PHARMACEUTICAL DOSAGE FORMS

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INTRODUCTION TO DIFFERENT DOSAGE FORMS: 

INTRODUCTION TO DIFFERENT DOSAGE FORMS Powered By NANDEDKAR.P.P. Dept. of Pharmaceutics

Drug: 

Drug Drug may be defined as an agent or substance, intended for use in the diagnosis, mitigation, treatment, cure or prevention of disease in human beings or animals. Drugs are rarely administered in their original or crude forms. They are administered in different dosage forms by converting them into suitable formulations. Crude Drugs

Dosage Forms: 

Dosage Forms Dosage forms are the carrier through which drug molecules are delivered to sites of action within the body. Every dosage forms is a combination of the drug and different kinds of non – drug components called as Excipients or additives. The additives are used to give a particular shape to the formulation, to increase stability, palatability & more elegance to preparations.

Need For Dosage Forms: 

Need For Dosage Forms Accurate dose. Protection e.g. coated tablets, sealed ampules. Protection from gastric juice, e.g. enteric coated tablets. Masking unpleasant taste and odour. Provide drugs within body tissues, e.g. injection Sustained release medication. Facilation of Insertion of drugs into body cavities (rectal, vaginal)

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Provide optimum drug action through inhalation therapy. Provide drug action through topical administration at local area of body. e.g. creams, ointment, emulsion, lotions etc. Use of desired vehicle for insoluble drugs.

Classification : 

Classification Solid dosage forms Unit dosage forms Tablets Capsule Powders Pills Bulk Internal Fine powders & granules External Dusting powders Insufflations Dentifrice Snuffs Ear powders Liquid dosage forms Biphasic Emulsion Suspension Monophasic Internal External Syrups Elixirs Linctus Drops Liniments Lotions Gargles Throat paints Mouth washes Sprays Eye lotions Eye drops Nasal drops Semi solid dosage forms Internal External Suppositories Pessaries Ointment Creams pastes Jellies

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Solid dosage forms

Solid dosage forms: 

Solid dosage forms Tablets Pills Dusting Powders Capsules Granules

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Solid dosage forms one of the oldest dosage forms and most of the solid dosage forms are available in Unit dose. Unit dose may be defined as a exact quantity of the drug administered at once. e.g. Tablets, Capsule, pills, cachets, powders etc. When drugs are to be administered orally in dry state, then tablets, capsules are most convenient dosage forms. Some solids are supplied in bulk (Means quantity available in large). Bulk powders can be supplied as Internal (Granules, Fine powders) as well as External (Dusting Powders, Insufflations etc)

Dusting Powders: 

Dusting Powders Dusting powders are applied externally to skin, so they should be applied in very fine state to avoid local irritation. Hence dusting powders should be passed through sieve no 80 to obtained fined powders. Dusting powders are prepared by mixing of more than one ingredients in which either starch, kaolin, or talc are used in their formulation. Generally talc or kaolin are used because they are inert in nature. Dusting powders are used for antiseptic, astringent, absorbent, antiperspirant etc. Dusting powders are of two sub type they are as I) Medical dusting powder II) Surgical Dusting powders

Medical Dusting Powders: 

Medical Dusting Powders Medical Dusting powders are used to increase superficial condition of skin. These are not applied on wounds, burns etc Medical dusting powders must be free from dangerous pathogenic micro- organism.

Surgical Dusting Powders: 

Surgical Dusting Powders Surgical dusting powders are used in body cavities and also on major wounds like as burns etc. They should be sterilized before use. They are mainly used for their antiseptic, absorbent action.

Insufflations : 

Insufflations These are medicated dusting powders meant for introduction into body cavities (nose, throat, ear, vagina etc) with the help of an apparatus known as a insufflator. It sprays the powders (in a state of fine particles) on site of application. Now a days insufflations are also available in pressure aerosols. This pressure aerosols are used for administration of potent drug. They are used in the treatment of ear, nose, throat infections with antibiotics to produce local effect of drugs.

Snuffs: 

Snuffs These are finely divided solid dosage forms of medicaments which are inhaled into nostrils. They are mainly used for their antiseptic, bronchodilator and decongestion action.

Granules: 

Granules Granulation is the process in which primary powder particles are made to adhere to form larger multiparticle or large particles entities called granules. The bitter, nauseous, unpleasant powders can not be given tablets, capsule due to bulk quantity are required to be taken, as well as they are not given in liquid dosage forms due to their stability such powders are given in the granules forms. These powders are mixed with suitable exicipent along with granulating agent, prepare a coherent mass then dried & passed through the sieve to obtained desired size of granules. E.g. Effervescent granules

Effervescent Granules: 

Effervescent Granules Effervescent granules are meant for internal use. They contained medicaments mixed with citric acid, tartaric acid & sodium bi carbonates , sometime saccharin or sucrose may be added for sweetening taste. Before, administration desired quantity of granules are dissolved in water, the acid & bicarbonate reacts with each other to produce effervescence. Effervescent granules are prepared by two methods, namely as, I) Heat method , II) Wet method

Heat method: 

Heat method A large porcelain or stainless steel evaporating dish is placed over the boiling water bath. The dish must be sufficiently hot (generally heating takes place for 1 – 5 min.) before transferring the powders into it, to ensure rapid liberation of water of crystallization from citric acid. If heating of the dish is delayed then the powder which is added to it, will heat up slowly & liberated water of crystallization will also be liberated simultaneously. As a result, sufficient water will not be available to make a coherent mass. This coherent mass will pass through the sieve to obtained suitable size of granules, dry it in oven at 60 0 c then packed in air tight container.

Wet method: 

Wet method In this methods all the ingredients are mixed thoroughly This powders mixture make moistened with non – aqueous vehicle (e.g. alcohol), to prepare a coherent mass which is then passed through sieve no 8 to obtained suitable granules. Then dried in oven at 60 0 c. The dried granules are again passed through the sieve to break the lumps which may be formed during drying. The dried granules are packed in air tight container.

Tablets: 

Tablets These are solid dosage forms of medicaments which are prepared by moulding or by compression with or without Excipients. The tablets can be prepared by two methods namely as a I) Dry granulation, II) Wet Granulation

Capsule: 

Capsule Capsules are solid unit dosage forms in which one or more medicaments enclosed within a shell. Capsules mainly divided in to two parts namely as – I) Body (Longest part of capsule shell), II) Cap (Smallest part of capsule shell) The capsule are generally prepared by gelatin. Depending on their formulation, two types of gelatin are used namely as – I) Hard gelatin , II) Soft gelatin . Body Cap

Pills : 

Pills These are small, rounded solid dosage forms containing medicaments intended for oral use. The medicaments are mixed with excipients to forms a firms plastic mass. The mass is rolled to uniform pill pipe, which cut into numbers of uniform pills. The pills are spherical in shape & produced by rolling them under wooden pill rounder. Sometimes pills are coated with varnish, gold leaf, etc to improve finish, unpleasant taste & stability. Now a days pills are outdated preparations because of number of disadvantages such as -

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Disintegration time of pill is uncertain means freshly prepared pills are disintegrates readily rather than old dried pills. It is difficult to prepare pills of uniform size & weight.

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Liquid dosage forms

Liquid dosage forms: 

Liquid dosage forms

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It may be defined as “A solution is a liquid-preparation that contains one or more soluble chemical substances dissolved in a specified solvent” Liquid dosage forms are intended for External, Internal or parenteral use. The component of the solution which is present in a large quantity is known as “SOLVENT” where as the component present in small quantity is termed as “SOLUTE” They mainly classified in to two category namely as – I) Monophasic Liquid dosage forms. II) Biphasic liquid dosage forms.

Advantage: 

Advantage Immediately available for absorption. Administration convenient, particularly for infants, psychotic patients. Easy to color, flavor & sweeten. Liquids are easier to swallow than solids and are therefore particularly acceptable for pediatric patient. A solution is an homogeneous system and therefore the drug will be uniformly distributed throughout the preparation. Some drugs like aspirin, KCl can irritate gastric mucosa if used orally as a solid dosage forms. But this effect can be reduce by solution system.

Disadvantage: 

Disadvantage Less stable in aqueous system. Incompatibility is faster in solution than solid dosage form. Patients have no accurate measuring device. Accident breakage of container results in complete loss. Solution often provide suitable media for the growth of micro organisms. The taste of a drug, which is often unpleasant, is always more pronounced when in solution than in a solid form. Bulky than tablets or capsule, so difficult to carry transport.

Monophasic liquid dosage forms: 

Monophasic liquid dosage forms

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Monophasic liquid dosage forms are represent by true or colloidal solution. The component of the solution which is present in a large quantity is known as “SOLVENT” where as the component present in small quantity is termed as “SOLUTE”. A solution is homogenous because the solute is an ionic or molecular forms of subdivision. In case of colloidal solutions, the solutes are present as aggregates although they cannot be seen by necked eye or ordinary microscope. It is sub classified as – I) Internal Use, II) External use

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Monophasic Liquid Dosage forms Internal Use External Use Syrup Elixirs Linctuses Drops Liniments Lotions Gargles Mouth Wash Throat paints sprays Inhalations Nasal drops Eye drops Eye lotions Ear drops

Monophasic liquid dosage forms for Internal Use: 

Monophasic liquid dosage forms for Internal Use

Syrup : 

Syrup It is a concentrated or saturated solutions of sucrose in purified water. The concentration of sucrose is 66.7% w/w & due to that it is a viscous preparations. The syrup which contains medical substance called as a medicated syrup & those containing aromatic or flavored substance known as a flavored syrup.

Importance of syrup: 

Importance of syrup It retards oxidation because its partly hydrolyzed into reducing sugar. It prevents decomposition of many vegetable substance because its have high osmotic pressure which prevent the growth of bacteria. They are palatable due sweet taste.

Elixirs: 

It is clear, sweetened, aromatic, hydroalcholic preparations meant for oral use. The medicated elixirs are generally contained potent drug like as antibiotics, antihistamine or sedative , where as non – medicated elixirs contained flavoured. The composition of elixirs contained mainly as ethyl alcohol (active ingredients),water, glycerin or propylene glycol, colouring agent, flavouring agent & preservative. Elixirs

Linctuses: 

Linctuses These are viscous liquid preparations that’s are used for the treatment of cough. They contain medicaments which have demulcent, sedative, expectorant action. They are taken in small doses without diluting with water to have prolonged effect of medicines. Simple syrup is used as a vehicle for most of the linctuses. Tolu syrup is preferred in certain cases because of its aromatic odour & flavour. Moreover it have a mild expectorant action

Drops: 

Drops These are liquid preparations meant for oral administration. The oil soluble vitamins, such as vitamin A & D concentrates in fish – liver oil are presented as drops for administration. Since these preparations contain potent medicaments, the dose must be measured accurately The following two methods are commonly used for this purpose. Use of a dropper which is accurately graduated in fractions of a milliliters. Use of a pre – calibrated dropper.

Monophasic liquid dosage forms for External use: 

Monophasic liquid dosage forms for External use

Liniments: 

Liniments Liniments are liquid or semi- liquid preparations meant for external application to the skin. They are usually applied to the skin with friction & rubbing of the skin. Are usually alcoholic and oily liquid preparations (monophasic) or emulsion (biphasic). Alcoholic liniments are used generally for their rubefacient and counterirritant effects. Such liniments penetrate the skin more readily than do those with an oil base. The oily liniments are milder in their action and may function solely as protective coatings Liniments should not be applied to skin that are bruised or broke n.

Lotions: 

Lotions Are usually aqueous, alcoholic or oily liquid preparations. They are intended for external application without friction or rubbing to the affected area Usually applied with the help of some absorbent material such as cotton wool or gauze. It is generally used to provide cooling, soothing and protective & antiseptic action.

Gargles: 

Gargles Gargles are aqueous solutions used for treating throat infection (pharynx and nasopharynx part) Supplied in concentrated forms with directions of dilution with warm water before use They are used into intimate contact with the mucous membrane of throat for few seconds, before they are thrown out of the mouth. They are used to relieve soreness in mild throat infection. They are also used for their antiseptics, antibiotics and/or anesthetics

Mouth wash: 

Mouth wash These are aqueous solutions with pleasant or acceptable taste & odour These are used to make clean & deodorise the buccal cavity or used for oral hygiene and to treat infections of the mouth. They mainly contain antibacterial agent, alcohol, glycerin, sweetening agent, flavoring agent & colouring agent.

Throat paints: 

Throat paints Throat paints are viscous liquid preparations used for mouth and throat infections Glycerin is commonly used as a base because being viscous it adheres to mucous membrane for long period and it possess a sweet taste.

Sprays : 

Sprays These are the preparations of drugs in media which may be aqueous, alcoholic, or glycerin. They are applied to the mucous membrane of throat or nose with an atomizer. The throat sprays must be sprayed from a special type of atomizer known as a nebulizer, which removes the large droplets by baffling system. Only precaution should be taken that the fine droplet will used to easily reach the lungs. Nebulizer

Inhalations : 

Inhalations These are liquid preparations containing volatile substance & are used to relieve decongestion & inflammations of respiratory tract. The volatile substance in inhalations would be volatile at room temperature so that they should be placed on some adsorbent pad or handkerchief. In some cases inhalations will added to hot water (65 0 c) then vapors will inhaled.

Nasal drops: 

Nasal drops Drugs in solution may be instilled into the nose from a dropper or from a plastic squeeze bottle. The drug may have a local effect, e.g. antihistamine, decongestant. Alternatively the drug may be absorbed through the nasal mucosa to exert a systemic effect. The use of oily nasal drops should be avoided because of possible damage to the cilia of the nasal mucosa & if it is used for long period may reach the lungs & cause lipoid pneumonia. To avoid that Nasal drops are prepared so that they are similar in many respects to nasal secretions, so that normal ciliary action is maintained thus aqueous nasal solutions usually are isotonic and slightly buffered to maintain a pH of 5.5 to 6.5.

Eye drops: 

Eye drops Sterile, aqueous/oily solutions or suspensions intended for instillation in eye sac. Eye drops may contain buffers, stabilizing agents, dispersing agents, solubilising agents, anti-oxidants & agents required for tonicity/ viscosity adjustment Single dose container should not contain anti-microbial preservative. In case of multi dose container a dropper should be supplied with it for administration. Maximum size of such containers is 10 ml.

Eye lotions: 

Eye lotions These are the aqueous solutions used for washing the eyes. These are supplied in concentrated forms & are required to diluted with warm water immediately before use. They should be free from foreign particles to avoids irritation to the eye. They are required to prepared fresh & should not be stored for more than two days to avoid microbial contaminations.

Ear drops: 

Ear drops These are the solutions of drugs that are instilled into ear cavity with the help of dropper. These are generally used for cleaning the ear, softening the wax & for treating the mild infections. The solutions is generally prepared in water, glycerin, propylene glycol & dilute alcohol.

Biphasic liquid dosage forms: 

Biphasic liquid dosage forms

Biphasic liquid dosage forms: 

Biphasic liquid dosage forms The liquid which consist of two phases are known as a biphasic liquid dosage forms. They are sub categorized into two different forms namely as – I) Emulsion II) Suspension In emulsion both phases are available in liquid where as in suspension, finely divided solid particles are suspended in liquid medium.

Emulsion : 

Emulsion Emulsion is a biphasic liquid preparations containing two immiscible liquid ( Continuous Phase & dispersed phase ) made missicible. The liquid which is converted into minute globules is called as dispersed phase & the liquid in which the globules are dispersed is called the continuous phase dispersed phase continuous phase Two Immiscible Liquids Dispersed Phase (Internal phase) Continuous Phase (External phase) An emulsion is a thermodynamically unstable system consisting of at least two immiscible liquid phases one of which is dispersed as globules in the other liquid phase stabilized by a third substance called emulsifying agent. The globule size in emulsion varies from 0.25 to 25 µm .

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Examples for emulsions:- milk, rubber latex, crude oil etc. A.: Two immiscible liquids not emulsified B. An emulsion of phase B dispersed in Phase A C. Unstable emulsion slowly separates. D. The emulsifying agent ( black film) places it self on the interface between phase A and phase B and stabilizes the emulsion.

Types of emulsions: 

Types of emulsions Simple type Water in oil (w/o) Oil in water (o/w) Depending on globule size Micro emulsion Fine emulsion Special type Multiple emulsion (w/o/w, o/w/o)

Water in oil (w/o): 

Water in oil (w/o) In this types of emulsion water is dispersed phase & oil is continuous phase w/o types of emulsion generally meant for External use. Examples are butter, lotions, creams etc. In rare case they are used internally. Water is dispersed phase Oil is continuous phase

Oil in water (o/w): 

Oil in water (o/w) In this types of emulsion oil is dispersed phase & water is continuous phase o/w types of emulsion meant for both Internal use & External use. Examples for internal use are Vitamin A in corn oil, liquid paraffin in water etc. Examples for External use are Benzyl benzonate emulsion. Oil is dispersed phase water is continuous phase

Micro Emulsion: 

Micro Emulsion These are clear dispersions of o/w or w/o in which the globules have small size like as a 10nm or 0.01 µm . . Being cleared products micro emulsion are more popular now a days. Micro emulsions are thermodynamically stable optically transparent , mixtures of a biphasic oil –water system stabilized with surfactants.

Fine emulsion: 

Fine emulsion Normally these have a milky appearance. The globule size ranges from 0.25 to 25 µm .

Multiple emulsion: 

Multiple emulsion These are emulsion with in emulsion & designated as w/o/w or o/w/o. The drugs that is incorporated in the innermost phase must cross two phase boundaries before getting absorbed. It is generally used in oral sustained release or intramuscular therapy.

Identification tests : 

Identification tests Dilution test Conductivity test Dye test Fluorescence test Cobalt chloride test Filter paper test

Dilution test: 

Dilution test The emulsion is diluted with water, after dilution emulsion remain stable then it is said to be o/w type of emulsion because water is in continuous phase. If emulsion is break after dilution with water then it is said to be w/o type of emulsion. Add drops of water Water distribute Uniformly Add drops of water O/W Emulsion W/O Emulsion

Conductivity test: 

Conductivity test Conductivity test can be performed by dipping a pair of electrode connecting with low voltage bulb & pass the current. If bulb glows then it is said to be o/w type of emulsion because water is in continuous phase & it is good conductor of electricity. If bulb doesn't glow then it is said to be w/o type of emulsion because oil is bad conductor f electricity. Bulb glows with O/W Emulsion Emulsion Bulb doesn’t glow with W/O

Dye test: 

Dye test Oil soluble Scarlet red dye is mixed with emulsion. Place a drop of emulsion on microscopic slide cover it with cover slip & examine under microscope. If disperse globules appears red & ground is colourless then it said to be o/w type of emulsion because water is present in continuous phase. If reserve condition occurs (If disperse globules appears colourless & ground is red colour then it said to be w/o type of emulsion because oil is present in continuous phase.) Oil is dispersed phase Water is continuous phase Water is disperse phase Oil is continuous phase

Fluorescence test: 

Fluorescence test Certain fixed oil posses the physical properties of fluorescing in the presence of ultraviolet radiations. If examine under microscope ground is fluorescence then it said to be w/o type of emulsion because oil is present in continuous phase. If examine under microscope droplet is fluorescence then it said to be o/w type of emulsion because oil is present in disperse phase.

Creaming test: 

Creaming test The direction of creaming identifies the emulsion type, if the densities of aqueous and oil phases are known. Water-in-oil emulsions normally cream downward as oil is usually less dense than water. Oil-in-water emulsions normally cream upwards .

Cobalt chloride test: 

Cobalt chloride test Pour the emulsion on filter paper then it is soaked in cobalt chloride solutions & allowed to dry turns from blue to pink. Then this emulsion is said to be o/w type of emulsion. This test may fail if emulsion unstable or breaks in presence of electrolyte .

Filter paper test: 

Filter paper test This test is based on the fact that an o/w emulsion will spread out rapidly when dropped onto filter paper. In contrast, a w/o emulsion will migrate only slowly. This method should not be used for highly viscous creams.

Suspension : 

Suspension Suspensions are the biphasic liquid dosage forms of medicament in which finely divided solid particles ranging from 0.5 to 5 micron are dispersed in a liquid or semisolid vehicle, with aid of single or combination of suspending agent. In which solid particles acts as disperse phase where as liquid vehicle acts as continuous phase The external phase (suspending medium) is generally aqueous in some instance, may be an organic or oily liquid for non oral use. The particle size for non oral suspension is so important to avoid grittiness to skin.

Advantage of suspension: 

Advantage of suspension Suspension can improve chemical stability of certain drug. E.g. Procaine penicillin Drug in suspension exhibits higher rate of bioavailability than other dosage forms. Solution > Suspension > Capsule > Compressed Tablet > Coated tablet Duration and onset of action can be controlled. E.g. Protamine Zinc-Insulin suspension. Suspension can mask the unpleasant/ bitter taste of drug. E.g. Chloramphenicol

Disadvantage of suspension: 

Disadvantage of suspension Physical stability , sedimentation and compaction can causes problems. It is difficult to formulate. Uniform and accurate dose can not be achieved unless suspension are packed in unit dosage form. All suspensions are required to be shaken before measuring of dose. The storage of suspension may lead to changes in disperse system especially, when there is fluctuations in temperatures.

Ideal qualities of good suspension: 

Ideal qualities of good suspensio n It should settle slowly & easily re – dispersed on shaking It should readily & evenly pour from container. It should be chemically inert. It should not forms hard cake. It should prevent degradation of drug or to improve stability of drug. It should mask the taste of bitter of unpleasant drug.

Flocculated suspension: 

Flocculated suspension In this type, solid particles are loosely aggregates themselves , means individual particles are come in contact with each other to forms network like structure called as a floccules. These flocs are light, fluffy in nature, which are held together by weak van der waals force of attraction. Aggregation is achieved by adding flocculating agent. This suspension will readily sediments. This suspension posses better physical stability but less bioavailability as compared to deflocculated suspension due to dissolution of floccules.

Deflocculated suspension: 

Deflocculated suspension In this type of suspension, individual particle exits as a separate entity, means particles carry a finite charges on their surface . Hence particles approaches each other, they experience repulsive forces. This force create a high potential barrier, which prevents a aggregation of particles. During storage, these suspension shows a sedimentation at slow rate, due to that particles forms a close packing arrangement. So that it is difficult to re dispersed on agitation & forms a cake or claying which is hard in nature. This type of suspension have shorter shelf life but high bioavailability as compared to flocculated suspension.

Difference between flocculated & deflocculated suspension: 

Difference between flocculated & deflocculated suspension Flocculated Suspension Deflocculated suspension Particles form loose aggregates & forms network like structure. Particle exist as separate entities. Particles experience attractive forces. Particles experience repulsive forces. Supernatant liquid is clear. Supernatant liquid is cloudy. The rate of sediment is high. The rate of sediment is slow. Sediment is rapidly formed. Sediment is slowly formed. sediment are loosely packed, hence hard cake is not formed. Sediments are closely packed, hence hard cake is formed. The sediment is easy to redisperse on shaking. Sediment is difficult to redisperse on shaking. (due to formation of hard cake) Bioavailability is comparatively less. Bioavailability is relatively high. The suspension is not pleasing in appearance. The suspension is pleasing in appearance.

Semisolid dosage forms: 

Semisolid dosage forms

Semisolid dosage forms: 

Semisolid dosage forms meant for external application Semisolid dosage forms subcategorized are as- I) ointment II) creams III) paste IV) Jellies V) Suppositories The suppositories are also included in this category but it is a unit dosage forms. Semisolid dosage forms

Ointment : 

Ointment Ointment are semisolid preparation meant for application to skin or mucous membrane. The ointments are mainly used for their protective or emollient properties It may be defined as a medicament or medicaments dissolved, suspended or emulsified in ointment base. There is no single ointment base which possesses all the qualities of ideal ointment base, so it become necessary to use more than one ointment base in the preparation of ointment.

Qualities of ideal ointment base: 

Qualities of ideal ointment base It should be inert, odourless & colourless & smooth. It should be physically & chemically stable. It should be compatible with the skin & with incorporated medicaments. It should be of such consistency that it spread & soften when applied to skin with stress. It should not retard healing of wound. It should produce irritation or sensitization of the skin.

Classification of ointment base: 

Classification of ointment base Oleaginous bases Absorption bases Emulsion bases Water soluble bases

Oleaginous base: 

Oleaginous base These bases consist of water soluble hydrocarbons, vegetable oils, animal fats & wax. The constituents of hydrocarbon bases are soft paraffin, hard paraffin & liquid paraffin. The vegetable oils are mainly used in ointment to lower the melting point or to soften the bases. These bases serve to keep the medicaments in prolonged contact with the skin & also act as occlusive dressings. They have a low capacity to absorb water & are used chiefly for their emollient effect. These bases losing their importance now a days for the many reason.

Disadvantages of oleaginous bases: 

Disadvantages of oleaginous bases They are greasy. They are sticky & are difficult to remove both from skin & clothing. They retain body heat which may produce an uncomfortable feeling of warmth. They do not help in the absorption of medicaments.

Absorption bases: 

Absorption bases These bases are generally anhydrous substance which have the property of absorbing considerable quantities of water but still retaining their ointment like consistency. The absorption bases are of two type namely as I) Non emulsified bases II) Water in oil emulsion Non emulsified bases absorb water & aqueous solutions producing w/o emulsion. E.g. Wool fat, wool alcohol, beeswax & cholesterol. Water in oil emulsions are capable of absorbing more water & have the properties of non- emulsified bases. E.g. hydrous wool fat ( lanoline)

Emulsion bases: 

Emulsion bases These bases are semisolid or have cream like consistency. Both o/w or w/o emulsions are used as a ointment base. The o/w emulsion base is more popular now days because ease of application will easily achieved. The w/o type of emulsion bases are greasy & sticky. The emulsifying ointment is prepared from emulsifying wax, white soft paraffin & liquid paraffin.

Water soluble bases: 

Water soluble bases These are commonly known as greaseless ointment bases. The water soluble bases consist of water soluble ingredients such as carbowaxes ( polyethylene glycol polymer) The carbowaxes are water soluble, non – volatile & inert substance. Selection of appropriate carbowaxes is depend on their molecular weight.

creams : 

creams These are viscous semisolid emulsions which are meant for external use. Cream is divided in to two types namely as I) Aqueous creams II) Oily creams In case of aqueous creams the emulsions are o/w type & it is relatively non greasy. The emulsifying waxes are anionic, cationic & non –ionic used. Generally polysorbate, triethanolamine soap are used as emulsifying agent. In case of oily creams w/o type & it is relatively greasy. The emulsifying agent such as wool fat, wool alcohols, beeswax & calcium soap is used. The cream should be store in collapsible tube & supplied in well closed container to prevent evaporation & contamination.

pastes : 

pastes Pastes are semisolid preparations intended for external application to skin. The pastes are generally very thick & stiff. They do not melt at ordinary temperature & thus forms a protective coating over the area where they are applied. Pastes are differ from ointment as they contain a high proportion of finely powdered medicaments. They are mainly used as a antiseptic, protective, soothing dressings. Pastes should be stored & supplied in containers made of materials which do not allow absorption or diffusion of content.

jellies: 

jellies Jellies are transparent or translucent, non greasy, semi solid preparations mainly used for external application to skin. These are also used for lubricating catheters, surgical gloves & rectal thermometer. The substance like gelatin, starch, tragacanth, sodium alginate & cellulose derivatives are used for the formulation of jellies. Jellies are of three types namely as Medicated jellies Lubricating jellies Miscellaneous jellies

New drug delivery system: 

New drug delivery system

Introduction: 

Introduction With the advancement of pharmaceutical sciences, a new concept have evolved various modern dosage forms & methods of their administration. Some of the modern dosage forms are Implants Films & strips Liposome drug carriers Controlled drug delivery modules Erythrocytes Nanoparticles prodrugs

Implants : 

Implants These are hypodermic tablets are placed under the skin by a minor surgery in order to release drugs over prolonged periods of time. Now the magnetically controlled implants have been developed which can be opened or closed at will in order to release or stop the drug. These implants are placed at upper thigh at a depth of 5mm. These implants are useful in hormone therapy.

Films & strips: 

Films & strips These are meant for topical application for slow release of drug over predetermined period of time. Films & strips are more popular these days. They are sub categorized in to following types namely as Zero order release films Buccal strips Spray bandages

Zero order release films: 

Zero order release films These are called as laminates & meant for topical application. E.g. Nitroglycerine laminates are prepared by mixing propylene glycol with about 1% carbopol resin. The mixture is neutralized with NaoH solution & then 0.1% of nitroglycerin is added. It is then placed in polythene sheet 5*5 cm & its edges are sealed by heat. It is then placed on pressure sensitive adhesive sheet of 5.5 * 5.5 cm so that it can be properly adhesive to skin. Such laminates release the drug slowly into circulation for about 12 hours.

Buccal strips: 

Buccal strips The buccal & sublingual tablets are now replaced with buccal strips. These strips consist of a thin absorbent base of fabrics, filter paper & cotton etc. The buccal strips are prepared by immersing a long piece of fabric made from polyamide fibers into a molten mixture of carbowaxes & dissolved or dispersed the drug. The fabric is then cooled & cut into small pieces. It should be contact with buccal mucosa for about 15 min. & then removed & discarded.

Spray bandage: 

Spray bandage These bandage are prepared by spraying the solution of drug in polylactide (polymer of lactic acid anhydride) A solution of purified lactide polymer is made in chloroform. It is then packed in aerosol container having suitable propellant. When these solution sprayed then it will be a comfortable bandage which can simply washed of with warm water.

Liposome drug carriers: 

Liposome drug carriers These are several carriers in our body which transport both to an other like as enzymes, proteins etc. These are phospholipids which can transport both hydrophilic & hydrophobic drugs. The large multilamellar vesicles (LMV), small unilamellar vesicles (SUV), large unilamellar vesicles (LUV) are some of the liposome's known today.

Applications : 

Applications Used in diseases caused by intracellular parasites. E.g. malaria, tuberculosis & amoebiasis. It entrapped insulin is active orally & can be replaced by IM administration of insulin. It can be used to transport functional DNA/RNA molecules into cell. It can be used to transport radio pharmaceuticals & immunological products. Liposomal daunomycin has longer duration of action than free daunomycin which is used in the treatment of neoplasia.

Controlled drug delivery modules: 

Controlled drug delivery modules These are the device which are formed by embedding the drug within a polymeric matrix so that it gets released slowly to the body over a long period of time. It will formed drug – polymer complex & may be formulated in to tablet, capsule or any other suitable formulation. These modules are punctured before administration with leaser beam to make a small orifice for release of the drugs. The drugs is released from these modules by diffusion, osmosis or chemical reactions. These are applied to skin, implanted subcutaneously or inserted into various body cavities.

Erythrocytes : 

Erythrocytes Erythrocytes are tried in order to achieve controlled release of drugs. The life span of erythrocytes are 120 days. It can allow a drug to circulate in the body for long period of time which help slow release of the drugs in to serum. Released erythrocytes are prepared by putting them in to a hypotonic medium. So that they can easily swollen. The aqueous solutions of the drug is added to the medium so that drugs gets in to erythrocytes through open pores. When isotonicity is adjusted the erythrocytes shrink, thus encapsulating the drug with in them. These erythrocytes may be suspended in normal saline solutions for preparing injections.

Applications : 

Applications Released erythrocytes of urease have been used in kidney failure to degrade serum urea. Released erythrocytes of asparaginase have shown good result in asparaginase dependent leukemia. Released erythrocytes of methotrexate & adrianycin have been tried in cancer therapy. Released erythrocytes of prednisolone have shown good result to prolong the anti-inflammatory action.

Nanoparticles: 

Nanoparticles It is based on colloidal drug delivery system. The particles size of this system is in nanometer range (200 – 500 mm) The system consist of a drug & carriers to deposit the drug at target site. The carriers used are naturally occurring macromolecules like human serum albumin, bovine serum albumin, & other substances like gelatin, casein & ethylcellulose.

Applications : 

Applications Flourescein isothinocyanate (FITC) nanoparticles have been used to incorporate cytotoxic agent into tumor cell in cancer chemotherapy. Nanoparticles along with biological maker like immunoglobulin can be used to target the drugs to very specific site.

Prodrugs : 

Prodrugs The compound which undergo biotransformation before showing desired pharmacological activity are called prodrugs or proagents. Prodrugs are generally the ester or amides of parent drugs. These are useful to improving the stability, solubility, bioavailability of drugs, masking the unpleasant taste & odour of the parent drug & reducing the toxicity

Applications : 

Applications Choramphenicol palmitate, the prodrug of chloramphenicol is used in the preparation of pediatrics suspension because it has no bitter taste. Procaine penicillin G & benzathine penicillin G are prodrugs of penicillin G which shows resistance to hydrolysis as compared to the parent drug. Cindamycin 2- phosphate the prodrug of cindamycin has no bitter taste of parent drug.

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