It consists of active ingredient or a mixture of active ingredients with other necessary agents such as solvents, antioxidants and surfactants. Propellants can be combined with the active ingredients in many ways producing products with varying characteristics.

Blends of various fluorocarbon propellants are generally used for pharmaceutical aerosols. These mixtures help in obtaining the desirable pressure, delivery and spray characteristics. By varying the proportion of each component, any desired vapor pressure can be achieved. The CFCs have been implicated in having ozone depleting effect, increasing the amount of UV radiations reaching the…

Liquefied gases have been used widely as propellants for most of the aerosol products. In a sealed container such as an aerosol can, the liquefied gas exists in two phases—liquid and gas, behaving as a two-phase system. The molecules in the vapor stage are responsible for exerting the pressure on the contents. As the number…

Liquefied gases are widely used as propellants for most of the aerosol products. These are materials that exist in the gaseous or vapor state at room temperature and atmospheric pressure and are capable of being liquefied easily by lowering the temperature below its boiling point or by increasing the pressure. The compounds chosen generally have…

Compressed gas propellants are widely used in pharmaceutical aerosols. The gases generally used include nitrogen, nitrous oxide and carbon dioxide. They can be used to dispense the product in the form of a solid stream, wet spray or foam. The gas is compressed in the container and occupies the head space above the liquid in…

Learning Objectives A propellant is responsible for developing the pressure within the container and in combination with other components it expels the product in the desired physical form like spray, mist or foam. Propellants may be broadly classified as follows: The types of propellants used for different pharmaceutical applications are listed in Table 12.1.   Table…

The aerosol formulation consists of the following two essential components:

Learning Objective A metered-dose inhaler (MDI), introduced in 1950s is a device that delivers a specific amount of medication to the lungs, in the form of a short burst of aerosolized medicine that is inhaled by the patient. It is the most commonly used delivery system for medications such as bronchodilator, corticosteroid or a combination…

The metering valves (Figure 12.13) are necessary for potent medicaments where the dose is important. These valves operate on the principle of a chamber, whose capacity determines the amount of medicament delivered per dose. Approximately 50 to 150 mg ± 10% of liquid material can be dispensed at a time. Figure 12.13 Metering Valves

Learning Objective Actuators are specially designed buttons required for easy opening and closing of the valve. The type and quantity of the propellant and the design and dimension of the actuator determine the type of product discharge whether it is in spray or foam or a solid stream. Special actuators are available for use with…