Semi-Solid Dosage form

Part 1

Examples of semi-solid dosage forms

• Ointments

• Creams

• Gels

Semi-Solid Dosage forms

Is a dosage form that is intended for topical application

Ointments

Semi-solid application intended for external application to the skin or mucous membrane.

• Medicated ointments

• Unmedicated ointments

Types of Ointments

• Oleaginous bases

• Absorption bases

• Water-removable bases

• Water-soluble bases

Types of ointment bases

Medicated ointments

Ointments are used for the effects of therapeutic agents they contain

Unmedicated Ointments

Ointments that are used for their physical effects such as a protectant, emollient, lubricant or as a vehicle for the medicated ointments 

Emollient

Softening or soothing effect to our skin

Lubricant

An agent that minimizes friction

Protectant

Provide protection against diseases and UV radiation

• Oleaginous bases

• Absorption bases

• Water-removable bases

• Water-soluble bases

USP classified ointment bases into four groups, they are?

• Petrolatum

• White petrolatum

• Yellow ointment

• White ointment

Examples of oleaginous bases

• Hydrophilic petrolatum

• Lanolin

Examples of absorption bases

Hydrophilic ointment

Examples for Water-removable bases 

Polyethylene glycol (PEG)

Examples for Water-soluble bases

Hydrocarbon Bases

Oleaginous bases are also known as

Occlusive dressings

Oleaginous Bases are effective as??

Oleaginous bases

• They have an emollient effect

• Protect against the escape of moisture/hold moisture

• Immiscible with water

• Difficult to wash

Petrolatum, USP (Yellow petrolatum)

Purified mixture of semisolid hydrocarbons obtained from petrolatum

Petrolatum, USP (Yellow petrolatum)

Its characteristics are

• Color: Yellowish to light amber

• Melting point: 38 C to 60 C

• Commercial product: Vaseline

Vaseline

A commercial product of yellow petrolatum?

38 C to 60 C

Melting point of Petrolatum, USP

White Petrolatum, USP

• Purified mixture of semisolid hydrocarbon from petroleum that has been wholly or nearly decolorized

• Lighter color thus considered more aesthetically pleasing

• Commercial product: White Vaseline

White Vaseline

Commercial product of white petrolatum?

Yellow ointment USP

• Is a preparation containing yellow wax + petrolatum

• It’s characteristics is it has slightly greater viscosity than plain petrolatum

50g Yellow wax + 950g Petrolatum

What is the formulation of Yellow ointment

Simple ointment

Other name for Yellow Ointment, USP

White ointment, USP

Differs from yellow ointment by substitution of white wax and white petrolatum in the formula

White wax

Is a bleach and purified yellow wax?

(Hydrophilic petrolatum)

Permit the incorporation of aq solutions resulting to an W/O Emulsion

(Lanolin)

W/O emulsions/emulsion bases that permit the incorporation of additional quantities of aq solutions

• Hydrophilic petrolatum

• Lanolin

Two Types of Absorption Bases

• Has emollient effect

• Oleaginous external phase

Characteristics of Absorption Bases

Hydrophilic Petrolatum, USP

Is a preparation containing:
Cholesterol + Stearyl alcohol + White wax + White petrolatum

Formulation:
30g Cholesterol

30g Stearyl Alcohol

80g White wax

860g White petrolatum

Formulation of Hydrophilic Petrolatum, USP

Aquapor

Commercial product example for Hydrophilic petrolatum, USP

Aquaphor

is a variation of hydrophilic petrolatum that has the capacity to absorb 3 times its weight in water and useful to help incorpoate water soluble drug into oleaginous bases.

Lanolin, USP (Anhydrous Lanolin)

A purified, wax-like substance that has been cleaned, deodorized and decolorized from the wool of sheep (Ovis aries)

0.25% water content

How much content of water is present in Lanoin, USP

Water-removable bases (Water-washable bases)

• O/W emulsion type

• Aq external phase

• Can absorb serous discharge

  • Hydrophilic ointment, USP

Hydrophilic ointment, USP

Preparation containing 

• Methylparaben and propylparaben

• Sodium Lauryl Sulfate

• Propylene Glycol

• Stearyl Alcohol

• White Petrolatum

• Purified Water

Methylparaben and Propylparaben

Antimicrobial preservatives in the preparation of Hydrophilic Ointment, USP

Sodium Lauryl Sulfate

Emulsifying agent in the preparation of Hydrophilic ointment, USP

Stearyl alcohol and White petrolatum

constitutes to oleaginous base in the preparation of Hydrophilic Ointment

Water-Soluble bases (Greaseless)

Characteristics:

• Do not contain oleaginous components

• Completely water-washable

The incorporation of solid substances

Water-soluble bases are used for?

PEG (Polyethylene Glycol) Ointment

Example base of water soluble bases

Polyethylene glycol ointment, NF

Is a polymer of ethylene oxide and water represented by formula H(OCH2CH2)nOH

Clear, colorless liquids

in PEG, a molecular weight below 600 are?

Wax-like white materials

in PEG, the molecular weight above 1000 are?

Semisolids

in PEG, Molecular weight in between 600-1000 are?

Viscosity

The greater the molecular weight in PEG the higher the?

• Desired release rate of the drug substances from the ointment base

• Desirability of topical or percutaneous drug absorption

• Desirability of occlusion of moisture from the skin

• Stability of the drug in the ointment base

• Effect for the drug on the consistency or other features of the ointment base

• Desire for a base easily removed by washing with water

• Tangina andame

Factors in selecting the appropriate ointment base

• Incorporation

• Fusion

Methods in preparing ointments

Incorporation

Method in preparing ointments in which components are mixed until uniform preparation is attained.

Fusion

Method in preparing ointments in which components are combined by being melted together and cooled with constant stirring until congealed.

• mortar and pestle

• ointment slab and spatula

• ointment mill, electronic mortar and pestle, unguator

Equipment used in Incorporation

• spatulation

• Levigation

• Pulverization by intervention

Methods used in incorporation of solids

• what method is intended for materials which do not lend themselves well to mixture by incorporation.

Incorporation of liquid

liquid substances or solutions of drugs are added to an ointment

Fusion

What method is intended for materials which do not lend themselves well to mixture by incorporation

• beeswax

• Paraffin

• Stearyl alcohol

• High MW PEGs

Examples of components that incorporate fusion

Ointments and other semisolid dosage forms must meet USP tests for

• Microbial content

• Minimum fill

• Packaging, storage and labelling

• Sterility and Metal Particles (Opthalmic Ointment)

Compendial requirements for ointments

• Methylparaben and propylparaben

• Phenols

• Benzoic acid

• Sorbic acid, and quaternary ammonium salts

Examples of Antimicrobial preservatives

• Staphyloccocus areus

• Pseudomonas aeruginosa

preparations with microbial content must meet the tests for absences of ?

• Yeasts

• Molds

Preparations with microbial content intended for rectal, urethral or vaginal use should be tested for

Minimum Content

Determination of the net weight or volume of the contents of filled containers to ensure proper contents compared with labelled amount.

• Large-mouth ointment jars

• Metal/plastic tubes

Appropriate packaging for ointments?

• Well-closed containers

• Must store in a cool place

Storage condition for ointments?

Should include the type of base used in ointments and creams

Labeling of ointments?

Creams

Semisolid preparation containing one or more medicinal agents dissolved in either W/O emulsion or an O/W emulsion or in another type of water-washable base.

• Vanishing cream

• Cold cream

Two types of creams

• more preferred than ointment

• Ease of spreadability and remove

• Less viscid and lighter than ointment

• Greater aesthetic appeal for their non-greasy character

• Ability to vanish into the skin upon rubbing

• Absorbs serous discharge from skin lesions

Advantages of Creams

Gel (Jellies)

Semisolid systems consisting of dispersions of small or large molecules in an aq liquid vehicle rendered jellly-like by the addition of gelling agent

• Synthetic macromolecules (Carbomer)

• Cellulose derivatives (Carboxymethylcellulose) (HPMC)

• Natural gum (Tragacanth)

Examples of gelling agents

Carbomers

A gelling agent that is used in a concentration of 0.5% to 2%

Single-phase gels

a phase of gels where macromolecules are distinguished somewhat uniformly in a liquid vehicle and no apparent boundary can be seen

Two-phase gels

a type of gel where it is made up of flocculated small distinct particles

Thickens on standing, forming a thixotrope

Characteristics of gels

Thixotrope

Is a time dependent viscosity

First classification scheme

Second classification scheme

Classification of gels

• inorganic gels

• Organic gels

Two categories of gels in first classification scheme

• Hydrogels

• Organogels

Two categories of gels in second classification scheme

Inorganic gels

Usually two-phase systems

Organic gels

Usually singe-phase systems

Hydrogels

organic and inorganic; synthetic gums

Organogels

Hydrocarbon type, can be polar and nonionic

Penetration enhancer

Are those topical ointment, creams and gels designed to deliver a drugs systematically through the addition of 

Transdermal Preparation

Are those topical ointment, creams and gels designed to deliver a drugs systematically through the addition of Penetration enhancer

• pastes

• plasters

• glycerogelatins

Types of miscellaneous semisolid preparations

Pastes

Semisolid preparations applied into the skin which generally contains larger proportion of solid material (About 25%) than ointment

• Stiffer than ointments

• Impenetrable

Characteristics of Pastes

Zinc oxide paste (Lassar’s plain zinc paste)

Example of Pastes

Lassar’s plain zinc paste

Other name of zinc oxide pastes

Plasters

Solid or semisolid adhesives masses spread on a backing of paper, fabric, moleskin or plastic that is applied to the skin to provide prolonged contact at the site

Nonmedicated plasters

Provide protection or mechanical support at the site of application

Medicated plasters

Provides effects at the site of application

• gelatin (15%)

• Glycerin (40%)

• Water (35%)

• Medicinal agents (10%)

Glycerogelatins are plastic masses containing

Zinc gelatin

Official product of glycerogelatins

a. Melted and cooled to slightly above the body temperature

b. Applied to affected area with a fine brush

c. Covered with a bandage and allowed to remain in place for weeks

Application process of glycerogelatins