Inhalation Preparation | Aerosol | MDI and Standard Test

Inhalation preparations, specifically Pressurized Metered-Dose Preparation (MDI) are liquid or solid dosage forms intended for administration as vapors or aerosols to the lung to obtain a local or systemic effect. They contain solutions or dispersions of one or more active ingredients that can be dissolved or dispersed in a suitable vehicle.

Inhalation preparations intended to be administered as aerosol (dispersion of solid or liquid particles of active ingredients in a gas) are administered by pressurized metered-dose inhalers or powder inhalers. Pressurized Metered Dose Inhalers are dosage forms containing therapeutically active ingredients that are packed under pressure in a sealed container and are released as a fine mist spray upon actuation of a suitable valve system.

Types of Hydro fluoroalkane inhalers: (Pressurized Metered Dose Inhalers or MDI):

1. Two-phase system: Consisting of gas and liquid.

2. Three-phase system: Consisting of gas, liquid, and solids or liquids.

Standard Tests or Evaluation for Inhalation Preparation:

1. Pressurized Metered-Dose Preparation (MDI):

• Description: It should comply with the Specifications of the Products.
• The content of active ingredients delivered per actuation Shall comply with the specification.
• Uniformity of delivered dose: For uniformity of delivered dose, the preparation should comply with the test if 9 out of 10 results fall between 75 to 125% of the average value, with all results falling between 65 to 135%. If 2 or 3 values lie outside the 75-125% limit, repeat the test for two more inhalers. The number of results outside the 65-135% range should not exceed 3 out of 30 values.
• Particle Size: The number of particles longer than 20-micron meter does not exceed 50, and no particles exceed 100-micron meters in length.
• The number of deliveries per container: The number of deliveries so discharged in the test for particle size is not less than the number stated on the label.
• Deposition of emitted dose: As per IP or other specifications.
• Leak Test: The average leakage rate of the 12 containers should not be more than 3.5 per container, and none of the containers leaks more than 5% of the net fill weight per year.

Related Post: Capsules, Types, and Formulation

2. Powder For Inhalation preparation or Dry Powder Inhalation (DPI)

Powder for Inhalation preparation is presented as single-Dose powders or multi-dose powders for pre-meter inhalers. The inhaler is loaded with powders pre-dispensed in capsules or other suitable pharmaceutical dosage forms.

1. Description: It should comply with the Specifications of the Products.
2. Uniformity of delivered dose: The Preparation complies with the test if 9 out of 10 results lie in between 75 to 125% of average value & all lie in between 65 to 135%. If 2 or 3 values lie outside the 75 to 125% limit, repeat the test for two more inhalers. Not more than 3 of the 30 values lie outside the limits of 65 to 135%.
3. Uniformity of content: As given in capsules.
4. The number of deliveries per container: The number of deliveries discharged in the test for particle size is not less than the number stated on the label.
5. Microbial contamination: Total viable aerobic bacterial count shall be not more than 100 CF per g of the powder. E. coli – absent in 10g of the powder. Salmonella – Absent in 50 g of the powder. S.Aureus – absent in 10 g of the powder. P. aeruginosa – absent in 10 g of the powder.