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Pharmaceutics > Behaviour of drug solids > Flashcards

Behaviour of drug solids Flashcards

1
Q

Ion-Ion bonding Outline

A

Interactions between 2 charged atoms eg Na+ and Cl-

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2
Q

Ion-Dipole Bonding

A

2 Types of Reaction. Electron dense ( relative negative) areas bind to cation (positive). Electron deficient (relative positive) and anion. Eg Na+ and O in water

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3
Q

H bonding (Dipole-Dipole)

A

Interaction between H atom and F, O or N (highly electronegative). Eg in water delta positive H and delta negative O

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4
Q

Dipole - Dipole Outline

A

Unequal sharing of electrons in covalent bond resulting in areas of high electron density (delta negative) attracting areas of electron deficiency (delta positive)

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5
Q

Hydrophobic Interactions

A

Interaction between 2 hydrocarbon areas in a molecule. Eg folding of proteins with hydrophobic side chains

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6
Q

Solubility Def.

A

Max concentration of substance that dissolves given solvent (usually water) at given temp. Important bioavailability determinent

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7
Q

Dissolution Def.

A

Rate by which a compound goes from solid to solution in a solvent. High solubility = high dissolution rate. Reflects absorption characteristics

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8
Q

What molecule size dissolves Faster

A

Small particles = faster solution (lower limit. Small airy particles have slower ( more cohesive, air pockets)). Thus particle size manipulation gives more controlled release rate

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9
Q

Melting Point is Reflective of

A

The strength if intermolecular interactions for drug-drug

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10
Q

High Melting Point Indicates

A

High molecular cohesion = low solubility

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11
Q

High Boiling Point Indicates

A

High molecular cohesion = low miscibility of liquids

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12
Q

Sorption Def.

A

Water binding to substance interface or core. Unknown if it’s absorption or adsorption

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13
Q

Do crystal absorb much water

A

No as it has no water pockets. Molecules are bound too close together. Can’t penetrate

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14
Q

Does amorphus form absorb much water

A

Yes, has holes for water to penetrate and pockets for water. However due to thermodynamic instability it loses water time as it converts back to crystalline

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15
Q

Why codine has a lower boiling point then morphine

A

When forming coedine hydroxyl group is broken off morphine. This means it can’t form a dimer with H bonds. Producing a weaker molecules and higher solubility

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16
Q

Unit Cell Def.

A

Simplest repeat unit in a crystal

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17
Q

Crystal Lattice

A

Orderly 3D molecule arrangement of unit cells. Permits optimal attractive interactions between adjacent molecules

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18
Q

Crystal Habit Def

A

Shape of specific drug molecules. Difference observed by visual inspection

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19
Q

7 Unit Cell Types

A

Simple cubic outline, tetragonal, orthorhombic, rhombohedral, monoclinic, triclinic and hexagonal

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20
Q

Simple Cubic Outline

A

All sides same length. All angles are 90 degrees

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21
Q

Tetragonal

A

2 out 3 dimeson’s sides are same length. All angles are 90 degrees

22
Q

Orthorhombic (1 of most common for drugs)

A

Dimension’s sides aren’t the same length. Angles are 90

23
Q

Rhombohedral

A

All sides same length. Angles are the same size (not 90 degrees)

24
Q

Monoclinic (1 of most common drug types)

A

Sides of 3 dimensions aren’t the same length. 2 angles 90 degrees 1 isn’t

25
Q

Triclinic (1 of most common drug types)

A

No sides are of same length. No angles of same size

26
Q

Hexagonal

A

2 out of 3 dimesions hav sides of same length. 2 angles are 90 degrees 1 angle 120 degrees

27
Q

Hexagonal Unit Habits

A

Acicular (needle-like, doesn’t flow, damages cells), Prismatic, Tabular (plate-like, not arosynamic so shouldn’t be used as aeroslol, cause bridges in funnels). 1 unit makes can make different habits

28
Q

Habit Type Considerations

A

Flow, Dispersibility, Aerodynamics, dissolution, solubility, bioavailability and compressibility

29
Q

Habit Shapes

A

Tabular, Columnar, Equant, Plate, Blade and Acicular

30
Q

Crystal Formation (/nucleation/ growth) Outline

A

Reverse of dissolution. Rate influences habit. Too fat = production of amorphous form (particles don’t have time to get in position). Done via; super saturation + cooling/evaporation/seed crystals/ precipitation (pH, water)

31
Q

Polymorphism Def.

A

Phenomenon where molecules arrange more then 1 pattern in crystal. Tend to have different crystal habits. Different polymorphs of same drugs have different properties.

32
Q

Most stable polymorphs have

A

Highest melting point

33
Q

Anhydrous Def.

A

Substance in solid state dissolved by water

34
Q

Solvates Def.

A

Solids with solvent in their crystal structure

35
Q

Which is more soluble aqueous or non-aqueos

A

Non-aqueous as water is bound to water

36
Q

Hydrates Def.

A

Water incorporated into crystal structure. Can lose water becoming sticky (efflorescent). 50% are monohydrate

37
Q

Co-crystals Def.

A

Crystals composed of active drug’s species and another organic molecule H bonded to it (reducing melting point, increasing solubility). More stable then polymorphs

38
Q

3 Outcomes Mixing Solids

A

2 phase coarse suspension(ad mixing), 2 phase eutectic (cooled molten mix, solvent evapouration), 1 phase solution (cooled molten, solvent evaporation)

39
Q

are hydrates stable

A

Hydrates are more stable then anhydrous. Increased stability reduces solubility and reduces bioavailability

40
Q

Lattice Type Differences

A

Energy, rigidity, hardness, shape, size, melting point, therapeutic application, dissolution and bioavailability

41
Q

Lattice Shape Forming

A

Meta-stables are of higher solubility, not thermodynamically stable, interfacial tension

42
Q

Glass Transition Temp (Tg) Def.

A

Temp below which material is in glassy state and is brittle. Above Tg molecules become more mobile and rubbery. Can be lowered by plasticers (making molecules more mobile)

43
Q

Amorphus Characteristics

A

Melts over large temp range, glass transition temp, greater solubility then crystals, poor flowability, better compression properties then crystals, absorb water, destroyed crystals

44
Q

Crystals Characteristic

A

Narrow melting range, melting point, defined geometry, polymorphism, 1 crystal stable at given temp/pressure, good flowability, poor compression

45
Q

Particle size Outline

A

Crystalline/amorphus solids are called particles. Particle size reduction is done by milling, bashing, grinding and trituration (pestle and mortar)

46
Q

Decreasing Particle Size Causes

A

Dissolution increase, increase solubility, pharmokinetics (slow/fast release), improves solid mixing, minimises size segregation (improving dose uniformity), increases degradation, decreases flowability (increased cohesion), increases pulmonary application (to lower limit), decreased wet ability

47
Q

Particle size and drug action

A

Only molecular dispersions are absorbed acrosses epithelium. Choosing particle size increases control of release (release is more sustained, plasma toxicity is avoided)

48
Q

Particle Size and Dissolution

A

Reduced particle size = decreased surface area = increased solvent contact = increased rate of solution

49
Q

Particle Size Reduction and Solubility

A

Substances increased below threshold size. High interfacial tension with decreased particle size = increased solubility

50
Q

Surface Free Energy Def.

A

Net inward force of attraction caused by chemical imbalance on surface. Shows as surface tension. Smaller particle = greater surface area = more energy in system = low flowability

51
Q

Hygroscopicity Def.

A

Ability to take up water from atmosphere

52
Q

Deliquescent

A

Pharmaceutics (13 decks)

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