BASIC UNDERSTANDING OF PRESSURIZED METERED DOSE INHALERS AND ITS AERODYNAMIC PARTICLE SIZE TESTING: A REVIEW

Abstract

There are so many classical pharmaceutical dosage forms available in market such as Tablets, Capsules, Syrups, Parentarals etc for treatment of different respiratory diseases. but they are with so many limitations such as long time taken for giving desired effect, kids can’t take tablets and capsules, while parentarals are painful for adults also as needle insert inside the body gives much pain. So, now a days a new and advance dosage form namely aerosol dosage forms (or Pulmonary dosage forms) such as Pressurized metered dose inhalers, Dry powder Inhalers and Nebuliser solutions or suspensions gets attraction and became more popular due to its so many advantages over the classical pharmaceutical dosage forms.

pMDI (Pressurized metered dose inhaler) is one of the aerosol dosage form. pMDI dosage form is mainly used for the treatment of respiratory diseases such as chronic obstructive pulmonary disease (COPD) and Asthma. Key components of Pressurized metered dose inhaler device are Aluminium Canister, Metering valve and Actuator. It contains propellants such as HFA 134a or HFA 227ea and formulation inside the canister. These devices are mainly multi dose devices and are known for consistent pre-metered delivery of drug in the form of short burst of aerosol cloud directly to the lungs of the patient. Aerodynamic particle size distribution is very important parameter in testing of pMDI products. Advanced analytical instruments such as Anderson cascade impactor with vacuum pump and Flow meter is used for analysis of aerodynamic particle size distribution.