Pharmaceutics and Solid Dosage Forms

Question 1

What is the difference between drugs and medicines?

Answer 1

A drug is the active ingredient, but a medicine includes active and inactive ingredients (the entire pill, injection, plant)

Question 2

What is the significance of dosage forms?

Answer 2

Convienirnt and safe delivey of accurarte dosage

Avoid drug degradation (oxidation, humidity, biological fluids)

To improve palatability (taste, texture, odour)

To provide in a form that can be administered (ex. injectable, inhalation aerosols, liquids for children)

To control drug release rate

Question 3

What are some dosage forms on the market?

Answer 3

Tablets
Capsules
Solutions
Suspensions
Emulsions
Powders
Ointments
Creams

Question 4

Why do pharmacists need to know about dosage forms in detail?

Answer 4

Patients may have questions about how they can take their drugs in a different way than intended or recommended by the drug manufacturer. Pharmacists need to use their knowledge of dosage forms and provide accurate advice or services

Question 5

Describe the components of a general drug delivery system

Answer 5

Any drug delivery system includes the drug and the excipients/delivery device that helps deliver the drug to the target.

Delivery systems are developed with the following in mind:
Physiochemical properties of drug (solubility, stability, etc.)
Biopharmaceutical (bioavailability, ADME)
Therapeutic considerations (time of onset, duration of action, site of action, local vs. systemic, age, illness)

Question 6

What are the steps involved in formulation development?

Answer 6

Pre-formulation studies:
Drug characterization, choice of excipients based on dosage form, drug/excipient interaction

Formulation:
Process variables, product parameters

Testing in a biological system
Bioavailability, biodistribution, therapeutic response, toxicological testing

Question 7

What are some solid dosage forms?

Answer 7

Powders

Capsules

Tablets

Modified-Release Dosage Forms

Question 8

What are the advantages of solid dosage forms?

Answer 8

Unit dose (dose is pre-packaged into right amount)

Low cost of shipping

Easier to mask taste

Requires less space per dose

Good physical and chemical stabililty

Question 9

What are some disadvantages of solid dosage forms?

Answer 9

Potential bioavailability problems
Potential irritant effect on GI mucosa
Occasional difficulty in formulation
Manufacturing can be more technical or specialized

Compared to powders, solid dosage forms have to disintegrate, dissolve into solution and get absorbed to be effective. Powders on the other hand are already disintegrated, so they only need to be dissolved into solution and absorbed.

Question 10

What are some properties of solids relevant to powders?

Answer 10

Particle size (affects flow properties) especially when mixing powders together.

Stability in the solid state

Soulubility and dissolution rate

Bioavailability

Question 11

What is bridging in terms of flow of powder through a funnel?

Answer 11

Particles stick together and form a plug near the funnel’s opening. The powder is resistant to flow through the funnel

Question 12

What is rat holing in terms of flow through a funnel?

Answer 12

Fine particles tend to stick along the sides of the funnel, effectively narrowing the opening of the funnel. This narrowing decreases flow through the funnel.

Question 13

What is segregation in terms of flow through a funnel?

Answer 13

In mixtures that have varied particle size, finer particles stick to the walls of the funnel. Narrowing the effective diameter of the opening. Through this opening, larger particles flow through. The different sizes of particles separate

Question 14

What is dissolution rate?

Answer 14

The rate at which the particle dissolves. This property pertains to particle size by comparing the total surface area. Smaller particle size present greater surface area, allowing greater exposure to solvents. This is a technique used in poorly soluble drugs.

Question 15

What is suspendability?

Answer 15

The ability of particle to remain undissolved but uniformly dispersed in a liquid vehicle (smaller particles take longer to sediment vs. larger particles)

Question 16

What is penetrability?

Answer 16

It is the ability of a particle to reach their intended location (ex. particles in an inhaler need to be 1-5 micrograms to be effective deep into the respiratory tract)

Question 17

What is non-grittiness?

Answer 17

Finer particles allow for a smoother texture and better appearance and flow. Thus property is also important for oral products such as chewable tablets

We do not want solid particle in dermal products to feel gritty

Question 18

What is chemical stability?

Answer 18

It refers to degradation reactions (oxidation and hydrolysis). Smaller particles have an increased surface area, leaving them more exposed and vulnerable to reactions with oxygen, water and light

Question 19

What is flowability?

Answer 19

It has an effect on flow properties of powders and mixing of powders and granules. This property is especially important in the manufacturing of tablets and capsules

Question 20

Do larger sieve numbers correspond with larger particles?

Answer 20

No, large sieve numbers correspond with the number of pores/inch. Therefore larger sieve number = smaller particle size

Question 21

What are some advantages and disadvantages of the sieving method?

Answer 21

Advantages (inexpensive, simple, and fast)

Disadvantages (Does not provide as much information as microscopy)

Question 22

What is the difference between monodisperse and polydisperse powders?

Answer 22

Monodisperse powders: powders containing particles of uniform size (rare in real life)

Polydisperse powders: particle size varies a great deal

Question 23

What is comminution?

Answer 23

Comminution is the mechanical process of reducing particle size of a solid substance to finer state of subdivision

Question 24

What are the three types of small-scale comminution?

Answer 24

Trituration: the process of grinding a drug in a mortar to reduce its particle (mechanical alone)

Levitation: the process of mixing a powder with a liquid or semi-solid vehicle (levitating agent)

Pulverization by intervention: particle size reduction with the aid of an addition material, which can be later, removed (ex. use of a volatile solvent)

Question 25

What is the place of industrial comminution/milling?

Answer 25

Milling is industrial scale or mechanical process of reducing particle size.

Coarse crushers: jaw, roll, and impact crushers

Intermediate grinders: hammer, roller, rotary cutters

Fine grinding mills: ball, hammer, colloid, fluid energy mills

Question 26

What are some common methods of small-scale mixing?

Answer 26

Trituration: using a mortar and pestle (combines comminution and mixing into a single operation)

Spatulation: blending powders with a spatula on a tile or paper (relatively inefficient and only for small amounts of powder)

Sieving: (used to help reduce loosely held agglomerates or to increase overall effectiveness of a blending process)

Question 27

What is involved in large-scale industrial mixing?

Answer 27

The ideal mixer should:
Produce a complete blend rapidly, with as gentle as possible a mixing action to avoid product damage

Be easily cleaned and discharged

Be dust-tight

Require low maintenance and power consumption

Question 28

What are the different types of powders used in pharmacy?

Answer 28

Oral powders: usually used after mixing in water. This dosage form is preferred by patients unable to swallow other solid dosage forms (soluble electrolytes)

Topical powders: external application to the skin. (Used directly in topical powders for fungal infections)

Powders are the most basic dosage form and all other dosage forms start at powder.

Question 29

What are the advantages of powders as a dosage form?

Answer 29

Flexibility in compounding
Suitable for infants and young children who cannot swallow tablets or capsules
Rapid onset of drug action because disintegration is not required (only needs to be dissolved and absorbed)
Can be applied to many body cavities such as ears, nose, tooth socket, and throat.
Relatively good chemical stability

Question 30

What are the disadvantages of powders as a dosage form?

Answer 30

Potential for the correct method of use that can lead to inaccurate dosing.

The dose is influenced by many factors including size of measuring spoon, humidity, fluffiness due to agitation, and personal judgement.

Undesirable for bitter or unpleasant tasting drugs

Question 31

What is the therapeutic role of powders for oral use?

Answer 31

A convenient method of dispensing nonpotent, powdered drugs, which have doses that require large volumes of powder

Dose is measured volumetrically by the patient or caregiver at the time of administration

Question 32

What is the therapeutic role of dusting powders?

Answer 32

They can be medicated or non-medicated powders for topical (external) application

Usually used to deliver powder to moist lesions on the skin (ex. tinactin for fungal infections)

Question 33

What are dentifrices?

Answer 33

Dental cleaning powders, denture powders

Question 34

Describe douche powders

Answer 34

They are completely soluble powders; intended to be dissolved in water prior to use as antiseptics or cleansing agents for a body cavity

Question 35

What factors can be altered to improve powder formulations?

Answer 35

Particle size

Taste masking

Route of delivery

Delivery device