Solid Oral Dosage Forms - Powders

Question 1

What is powders?

Answer 1

Dry solid dosage formulation composed of a mixture of finely divided drug and/or excipients used internally/externally

Question 2

Uniform particle size distribution leads to?

Answer 2

• Uniform dissolution rate
• Uniform sedimentation rate
• Decreased stratification

Question 3

Effect of particle size?

Answer 3

• Dissolution rate: micronization increase dissolution rate and bioavailability
• Suspendability of particles
• Uniform distribution: critical for dose uniformity
• Penetrability of particles intended to be inhaled for deposition deep in the respiratory tract (1-5um)
• Grittiness: fine powders may be 50-100um in size

Question 4

Advantages of powders

Answer 4

• Stability: solids more stable
• Dose can contain different amounts of active drug
• Fast dissolution rate -> drug absorption is rapid -> faster onset of action
• Administered for patients that cant swallow
• Can administer large quantities
• Versatile: made into many different dosage formulations

Question 5

Disadvantages of powders

Answer 5

• Less convenient to carry
• Not suitable for administering potent drugs with a low dose
• Not suitable for administering drugs which are inactivated in/cause damage to stomach
• Taste

Question 6

Classification of powders

Answer 6

• Bulk powder: non-toxic, non-potent
• Divided powder: single doses of powdered medicinals individually
• Dusting powder: On the skin used sifter-tops
• Douche powder: Used to prepare solutions to cleanse the vagina; used for their hygenic effects
• Insufflations: Extremely fine powders used into body cavities
• Dry powder inhalers: Dispensed under pressure at the desired size

Question 7

Comminution Techniques

Answer 7

• Trituration: Continuous rubbing/grinding of the powder in a mortar with a pestle
• Pulverization by intervention: Dissolve powder and mixed in a mortar/spread on slab for solvent to evaporate -> powder recystallize as fine particles; used with hard crystalline powders that do not triturate easily or with gummy-type substances
• Levigation: reduces the powder particle size by triturating using viscous liquid in which the solid is not soluble

Question 8

Size of powders?

Answer 8

Generally 0.1 - 10 micron

Question 9

Examples of bulk powders

Answer 9

magnesium trisilicate, oral powder

Question 10

Examples of dusting powders

Answer 10

• Bentonite kaolin, magnesium carbonate, starch, and talc absorb secretions and relieve conjestion
• Hexachlorophene used as anti-bacterial agent