Inhalation preparations OR 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 which may be dissolved or dispersed in a suitable vehicle.
Inhaler.

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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 o 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:
- Pressurized Metered-Dose Preparation (MDI)
- Description: It should comply with the Specification of Products.
- Content of active ingredient delivered per actuation Shall comply with the specification.
- Uniformity of delivered dose: The Preparation complies with the test if 9 out of 10 results lie between 75 to 125 % of the average value and all lie in between 65 to 135 %. If 2 or 3 values lie outside the 75 — 125 % limit, repeat the test for two more inhalers. Not more than 3 of the 30 values lie outside the limits of 65 —135 %.
- 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
- Powder For Inhalation preparation or Dry Powder Inhalation (DPI)
Powder for Inhalation preparation is presented as single-Dose powders or multi-dose powders Fo pre-meter inhalers. The inhaler is loaded with powders pre-dispensed in capsules or other suitable pharmaceutical dosage forms.
- Description: It should comply with the Specification of Products.
- Uniformity of delivered dose: The Preparation complies the test if 9 out of 10 results lie in between 75 to 125% of average value & all lie in between 65 to 135 To. If 2 or 3 values lie outside the 75 -125 % limit, repeat the test for two more inhalers. Not more than 3 of the 30 values lie outside the limits of 65 -135 %.
- Uniformity of content: As given in capsules.
- 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.
- 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.