Pharmaceutics and Solid Dosage Forms Flashcards
What is the difference between drugs and medicines?
A drug is the active ingredient, but a medicine includes active and inactive ingredients (the entire pill, injection, plant)
What is the significance of dosage forms?
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
What are some dosage forms on the market?
Tablets
Capsules
Solutions
Suspensions
Emulsions
Powders
Ointments
Creams
Why do pharmacists need to know about dosage forms in detail?
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
Describe the components of a general drug delivery system
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)
What are the steps involved in formulation development?
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
What are some solid dosage forms?
Powders
Capsules
Tablets
Modified-Release Dosage Forms
What are the advantages of solid dosage forms?
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
What are some disadvantages of solid dosage forms?
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.
What are some properties of solids relevant to powders?
Particle size (affects flow properties) especially when mixing powders together.
Stability in the solid state
Soulubility and dissolution rate
Bioavailability
What is bridging in terms of flow of powder through a funnel?
Particles stick together and form a plug near the funnel’s opening. The powder is resistant to flow through the funnel
What is rat holing in terms of flow through a funnel?
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.
What is segregation in terms of flow through a funnel?
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
What is dissolution rate?
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.
What is suspendability?
The ability of particle to remain undissolved but uniformly dispersed in a liquid vehicle (smaller particles take longer to sediment vs. larger particles)
What is penetrability?
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)
What is non-grittiness?
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
What is chemical stability?
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
What is flowability?
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
Do larger sieve numbers correspond with larger particles?
No, large sieve numbers correspond with the number of pores/inch. Therefore larger sieve number = smaller particle size
What are some advantages and disadvantages of the sieving method?
Advantages (inexpensive, simple, and fast)
Disadvantages (Does not provide as much information as microscopy)
What is the difference between monodisperse and polydisperse powders?
Monodisperse powders: powders containing particles of uniform size (rare in real life)
Polydisperse powders: particle size varies a great deal
What is comminution?
Comminution is the mechanical process of reducing particle size of a solid substance to finer state of subdivision
What are the three types of small-scale comminution?
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)
What is the place of industrial comminution/milling?
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
What are some common methods of small-scale mixing?
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)
What is involved in large-scale industrial mixing?
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
What are the different types of powders used in pharmacy?
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.
What are the advantages of powders as a dosage form?
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
What are the disadvantages of powders as a dosage form?
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
What is the therapeutic role of powders for oral use?
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
What is the therapeutic role of dusting powders?
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)
What are dentifrices?
Dental cleaning powders, denture powders
Describe douche powders
They are completely soluble powders; intended to be dissolved in water prior to use as antiseptics or cleansing agents for a body cavity
What factors can be altered to improve powder formulations?
Particle size
Taste masking
Route of delivery
Delivery device
