Contents:aerosols history Advantages and disadvantages Components of aerosols formulation Preparation and filling Types of aerosols spray Packaging storage and labeling
Aerosols:“A system that depends on the power ofa compressed gas or liquefied gas toexpel the contents from the container.”Pharmaceutical aerosols:Aerosol product containing activeingredients dissolved ,suspended oremulsified in a propellant or a mixture ofsolvent and propellant and intended for oralor topical administration or foradministration into the eye, nose ,ear,rectum and vagina.
History of aerosols The concept of an aerosol originated asearly as 1790, when self-pressurizedcarbonated beverages were introduced inFrance. on 1927, Norwegian engineer ErikRotheim patented the first aerosol canand valve that could hold and dispenseproducts and propellant systems. During World War II, Lyle Goodhueand William Sullivan, developed a smallaerosol can pressurized by a liquefiedgas (a fluorocarbon) in 1943.
Cont… In 1949, 27-year-old Robert H. Abplanalp’s invention of a crimp on valve enabled liquids to be sprayed from a can under the pressure of an inert gas. Spray cans, mainly containing insecticides, were available to the public in 1947 as a result of their use by U.S. soldiers for preventing insect-borne diseases.Abplanalp’s invention made oflightweight aluminum made the cans acheap and practical way to dispenseliquids foams, powders, and creams.
Advantages of aerosolsPulmonary Therapeutics.First Aid.No More Bug Bites.Breathe Easy.Right On Target.No Mess.Safety .Child Resistant.
DISADVANTAGES:Limited safety hazard (FlammableNature)It is a costly preparationExpensive Catalytic oxidation of drugs.e.g. Ascorbic acid and EpinephrineIt is a chance for continuous depositionof particle in upper respiratory tractThe propellant may cause chillness to theskin, Discomfort on injured skinChlorofluorocarbon propellants causeOzone layer depletion
Qc testing for aerosols:1. Physical & chemical inspectionof the valves, actuators and diptubes.2. Specifications of propellants3. Containers should be cheskedfor conuctivity, flaws, weight anddimensiond4. Leak testing5. Spray testing
COMPONENTS OF AEROSOLPropellant ContainerValve and actuatorProduct concentrate
Propellant:It is responsible for developing the vaporpressure within the container and alsoexpel the product when the valve isopened foam production of the product.Liquefied gas propellants:Liquefied propellants are gases that existas liquids under pressure.
Containers:They must be able to with stand pressures as high as 140 to 180 psig (poundsper sq. inch gauge) at 130 ° F. 1. Tin Plate container: Consist of sheet of that has been electroplated on both sides with tin. 2.Aluminum Containers: Greater resistance to corrosion Light weight Good for light sensitive drugs.
3. Stainless Steel Container: Limited for smaller size Extremely strong and resistant to moist materials Pressure stand4. Glass Container: Available with plastic or without plastic coating Compatible with many additives No corrosion problems Can have various shape because of molding Not for light sensitive drug
Valve:Capable of delivering the content in thedesired form such as spray, foam, solidstream etc. TYPES OF VALVES : 1. Continuous spray valve - for topical aerosols 2. Metering valve
Valve assemblyValves assembly consists:• Ferrule or mounting cup- attach valve tocontainer• Valve body or housing- contains aopening at the point of attachment of diptube.• Stem• Dip tube• Gasket• SpringMETERING VALVES: Used for dispensingof potent medication .Operates on theprinciple of a chamber whose sizedetermines the amount of medicationdispensed.
ACTUATORS:These are specially designed buttons which helps in deliveringthe drug in desired form i.e., spray, wet stream ,foam or solidstream .TYPES OF ACTUATORS:• Spray actuators - used for topical preparation. Itallows the stream of product concentrate andpropellant to pass through various openings anddispense as spray.• Foam actuators - consist of large orifice• Solid steam actuators - required for dispensingsemi solid products such as ointments .• Special actuators - used for a specific purpose. Itdelivers the medicament to the appropriate site ofaction
Formulation consists of two essential components:1. Product concentrate2. PropellantPRODUCT CONCENTRATE:Active ingredient or mixture of active ingredients and othernecessary agents such as solvents, anti oxidants andsurfactants.PROPELLANT:Single or blend of various propellants is used. Blend ofsolvents is used to achieve desired solubilitycharacteristics. Various surfactants are mixed to give the proper HLB valuefor emulsion system. The propellants are selected to givethe desired vapor pressure, solubility and particle size. Type of system selected depends on1. Physical, chemical and pharmacological properties ofdrug.2. Site of application
TYPES of AEROSOLSYSTEMS:• Solutionsystem• Water based system• Suspension or Dispersion systems• Intranasal aerosols• Foam systems1. Aqueous stable foams 2. Non aqueous stable foams3. Quick-breaking foams4. Thermal foams
SOLUTION SYSTEM This system is also referred to as two phase system consists of vapor and liquid phase. If active ingredient is soluble in propellant, no other solvent is requiredWATER BASED SYSTEM Large amounts of water can be used to replace all or part of the nonaqueous solvents used in aerosols. Produce spray or foam. To producespray, formulation must consist of dispersion of active ingredients andother solvents in emulsion system in which the propellant is in theexternal phase.
FOAM SYSTEM :They contain Dispersion of AI, aqueous vehicle, surfactant and propellant.Liquefied propellant used as internal phase.•Aqueous stable foam : Active Ingredients (antiseptic),oil waxes O/W surfactant, Water and Hydrocarbonpropellant•Non aqueous stable foam: These are prepared by usingGlycols Emulsifying agent used this type PEG Esters•Quick breaking foam: The product is dispensed as foamwhich then collapsed into liquid. Useful for topicalmedication.•Thermal foams: Used for shaving
INTRANASAL AEROSOLS : Intended to deposit medication into nasal passages for local orsystemic effect. Advantages: Deliver measured dose of drug.
It consists of a pressure burettecapable of metering smallvolumes of liquefied gas into theaerosol container underpressure. PRESSURE BURETTE
• Solutions, emulsions,suspensions can be filled by thismethod as chilling does not occur.• Contamination due to moistureis less.• High production speed canbe achieved.• Loss of propellant is less.
• Certain types of meteringvalves can be handled onlyby the cold filling process.• Process is slower thancold filling method.
It consist of an insulated box fitted withcopper tubing & the tubings are coiledto increase the area exposed to cooling.
• Easy process .• Aqueous products,emulsions & those productsadversely affected by coldtemperature cannot be filled by this method.
Compressed gases have high pressure hence apressure reducing valve is required.The apparatus consists of deliverygauge.
TYPES OF AEROSOLS SYSTEM 1) Solution system / Two phase system 2) Water based system / three phase system 3) Compressed Gas System
SOLUTION SYSTEM Or TWO PHASE SYSTEM Simplest system The two phases are:Liquid phase (liquefied propellant & product concentrate)Vapor phase Product concentrate is dissolved or dispersed in liquefiedpropellants and solvents creating a homogenous system Propellants exist in both Liquefied phase & Vapor phase On activation of valve, pressure of vapor phase causesliquid phase to rise in dip tube and expelled from thecontainer.
THREE PHASE SYSTEMS The three phases are:1) A layer of water-immiscible liquid propellant2) A layer of highly aqueous product concentrate3) A vapor phase This type of system is used when formulation requires the presence of a liquidphase that is not propellant miscible. When aerosol valve is actuated, the pressure of vapor phase causes the liquid phase to rise in the dip tube and be expelled from the container because liquefied propellant has greater density than aqueous layer. It generally resides at the bottom of container with the aqueous phase floating above it.
COMPRESSED GAS SYSTEM Compressed gas other than liquefied gases may be used to prepare aerosols. The pressure of the compressed gas in the head space of aerosolcontainer forces the product concentrate up the dip tube and out of thevalve. Gases used are insoluble in product concentrate. Like nitrogen.It results in emission of a product that is essentially in the same form asit was placed in the container. Compressed gas-filled aerosols have no reservoir of propellant. Higher gas pressures are required in these systems, and pressure inthese aerosols diminishes as the product is used.
TYPES OF AEROSOLS SPRAY There are 3 types of Aerosol Sprays: 1. Space sprays 2. Surface coating spray 3. Foam spray
1) SPACE SPRAY: 2) SURFACE COATING SPRAY:• Its products are delivered in a fine • Aerosols intended for carrying active mist ingredients to surface are termed as surface sprays or surface coating• It contains 85% propellant and it is spray. pressurized at 30-40psi and 70 °F• It contains not more than 50µm of particle. So it can be retaining in air.• Example: Room Sprays • It contains 30 –70% propellant operates between 22–55 psig at 70F. • E.g. Topical Aerosol 3) FOAM SPRAY: Foam aerosols (emulsion) usually operate between 35 and 55 psi at21°c and contains only 6-10% propellant
• Pharmaceutical aerosols compared to other dosage forms is that theproduct is actually packaged as part of the manufacturing process.• Most aerosol products have a protective cap or cover that fits snugly overthe valve and mounting cup. This protects the valve against contaminationwith dust and dirt.The cap, which is generally made of plastic or metal, also serves adecorative function.• Aerosols should be maintained with the protective caps in place toprevent accidental activation of the valve assembly or contamination bydust and other foreign materials.
LABELLING & STORAGE OF AEROSOLS Medicinal aerosols that are to be dispensed only upon prescription are labeled by the manufacturer with plastic peel-away labels or easily removed paper labels so that the pharmacist may easily replace the manufacturer’s label. An aerosol required to be labeled "Flammable“ Safety labels must warn users not to puncture pressurized containers, not to use or store them near heat or an open flame, and not to incinerate them. Name and address or trade mark of the person responsible for marketing the aerosol dispenser. There are now only two classes for flammability – ‘flammable’ and ‘extremely flammable’) it is now required to be marked with the ‘flame symbol’ in addition to marking it with the words ‘flammable’ .
STORAGE OF AEROSOLS Exposure to temperatures above 49°C(120°F) may burst an aerosol container. When the containers are cold, less thanthe usual spray may result.This may be particularly important to usersof metered-dose inhalation sprays. They are generally recommended forstorage between 15°C and 30°C (59°F and86°F).
Reference:http://books.google.com.pk/books?id=MhCnOfCHuKUC&pg=PA1&lpg=PA1&dq=Disadvantages+of+Pharmaceutical+aerosols&source=bl&ots=wjSNhi7t7T&sig=94wsYvgtvgcmbz7AtLZUWuQJHUc&hl=en&sa=X&ei=EXqFUK-LB4PtrQeE2IC4AQ&ved=0CBoQ6Ahttp://www.scribd.com/doc/36285406/1/DISADVANTAGEShttp://faculty.ksu.edu.sa/nsybarakat/Course%20252%20handout/Aerosol%20Dosage%20Forms.htmEwAA#v=onepage&q=Disadvantages%20of%20Pharmaceutical%20aerosols&f=false (The Mechanics of Inhaled Pharmaceutical Aerosols:An Introduction by Warren H. Finlay)http://www.pharmainfo.net/sivaganesh/blog/pharmaceutical-aerosolshttp://www.nationalaerosol.com/aerosol.htmhttp://www.yorks.karoo.net/aerosol/link6.htm
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