liquid dosage form

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Liquid dosage forms


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LIQUID DOSAGE FORMS Presented By : Mr. Naresh Rajgor, Assistant Professor, M.P. Patel College of Pharmacy, Kapadwanj


INTRODUCTION Definition: “A solution is a liquid-preparation that contains one or more soluble chemical substances dissolved in a specified solvent.” Liquid dosage form mainly divided into Solution 2. Syrup 3. Suspension 4. Emulsion

Advantages :

Advantages 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.

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Disadvantages Bulky than tablets or capsule, so difficult to carry transport. 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.


ADDITIVES USED IN LIQUID DOSAGE FORMS Vehicles Buffers Density modifiers Stabilizer Isotonicity modifiers Viscosity enhancement Preservatives Sweetening agents Reducing agents and antioxidants Flavors and perfumes Colors

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VEHICLES: Two types of vehicles; a. Aqueous vehicles b. Non- aqueous vehicles.

a. Aqueous vehicles:

a. Aqueous vehicles Water is the solvent most widely used as a vehicle for pharmaceutical products because of its physiological compatibility and lack of toxicity. It possesses a high dielectric constant, which is essential for ensuring the dissolution of a wide range of ionizable materials.

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Types of pharmaceutical water. Sr . No. Name Properties Remarks 1 Water -Cheap -High Dielectric Constant -Miscible with alcohol, glycerol and other polar solvents -Non flammable -Inert -Impurities 2. Purified Water -Prepared by Distillation or ion exchange resin -used for Parenterals Preparation 3. Water for injection -Sterile -Pyrogen free -Parenterals Preparation 4. Sterile water for injection Sterilizes and suitably packed -No antimicrobial added -Parenterals Preparation 5. Bacteriostatic water for injection Sterile water contain one or more suitable anti microbial - Parenterals Preparation

Approaches to improve aqueous solubility:

Approaches to improve aqueous solubility Co-solvency pH control Solubilization (macrogol ethers, polyoxyethylated sorbitan, sucrose monoesters, lanolin esters) Complexation Chemical modification Particle size control

b. Non-aqueous vehicles:

b. Non-aqueous vehicles Fixed oils of vegetable origin Alcohols Polyhydric alcohols Dimethylsulfoxide Ethyl ether Liquid paraffin Miscellaneous solvents

1. Fixed oils of vegetable origin :

1. Fixed oils of vegetable origin These are non-volatile oils that consist mainly of fatty acid esters of glycol. Almond oil, consist of glycerides mainly of oleic acid is used as a solvent for oilyphenol injections Arachis oil is used as the solvent in dimercaprol injection. Olive oil, sesame oil, maize oil, cottonseed oil, soya oil and caster oil are all suitable for parenteral and eye, ear drop formulation. Ethyl oleate is useful solvent for both ergocalciferol injection and testosterone propionate injection. Vegetable oils are also used for veterinary formulations.

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Sr . No. Name Properties Remarks 1 Corn oil -Clear -Light yellow oily liquid -Solvent and vehicle for injection 2. Cotton seed oil -Pale yellow oily liquid -Odourless -Solvent and vehicle for injection 3. Peanut oil -Colourless to Pale yellow -Solvent and vehicle for injection -- Liniments 4. Sesame Oil -Pale Yellow -Odourless - Solvent and vehicle for injection - Cosmetics, liniments and ointments. 5. Ethyl Oleate -Pale yellow oily liquid Low viscosity Vehicle for I.M, 6. Silicons Different Grade Dermatological Preparations

2. Alcohols :

2. Alcohols Ethyl alcohol is the most widely used solvent in this class, particularly for external preparation, where it evaporates and produce a cooling effect Ex: salicylic acid lotion At concentrations greater than 15%, ethanol exhibits anti microbial activity but because of its toxicity, it is used orally or parenterally only at low concentrations, usually as a co solvent with water. In some case isopropyl alcohol is also used externally as a solvent.

3. Polyhydric alcohols:

3. Polyhydric alcohols Alcohols containing two hydroxyl groups per molecule are known as glycols but because of their toxicity, they are rarely used internally. Propylene glycol is only the exception. It is often used in conjunction with water or glycerol as a cosolvent. It is used n formulation of digoxin inj, phenobarbital inj etc preparation. They are used with various range like PEG 400, PEG 600 etc. Glycerols an alcohol possessing three hydroxyl groups per molecule, is also used as a cosolvents with water for oral use.

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Sr . No. Name Properties Remarks 1 Ethanol -Miscible wit hwater -Antimicrobial Property -Costly due to high excise duty 2. Propylene Glycol -solvent as well as preservatives - miscible with water -Oral Preparation -Hydrophilic ointments - injection of barbiturates,iodine 3. Glycerol -Colorless -Syrupy -Sweet taste -Hygroscopic Use as -solvent -Preservative -Humectant -Use in throat paints, linctuses, syrups, Elixirs 4. 1,3 butylene glycol -Colourless -Viscous -Miscible with water - solvent for morphine injection 5. Polyethylene glycol -colourless -Used in lotion 6. Sorbitol -white -miscible with water -sweet taste -70% w/w used as vehicle

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4. Dimethylsulfoxide This is highly polar compound and is thought to aid the penetration of drugs through the skin, used as a solvent for veterinary drugs, and as a permeation enhances for transdermal system. 5. Ethyl ether: Widely used for the extraction of crude drugs. Not used internally Used as a cosolvent with alcohol in some collodion.

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6. Liquid paraffin: The oily nature makes its unplease so used externally. It is used as a solvent fot the topical application of drugs in emulsion formulations. It was widely used as the base for nasal drops. 7. Miscellaneous solvents: Isopropyl myristate, isopropyl palmitate used in cosmetics. Dimethylformamide, dimethylacetamide use as solvent in veterinary preparation. Xylene is present in some ear drops for human use to dissolve ear wax.

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