Suspensions

Front 1

Define: suspensions

Back 1

Preparations containing finely divided drug particles distributed uniformly in a vehicle which the drug exhibits a minimum degree of solubility

Front 2

3 types of coarse disperse systems

Back 2

Powder in Liquid
Liquid in Liquid
Powder in Powder

Front 3

Suspensions are what phase?

Back 3

2 phase systems comprising of
1) finely divided drug particles: suspensioid, dispersed phase,
2) vehicle: dispersing phase or dispersion medium

Front 4

4 advantages of suspensions

Back 4

1) chemical stability protects drug being suspended even if it interacts with solvent
2) liquid preparation allows ease of swallowing, range of doses, flexible administration
3) bioavailability: 2nd best to solutions (then capsules, tablets, coated tablets)
4) taste: flavor preference of patient because drug is coated by solvent and patient cannot taste

Front 5

3 types of suspensions

Back 5

1) oral suspensions: sweetened, flavored, viscous vehicle
2) topical suspensions (skin or opthalmic, otic, nasal or rectal)
3) parenterals

Front 6

Commercial preparations of suspensions
Ready to use vs Dry powders

Back 6

Ready to use: with/without stabilizers or additives
"Oral Suspension"

Dry Powders: "FOR oral suspension" to be reconstituted because unstable in aqueous vehicle. Powders: drug, suspending agents to be diluted and agitated

Front 7

2 Components of a suspension

Back 7

1) Dispersed phase: insoluble particles
2) Dispersion medium: Additives: flavoring, sweeteners, preservatives

Front 8

Order of mixing is important to what?

Back 8

Stability

Front 9

What is Stoke's Law?

Back 9

Looks at sedimentation rate
Ideally: "Uniform, spherical particles settle without turbulence or colliding and have no chemical or physical attraction to solvent"

Front 10

S=dx/dt = d2 (pi - pe)g/18n

Back 10

D: particle size, smaller = slower sedimentation rate
Pi: density of particle (higher = faster, but too small or low density - particles float bad!)
N = viscosity (increase viscosity = slower sedimentation but too high cause problems pouring)
Pe = density of medium
G = gravitational constant

Front 11

What 2 comments of stokes law are in the dispersed phase?

Back 11

D = diameter of particles
Pi = density of particles

Front 12

What is most important consideration of dispersed phase?

Back 12

Size of particles, want 1 - 50 mcm, commercially available

Front 13

5 ways to get size reduction

Back 13

1) comminution (difficult to get uniform)
2) dry milling
3) micropulverization (rapid, inexpensive, 10 - 50 mcm produced)
4) fluid energy grinding (jet milling, micronizing) produce less than 10 mcm sizes (opthalmics and parenterals)
5) spray drying

Front 14

Particle size affects what?

Back 14

Physical stability of the suspension

Front 15

3 main characteristics of particle size?

Back 15

1) smaller -= reduces sedimentation rate and uniform
2) particles too small may cake on bottom
3) caking: resists breaking when shaken and forms aggregates that are less suspendable

Front 16

How does particle shape affect caking?

Back 16

Symmetrical barrel shaped particles more stable than asymmetrical needle shaped particles (cake upon standing)

Front 17

2 ways to avoid caking

Back 17

1) floc, floccule
2) flocculating agents

Front 18

What is a floccule?

Back 18

Loose aggregates of particles held together by weak bonds, form lattice that resists complete settling but do settle faster than fine particles, less prone to caking, and break up easily

Front 19

What are flocculating agents?

Back 19

Clays (bentonite magma)
Electrolytes
Surfactants
pH of dispersed phase for parenterals

Front 20

What parts of stoke's law are in dispersion medium?

Back 20

Pe = density of medium
N = viscosity of medium

Front 21

What 3 things that support suspensoid

Back 21

1) density of suspension
2) flocculation of suspension
3) amount of material needing support
(more materials needing support means increased density of medium)

Front 22

What is viscosity and rehology

Back 22

1) Rehology: study of flow
2) Viscosity: maintain drug and excipients in suspension, enhance stability and alter release rate

Front 23

Types of thickening/suspending agents used to help suspend suspension and provide structure

Back 23

Carboxymethylcellulose: 0.5 - 1.5%
Methycellulose: 0.5 - 5%
Microcrystalline Cellulose
Polyvinyl Pyrrolidone
Xantham Gum
Bentonite (also a flocculant)

Front 24

What is the pennkinetic system?

Back 24

Sustained release of suspension by forming a complex of drug and ion exchange resins coated in ethyl cellulose --> coated particles allows drug to remain adsorbed onto resin but slowly released in GI

Ex: tussionex pennkinetic ER suspension

Front 25

Use of suspensions?

Back 25

For patients not able to swallow solid dose forms and can be compounded from available solid dosage forms

Front 26

Information of stability of drugs in suspension needed why?

Back 26

1) faster decomposition rates
2) affects of pH
3) package insert
4) professional literature
5) contact manufacture of solid dose form

Front 27

2 types of commonly compounded suspensions?

Back 27

1) theophylline
2) metoprolol

Front 28

Dispersed phase in suspensions 2 steps of compounding

Back 28

1) obtain uniform small particle of drug
2) wet the insoluble active material by displacing air to allow penetration of dispersion medium by using a wetting/levigating agent to form a paste

Front 29

Dispersion medium in suspensions 4 steps of compounding

Back 29

1) add vehicle to paste by parts with stirring
2) portion of vehcile used to wash suspension
3) vehicle used to q.s. final volume
4) final product passed through mill or blending for uniformity

Front 30

3 additives in suspensions

Back 30

Flavors
Colors
Preservatives

Front 31

Formulations of neonates should NOT include 4 things

Back 31

1) color
2) flavorings
3) preservatives
4) alcohol

Front 32

What does preservatives cause in neonates?

Back 32

Benzyl alcohol: gasping syndrom and multiple organ failure and death

Propylene glycol: seizures or stupor

Front 33

What do alcohols cause in neonates?

Back 33

1) alter liver function
2) gastric irritation
3) CNS depression
Ex: aromatic elixir NF: 21 - 23% alcohol

Front 34

3 things for packaging suspensions

Back 34

1) wide mouth container for easy pouring
2) air tight, light resistant container
3) adequate space for mixing in container

Front 35

3 things for storage of suspensions

Back 35

1) protect from freezing
2) protect from excessive heat
3) store at RT or refrigerate depending on drug

Front 36

4 things for labeling

Back 36

1)Internal versus external use
2) storage requirements
3) beyond use date
4) shake well prior to use

Front 37

2 other things to watch for or use for suspensions

Back 37

1) use correct measuring tool
2) watch for color changes or changes in consistency