pharmaceutics 1st notes
(d pharmacy notes)
Dosage Forms/Importance Of Dosage forms
dosage forms/ importance of dosage form are the main factors in medicines while intake of drugs
…Transformation of a drug into different dosage forms is done for the following reasons;
1. to provide safe and convenient delivery of accurate dosage.
2. Many dosage forms can be easily identified forms their distinct colour, shape or identifying marketings.
3. To protect the drug substances from oxidation, hydrolysis and reduction e.g..coated tablets and sealed ampoules.
4. To protect the drug from the destructive effect of gastric juice[hydrochloric acid] of the stomach after oral administration e.g..enteric-coated tablets.
5. To conceal bitter, salty, or obnoxious taste or odour of a drug substances e.g.capsules, coated tablets and flavourite syrups etc.
6. To provide for the insertion of the drug into one of the body cavities e.g.veghinal suppositories.
7. To provide for the optimum drug action through inhalation therapy e.g.inhalation aerosols and inhaled.
8. To provide the maximum drug action tropical administration site e.g.creams, ointments, ophthalmic preparation and E.N.T.[Ear, nose and throat] preparation.
9.TO provide substances release action though controlled released mechanisms, e.g. sustained released tablets, capsules and suspension.
10. To provide liquid dosage form of the drug soluble in suitable vehicles e.g. solutions.
11. To provide the liquid preparation drug which is insoluble or unstable in different vehicles e.g. suspension.
12. To provide the drug within body tissue e.g. injection.
Classification Of Dosage forms
Types of dosage forms
Dosage forms may be classified on the basis of the final product which is as under;
1.Solid dosage forms.
2.Liquid dosage forms.
3. Semi-solid dosage forms.
Solid Dosage Forms
The solid dosage forms are available mostly in unit dosage forms [consisting of doses which are taken by number] such as tablets, capsules, pills, cachets or powders.
Powders are a solid dosage form of medicaments, which are meant for internal or external use. They are available in crystalline or amorphous form. The powder is generally used in the following forms;
1. Bulk powder for internal use e.g. fine powders or granules.
2. Bulk powder for external use e.g. snuffs, dusting powders tooth powders and installation.
3. Simple and compound powders for internal use.
4. Powder in the form of compressed tablets and tablets triturates.
5. Powders inclosed in cachets and capsules.
These are meant for external application to the skin and are generally applied in a very fine state of subdivision to avoid local irritation.
These are medicated dusting powders meant for introduction into the body cavities such as the nose, though, ears and vagina with help of an apparatus known as ”insufflator”.
These are finely divided solid dosage forms of medicament which are inhaled into nostrils for its antiseptics, bronchodilator and decongestion action.
Dentifrices [Tooth Powders]…
These are applied with the help of a toothbrush for cleaning the surface of the teeth. They contain suitable detergents or soap, some abrasive substances and a suitable flavour.
These are solid dosage forms of medicament or medicaments which are prepared by moulding or by compression.
The capsules are solid unit dosage form in which one or more medicaments and inert substances are enclosed within a small shell, generally prepared from a suitable form of gelatin.
Pills are small, rounded solid dosage forms containing medicaments and are intended to be administered orally.
Liquid Dosage Forms
Liquid stage forms are meant for internal, parenteral or external use. They are available in monophasic or biphasic forms.
Dosage Forms/Importance Of Dosage forms
Monophasic Liquid Dosage Forms…
Monophasic liquid dosage forms are represented by the true or colloidal solution. The component of the solution which is present in the large quantity is known as ”solvent”. whereas the component present in a small quantity is termed as ”solute”.
Monophasic liquid dosage forms are available as;
1. liquid for internal use e.g.. syrups, elixirs, linctus, drops, and draughts.
2. Liquid for external use which is two types;
[a]. liquids to be applied to skin e.g. liniments and lotions etc.
[b]. liquid meant for body cavities e.g. gargles, throat paints, mouthwashes, ey drops, eye lotions, ear drops, nasal drops, sprays and inhalations.
simple syrup is a saturated solution of sucrose in purified water. The concentration of sugar is 66% w/w.
Elixirs are sweet aromatic preparations and are usually coloured. The main ingredient of elixirs is ethyl alcohol (4-40%), water, glycerin, or propylene glycol, flavouring agent, syrup and some suitable preservative.
Linctuses are viscous liquid and oral preparation that are generally prescribed for the relief of cough. they contain medicament which has a demulcent, sedative or expectorant action.
These are liquid preparation meant for oral administration. The oil-soluble vitamins, such as vitamin A and vitamin D concentrate in fish-liver oil are present as drops for administrations.
(a). Use of a dropper which is accurately graduated infraction in a millilitre.
(b). Use of pre-calibrate dropper in which the number of drops equivalent to the prescribed dose of the particular preparation beings administered is known.
Liniments are liquid and semi-liquids preparation meat for application to the skin. Liniments are usually applied in the skin with friction and rubbing of the skin. The liniments may be alcoholic or oily solutions or emulsion. Alcohol helps in the penetration of medicaments into the skin and also increase its counter-irritant or rubefacient action.
Generally, liniments contain medicament possessing analgesic, rubefacient, smoothing and counter-irritant or stimulating properties.
Lotions are liquid preparations meant for external applications without frictions. They are applied directly to skin with the help of some absorbent materials, such as cotton wool or gauze soaked in it. Dissolve sodium citrate in about 700ml of rose water. Alcohol is sometimes included in aqueous lotion for its cooling and soothing effect e.g. salicylic acid lotions.
Gargles are the aqueous solution to use prevent or treat throat infections. They are usually available in concentrated forms with direction for dilution with warm water before use. They are thought into intimate contact with the mucous membrane of the throat and are allowed to remain in contact with it for a few seconds before they are thrown out of the mouth.
These are an aqueous solution with a pleasant taste and odour use to make a clean and deodorise the buckle cavities. Generally, they contain antibacterial agents, alcohol, glycerin, sweetening agents, flavouring agents and colouring agents.
Throat paints are viscous liquid preparation used for mouth and throat infections. Glycerin is commonly used as a base because, being vicious, it adheres to the mucous membrane for a long period and it possesses a sweet taste.
Sprays are preparation of drug in media which may be aqueous, alcoholic and glycerin. they are applied to the mucous membrane of nose or throat with an atomiser.
These are liquid preparations containing volatile substances are used to relieve congestion and inflammation of the respiratory tract. The inhalation containing the volatile at room temperature may be placed on an absorbent pad or handkerchief yo inhale therefrom.
These are the solution of drug that is instilled into the nose with a dropper. These are usually aqueous and not oily drops since the latter inhibits the movement of cilia in the nasal mucosa and if used for long periods, may reach the lungs and cause lipoid pneumonia. Nasal drops should be isotonic having neutral pH and viscosity similar to nasal secretion by using methylcellulose.
These are sterile or suspension of drug that are instilled into the ear with a dropper. These are generally used for cleaning the ear, softening the wax and for treating the mild infections.
Biphasic Liquid Dosage Forms…
The liquids which consist of two-phase are known as biphasic liquid e.g. emulsions and suspensions. In general, both the phase are liquid, while in suspensions the finely divided solids are dispersed in a liquid which acts as a continuous phase.
An emulsion is a biphasic liquid preparation containing two immiscible liquid, one of which is dispersed as minute globules into the other. The liquid which is converted into minute globule is called the ‘ dispersed phase’ and the liquid which in which the globules are dispersed is called the ‘continuous phrase’.
Emulsions for oral administration;
These are generally o/w type emulsions and are used for administration of medicinal oil. The emulsification helps to mask the disagreeable taste and the ‘ oily ‘ feel of the medicinal oil and thus increase its palatability e.g. liquid paraffin emulsion.
Dosage Forms/Importance Of Dosage forms
The oil-soluble sex hormones, vitamin A, D and K are administered as intravenous injections. The emulsified oils are also injected as diagnostic aids. These emulsions should have small globule size and must be sterile.
Emulsions for external use;
The emulsions for external application may be both o/w or w/o type but o/w type emulsions is preferred. When a drug is emulsified its rate of penetration through the skin may get reduced. Its help to prolong the action of the drug. Generally, the emulsions for application to the skin are semi-solid at room temperature and are considered to be an excellent vehicle.
The suspension is the biphasic liquid dosage forms of medicaments in which finely divided solid particles are dispersed in a liquid and semi-solid vehicle. The solid particles act as a disperse phase whereas liquid vehicles act as a continuous phase.
An ideal suspension must possess the following properties;
1. It should settle slowly and should be readily re-disperse on gentle shaking of the container.
2. The particle size of the suspension remains fairly constant throughout its long period of undisturbed standing
3. The suspension should pour readily and evenly from its container.
4. It should be free from large particles which spoil its appearance, give a gritty taste to oral preparation and also causes irritation to sensitive tissue when applied externally.
The suspension is classified int four main clauses to according to its pharmaceutical use. These are ;
[a]. Oral Suspension.
[b]. parenteral Suspension.
[c]. Ophthalmic Suspension.
[d]. Suspension of external use.
The suspension is to be consumed by the patient by the oral route. Oral suspension generally contains flavouring and sweetening agent to mask the bitter taste of the drug.
The suspensions which are administered by the parenteral route it is called Parenteral Suspensions. The particle size of drug these suspensions should be such that it can be easily pass through the needle of the syringe. The viscosity of suspensions should not interfere with its flow through the syringe needle. The suspension should be sterilized.
These are not commonly used as compared to the eye- drops. These are prepared only those cases when the drug is insoluble in the desired solvent or unstable in liquid form.
Suspensions For External Use;
These suspensions are meant for external use e.g. lotions, inhalations, ear drops etc. These suspensions contain very small particles to avoid grittiness.
The suspensions are also classified as flocculated and non-flocculated suspensions. The suspensions are said to be flocculated when the individual particles are in contact with each other and form a network-like structure.
Semi-Solid Dosage Forms
Semi-solid dosage forms are mainly meant for external application e.g. ointments, creams paste jellies etc. The suppositories are also included in the category although these are unit dosage.
Ointments are semi-solid preparation meant for application to the skin and mucous membrane. They usually contain medicament or medicaments dissolved, suspended and emulsified in the ointment base. They may contain a suitable antimicrobial preservative. The ointment are mainly used as protective or emollient for the skin. The medicated ointment is meant for action on the epidermis or for action on the deeper layer of cutaneous tissue or to penetrate deep and release medicaments to body fluids. The ointments which are meant for application to the eye are called ophthalmic Ointmentes”.
Dosage Forms/Importance Of Dosage forms
The ointment bases are classified into;
1. Oleaginous bases.
2. Absorption bases.
3. Emulsions bases.
These bases consist of water-soluble hydrocarbons, vegetable oils, animal fats and waxes. The constituent of hydrocarbon bases is soft paraffine, hard paraffine and liquid paraffine.
These bases are losing their importance nowadays for the following reasons;
1. They are greasy.
2. They are sticky and are difficult to remove both from skin and clothing.
3. They retain body heat which may produce an uncomfortable feeling of warmth.
4. They do not help in absorption of medicament.
These bases are generally anhydrous substances which have the property of absorption (emulsifying) considerable quantities of water but still retaining their ointment – like consistency.
the absorption bases are two types;
1. In- emulsified bases
2. Water in soil emulsions.
These bases are semi-solid or have a cream-like consistency. Both o/w and w/o emulsions are used as ointment bases. The oil in water type of emulsions baases is more popular because these can be easily removed from the skin or cloths by washing with water.
Water Soluble Bases;
These are commonly known as ”greaseless ointment bases”. The water-soluble bases consist of water-soluble ingredients, such as, polyethene glycol polymers which are popularly known as carbo waxes. The carbowaxes are water-soluble, non-volatile and inert substances. These are available in varying constituencies depending upon there molecular weight.
These are viscous semi-solid emulsions which are meant for external use. The creams are two types, aqueous and oily creams. In the case of aqueous creams, the emulsions are oil-in-water type and the case of oily creams, emulsions are water in oil types. The oil-in-water type creams are relatively not- greasy. Creams should be stored and supplied in well-closed containers which prevent evaporation and contamination.
Pastes are semi-solid preparations intended for external application to the skin. They differ from ointment as they contain a high proportion of finely powdered medicament, such as zinc oxide, calcium carbonate, starch etc. These substances make the past very thick and stiff.
Jellies are transparent or translucent, non-greasy, semi-solid preparation mainly used for external application to the skin. These are also used for lubricating catheter, surgical gloves and rectal thermometers. The substance like gelatin, starch, tragacanth, sodium alginate and cellulose derivative is used in the preparation of jellies.
Suppositories are semi-solid dosage form of a medicament for insertion into body cavities other than the mouth. they may be inserted into rectum, vagina or nasal cavity.
The various types of suppository bases are used to prepare suppositories so that they can retain their shape and firmness during storage and administration. They should melt or dissolve in body cavity fluids when inserted in the body cavity.
They are meant for introduction into the vagina. They are larger than rectal suppositories and vary in weight from 4 to 8 grammes or more. The pessaries may be conical, wedge-shaped or road shaped.
New Drug Delivery System
The drug is administered with the main aim of curing a patient of his or her disease. The drug is never administered their pure form but is converted into suitable formulation so that its onset and intensity of the action, as well as the total duration of action, can be check according to the need.
Some of the modern dosage forms are;
2. Films and strips.
3. Liposome drug carriers.
4. Controlled drug delivery modules.
Dosage Forms/Importance Of Dosage forms
The hypodermic tablets are placed under the skin by a minor surgery in order to release drug over prolonged periods of time. Now the magnetically controlled implant has been developed which can be opened or closed at will in order to release or stop the drug.
Films And Strips
These are meant for tropical application for slow release of a drug over a predetermined period of time. The films and strips which are becoming popular these days are;
1. Zero-order release films.
2. Buccal strips.
3. Spray bandages.
Zero Order Release Films;
These films are called ”laminates”, and are meant for topical applications. Nitroglycerine laminates are prepared by mixing propylene glycol with about 1 per cent carbopol resin. The mixture is neutralised with a sodium hydroxide solution and then 0.1 per cent of nitroglycerine is added.
The buccal and sublingual tablets are now replaced with buccal strips. These strips consist of a thin absorbent base of fabrics, filter paper and cotton etc. The buccal strips are prepared by immersing a long piece of fabric made from polyamide fibres into a molten mixture of carbowex and dissolved or dispersed drug [aroud 20 per cent].
These bandages prepared by spraying a solution of drug in polylactide [polimer of lactic acid anhydride]. A 2 per cent solution of purified lactide polymer is made in chloroform and the drug in the concentration of 0.01 per cent to 90 per cent is dissolved or dispersed in it.
Liposome Drug Carriers
There are several carriers in our body which transport bio-chemicals from one part of the body to another e.g. proteins, enzymes etc. liposomes are phospholipids which can transport both hydrophilic and hydrophobic drugs. Large multilamellar vesicles [LMU], small unilamellar vesicles [SUV] and large unilamellar vesicles [LUV] are some of the liposomes which are known today.
Applications; Liposomal drug have wide therapeutic applications, some of which are as follows;
1. Used in disease caused by intracellular parasites e.g. malaria, tuberculosis, and amoebiasis.
2. Liposome entrapped insulin is active orally and can be replaced by intramuscular administration of insulin.
3. Liposomes can be used to transport functional DNA/RNA molecules into cells.
4. Liposomes can be used to transport radiopharmaceuticals and immunological products.
5. Liposomal daunomycin has a longer duration of action than free daunomycin which is used in the treatment of neoplasia.
6. Liposome entrapped actinomycin-D and nitrogen mustard are more effective than the parent drug.
Controlled Drug Delivery Modules [CDDM]
Controlled drug delivery modules are devices which are formed by embedding the drug within a polymeric matrix so that it gets realis slowly to the body over a very long period of time. The polymeric matrices used to hold the drug reversibly are polyethylenes, silicone elastomers and cellulose esters. The drug-polymer complex may be formulated into tablet, capsules or any other suitable formulation.
Erythrocytes have also been tried in order to achieve controlled release of the drug. The life of an erythrocyte is about 120 days. Erythrocytes can allow a drug to circulate in the body for a long time which helps in the slow release of drug in serum.
Released erythrocytes are prepared by putting them into a hypotonic medium so that they can be swollen. The aqueous solution of the drug is added to the medium so that the drug gets into erythrocytes through the open pores.
The techniques can be used on a commercial scale only if erythrocytes are made available in test tubes.
1. Resealed erythrocytes of urease have been used in kidney failure to degrade serum urea.
2. Resealed erythrocytes of asparaginase have shown good results in asparaginase dependent leukaemia.
3. Resealed erythrocytes of methotrexate and adriamycin have been tried in cancer therapy. It has shown good result.
4. Resealed erythrocytes of prednisolone have shown good results to prolong the anti-inflammatory action.
It is based on a colloidal drug delivery system. The particle size of this system is in nanometer range i.e. 200-500 mm. That is why they are called nanoparticles. The system consists of a drug and a carrier to deposit the drug at the target site. The carriers used are naturally occurring macromolecules like human serum albumin, bovine serum albumin and other substances like gelatin, casein and ethylcellulose.