Evaluation Of Pharmaceutical Aerosol

Sudheerkumar kamarapuAssistant Professor

Sri Shivani College Of Pharmacy

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EVALUATION A. Flammability & Combustibility

1. Flash Point2. Flame extension, including flashback

B. Physicochemical Characteristics1. Vapor pressure2. Density3. Moisture content4. Identification of propellant (s)5. Concentrate-propellant ratio

C. Performance1. Aerosol valve discharge rate2. Spray pattern3. Dosage with metered valves4. Net contents5. Foam stability6. Particle Size determination7. Leakage

D. Biologic Characteristics

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Flame Projection• Effect of an aerosol formulation on an open flame.• The product is sprayed for about 4 sec into a

flame• Depending on the nature of the formulation, the

flame is extended, the exact length is measured with a ruler.

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Flash Point• Determined by using the Standard

Tag Open Cup Apparatus.• The aerosol product is allowed to

chilled to a temp of about -250F & transferred to test apparatus.

• The test liquid is allowed to increase slowly in a temperature & the temp at which the vapor ignites is taken as the flash point.

• Calculated for flammable components, which in case of topical hydrocarbons.

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Measurement Of Vapor Pressure

• To determine pressure variation from container to container.

• Determine by pressure gauge or can puncturing device.

• Variation in pressure indicates the presence of air in headspace.

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Measurement Of Density•Determination by Hydrometer or a Pycnometer.PROCEDURE:•A pressure tube is fitted with metal fingers and hoke valve, which allow for the introduction of liquids under pressure.•The hydrometer is placed in to the glass pressure tube.•Sufficient sample is introduced through the valve to cause the hydrometer to rise half way up the length of the tube.•The density can be read directly.

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Identification of Propellants

• GC & IR spectroscopy.• These methods are used for the

identification as well as measurement for proportion of each components in blend.

Moisture• Karl Fischer Method• GC

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Aerosol Valve Discharge Rate

• This is determine by taking an aerosol product of known weight and discharge the content for a given period of time using standard apparatus.

• By reweighing the container after the time limit has expired, the change in weight per time dispensed is the discharge rate, which can then be expressed as grams per second.

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Spray pattern • Method is based on the impingement of

the spray on a piece of paper that has been treated with a dye-talc mixture.

• Depending on the nature of the aerosol, an oil-soluble or water-soluble dye is used.

• The particles that strike the paper cause the dye to go into solution and to be absorbed onto the paper.

• These gives the record of the spray, which can then be used for comparison.

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Dosage With Metered Valve

1. Reproducibility of dosage each time the valve is depressed.

2. Amount of medication actually received by the patient.

• It is done by assay method.• Either by spraying the content into the

solvent or on the material which absorb the API. Which then assay for the content uniformity.

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Net content

• Weight of empty container =W1 gm• Weight of the filled container =

W2gm• Difference in the weight = W1-W2gm

net content.• Distractive method: weight the filled

container, dispensing the content and than contents are weigh.

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Foam Stability

• Visual evaluation• Time for a given mass to penetrate

the foam• Time for a given rod that is inserted

into the foam to fall• Rotational viscometer

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Particle Size Determination Cascade impector.•Operates on the principle that in a stream of particles projected through a series of nozzles and glass slides at high velocity, larger particles became impacted first on the lower velocity stages and the smaller particles pass on and are collected at higher velocity stages.•Particle size = 2-8 µ.

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Light Scatter Decay

• As the aerosol settles under turbulent conditions, the change in the light intensity of a Tindal beam is measured.

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Leakage • Select 12 pressurized containers at

random, and• record the date and time to the nearest

half-hour. • Weigh each container to the nearest mg,

and record the weight, in mg, of each as W1.

• Allow the container to stand in an upright position at room temperature for not less than 3 days,

• and again weigh each container, recording the weight, in mg, of each as W2 .

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Cont….

• recording the date and time to the nearest half-hour.

• Determine the time, T, in hours, during which the containers were under test.

• Calculate the leakage rate, in mg per year, of each container from the expression .

• 365 x 24/T x (W1 - W2).

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Biological Test

• Therapeutic activity• toxicity

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Official Test

1. Content uniformity2. Uniformity of delivered dose3. Particle size and4. Leak test

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References

• Remington: the science and practice of pharmacy, volume 1, pg no.974-978.

• The Theory and Practice of Industrial Pharmacy, By Lahman and Lieberman (3rd Edition),pg no.613-618.

• Pharmaceutical dosage forms: disperse systems, volume 2, pg no.353-355.

• Indian pharmacopoeia 2007, volume 2.• www.google.com , images.

Thank You ….