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Dosage - Exam 3 > Lecture 17 > Flashcards

Lecture 17 Flashcards

Pharmaceutical Polymers - Yeo

1
Q

nitrocellulose

A

gun cotton, 1845
the first semisynthetic polymer
discovered by Christina Schonbein in Basel, Switzerland in his kitchen

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2
Q

Bakelite

A

1907
first synthetic polymer based on phenol and formaldehyde
discovered by Leo Baekeland
strong and durable
substitute for parts in auto and electric industries

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3
Q

history of polymers

A

polyethylene (1933) –> Polyvinyl chloride (1933) –> Polystyrene (1933) –> Polyamide (1935) –> Teflon (1938) –> Synthetic Rubbers (1942)

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4
Q

polyethylene

A

discovered in 1933
used to insulate radar equipment for airplanes

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5
Q

polyamide

A

discovered in 1935
nylon (wallace carothers at DuPont) to replace silk
used in parachutes

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6
Q

teflon

A

discovered in 1938
used in atomic bombs to isolate hot isotopes of uranium

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7
Q

synthetic rubbers

A

discovered in 1942
1h to synthesize (7 years of natural rubbers)
used for tires and military supplies

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8
Q

polymers in pharmaceutical and biomedical products

A

controlled drug delivery
scaffolds for tissue engineering
oral drug delivery
transdermal patches

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9
Q

oral drug delivery types

A

coating
binders
taste maskers
protective agents

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10
Q

polymer

A

a large molecule made up of many small repeating units (parts)

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11
Q

macromolecules

A

any large molecule
not necessarily those made of repeating units
polymers are subsets

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12
Q

plastics

A

plastic materials that can be molded, cast, extruded, drawn, thermoformed, or laminated into a product

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13
Q

natural polymer examples

A

nucleic acids (DNA,RNA)
proteins (gelatin)
polysaccharides (cellulose, chitosan, alginic acid)

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14
Q

synthetic polymer examples

A

polyethylene
poly(vinyl chloride)
poly(tetrafluoro ethylene) aka teflon
polyurethane
polyacrylate
poly(p-phenylene terephthalamide) aka Kevlar
nylon
silicon rubber
rayon

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15
Q

polymer naming

A

in repeating units
poly(repeating unit)

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16
Q

types of structures

A

homopolymer (all the same)
random copolymer (random insert of different type)
alterante copolymer (every other type)
block copolymer (type 1 then type 2)
graft copolymer (side chain of different type)

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17
Q

linear structure

A

increased
- viscosity
- processability
- solubility

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18
Q

cross-linked structure

A

connected at different points in the polymer
increased
- glass transition temperature
- swellability
- rigidity
- thermal stability

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19
Q

condensation polymerization

A

also known as step polymerization
two or more (bifunctional) monomers carrying different reactive functional groups interact with each other
example - nylon

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20
Q

addition polymerization

A

also known as free-radical polymerization or chain polymerization
stages: initiation (by radical), propagation, and termination (by an inert molecule)
example - polyacrylate, polystyrene

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21
Q

types of polymer synthesis

A

condensation polymerization (small grouping)
addition polymerization (chains)

22
Q

monodispersed

A

number average (Mn) = weight average (Mw)
polydispersity (Mv/Mn): 1

23
Q

polydispersed

A

weight average (Mw)&raquo_space; number average (Mn)
polydispersity&raquo_space; 1

24
Q

crystalline

A

linear polymer
polymer can pack together in regular arrays at T < Tm
manifests a sharp Tm
good barrier to drug diffusion
durable

25
Q

first order (Tm)

A

specific volume (diagonal, up, diagonal)
enthalpy (straight, V, straight)

25
Q

amorphous

A

more common
polymers with irregular structure
polymers forms “glass” at T < Tg
softens over a wide temperature range (Tg)

26
Q

Glass transition temperature (Tg)

A

temperature range where a polymer changes from a hard, rigid, or glassy state to a more pliable, compliant, or rubbery state

27
Q

at T &laquo_space;Tg

A

polymers are hard, stiff, and glassy

28
Q

at T&raquo_space; Tg

A

polymers are rubbery and may flow

29
Q

chewable dosage forms

A

example - nicotine gum
contain a polymer with Tg close to 37 degrees C so that the gum is softened at mouth temperature
chew would then release nicotine quickly
parking it between cheek and gums slow down nicotine release

30
Q

factors affecting Tg

A

polymer length
side chains
crosslinking
plasticizers

31
Q

polymer length

A

the longer, the higher Tg

32
Q

side chains

A

the bulkier, the higher Tg

33
Q

crosslinking

A

the more crosslinked, the higher Tg

34
Q

plasticizers

A

molecules that increase the entropy and mobility of the polymer chains
lower Tg when included in polymer products
example - water

35
Q

high Tg components

A

longer polymer length
bulkier side chains
more crosslinked
less plasticizers

36
Q

mechanical properties

A

stress vs strain
slope
area under the curve
elastic polymers
rubbers or elastomers

37
Q

stress vs strain

A

force/are VS deformation

38
Q

slope

A

stress/strain
: modulus (or stiffness)

39
Q

area under the curve

A

: toughness

40
Q

elastic polymers

A

test linear stress vs strain curve up to breaking point
deform limitation
example - fibers; highly crosslinked polymers

41
Q

rubbers or elastomers

A

may deform 10 to 15 times their original lengths

42
Q

hydrogels

A

crosslinked networks of hydrophilic polymers
swell rapidly when placed in water
retain large volume of water in their structures

43
Q

chemical hydrogels

A

covalently crosslinked

44
Q

physical hydrogels

A

crosslinked via hydrogen bonding, hydrophobic interaction, or complexation

45
Q

reason for hydrogels swelling rapidly

A

chain-water interaction
electrostatic repulsion
osmotic forces

46
Q

polymers in dosage forms

A

cellulose-based polymers
hydrocolloids
water-soluble synthetic polymers
water-insoluble synthetic polymers

47
Q

cellulose-based polymer examples

A

ethylcellulose (tablet coating)
carboxymethyl cellulose (superdisintegrant; emulsifier)
hydroxpropyl methyl cellulose (tablet binder, coating)

48
Q

hydrocolloids examples

A

alginic acid (thinking agent in suspension)
chitosan (mucoadhesive dosage forms)

49
Q

water-soluble synthetic polymers examples

A

poly(ethylene glycol) (plasticizer, suppository base, stealth coating)
poly(vinyl alcohol) (tablet binder, coating)

50
Q

water-insoluble synthetic polymers examples

A

poly(lactic-co-glycolic acid) (controlled drug release)
polylactic acid (controlled drug release)

Dosage - Exam 3 (9 decks)

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