Lesson - 31 Pharmaceutical Aerosols I

Lesson - 31

Pharmaceutical Aerosols I

-Dr Ajay Semalty

Department of Pharmaceutical Sciences,

H.N.B Garhwal University (A Central University)

Srinagar Garhwal-246174

Learning outcomes

After learning this module you will be able to understand

• Basic principle of Aerosol

• Advantages, Limitation of aerosol

• Uses of aerosol

Lesson Plan

• Aerosol: Definition

• Advantages,

• Limitation

• Uses of aerosol

Aerosols

You know it very well, but you just don’t know that it is aerosol. Can you

guess? We use/see it almost daily. Not necessarily for medical use. E.g.

Module 31 Pharmaceutical Aerosols I

2 MOOC: Industrial Pharmacy-I by Dr Ajay Semalty (Course Coordinator), HNB Garhwal

University (A Central University) Srinagar (Garhwal) Uttarakhand, India

Deospray, perfume spray, Mosquito/cockroach repellant spray. Yes they are

aerosols.

The beautiful rainbow is the best example from the nature. It is a quite stable

liquid aerosol. On the other hand, Irrigation fountain is the example of coarse

unstable liquid aerosol.

Pharmaceutical aerosols

Aerosols are being used from decades for therapeutic purpose globally. E.g.

pressurized metered dose inhalers (MDIs), dry powder inhalers (DPIs),

nebulizers, skin sprays (pain killer spray) etc. Ever increasing incidence of

asthma globally is increasing the demand of aerosols.

The technology’s continual advancement, the ease of use and the more

desirable pulmonary-rather-than-needle delivery for systemic drugs has

increased the attraction for the pharmaceutical aerosol in recent years.

Moreover, the increasing incidence of asthma at an average rate of 5 % per

year in developed as well as developing countries is creating a consistently

high demand of inhalers or MDIs (about 50 to 60 million patients are relying

on MDIs).

Definition




The word aerosol means: “Aero= air, Sol = solution”. Aerosol is a

“Pressurized package”.

“Aerosols are a suspension of small solid particles or droplets suspended

in a gas or vapor.”

“Aerosols are the products that depend on the power of a compressed or

liquefied gas to expel the contents from the container.”

“Pharmaceutical aerosols are products that are packaged under pressure and

contain therapeutically active ingredients that are released upon activation of

an appropriate valve system. They are intended for topical application to the

skin as well as local application into the nose (nasal aerosols), mouth (lingual

aerosols), or lungs (inhalation aerosols). These products may be fitted with

valves enabling either continuous or metered-dose delivery; hence, the terms

“[DRUG] Metered Topical Aerosols,” “[DRUG] Metered Nasal Aerosols,”

etc.” [USP definition]

Learning the definition

Active drug dissolved, suspended or emulsified in propellant to

release drug in the form of mist, spray to topical, nasal, oral, pulmonary

and other body cavities for local and systemic therapeutic uses




Advantages

Easy administration: The product is administered easily and quickly.

Portable: Aerosols are portable and tamper-proof.

Minimum dose required: Lower dose of drug can be used and hence

Minimize adverse and side effects A dose can be removed without

contamination of materials.

Direct delivery of drug to target area: The medication can be

delivered directly to the affected area

Better spreading due to spray/ mist type of delivery: Drug is

delivered in a desired form, such as spray, steam, quick breaking foam

or stable foam, Application of medication in thin layer.

Quick onset of action: Drug acts quickly due to direct delivery at

affected area and that to in spray form.

Lower irritation: Irritation produced by the mechanical application of

topical medication is reduced or eliminated.




Dose to dose to maintenance of sterility: When sterility is an

important factor, it can be maintained while a dose is being dispensed.

Better protection for oxygen and or moisture sensitive drugs:

Stability is enhanced for these substances adversely affected by oxygen

and or moisture

Avoid first pass metabolism: Avoidance of degradation of the drug in

the GIT and first pass effect

Limitation

Not Cost effective (diclo spray v/s diclo tablet)

Proper use needed to get the effect. (prone to incorrect use)

Limited safety hazard

o Flammable

o Pressurized

o Inadvertent inhalation

Ancillary devices are required with an MDI (like holding chambers and

spacers )

Uses of Pharmaceutical Aerosols

Since decades, pharmaceutical aerosols have played an important role in

treating respiratory disorders like asthma and chronic obstructive pulmonary

disease (COPD), and MDIs and DPIs have become an important part of that

treatment. But the use of aerosol products are not limited to the pulmonary




route, these can be administered by various routes of administration (ROA)

for various therapeutic effects (Table 1). These can be administered by

topical, nasal, ocular, oral, rectal and vaginal routes also.

Oral and Lingual Aerosols

Easy access to hard-to-reach sites

Easy access to systemic circulation

Avoid FPM

Examples: Anti-anginals (e.g. Nitroglycerin) in emergency, Local

anesthetics (e.g. Lidocaine) for dental use, Antacids (e.g. Aluminum

and magnesium silicate), Antiseptics (e.g. Chloroseptic)




Topical Aerosols

Convenient as compared to application

No need to touch skin

Unused product is not contaminated

Examples: Spray on bandages, Antifungal sprays (Miconazole),

Antibacterials(e.g. Neomycin), Wound washing, Rubiferants (e.g.

Methylsalicylate), Anti-inflammatory steroids (e.g. Dexamethasone),

Local anesthetics (e.g. Benzocaine)




Vaginal Aerosols

• Easy access

• Expands to fill available space

• Provide complete surface coverage

• Example: Contraceptive Foams (e.g. Nonoxyenol-9)

Rectal Aerosols

• Easy access

• Expands to fill available space




• Provide complete surface coverage

• Example: Anti-inflammatory steroids (e.g. Hydrocortisone), Local

anesthetics (e.g. Pramoxine)

Nasal Aerosols

• Easy access

• Minimal dripping

• Example: Decongestants (e.g. Phenylephrine), Antiallergics (e.g.

Cromolyn sodium), Anti-inflammatory steroids (e.g. eclomethasone),

Antismoking (Nicotine), Moisturizers (e.g. Normal saline), Systemic

access of Antidiuretics (e.g. Desmopressin)




Ocular Aerosols

• Easy access

• Minimal dripping

• Contact lens cleaning solutions (not applied directly to eye)

Respiratory Aerosols

• Local as well as systemic action is obtained

• E.g. Anti-inflammatory steroids (e.g. Beclomethasone), Antiallergics

(e.g. Cromolyn sodium), Antivirals (e.g. Ribavirin), Bronchodilators




(e.g. Albuterol), Migraine (e.g. Ergotamine tartrate), Smoking

cessation (e.g. Nicotine)

Take away Message

• Aerosols are pressurized package

• Drug is dissolved suspended or emulsified in propellant and dispensed

in the form of mist or spray for local or systemic action.

• These are used by various ROA like oral, rectal, vaginal, topical etc.

• Low dose, quick onset of action, high bioavailability, low adverse

effect, avoiding FPM are the main advantages

• Refer further reading links; take part in discussion forum.

• We will discuss the components of aerosol in the next module.

Further Readings

• Banker & Rhodes, Modern Pharmaceutics, CRC Press.

• Aulton ME (ED), Pharmaceutics: The science of Dosage form design,

II edn, Churchill Livingstone, London, 2002.

• Semalty et al., Essentials of Pharmaceutical Technology, II Edn.

Pharma Med press, Hyderabad, India




Credits/References

• USP

• Semalty et al., Essentials of Pharmaceutical Technology, II Edn.

Pharma Med press, Hyderabad, India, ISBN 9789386819994

Documents

Lesson - 31 Pharmaceutical Aerosols I