
Prolonged release
Sustained release (SR)
Extended release (EX)
Extended release (EL)
Controlled release (CR
are used for?
Releases its active ingredient in specified
doses to release the drug slowly over a
prolonged period of time
65
How do 'delayed release' drugs/tablets work?
exhibits a lag time in drug release after administration
66
What is a extended-release drug?
Extended-release drug = able to maintain therapeutic blood levels of a drug for a
prolonged period
67
State some advantages of modified release tablets?
- lower health care costs
- enhanced convenience
- total amount of dose is decreased
- reduced side effects
68
What are the disadvantages of modified release tablets?
- need for additional patient education
- higher development costs
- possibility of dose dumping
- retrieval of drug is difficult
-accurate dose adjustment is difficult
69
What are some common factors in GI tract that affect drug release of extended-release tablets?
➢ The rate of GI transit / gastric emptying
➢ Variation in GI pH
➢ Blood flow in GI tract
➢ Presence of food in the GI tract
➢ Presence of enzymes and bacteria in the GI tract
70
What are the 3 types of technologies that are used in modified release tablet?
- Hydrophilic matrix system
- membrane controlled system
-osmotic delivery system
71
Describe the hydrophilic matrix system
- The drug is mixed with a water-swellable, hydrophilic polymer (with some other excipients) and compressed into a tablet.
* On exposure to fluid, the polymer material in the table starts to swell,
producing a gel matrix.
* The gel can allow drug release by dissolution of the gel and the drug trapped within it.
72
Describe membrane controlled system
* Drug is concentrated in the core, and must traverse a polymeric membrane or film.
* Drug release through a
membrane is controlled by the thickness and the porosity of the membrane.
73
What factors affect drug release rate of membrane-controlled system?
-membrane thickness
-membrane porosity
-chemical nature of the drug and excipients
-chemical nature of the membrane material
74
What factors affect the drug release rate of hydrophilic matrix system?
-polymer properties
-diffusivity of deug in matrix
-nature of drug and excipients
-geometry
75
Describe osmotic delivery system (elementary osmotic pump)
* Drug is mixed with water-soluble core material
* Core surrounded by water-insoluble semi-
permeable polymer membrane, in which there
is a small laser-drilled orifice
* Water diffuses into core through outer
membrane to form concentrated solution
inside
* Osmotic gradient established across semi-
permeable membrane and drug is pushed out
of hole
* Release rate tailored by modifying excipients
76
In osmotic delivery systems, release rate is tailored by _________________________.
modifying excipients
77
Describe the process by which drugs are released in osmotic delivery systems (push-pull osmotic pump)
* When the tablet enters the GI fluid, the osmotic agent “pulls” water into the
osmotic pump via the semipermeable membrane
* Osmotic pressure is generated by the osmotic agent
* The increased osmotic pressure “pushes” against the drug layer.
* The drug is released from the tablet through the delivery orifice.
78
Name a type of tablet that is used in delayed release system
enteric-coated tablet
79
Describe the mechanism of enteric-coated tablet
Enteric-coated tablets (e/c tablet) remain intact in the stomach and disintegrates quickly in the intestine.
80
enteric-coated tablets are good for when:
➢ The stomach mucosa need to be protected from the drug
➢ The drug is sensitive to the stomach and need to be protected
81
What are some common tablet defects?
Capping, lamination, cracking, chipping, pitting, picking, binding and mottling
82
What types of drugs can contained in a capsule?
powders, tablets, semisolids and nonaqueous liquid (i.e. NO water!!!)
83
What is the major componenet of the capsule shell?
gelatin
84
What are the 2 types of capsules?
- hard capsule
- soft capsule
85
What is gelatin?
- protein that is extracted from animal collagen
- derived from animal skins, fibrous tissues and/or bovine bones
86
What are the advantages of a capsule?
-mask the taste and odour of unpleasant drugs
-sliippery when moist --> easy to swallow
-capsule shells are inert, easily digested by GI tract
-economical
-easy to handle and carry
-shell can be colored to give protection from light
87
What are the disadvantages of a capsule?
- require specialised manufacturing equipment
-staility problems associated with capsules containing liquid fills
-problems regarding the homogeneity of fill weight
88
Describe hard capsules
-less flexible
- composed of 2 pieces: capsule and the body
89
What are hard capsules composed of?
capsule (cap) and the body
90
Describe the hand filling (manual) process of hard capsule
1.Calculate
2.Weigh components
3.Mix and blend
4.Block powder
5.“Punch” or “Scoop”
6.Weigh for accuracy
7.Secure and lock cap
8.Polish
91
What are the coatings used on hard capsules to prevent them from dissolving in acid?
Enteric coatings, which are polymers
92
What is microencapsulation (hard capsules)>
Microencapsulation=protective coating called a matrix around a small particle called the core or
active.
93
What dosage form types could be encapsulated in capsules?
1. powder and granulate
2. pellet mixture
3. paste
4. capsule
5. tablet
94
Why is plasticizer used in soft capsules?
for flexible capsule
95
What is added to gelatin of soft capsules to make the capsule more flexible?
Plasticizer (glycerin or polyhydric alcohol)
96
What is the advantage of soft capsule of hard capsule?
better rate of dissolution
97
What is commonly used as fill material in soft capsules?
lipophilic liquids (vegetable oil and fatty acid esters)
98
Why are surfectants added to fill materials of soft capsules?
1.Enhance solubility of drug during manufacturing
2.Assist in emulsification of drug upon ingestion
99
What is the one substance that is never used to fill soft capsules? Why?
Water is NOT used as a fill material as water would decrease the physical stability of soft capsule
100
Name the 2 types of expedients used in soft capsules and theri usage
Plasticizers (glycerin or polyhydric alcohol) in gelatin to make felxible capsule
Surfectants in fill materials to enhance solubility of drug during drug manufacturing and to assist in emulsification of drug upon ingestion
