Dosage Form & Calculations Exam 2 Study Guide

What is a suspension?

Two-phase system with finely divided solid dispersed in a liquid; can be oral, topical, or parenteral

Define flocculated suspension

Loose aggregates that settle rapidly but are easily redispersed; held together by Van der Waals forces

Define deflocculated suspension

Individual particles that repel each other, settle slowly, form a hard cake

What are the methods for particle size reduction?

-Trituration

-Levigation

-Pulverization by intervention

-Mechanical

Define trituration particle size reduction

Grinding in mortar & pestle

Define levigation particle size reduction

Trituration with small amount of liquid in which drug is insoluble

Define pulverization by intervention particle size reduction

Dissolve in volatile solvent → evaporate

Define mechanical particle size reduction

Grinders, ball mills

How do you prepare a suspension?

Reduce particle size → wet particles → add vehicle gradually with stirring → use suspending agents

How does viscosity affect sedimentation?

↑ Viscosity → ↓ Sedimentation rate

What is the BUD for aqueous suspensions?

Non-preserved: 14 days, Preserved: 35 days

What counseling points for suspensions?

Shake well, use proper measuring device, store at room temp or fridge depending on drug

Name the common suspending agents & their final concentrations

-Acacia NF: 2-5%

-CMC USP: 0.5-1.5%

-Methylcellulose USP: 0.5-5%

-Tragacanth NF: 0.5-2%

What is a common commercial vehicle pH?

-Ora-Plus: 4.0-4.5

-Versa-Plus: 4.5-5.0

What is an emulsion?

Thermodynamically unstable mixture of immiscible liquids stabilized by an emulsifier

What are the different types of emulsions?

-Oil-in-water (o/w)

-Water-in-oil (w/o)

Describe an oil-in-water (o/w) emulsion

Water external, non-greasy, washable

Describe an water-in-oil (w/o) emulsion

Oil external, greasy, occlusive

What are factors that determinine emulsion type?

Nature of emulsifier (HLB value) and phase in which emulsifier is more soluble

What are the emulsion instabilities?

-Creaming: reversible

-Coalescence/breaking: irreversible

-Phase inversion: o/w ↔ w/o

What are the emulsion stabilization methods?

-Reduce droplet size

-Increase viscosity

-Optimize oil:water ratio

HLB system

<10 → lipophilic → w/o, ≥10 → hydrophilic → o/w

Pharmaceutical uses of emulsions

Creams, lotions, taste-masking, IV lipid nutrition

BUD for emulsions

Same as suspensions: aqueous non-preserved 14 days, preserved 35 days

What are some counseling points for emulsions?

-Shake well

-Store properly

-Watch for phase separation

What are examples of carbohydrate emulsifiers?

Acacia, Pectin, Tragacanth

What is an example of a protein emulsifier?

Egg yolk (Lecithin)

What are examples of high MW alcohol emulsifiers?

-Cetyl/Stearyl Alcohol

-Glyceryl Monostearate

What are examples of solid emulsifiers?

-Aluminum Hydroxide

-Bentonite

-Magnesium Hydroxide

What is a gel?

Semisolid system with liquid trapped in polymer network

What are the two types of gels?

-Hydrogel

-Orangogels

Describe a hydrogel

Water-based, dispersible or soluble; can be inorganic (metal oxides) or organic (long polymer chains)

Describe an organogel

Oil-based, include hydrocarbon, natural fats, soap-base, or hydrophilic organogels

What are some advantages of gels?

Versatile, water-washable, cosmetically elegant

What is the BUD of a non-preserved aqueous gel?

14 days

What is the BUD of a preserved aqueous gel?

35 days

What is the BUD of a non-aqueous gel?

180 days

What are some important counseling points for gels?

-Proper application

-Avoid contamination

-Store in a tight container

What are some examples of hydrogels?

-Methylcellulose

- CMC

-Pluronic F-127

What is an example of an organogel?

Hydrophilic (Carbowax bases)

What are the advantages of transdermal patches?

-Avoid first-pass

-Constant drug delivery

-Removable

-Noninvasive

What is a limitation of a patch?

Only potent drugs (<500 Da, logP 1-3) can be used

What are the layers contained in a matrix patch in order from furthest to closest to the skin?

-Film backing

-Drug/adhesive layer

-Protective line

What are the layers contained in a reservoir patch in order from furthest to closest to the skin?

-Film backing

-Drug layer

-Rate-controlling membrane

-Contact adhesive

-Protective peel strip

Define a matrix patch

A system in which the drug is incorporated directly into the adhesive, rather than into a separate layer

Define a reservoir patch

A system in which the drug has a separate layer from the adhesive

What are some counseling points for patches?

-Apply to intact skin

-Rotate sites

-Do not cut (ok is some matrix)

-Remove after use

Define ointment

Semisolid, greasy, occlusive, soften at body temp, spread easily; used for dry scaly lesions

Define creams

Emulsions (o/w or w/o), cosmetically acceptable; used for moist, weeping lesions

Define pastes

Stiff semisolids with ≥20% solids, protective, not rubbed in

Define an oleaginous base

-No water

-No absorption

-Not washable

-Emollient, Occlusive

-Example: White Petrolatum

Define an absorption base

-No water

-Has absorption

-Not washable

-Emollient, Occlusive

-Example: Hydrophilic Petrolatum

Define a W/O base

-No water

-Has absorption

-Not washable

-Emollient, Occlusive

-Example: Cold Cream

Define an O/W base

-Has water

-Has absorption

-Is washable

-Non-occlusive, non-greasy

-Example: Hydrophilic Ointment

Define a water-soluble base

-Has water

-Has absorption

-Is washable

-Non-occlusive, non-greasy

-Example: PEG Ointment

What type of skin penetration does an oleaginous base have?

Epidermic

What type of skin penetration does an absorption base have?

Endodermic

What type of skin penetration does an emulsion/water-soluble base have?

Diadermic

What is the BUD for an aqueous preserved ointment?

35 days

What is the BUD for an non-aqueous preserved ointment?

180 days

What are some counseling points for ointments?

-Apply thin film

-Do not wash off immediately

-Store properly

-Avoid contamination

What are the advantages of powders?

-Flexible dosing

-Rapid onset

-Large surface area

What are the disadvantages of powders?

-Poor taste

-Stability with moisture

-Not convenient

What are the powder types?

Hygroscopic, Deliquescent, Efflorescent, Effervescent salts

What are the BUD for powders?

Usually 6 months (non-aqueous, USP/NF ingredients)

How should bulk oral powders be stored/dispensed?

glass/plastic/metal wide-mouth containers

How should divided powders be stored/dispensed?

individually folded

How should topical powders be stored/dispensed?

sifter or powder shakers

How should insufflation powders be stored/dispensed?

plastic puffer units; Avoid polyethylene

Define a hygroscopic powder

A powder that absorbs moisture from the surrounding air through adsorption or absorption

Define a deliquescent powder

A solid substance that absorbs so much moisture from the surrounding air that it dissolves into a liquid solution

Define an efflorescent powder

A crystalline substance that contains water of crystallization, which it can spontaneously release into a low-humidity atmosphere

Define an effervescent salt powder

A granulated or coarse powder containing a medicinal agent mixed with an acid and a carbonate or bicarbonate

What are some counseling points for powders?

-Store in a dry container

-Measure properly if bulk oral

-Mix with specified liquid/food

-Avoid premixing unless instructed