Solid Dosage Forms - powders and granules Flashcards
What are powders?
Pharmaceutical dosage form in Heinrich a drug has been mixed with other powdered excipients e.g. Colouring, flavouring and sweetening agents (for oral use) to produce the final product
What are examples of solid dosage forms?
Powders
Granules
Tablets
What are granules?
Powder particles which have been aggregated using solvent to form large particles with a diameter of approx 2-4mm
What is different about granules used as a dosage form?
These granules are much larger than those prepared as an in-process material for tablet manufacture
What is an advantage of granules over powders ?
Granules have been designed to overcome problems associated with the use of powders such as segregation
What are the types of dispensed solid dosage form preparations and their uses?
Internal use:
Bulk powders or granules
Divided powders or granules (single preparations)
External use:
Dusting powders
Other:
Insufflations for ear/nose/throat administration
Antibiotic powders for reconstitution before use
What are the advantages of powders and granules?
More chemically stable than liquid dosage forms
Convenient form of dispersing drugs with large doses e.g. Antacids
Faster dissolution rate compared to tablets and capsules
What are the disadvantages of powders and granules?
Less convenient for patient to carry
Not suitable for administration of potent drugs with low doses
Difficult to mask unpleasant tastes
Not suitable for administration of drugs that are inactivated, not absorbed or destroyed in stomach or cause gastric irritation
What are the different classes of powders?
Bulk powders Divided powders Dusting powders Dry powder inhalers Powdered antibiotic for reconstitution
What are bulk powders?
A mixture of ingredients packed into large containers such as glass or jars.
- non potent
- can be dosed with acceptable accuracy and safety just by using measuring devices (e.g. Teaspoon, cup, etc)
- ingredients usually non toxic if they are given in large doses (e.g. Magnesium trisilicates and chalk in antacids)
What are divided powders?
Single doses of powdered medicinals which are individually wrapped in cellophane, metallic foil, or paper satchels.
What are dusting powders?
- Formulation used for therapeutics, prophylactic or lubricant purposes.
- for external use only
- requires good flow properties so they can be dusted over the skin
- dispensed in glass or metal containers with a perforated lid
- e.g. Baby powder
What are dry powder inhalers?
- used to extensively deliver active ingredients to lungs (e.g. in asthma & COPD )
- there are now a many commercial preparations available in the market as dry powders for inhalation in sophisticated devices e.g. Terbutaline
What are oral antibiotic powders?
- powders or granules intended for preparation of solution or suspension
- designed for patients who have difficulty swallowing whole tablets or capsules
- designed to overcome instability problems of some drugs
- reconstituted by adding water at time of dispensing
- reconstituted syrup or suspension has shelf life of 1-2 weeks
What are the different granule preparations?
Bulk granules
Divided granules
What are bulk granules?
- contain medicaments of low toxicity in high doses
- e.g. Methylcellulose used as bulk laxative (1-4g/day)
What are divided granules?
- small particles containing medicinal agent in a dry mixture usually composed of sodium bicarbonate, citric acid and tartaric acid
- releases gas in contact with water resulting in effervescence
What is micromeritics?
The science and technology of small particles
What is the unit of particle size most frequently used in micromeritics ?
μm
Why is particle size studied?
Particle size influences production of formulated medicines as solid dosage forms e.g. Tablets vs. Capsules
Powders with different particle sizes can have different flow and packing properties, affecting the production of tablets and capsules
Particle size affects rate of release of drug into solution and its bioavailability e.g. Griseofulvin
How is particle size of an individual particle defined?
If the particle is spherical, its size is expressed in diameter
If the particle is non spherical, the solid particle is often considered to approximate a sphere
The hypothetical sphere particle is expressed by its equivalent spherical diameter
What are the methods of determining particle size?
Sieving Microscopy Coulter counter/sensing zone counters Laser light scattering Sedimentation
How are the methods of determining particle size selected?
Based on The size range of sample If the sample is wet or dry If a manual or automatic determination is required The speed of analysis
What is sieving?
The oldest method of classifying powders and granules by particle-size distribution based on the intermediate size dimension (width)
Particle size analysis is carried out in the dry state