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micronized with a particle size typically between $1$ to $5~\mu m$ for proper delivery
deep into the lungs using dry powder inhalers (DPIs) .

• For External Use (Topical Powders):

o Dentifrices (Tooth Powder): Non-official powders used to clean teeth, often
containing finely precipitated calcium carbonate .

o Dusting Powders: Very fine powders applied to the skin (e.g., talc powder) . They
must have a small particle size to prevent skin irritation, be free-flowing for
easy application, and adhere easily to the skin . Powders applied to open
wounds must be sterilized .

Classification Based on Dispensing

• Bulk Powders: Mixtures of all materials (usually non-potent drugs) packed into a bulk
container, such as a wide-mouthed bottle . The major problem is the inaccuracy of the
dose, which can be affected by the measuring device (spoon) . Used for drugs with a
wider therapeutic index and large dose (e.g., sodium bicarbonate, antacids) .

• Divided Powders: Single doses of a powdered drug mixture individually enclosed in a
packet or paper . They are a more accurate dosage form because the patient is not
involved in measurement . The choice of packaging paper (e.g., simple bond, waxed
paper, glassine) depends on the nature of the powder, especially its moisture resistance
and the volatility of components .

Granules

Granules are defined as dry aggregates of powder particles that may contain one or more Active
Pharmaceutical Ingredients (APIs) . They are larger than fine powders, typically ranging from
$0.2$ to $4.0~mm$ in the pharmaceutical industry, and usually within the 4- to 12-mesh sieve
size range .

Advantages of Granules over Powders

Granules offer several advantages, making them the "factory's favorite child" :

• Better Flowability: They flow better than fine powders, which is critical for
manufacturing processes like tablet-making and volumetric dispensing .

• Enhanced Stability: They are generally more resistant to humidity and less likely to
harden when exposed to liquids, making them physically and chemically more stable
than powders .

• Reduced Dust: They produce less dust, improving safety and reducing loss during
handling .

• Improved Uniformity: They enhance the uniformity of the API in the blend .

Effervescent Granulated Salts

These are granules or coarse powders that release carbon dioxide upon contact with water,
typically containing sodium bicarbonate, citric acid, and tartaric acid . The effervescence

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