Semisolids

Question 1

semisolid preparations intended for external
application to the skin or mucous membranes. They usually, but not always, contain medicinal substances. The types of _______ bases used as vehicles for drugs are selected or designed to facilitate drug transfer into the skin.

Answer 1

Ointment

Question 2

use for wet wounds

Answer 2

Creams

Question 3

use for dry wounds

Answer 3

Ointment

Question 4

function as protectives and emollients for the skin, but are used primarily as vehicles or bases for the topical application of medicinal
substances.

Answer 4

Ointment

Question 5

An ointment base should be:

Answer 5

compatible w/ the skin,
stable,
permanent,
smooth & pliable,
nonirritating,
non sensitizing,
inert,
readily able to release its incorporated medication.

Question 6

The USP recognizes four general classes of ointment bases:

Answer 6

1. hydrocarbon bases (i.e., oleaginous bases)
2. absorption bases
3. water-removable bases
4. water-soluble bases.

Question 7

an emollient effect, protect against the escape of moisture, occlusive dressing, remain on the skin (prolonged periods) w/o drying = immiscible in H2O.
H2O & aqueous preparations may be incorporated but only in small amounts and w/ some difficulty.
When incorporating powder into hydrocarbon bases, used levigating agent liquid petrolatum (mineral oil).

Answer 7

HYDROCARBON (OLEAGINOUS) BASES

Question 8

1. HYDROCARBON (OLEAGINOUS) BASES Examples:

Answer 8

● White Ointment
● Yellow Ointment
● Cetyl Esters Wax
● Oleic Acid
● Paraffin
● Petrolatum
● White Petrolatum

Question 9

contain an oleaginous material and a water-in-oil (w/o) emulsifier so they can absorb H2O to form or expand w/o (water-in-oil) emulsions, useful as emollients, do not provide the degree of occlusion afforded by the oleaginous bases. Soften and soothe the skin, reduce the dryness and scaling of skin. Greasy; external phase of the emulsion is oily. Not easily removed from the skin with water.

Answer 9

2. ABSORPTION BASES
   2 Types:
   Anhydrous bases - permit the incorporation of aqueous solutions, = w/o (water-in-oil) emulsions. ex. Hydrophilic petrolatum USP
   Bases that are already w/o (water-in-oil) emulsions (emulsion bases) - permit
   the incorporation of small additional quantities of aqueous solutions. ex. Lanolin & Cold cream

Question 10

Commercially available absorption bases include;

Answer 10

● Aquaphor (Beiersdorf) and Polysorb (Fougera).
● Nivea Cream (Beiersdorf)

Question 11

they are O/W (oil-in-water) emulsion bases, commonly referred to as “creams”, commonly used type of ointment base. The majority of commercial dermatologic drug products are formulated in
an emulsion (or cream) base.
➢ Emulsion bases are washable & removed easily from skin/clothing.
➢ They can be diluted with H2O, although such additions are uncommon.

Answer 11

3. WATER-REMOVABLE (WATER-WASHABLE) BASES
   Two groups:
4. Emulsion ointment base water-in-oil (W/O) type
5. Emulsion ointment base oil-in-water (O/W) type.

Question 12

soluble components or may include gelled aqueous solutions (gels). Formulated specifically to
maximize drug availability.
➢ Major components & in some instances the only components, of water-soluble bases are the polyethylene glycols (PEGs). Innocuous, long-term use, nonirritating.
PEGs are relatively inert, nonvolatile, water-soluble or water-miscible liquids or waxy solids identified by numbers that are an approximate indication of molecular weight. Polyethylene glycol 400 is a liquid superficially similar to propylene glycol, while polyethylene glycol 6000 is a waxy solid.

Answer 12

4. WATER SOLUBLE BASES

Question 13

CHARACTERISTICS OF AN IDEAL OINTMENT BASE:

Answer 13

● Stable
● Neutral in nature
● Non greasy
● Non-toxic
● Non-irritant
● Non dehydrating
● Non hygroscopic
● Non staining
● Non pH dependent
● Non degreasing in action
● Water removable
● Compatible with all medicaments
● Free from objectionable odor
● Efficient on all types of skin
● Capable of stock preparation for extemporaneous use
● Melting or softening at body temperature
● Capable of holding at least 50% water
● Composed of readily available ingredients of known chemical composition.

Question 14

Manufacturing Procedure of Ointment:

Answer 14

A. Automatic Process: aqueous phase dissolved in H2O (“water phase”) + oil & components (“wax phase”). mix + heat + ointment manufacturing vessel + drug component + mix + heat
B. Semi-Automatic Process: H2O + heat + wax, then stirred, + drug components + continuous heating and stirring + colloid mill +triple roller mills.

Question 15

is an ideal tool for the pharmaceutical & cosmetic
industries for the production of Ointment, Cream, Lotions, Toothpaste & other emulsions & homogenizations. It is specially designed to take care of two critical factors that directly affect the quality of the Ointment / Creams.

Answer 15

Ointment Manufacturing Plant

Question 16

Method of preparation of ointment:

Answer 16

1. Incorporation.
2. Fusion.

Question 17

This method, the components are mixed until a uniform preparation is attained; this is done by using mortar and pestle or slab and spatula.
Subdivided:
A) Incorporation of solids:
B) Incorporation of liquids:

Answer 17

1.Incorporation:

Question 18

all or some of the components of an ointment are combined by being melted together and cooled with constant stirring until congealed. Components not melted are added to the congealing mixture as it is being cooled and stirred.

Answer 18

2. Fusion:

Question 19

Ointment Storage and Dispensing:

Answer 19

Stored in tightly closed and completely filled containers.
Changes in temperature can lead to the crystallization of the drug and to changes in the ointment base.
Dispensed in jars of glass or plastic material/ collapsible tubes.
Sterile ointments: dispensed in tubes or single dose units to protect product against contamination during use.
W/ tin tubes, risk of corrosion with hydrophilic ointments.

Question 20

The various types of ointments are:

Answer 20

Unmedicated ointments: do not contain any drugs. They are useful as emollients, protectants.
Ex:Petroleum jelly
Medicated ointments: contain drugs which show local or systemic effects.
Ex: Hydrocortisone acetate Ointment

● Dermatological ointments - Ketoconazole ointment, Demodex ointment & Nitroglycerine ointment.
● Ophthalmic ointments - Sulfacetamide sodium ointment
● Rectal ointments - Benzocaine ointment
● Vaginal ointments - Candicidin ointment
● Nasal Ointments - Ipratropium bromide ointment

Question 21

viscous liquid or semisolid emulsions of either the O/W or W/O type. Pharmaceutical creams are classified as water-removable bases in the USP and
are described under Ointments.
O/W: shaving creams, hand creams, foundation creams
W/O: cold creams & emollient creams.

Answer 21

Creams

Question 22

Characteristics of Creams:

Answer 22

Absorption: high water content, easily absorbed, can cover large areas of skin. Their oil content means they stay on skin’s surface to help protect against moisture loss, which makes them ideal for treating dry
skin, rashes or skin lesions.
Consistency: smooth texture w/ thicker consistency than lotions, which tend to be runnier, non-greasy to mildly greasy.
Appearance:

Question 22

Characteristics of Creams:

Answer 22

Absorption: high water content, easily absorbed, can cover large areas of skin. Their oil content means they stay on skin’s surface to help protect against moisture loss, which makes them ideal for treating dry
skin, rashes or skin lesions.
Consistency: smooth texture w/ thicker consistency than lotions, which tend to be runnier, non-greasy to mildly greasy.
Appearance: Because of O/W ratio, tend to be thick enough to maintain their shape whether squeezed from a tube or scooped from a jar, opaque and viscous.

Question 23

Understanding the process involved in creams:

Answer 23

Preparation of the oil phase:
Hydration of aqueous phase ingredients:
Forming the emulsion:
Dispersion of the active ingredient:

Question 24

is designed for mixing thick body cream mixtures and other skincare products with a viscous body.

Answer 24

Cream mixer

Question 25

improve the particle size and consistency of creams by managing mixing times and reaction rates.

Answer 25

Industrial grade mixers

Question 26

perform high shear mixing through homogenization,
emulsification, and blending cosmetic cream ingredients into a consistent, viscous cream.

Answer 26

Propeller mixer

Question 27

can improve the consistency of creams by minimizing the reduction rate.

Answer 27

three-roller mix

Question 28

Pharmaceutical examples of the Cream:

Answer 28

• Cold Cream
• Cleansing Cream
• Vanishing Cream
• Foundation cream
• Moisturizing Cream
• Cream Base
• Antimicrobial preservatives in creams

Question 29

(sometimes called jellies) are semisolid systems consisting of dispersions of small or large molecules in an aqueous liquid vehicle rendered jellylike by the addition of a gelling agent. Usually clear transparent semisolids, homogenous, have a viscous consistency, fluid, elastic and plastic.

Answer 29

Gels

Question 30

are aqueous colloidal system of hydrated forms of insoluble medicaments.

Answer 30

Gels

Question 31

are transparent or translucent, nongreasy, semisolid, and contain more water than gel

Answer 31

Jellies

Question 32

Gels may be thickened on standing, forming a ______, and must be shaken before use to liquefy the gel and enable pouring. Because of high degree of attraction between the dispersed phase and water medium, the gels remain fairly uniform upon standing and does not readily settle.

Answer 32

THIXOTROPE

Question 33

gelling agents examples:

Answer 33

carbomer 940
cellulose derivatives (carboxymethylcellulose or hydroxypropyl methylcellulose.
natural gums (tragacanth)
alcohol and/or propylene glycol.
antimicrobial preservatives (methylparaben and propylparaben or chlorhexidine gluconate)
stabilizers (edetate disodium)

Question 34

Gels is classified as:

Answer 34

Two-phase system
Single-phase gels

Question 35

Two-phase system: if the particle size of the dispersed phase is relatively large, the gel mass is sometimes referred to as a _____.

Answer 35

magma

Question 36

Single-phase gels: may be made from synthetic macromolecules or from natural gums. The latter preparations are also called ______.

Answer 36

mucilage

Question 37

Types of Gel:

Answer 37

Hydrogel - Include ingredients that are dispersible as colloidal or soluble in water; they include organic hydrogels, natural and synthetic gums, and inorganic
hydrogels. It is a network of polymer chains that are hydrophilic or colloidal gel in which water is the dispersion medium. Highly absorbent and presents a degree of flexibility.
Organogel - include the hydrocarbons, animal and vegetable fats, soap base greases, and the hydrophilic organogels. Solid materials composed of liquid organic phase entrapped in three-dimensional cross-linked network; non-crystalline, non-greasy, thermoplastic.
Xerogels - gels in which vehicles has been removed, leaving a polymer network

Question 38

are substances which, when added to an aqueous mixture, increase its viscosity, without substantially modifying its other properties, such as taste. They provide body, increase stability, and improve suspension of added ingredients.

Answer 38

Gelling agents

Question 39

Preparation of Gels:

Answer 39

Step 1: By freshly precipitating the dispersed phase upon reacting an inorganic agent, a gelatinous precipitate results.
Step 2: By direct hydrating the inorganic material in water

Question 40

Applying the different methods of production in Gels:

Answer 40

1. Fusion Method - In this method various waxy materials are employed as gellant in non polar media.
   ➢ Drug was added when waxy materials melted by fusion.
2. Cold Method - Water was cooled to 4-10°c and placed in a mixing container.
   ➢ Gelling agent was slowly added and agitated until the solution was complete.
   ➢ Maintained temperature below 10°c.
   ➢ Drug was added in solution form slowly with gentle mixing.
   ➢ Immediately transfer to container & allow to warm to R.T whereupon liquid becomes clear gel.
3. Dispersion Method - Gelling agent was dispersed in water while stirring at 1200 rpm for 30 min.
   ➢ Drug was dissolved in a non-aqueous solvent with a preservative.
   ➢ This solution was added in the above gel with continuous stirring.

Question 41

machines and equipment used for production of gels:

Answer 41

Colloidal Mill - consists of two steel discs. Here one disc rotates and another one is stationary. When
the material is passed through these discs they get sheared. Thus, coarse particles break down to small particles due to shear.
Sigma Blade Mixer - sigma shaped blades create high shear.
Double-planetary Mixer - well-proven equipment for the processing of pharmaceutical gels.
● Traditional designs move material by rotating two rectangular-shaped paddles on their respective axes as they orbit on a common axis.
● The blades contact virtually every point of the batch in just 36 revolutions, imparting a very thorough but gentle mixing action
Arenco Tube-filling Machine - Automatically fills 125 tubes a minute with the proper amount, tightens the cap, orients each tube by electric eye so that the label faces forward, then closes and crimps the end.
Stainless Steel Jacketed Kettle with Agitator - Used for mixing liquid and slightly solid materials, specifically, for the hydrogel’s preparation.

Question 42

Pharmaceutical examples of gels:

Answer 42

1. Clobetasol Propionate - Temovate Gel
   Dermatologic: Antipruritic
2. Acetic Acid - Aci-gel
   Vaginal: Restoration and maintenance of acidity
3. Progesterone - Crinone jel
   Vaginal: Bioadhesive gel; progesterone supplement and replacement
4. Benzoyl peroxide - Desquam-X Gell
   Dermatologic: acne vulgaris
5. Metronidazole - MetroGel Vaginal
   Vaginal: bacterial vaginosis
6. Podofilox - Condylox Gel
   Rectal: anogenital warts

Question 43

In broad terms, semisolid preparations may be classified as ointments, creams, pastes, and gels.

Though the nature of the underlying structures differ remarkably across all the different semisolid systems, they allbshare the property that their structures are easily broken down, rearranged, and reformed.

Answer 43

N/A

Question 44

Composed mostly of fluid hydrocarbons meshed in a matrix of higher melting solid hydrocarbons.

Common examples of ___ bases include mineral oil, petrolatum, and polyethylene glycol.

Answer 44

Ointments

Question 45

are semisolid emulsion systems with an opaque appearance. Their consistency and rheological properties are based on whether the emulsion is o/w or w/o and on the nature of the solid in the internal phase.

Answer 45

Creams

Question 46

are basically ointments into which a high percentage of insoluble solids has been added. Powders such as zinc oxide, titanium dioxide, starch, and kaolin are incorporated in high concentrations into a preferably lipophilic greasy vehicle to form a ____ like mass.

Answer 46

Pastes

Question 47

are semisolid systems in which a liquid phase is constrained within a three-dimensional polymeric matrix in which a high degree of physical cross-linking has been introduced.

Answer 47

Gels

Question 48

In general, ointment bases may be classified into four general groups: Hydrocarbon, Absorption, water-removable, and water soluble bases.

▶️Hydrocarbon Bases also known as oleaginous bases, the hydrocarbon bases are essentially water-free, incorporating aqueous preparations only in small amounts and with considerable difficulty.
- Hydrocarbon vehicles have several advantages, such as stability and emolliency; however, they suffer from one major disadvantage- greasiness which may stain clothing and is usually difficult to remove

-The primary features of this type of base include its emollient effect, retention on the skin for prolonged periods, prevention of escape of moisture from the skin to the atmosphere, and difficulty in washing off.

They act as occlusive dressings, thus increasing skin hydration by reducing the rate of loss of surface water.

Also, they do not dry out or change noticeably on aging. Hydrocarbon-based semisolids comprise fluid hydrocarbons C16 to C30 straight chain and branched, entrapped in a fine crystalline matrix of yet higher- molecular-weight solid hydrocarbons. Common examples of these bases include:
•Petrolatum, USP -va mixture of semisolid hydrocarbons obtained from petroleum. It is an unctuous mass, varying in color from yellowish to light amber. It melts at temperatures between 38 and 608C and may be used alone or in combination with other agents as an ointment base.
•White petrolatum, USP-a petrolatum that has been decolorized, either partially or wholly. It is used for the same purpose as petrolatum but is more esthetically acceptable to a patient than petrolatum because of its lighter color.
•Yellow ointment, USP - the purified wax obtained from the honeycomb of the bee. It contains 5% yellow wax and 95% petrolatum in the formulation.
•Mineral oil - a mixture of liquid hydrocarbons obtained from petroleum. These are useful as levigating agents to wet and incorporate solid substances (e.g., salicylic acid, zinc oxide) into the preparation of ointments that consist of oleaginous bases as their vehicle.
There are two types of mineral oils listed in the U.S. Pharmacopeia / National Formulary (USP/NF).
1. Mineral oil USP - also called heavy mineral oil with a specific gravity between 0.845 and 0.905.
2. Light mineral oil, NF - has a specific gravity between 0.818 and
0.880
▶️Absorption Bases- are hydrophilic, anhydrous materials (w/o emulsions) or hydrous bases (w/o emulsions that have the ability to absorb additional water). Addition of lanolin, lanolin isolates, cholesterol, lanosterol, or acetylated sterols renders the hydrocarbon base hydrophilic.
Such hydrophilic mixtures have been known as absorptionb bases.
These bases are useful as emollients, although they do not provide the degree of occlusion as oleaginous bases. They are also used pharmaceutically to incorporate aqueous solutions of drugs (e.g., sodium sulfacetamide solution) into oleaginous bases.
A typical example of an anhydrous absorption base is hydrophilic petrolatum, USP.

Commercially available absorption bases include Aquaphor and Polysorb.
A new group of w/o emulsifiers based on the linkage of polymethoxysiloxane chains with alkyl side chains and polyol groups known as organosilicone polymers, have the capability of producing w/o emulsions with a high water content.
Although the polymethylsiloxane chains possess both hydrophilic and lipophilic properties, the alkyl side chains supply the necessary lipophilic and polyol groups to provide the hydrophilic characteristics of the emulsifier.
Other examples of w/o emulsifiers include cetyl dimethicone copolymer, polyethylene glycol-20- com glycerides, and at series of caprylic-capryl stearates.
▶️Water-Removable Bases (Water-Washable Creams) - These are the most commonly used o/w emulsion bases that are capable of being washed from skin or clothing with water.
They may contain water-soluble and insoluble components. From a therapeutic viewpoint, they have the ability to absorb serous discharges in dermatologic conditions.
The water-removable bases form a semipermeable film on the site of application after the evaporation of water.
A typical water-removable emulsion base is hydrophilic ointment, USP and vanishing cream.
▶️Water-Soluble Bases - These bases contain only water-soluble components.
Water-soluble bases are also referred to as greaseless because of a lack of oleaginous materials. Incorporation of aqueous solutions is difficult because they soften greatly with the addition of water.
They are better used for nonaqueous or solid substances. Polyethylene glycols (PEG) make up the majority of components of the watersoluble base.

Answer 48

N/A

Question 49

Gelling agents-commonly used are synthetic macromolecules (e.g., carbomer 934), cellulose derivatives (e.g., carboxymethylcellulose and hydroxypropylmethylcellulose), and natural gums (e.g., tragacanth).

Carbomers in particular are high-molecular-weight water-soluble polymers of acrylic acid cross-linked with allyl ethers of sucrose and/or pentaerythritol.

The NF contains monographs for six such polymers: carbomers 910, 934, 934P, 940, 941, and 1342. They are used as gelling agents at concentrations of 0.5-2.0% in water. Carbomer 940 yields the highest viscosity: between 40,000 and 60,000 CP as a 0.5% aqueous dispersion.

Depending on their polymeric composition, different viscosities result. Gels may be classified as two-phase or single-phase systems.

A two-phase gel system consists of floccules of small distinct particles rather than large molecules, thus called a two-phase system often referred to as a magma.

Answer 49

N/A

Question 50

Antimicrobial preservatives such as methylparaben (0.05%) and propylparaben (0.01%) and its combinations phenylmercuric acetate (0.0008%), chlorobutanol (0.5%), and benzalkonium chloride (0.008%) are used.

In the case of emulsion manufacture, the process of heating between 70 and 80.8°C usually kills most of the microorganisms.

Answer 50

Preservatives

Question 51

Mechanical mixers are used to prepare ointments in large quantities, especially in the Pharmaceutical industry.

Stainless steel kettle mixers may be used to manufacture hydrocarbon and water-soluble base ointments

The stainless steel kettle is jacketed for heating and cooling and is equipped with a mixing device. The kettle configuration is especially well-suited for the melting and mixing of oils and waxes and for complete bottom emptying.

Depending on the formulation to be processed, the mixer may be either a

propeller or an anchor-agitator design. If the formulation is primarily liquid, a propeller mixer is more suitable.

If the formulation consists of solid waxes, lanolin, petrolatum, and similar components, a kettle with a removable agitator is suitable.

Answer 51

Incorporation (Industrial scale)

Question 52

Planetary mixers may also be used for largescale preparations of the ointments. Here, the finely divided powdered materials are added slowly or sifted into the vehicle (ointment base) previously placed inside the rotating mixer.

On achieving a uniform consistency, the ointment preparation may be processed through the roller mill to ensure complete dispersion and reduce the size of aggregates that may have formed during processing.

The roller mills force the coarsely formed ointments through stainless steel rollers to produce ointments that are uniform in composition and smooth in texture.

Answer 52

N/A

Question 53

The process of ___ uses heat to melt all or some of the components of the ointment; the mixture is then allowed to cool with constant stirring until congealed.

Additional components of the ointment preparation that were not subject to the initial melting process are added to the congealing mixture as it is being cooled and stirred.

Heatlabile substances are added to the preparation after careful observation that the temperature of the mixture is sufficiently low so as not to cause decomposition or volatilization of the components.

All the other components may be added with constant stirring

and cooling of the melt until the mixture is congealed. Alternatively, the component with the lowest melting point may be added first. With increasing temperature, the remaining materials may be added to melt the entire mixture and then the process of cooling and congealing.

Some common examples of components that are subjected to the fusion process include beeswax, paraffin, stearyl alcohol, and high-molecular-weight polyethylene glycols (PEG). The order of addition of components in the process of fusion plays a role in the manufacture of ointments.

Answer 53

Fusion

Question 54

Emulsions are prepared by means of a two-phase heat system. In the first phase, the oil phase ingredients are combined in a jacketed tank and heated between 70 and 75.8°C to melt or liquefy all the ingredients to a uniform state.

In a separate tank, the second phase, aqueous phase ingredients are heated together to slightly above 75.8°C.

The aqueous phase is then slowly added to the oil phase through constant agitation.

The mixture is cooled slowly with continuing agitation as the emulsion is formed. The medicinal ingredients may be added when the emulsion is in the cooling stage. For capacities of 200 gallons or less, a single high-turbulence agitator may be used in most cases.

For larger batches of up to 1000 gallons, a large-scale multiagitator mixer may be used that involves a mixer-emulsifier (for high degree of shear), a high-speed disperser (to disperse solids into viscous liquids), and an anchor-agitator (to provide maximum movement of product under low shear conditions in the mix vessel).

Answer 54

Emulsion Products

Question 55

To improve the stability of the oil phase, colloid mills may be used to disperse the oil phase further once the emulsion is formed.

A homogenizer may be used to reduce the size of the oil globules by exerting a smearing action in which the emulsion is forced through a small orifice under high pressure.

The advantage of the homogenizer over the colloid mill is that it does not incorporate air into the emulsion. The throughput of the homogenizer is 10-100 times lower than that of the colloidal mill.

Another in-line method of emulsification is the ultrasonic process, which uses a sonolator

This process uses a very high-intensity mixing device that mechanically generates ultrasonic acoustic energy to produce emulsions and dispersions.

Liquid to be processed is pumped through a special orifice, forming a flat, high-pressure stream. This jet impinges on the edge of a flat blade enclosed in a tube, causing it to vibrate at ultrasonic frequencies.

Cavitation produces violent local pressure changes that act on the liquid, causing instantaneous and intense dispersion of any immiscible liquids or insoluble particles.

Answer 55

N/A

Question 56

Packaging:

Answer 56

The packaging of semisolid products, usually in jars and tubes, represents the best and worst conditions for microbial contamination. When using jars, the risk of contamination is higher time fingers touch the product.
semisolid products in jars require a highly effective, long-acting preservative system to remain active throughout the life of the product. With tubes, the risk of microbial contamination is significantly reduced because they expose only a very small area each time a cap is removed.
Tubes also provide control of dose by an amount expressed with minimum exposure to the environment or human contact. Therefore, because products packaged in tubes are less likely to become contaminated, the use of preservative is also reduced.

All drug product containers and closures must be approved by stability testing of the product in the final container in which it is marketed.
The stability test includes testing filled containers at room temperature (e.g., 70°F) as well as under accelerated conditions (e.g., 105 and 120°F).
Opaque jars are used to protect light-sensitive products and are available as porcelain white or dark green or amber in color. Plastic containers used for emulsion systems must be thoroughly evaluated for physical and chemical changes in the emulsion as well as for physical changes in the container.

Question 57

Stability testing is a routine procedure performed on drug substances and products. It is involved at various stages of product development. In early stages, accelerated stability testing (at relatively high temperatures and/or humidities) can be used to determine the types of degradation products that may be found after long-term storage. Testing under more gentle conditions (those recommended for long-term shelf storage) and slightly elevated temperatures can be used to determine product shelf life and expiration dates.

According to the FDA draft guidelines to the industry,semisolid preparations should be evaluated for appearance, clarity, color, homogeneity, odor, pH, consistency, viscosity, particle size distribution (when feasible), assay, degradation products, preservative and antioxidant content (if present), microbial limits/sterility, and weight loss (when appropriate).
Additionally, samples from production lots of approved products are retained for stability testing in case of product failure in the field. Ointments, pastes, gels, and creams in large containers including tubes should be assayed by sampling at the surface, top, middle, and bottom of the container. In addition, tubes should be sampled near the crimp.
Tests for evaluating the compatibility of the product with the container include weight loss and moisture loss (if applicable). Reduction in the concentration of critical ingredients would indicate loss owing to binding with the container material or permeation through the container walls.

Answer 57

Stability