[MIDTERMS] PMQA LEC - Suspensions

Question 1

A disperse system in which solid, vehicle-insoluble particles (internal phase) are uniformly suspended by mechanical agitation and formulation design throughout the liquid vehicle (external phase).

Answer 1

Suspensions

Question 2

Two (2) Phases of Suspensions

Answer 2

1. Continuous Phase
2. Discontinuous Phase

Question 3

It is also called the External Phase or Dispersion System

Answer 3

Continuous Phase

Question 4

It is also called the Internal Phase or Dispersed Phase

Answer 4

Discontinuous Phase

Question 5

Purposes of Suspensions

Answer 5

• Sustaining Effect
• Stability
• Taste
• Basic Solubility

Question 6

For sustained release preparation, the suspension necessitates drug dissolution prior to absorption.

Answer 6

Sustaining Effect

Question 7

Drug degradation in suspension or solid dosage forms occurs much more slowly than degradation in solution form.

Answer 7

Stability

Question 8

A drug with unpleasant taste can be converted into an insoluble form and then prepared as suspension.

Answer 8

Taste

Question 9

When suitable solvents are not available. For example, ophthalmic suspensions provide an alternative to ophthalmic solutions.

Answer 9

Basic Solubility

Question 10

(T/F): After gentle shaking, the medicament stays in suspension long enough for the dose to be accurately measured.

Answer 10

T

Question 11

(T/F): Particles are small and relatively uniform in size.

Answer 11

T

Question 12

Three (3) Steps in Ensuring Formulation of Suspension

Answer 12

1. Control Particle Size
2. Use of Thickeners
3. Use of Wetting Agent

Question 13

Diffusible Solids (Dispersible Solids)

Answer 13

Insoluble Medicament

Question 14

Example/s of Diffusible Solids

Answer 14

• Light Kaolin
• Magnesium Trisilicate
• Light Magnesium Carbonate
• Bismuth Carbonate

Question 15

Not Easily Wetted

Answer 15

Indiffusible Solids

Question 16

Example/s of Indiffusible Solids

Answer 16

(Internal Use)
• Aspirin
• Chalk
• Phenobarbitone
• Sulphadimine

(External Use)
• Calamine
• Hydrocortisone
• Sulphur
• Zinc Oxide

Question 17

Four (4) Problems Encountered when Formulating Insoluble Solid to Suspension

Answer 17

1. Sedimentation
2. Flocculation
3. Wetting Agent
4. Preservatives Used

Question 18

(T/F): The greater the density, the greater the descent.

Answer 18

T

Question 19

Aggregation will determine the type of suspension.

Answer 19

Flocculation

Question 20

To prevent air trapping.

Answer 20

Wetting Agent

Question 21

Preservatives Used

Answer 21

• Chloroform Water
• Benzoic Acid
• Hydroxybenzoates

Question 22

Two (2) Types of Suspension System

Answer 22

1. Flocculated System
2. Deflocculated System

Question 23

It is also known as Coagulated or Colloidally Unstable System

Answer 23

Flocculated System

Question 24

It is also known as Peptized or Colloidally Stable System

Answer 24

Deflocculated System

Question 25

Particles appear as floccules like tufts of wool with loose fibrous structure. When the system settles two distinct layers forms clear particle free supernatant liquid and sediment. Appears to be coarse, because of the floccules formed. Exhibits minimum serious separation, depending on the solid content and the degree of flocculation that took place.

Answer 25

Flocculated System

Question 26

Particles settles as the dense sediment, which becomes more compact after given time interval.

Answer 26

Deflocculated System

Question 27

Two (2) Methods of Preparation of Suspensions

Answer 27

1. Discipitation Method 2. Precipitation Method

Question 28

This process is done by dispersing the finely divided powders in an appropriate liquid vehicle. The use of surfactants is desirable to ensure uniform wetting of the hydrophobic surfaces.

Answer 28

Discipitation Method

Question 29

This is performed by effecting precipitation in the liquid vehicle.

Answer 29

Precipitation Method

Question 30

Three (3) Methods of Precipitation Methods

Answer 30

1. Organic Solvent Precipitation 2. Precipitation Effected by Changing the pH 3. By Double Decomposition Method

Question 31

Water insoluble drugs are precipitated by dissolving them in the water miscible organic solvent. Then adding the organic phase to purified water under standard conditions.

Answer 31

Organic Solvent Precipitation

Question 32

This is applicable to those drugs in which its solubility is dependent on pH value.

Answer 32

Precipitation Effected by Changing the pH

Question 33

Where simple chemistry is involved. Example is the preparation of White Lotion USP (made by interacting zinc sulfate with sulfurated potash solution to form zinc polysulfide).

Answer 33

By Double Decomposition Method

Question 34

Polyoxyethylene Esters of Mixed Fatty Acid Esters of Sorbitol Anhydride

Answer 34

Tweens

Question 35

Mixed Fatty Acid Esters of Sorbitol Anhydride

Answer 35

Spans

Question 36

Higher Molecular Weight Polyethylene Glycols

Answer 36

Carbowax

Question 37

It forms mechanical sheath or barrier around particles.

Answer 37

Protective Colloids

Question 38

Example/s of Protective Colloids

Answer 38

• Silica Gel • Aluminum Hydroxide

Question 39

Suspending Agents

Answer 39

1. Hydrophilic Colloids (Hydrocolloids) 2. Clay Group 3. Other Agents

Question 40

Increase the viscosity of water by binding water molecules, limiting their mobility or fluidity. It is mostly anionic, except methylcellulose (neutral) and chitosan (cationic).

Answer 40

Hydrophilic Colloids (Hydrocolloids)

Question 41

These are incompatible with quarternary antibacterial agents and other positively charged ions.

Answer 41

Anionic Hydrocolloids

Question 42

It is incompatible with negatively charged drugs and excipients.

Answer 42

Chitosan

Question 43

It is usually 35% dispersion in water (mucilage). Its viscosity is greatest between pH 5 and 9.

Answer 43

Acacia

Question 44

It is usually used as 6% dispersion in water (mucilage). The viscosity is greatest at pH 5.

Answer 44

Tragacanth

Question 45

A polymer that is nonionic and stable to heat and light.

Answer 45

Methylcellulose

Question 46

Example/s of Clay Group

Answer 46

• Bentonite • Veegum

Question 47

They are strongly hydrated and exhibit thixotrophy.

Answer 47

Clay Group

Question 48

Certain Kinds of Pharmaceutical Suspensions

Answer 48

1. Gels 2. Magmas and Milks 3. Lotions 4. Mixtures

Question 49

Suspending Agent - 0.5% to 1.0% Gelling Agent - 0.5% to 2.0%

Answer 49

Carbomer

Question 50

It requires high speed equipment and which is suitable for internal and external use.

Answer 50

Carbomer