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PHARM 124 Midterm > Preformulation > Flashcards

Preformulation Flashcards

1
Q

Purpose of preformulation (3)

A
  1. Identifying possible dosage forms
  2. to use sustainable excipients
  3. predicting any formulation problems
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2
Q

Contrast between intrinsic properties and derived properties

A

Intrinsic: inherent to the molecule; affected by CHEMICAL modifications
- solubility, pKa, LogP
Derived properties: related to intermolecular interactions, affected by PHYSICAL shape
- melting point, density, excipient compatibility, particle size

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3
Q

When does preformulation take place

A

After candidate drugs are identified, and BEFORE dosage form design and optimization

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4
Q

Important physicochemical tests during preformulation

A
  • chemical identity and purity tests
  • Solution properties (pKa, solubility)
  • Solid state properties: crystal structure, particle size
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5
Q

What are 2 mandatory fundamental solubility parameters for an NCE

A

intrinsic solubility: solubility when the drug is unionized
Dissociation constant (pKa): ionization of weak bases and weak acids at different pH

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6
Q

What is the acceptable range for aqueous solubility.
What do we need if it is below?

A

Range is 1-10mg/mL

If less: indicates a need for salt
If cannot be manipulated this way (for weak acids and weak bases) : liquid filling in capsules

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7
Q

What are ways to increase solubility of an NCE (4)

A
  1. Salt formation
  2. Use of solvents, co-solvents (oils)
  3. Complexation
  4. Solubilization by surfactants
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8
Q

Define intrinsic dissolution rate

A

dissolution solely controlled by diffusion

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9
Q

What does Log P = 3 mean

If Log P > 0 : ?
If Lop P < 0: ?

A

Log P = 3 means that the compounds is 1,000 times more soluble in OCTANOL

0+ = lipid soluble
Below 0 = water soluble

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10
Q

What is the difference between polymorphism and pseudopolymorphism

A

polymorph: substance exists in more than 1 solid state form

pseudopolymorph: solvents in crystal lattice lead to change in crystal habit

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11
Q

What is the amorphous form

A
  • Non-crystaline materials , possess no long range order
  • thermodynamically unstable; tend to revert to a more stable form
  • most energetic form
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12
Q

What are the special considerations when selecting salt forms for an NCE (5)

A
  1. IV vs oral formulations
  2. High dose vs low dose
  3. Excipient compatibility
  4. Interaction with other actives
  5. Toxicological consideration
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13
Q

What are the 2 different classifications of polymorphs

A
  1. Enantiotropic: can be REVERSIBLY changed into another polymorph by temp. or pressure
  2. Monotropic: change is IRREVERSIBLE
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14
Q

What are some ways to screen for polymorphism

A
  • Crystallization from different solvents
  • Precipitation
  • Concentration or evaporation
  • Crystallization from the melt
  • Grinding and compression
  • Lyophilization
  • Spray drying
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15
Q

What are 4 common drug degradation pathways

A
  1. Hydrolysis
  2. Oxidation
  3. Photolysis
  4. Trace metal catalysis
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16
Q

What does the Arrhenius plot test for?
What is it affected by

A

Affected by temperature
Test for accelerated stability

17
Q

What are 3 physical properties that help with stability of solids

A

Hygroscopic: solids that absorb moisture from environment
Deliquescent: absorb moisture from environment until it becomes liquids
Efflorescent: loses water

18
Q

What is the relative humidity for solids

A

55% temperate, 87% tropics

19
Q

What are some protection that help with stability

A
  • good packaging
  • picking best excipients to reduce hydrolytic instability
20
Q

What are 4 main solid-state characterization properties

A
  1. Crystal morphology
  2. Particle size
  3. Powder flow properties
  4. Excipient compatibility
21
Q

When are small particle size important?

A
  1. Low dose is needed
  2. Using high potency drugs
  3. Using drugs with poor solubility (dissolution rate is directly prop. to SA)
22
Q

What are important powder flow properties for tablet and capsule formations (3)

A
  1. bulk density (Carr’s index)
  2. Angle of repose
  3. Compression properties (elasticity, plasticity)
23
Q

What is the most common method use to evaluate excipient compatibility

A

Thermal analysis. Eg DSC (differential scanning calorimetry)

24
Q

What are the goals of excipient compatibility

A
  • to help select excipients that will result in a stable and effective dosage form
  • to identify excipients that are compatible with the API with no effect on its stability
25
Q

What is the difference between solubility and dissolution rate

A

Solubility: the max AMOUNT of drug that can be dissolved in a solvent at a specific temp

Dissolution rate: the TIME it takes for the drug to dissolve in the fluids at the absorption rate

PHARM 124 Midterm (6 decks)

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