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Dosage form design > Lecture 8 > Flashcards

Lecture 8 Flashcards

1
Q

DEF:A large molecule (macromolecule) built up by repetitive

bonding (covalent) of smaller molecules (monomers= A, B, …etc)

A

Polymer

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2
Q

Polymers could be classified based on:

A
  • chain chemical structure backbone
  • monomers type
  • Arrangement of monomer
  • Structure
  • Thermal behaviour & Molecular Forces
  • Origin (Sources)
  • Mode of polymerization
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3
Q

Polymers are formed by linking monomers through chemical

reaction_____

A

Polymerization

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4
Q

is represented by chains with two ends.

A

Linear polymer

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5
Q

have side chains, or branches, of significant
length which are bonded to the main chain at branch points, and are
characterized in terms of the number and size of the branches.

A

Branched polymer

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6
Q

___have three dimensional
structures in which each chain is connected to all others by a
sequence of junction points and other chains.

A

Cross-linked or network polymer

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7
Q

Thermal Behaviour between polymerchains:

A

Thermoplastic

Thermosetting

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8
Q

____These are the linear or slightly branched

long chain molecules capable of repeatedly softening on heating and hardening on cooling.

A

Thermosplastic

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9
Q

______These polymers are cross linked or heavily branched molecules, which on heating undergo
extensive cross linking in molds and again become infusible.

A

Thermosetting polymers

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10
Q

Polymers can be classified into two categories based on the

forces of attraction:

A

Elastomers

Fibers

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11
Q

How does the forces of attraction affect polymer chain:

A

Forces of attraction bind the polymer chains and affect polymer mechanical properties like tensile strength, elasticity, toughness,
…..etc. which determine polymer applications.
These mechanical properties are governed by intermolecular forces, e.g., van der Waals forces and hydrogen bonds, present in the polymer.

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12
Q

____is a randomly oriented amorphous polymer.

A

Elastomer

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13
Q

stretches
and then reverts back to its original shape. In these elastomeric polymers, the
polymer chains are held together by the weakest intermolecular forces. These
weak binding forces permit the polymer to be stretched

A

Elastomers

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14
Q

are the thread forming solids which possess high tensile
strength. These characteristics can be attributed to the strong
intermolecular forces like hydrogen bonding

A

Fibers

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15
Q

Natural polymers aka:

A

Bio-polymer

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16
Q

examples of Natural polymers

A

Proteins, nucleic
acids, polysaccharides,
rubber and resins.

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17
Q

examples of Semi-synthetic

polymers

A

Cellulose
derivatives as cellulose
acetate and cellulose
nitrate

18
Q

examples of Synthetic polymers:

A

Man-made polymers
produced industrially: plastic
(polythene), synthetic fibres
(nylon) and synthetic rubbers

19
Q

Whats the first synthetic polymer:

A

organic polymer polyvinylchloride

20
Q

Methods of preparation of synthetic polymers:

A
  • Addition Polymers

- Condensation polymers

21
Q

Addition polymers aka:

A

Chain growth

22
Q

condensation polymers aka:

A

Step growth

23
Q

example of addition polymer:

A

the formation of polythene from ethene and polypropene from propene

24
Q

When 2 or more monomers are

involved in the addition polymer, the product is referred to as:

A

Co-polymer

25
Q

3 steps involved in polymerization:

A
  • Initiation
  • Propagation
  • Termination
26
Q

reactive intermediates used in addition polymer:

A

reactive intermediate such as free radicals, cation or anions without loss
of small molecules.

27
Q

The reactive intermediate involved in the polymerization of ethene:

A
  • product: polythene

- reactive intermediate: Benzoyl peroxide initiator that produces phenyl

28
Q

an important requirment in condesation polymers:

A

2 functional groups

29
Q

examples of condensation polymers:

A

Nylon: formation of amide linkage with water loss

30
Q

Properties of polymers:

A

1.Polydispersity:all synthetic polymers and naturally occurring macromolecules possess a range of molecular weights,because there is a range of sizes for polymer chains
2.Thermal behavior:Polymers do not have a sharp melting point because they
are transformed from semi-crystalline to a solid amorphous
phase and subsequently they have a melting range.
3.solubility: Water-soluble polymers have an ability to increase the viscosity of solvents at low
concentrations, to swell or change shape in solution. they are used as suspending
agents, in drug-polymer conjugates and in the formation of soluble macromolecular
drug carriers.

31
Q

polymers that dont posses polydispersity:

A
  • proteins or naturally occuring macrmolecules
32
Q

The rate of dissolution of a water-soluble polymer depends on its

A

molecular weight

33
Q

solubility property of large water-soluble polymers:

A

the larger the molecule, the stronger are the forces holding the chains together and more energy is needed to force the chains apart in the solvent

34
Q

the greater the degree of crystallinity of the polymer, the lower is the___

A

rate of dissolution

35
Q

Insoluble polymers or polymers with a low rate of solution are used in:

A
  • To form thin films
  • As film coating materials
  • As surgical dressings
  • As membranes for dialysis or filtration
  • As matrices for enveloping drugs to control their release properties
  • As packaging materials
36
Q

Drug entrapped in a micro/nanoparticulate polymer:

A
  • Matrix System:

- Reservoir System

37
Q

def: Drug is dispersed in an insoluble matrix of rigid non-swellable hydrophobic materials or swellable hydrophilic substances

A

Matrix system

38
Q

def: these system are hallow containing inner core of drug surrounded in a water-insoluble polymer membrane

A

Reservoir system

39
Q

factors that affect matrix system vs reservoir system:

A

Matrix system: polymer property, the diffusivity of drug in the matrix, nature of drug and excipients, geometry
Reservoir system: membrane thickness, membrane porosity, chemical nature of membrane material, nature of drug & excipients

40
Q

How are molecules weighed in polydispersity?

A

Determined by:

  • Chemical Analysis
  • Osmotic pressure
  • Light-scattering measurements

Dosage form design (9 decks)

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