Sachedva Test

What is rheology?

study of flow and deformation of matter under stress.

What is enteric coating?

we coat drugs so that it does not disturb the ph of GI which is 1.2.

examples of enteric coating

cellulose acetate phthalate, Omerprazole, Nexium, Pantoprazole

What is Viscosity?

resistance to flow

Viscosity formula

viscosity = shear stress/shear rate

Newton's Laws

States that the HIGHER the viscosity of a liquid, the GREATER the force per unit area(shear stress F) required to produce a certain rate of shear(G)

Newton's law formula

F = (n)(G)

What is the formula for F? force per surface area

F = F'/A

What is the formula for G? speed at which liquid is moving

dv/dr, gravity = 9.8m/s^2

Newtonian Fluid

- a fluid whose stress against shear rate curve is linear - passes through the origin
- a constant proportionate.

Example of Newtonian fluid

water, ethanol, castor oil, chloroform, honey

What are the 3 types of Non-Newtonian Fluids?

Plastic, Dilatant, Pseudo-Plastic

What are the characteristics of a PLASTIC FLOW?

- Does not pass through the origin
- Also known as Bingham Bodies/Plastic
- Requires a Yield Value(certain amount of stress to induce a shear

Which Floccules have a high ass yield value?

Deflocculated

What are some examples of Plastic Flow?

Toothpaste, Ointments, Gel

Plastic Flow formula

U = F - f/G

What are the components of the Plastic Flow formula? Like what does f, G, F stand for?

f = yield value
F = Shearing stress
G = Rate of shear

What are the characteristics of Pseudo Plastic Flow?

- as Shear Stress INCREASES, the Shear Rate INCREASES
- NOT linear

Polymer Example of Plastic Flow?

put a polymer in water, once you apply the stress, the polymer will be stretched and more dispersable. Shear thinning system

Regular examples of Pseudo Plastic Flow

Squeezing Ketchup, Sodium Alginate, Methyl Cellulose

What are the characteristics of a Dilatant Flow?

- aka shear THICKENING system
- passes though the origin
- NO yield value, NOT linear

When stress is removed in a dilatant flow, what happens?

It returns to its original position

What is a Dilatancy rate?

The point at which you stop mixing, like with the acacia of an emulsion

What is the Dilatant Flow Formula?

F^N = (n)(G)

What is Thixotrophy?

isothermal and comparitively slow recovery of standing of material of a consistency lost through shearing aka flocculated

What is thixotrophy in simpler temrs?

gel to solution to gel

Which flows can thixotrophy be exhibited?

Plastic and pseudoplastic

What are the 2 rheological properties?

Viscosity and Elasticity

What is antithixotropy?

represents an increase in consistency(high viscosity) rather decrease in consistency in the down curve

What is polymorphism?

Solid Crystalline phase of a given compound resulting from the possibility of at least two different arrangements of that compound in solid state.

What properties vary with polymorphism?

1. Solubility

2. Melting Point

3. Density

4. Hardness

5. Crystal Shape

6. Optical & Electrical Properties

How many forms does Ammonium Nitrate have?

5

How many forms does Progesterone have?

5

How many forms does Tripalmitin have?

7

Different Polymorphic forms are produced by factors like:

1. Storage Temperature

2. Recrystallization of the solvent

3. Rate of Cooling of the solvent

4. Heating Temperature

What temperature does theobroma oil(cocoa butter) melt?

It is a single glyceride that melts between 34-36C.

What are the 4 different melting point polymorphs?

1. Unstable gamma

2. Metastable alpha

3. Metastable betaprime

4. Stable beta

What temp does unstable gamma form melt?

18C

What temp does metastable alpha form melt?

22C

What temp does metastable betaprime form melt?

28C

What temp does stable beta form melt?

34.5C

what does ENANTIOTROPIC mean?

When changes from one polymorphic form to another are reversible.

what does MONOTROPIC mean?

When transition takes place in one direction only.

what does TRANSITION TEMPERATURE mean?

The temperature at which transition from one polymorhic form to the second takes place.

What drugs show polymerphism?

1. Chloramphenicol Palmitate

2. Carbamazephine

3. Haloperido

4. Bromperidol

What happens to suspensions as it affects polymorphism?

It make cause Crystal Growth and caking, which can cause syringibility problems

How many methods are there to study Polymorphism?

8

What are the 8 methods to study polymorphism?

Optical Crystallography, Hot Stage Microscopy, X-Ray, Infrared, Differential Thermal, PMR, NMR, Electron Microscopy NMR

Why do we use excipients?

to improve stability, dissolution, manufacturing speed and quality, flavoring

What are the 10 Dosage forms?

Tablets, Suppository, Solution, Capsules powder and liquid filled, Suspension, Ointment, Cream, Gel, Aerosol

What are solutions?

are clear liquid preparations containing one or more active ingredients dissolved in a suitable vehicle.

What are suspensions?

Solid in liquid dispersion

What are emulsions?

Liquid in liquid dispersion

Size of colloids?

1 micrometer

Another definition of solution.

a homogenous mixture composed of two or more substances.

Route of administration for solutions.

Oral, Otic(ears), Ophthalmic, Topical(over the skin)

What are the 2 syrups aqueous solutions containing sugar?

Elixir and Spirit

What is an elixir?

sweetened hydro-alcoholic (combination of water and ethanol solution). 5-15%

What is a spirit?

sweetened hydro-alcoholic (combination of water and ethanol solution). 60-70%

Example of aqueous solutions.

sugar in water, carbon dioxide in water

Signs of instability in drugs

Color change, precipitation, microbial growth, chemical gas formation.

What are the size coarse dispersions?

1 - 200 micrometers

What is better for coarse dispersions?

emulsions and suspensions

Types of simple.macro emulsions

OIl in water, water in oil

Types of multiple emulsions

Oil in water in oil, Water in oil in water.

Determination of emulsion type tests.

1. Dilution Test

2. Dye Test

3. Drop Test

Lipophillic agents

(oil-soluble, low HLB) surfactants are used to stabilize w/o emulsions

Hydrophillic agents

hydrophilic (water-soluble, high HLB) surfactants are used to stabilize o/w systems.

Size of Microemulsions

What is an emulsifying agent

They are the substances added to an emulsion to prevent the coalescence of the globules of the dispersed phase.

Hydrophilic-Lipophilic Balance (HLB) System

- HLB system was developed to assist in making systematic decisions about the amounts and types of surfactants needed in stable products.
- It has an arbitrary scale of 1-18, but some compounds have values greater than 18.

HLB Value 1-3

Antifoaming agents

HLB Value 3-8

Emulsifying agents w/o emulsions

HLB Value 7-9

Wetting agents

HLB Value 8-16

Emulsifying agents for oil in water emulsions

HLB Value 13-16

Detergents

HLB Vaule 15-20

Solubizing Agents

Which surfactant has a higher than 20 HLB value?

Sodium Lauryl Sulphate

What are the 3 Synthetic Emulsifying agent groups?

Anionic, Cationic, Non-ionic

Anionic surfactants

Surfactant ion bears a negative charge, free HIGH pH

Cationic surfactants

Surfactant has a positive charge, a good example is Benzethonium chloride. Can only be used to external topical use.

Non-ionic surfactants

Undissociated surfactants. Don't have a pH, so it is preferred more with forming emulsions.

What is meant by GRAS?

Generally recognized as safe.

When a solution is hypertonic...

you DONT need a preservative

When a solution is hypotonic...

you DO need a preservative because of the low concentration of particles

Examples of preservatives

Benzoic Acid

Alcohol

Phenol

Phenylmercuric Nitrate

Cresol

Chlorobutanol

Methylparaben

Benzalkonium Chloride

Aldhydes, Phenolics, Quaternaries - Chlor, Mercurials

Why do we need preservatives?

For lysis and cytoplasmic leakage, modification of cell permeability, hydrolysis.
Fight spoilage caused by bacteria, molds, fungus, and yeast.

Creaming

Unstable emulsions, there is downward and upward. This is when the oil globules go upwards or downwards. Creaming can be reversible by agitation.

Flocculation(early stages of creaming)

This is when nearing globules come closer together and form colonies. Have not gone up pr downward yet. Is reversible

Coalescence(crossed the creaming stage)

- Is NOT reversible

Breaking

Two separate layers of emulsions that does not want to come together at all. Also Irreversible.

What is stokes law?

used to explain velocity of sedimentation

The higher the particle size...

the faster the velocity

How to overcome creaming?

- Reduce particle size by homogenization.
- Raise the viscosity of the external phase. HIGHER Viscosity, the LOWER the Velocity
- Lowering the density of the internal phase and the external phase. The less of a difference between the ps and the po, the LOWER the velocity

How does Coalescence occur?

1. Not enough of the emulsifying agent.

2. Altered partitioning of the emulsifying agent.

3. Incompatibilities between emulsifying agents

What type of suspension are propellents?

NON AQUEOUS

What is sedimentation?

settling of a particle of FLOCULES occur under gravitational force in liquid dosage form.

What are the types of suspending agents?

Natural, Semi-Synthetic, Synthetic

HLB Value 6-8

Suspensions

Example of preservative for lotion.

Propylparaben