Granules and Powders
Granules and powders are solid dosage forms that
contain one or more medicinal and inert substances in finely divided form. They
are among the oldest and simplest forms of drug administration. Powders can be
used internally (orally) or externally (topically), while granules are often
larger, free-flowing particles that are easier to handle and may be used for
preparing solutions, suspensions, or for direct swallowing.
Definition:
- Powders:
Finely divided solid particles containing one or more drugs intended for
internal or external use.
- Granules:
Agglomerates of powder particles formed into small, dry, and free-flowing
masses for ease of handling and better stability.
Composition:
- Active
ingredients: Medicinal substances in powdered form
- Diluents
or fillers: To increase bulk (e.g., lactose, starch)
- Flavouring
agents and sweeteners: To improve taste for oral use
- Coloring
agents: For appearance
- Lubricants
or binders (for granules): To aid granule formation and flow
Advantages:
- Simple
and economical to prepare
- Stable
compared to liquid dosage forms
- Rapid
drug absorption due to large surface area
- Flexible
dosing — can adjust the amount as needed
- Easy
to store and transport
- Used
for patients who have difficulty swallowing tablets or capsules
- Granules
have better flow properties and are less dusty than powders
- Can be
dissolved in water before administration for easy intake
Disadvantages:
- Not
suitable for unpleasant-tasting or hygroscopic drugs
- Less
convenient to carry and measure compared to tablets
- Dosing
errors possible if not properly measured
- May
irritate the stomach when taken dry
- Sensitive
to moisture and must be stored properly
Examples:
- ORS
powder – for dehydration
- Antibiotic
powders – for reconstitution before injection or oral use
- Effervescent
granules – like Eno or Disprin for acidity relief
- Talcum
powder – for external application
- Dusting
powders – for skin infections or wounds
Importance of Granules and Powders
- Allow
flexible and accurate dosing:
Powders can be easily measured according to the prescribed dose, and granules can be divided into single-dose sachets for accuracy.
Example: ORS (Oral Rehydration Salts) powder is dissolved in water before use, ensuring the correct amount per dose. - Provide
faster drug absorption and onset of action:
Since powders and granules disintegrate quickly, the drug dissolves faster in the body and acts rapidly.
Example: Antacid powders like Eno or Disprin act quickly for acidity or headache relief. - Enhance
drug stability and shelf life:
In dry form, many drugs are more stable and less likely to degrade compared to liquid preparations.
Example: Antibiotic dry powders (like amoxicillin dry syrup) are reconstituted with water only before use to maintain potency. - Useful
for large doses that are difficult to compress into tablets:
Some drugs require a high dose or large volume, which cannot be made into tablets or capsules.
Example: Bulk laxative powders like Ispaghula husk (Isabgol) are taken directly with water. - Convenient
for reconstitution into other dosage forms:
Powders and granules can be easily converted into solutions or suspensions before administration.
Example: Dry syrup formulations are prepared by adding water to make a liquid antibiotic for children. - Improved
flow and handling properties in granule form:
Granules flow more easily than fine powders, reducing dust and improving uniform mixing during manufacturing.
Example: Effervescent granules like Vitamin C granules are easier to handle and dissolve rapidly in water. - Provide
enhanced palatability and reduced irritation:
Granules or coated powders can mask unpleasant tastes or minimize irritation in the mouth or stomach.
Example: Effervescent granules mask the taste of bitter drugs and are gentle on the stomach.
