Midterm 1 Flashcards
Define pharmaceutics
Area of study that provides the scientific foundation for the design, development, formulation, maufacture, stability, effectiveness, acceptable delivery and appropriate use of pharmaceutical dsage forms and drug delivery systems
Define dosage form
Form in which the drug is taken: tablet, syrup, ointment, etc.
Define drug delivery system
Includes products that are designed to provide optimal control over the release of a drug to achieve enhanced safety or efficacy
Name some considerations regarding the formulation of a drug that is stable, efficacious, attractive, easy to administer and safe
- The therapeutic indication of the drug
- The profile and psychological characteristics of the inteded patient
- The bioavailability of the drug substance
- The compatability of medicinal and non-medicinal ingredients with one another
- The stability and physiochemical properties of he drug
- Anticipated adverse drug effects
The product should be manufacteured with appropriate measure of:
Quality control
The product should be packaged in a container that keeps the product:
Stable
The product should be labeled to promote:
Correct use
The product should be stored under conditions that contribute to:
maximum shelf life
Define ‘drug’
Any substance, other than food, intended for use in the diagnosis, mitigation, treatment, cure of prevention of disease in humans or in other animals
Name two examples of early drugs
- The sumerian tablet
- The Eber’s papyrus
Who introduced the scientific viewpoint to science?
Hippocrates
What are the two broad steps of new drug devel.?
- Identify the cause and process of a disease
- Design molecules capable of interfering with that process
Name some priorities in selecting diseases for a new drug
- The disease affects the developed world
- The disease is widespread
- If there are drugs already on the market for the disease, what are their advantages & disadvantages
- A market advantage for a new drug can be ID
- The profits from marketing a new drug should outweigh the cost of developing and testing that drug
What is the binding site?
A hollow or canyon on the surface of the molecular target which allows the incoming drug to sink into it
What are the main molecular drug targets?
- Proteins (enzymes, receptors, transport proteins…)
- Nucleic acids (RNA, DNA)
Proteins are the most important
What is tubulin?
- The only structural protein that serves as a drug target
- Molecules of this protein polymerize to form small tubes called microtubules
- The protein is critical to cell division
Why is tubulin critical to cell division?
In preperation for division:
* The cell’s microtubules depolymerize to produce tubulin
* Tubulin re-polymerizes to form spindles
* Spindles seperate the 2 new cells
* Spindles act as a framework for transferring the parent cell’s chromosomes to daughter cells
Tubulin is used as a drug target to treat which disease?
Cancer
Describe the effects of the taxane family of drugs on tubulin and name two of these taxane drugs
Taxanes bind to microtubules and stabilize them, therefore inhibiting depolymerization:
* Taxol (paclitaxel)
* Docetaxtoere (docetaxel)
Describe the effects of the vinca family of drugs on tubulin and name two of these vinca drugs
Vinca bind to tubulin and inhibit its polymerization process
* Vincristine
* Vinblastine
What drug targets are the most important in biopharm research?
Receptors
Describe the general anatomy of a receptor
- Embedded in cell membrane with part of the structure facing the outside, also located intracellularly
- Surface contains hollows, ravines, etc.
- One area of the surface posesses the matching shape to house the incoming chemical messenger molecule or drug (binding site)
- Endo. ligand leaves the receptor once it has activated it and triggered a reaction intracellularly
How do drugs target receptors?
Drugs mimic the endo. ligand and bind to receptors when the drug’s molecular structure is similar in shape
When a drug with a similar shape as the endo ligand binds to the receptor, it can be an:
- Agonist: same effect as endo ligand
- Antagonist: drug produces no effect but prevents the receptor’s natural messenger from binding and inducing expected effects (blockers)
What is a sub-category of antagonist?
Beta-blocker: bind to adrenoreceptors in the heart and block adrenaline from activation, thus reducing workload and preventing heart failure
What are the possible outcomes concerning the amount of drugs at the action site?
- The cell’s receptors ma or may not become fully saturated with the interacting drug
- When the receptors are saturated, the effects of the specific interactions are maximized
- Any additional drug present ( as in the circulatory system) and not participating in the interaction may serve as a reservoir to replace the drug molecules released from the complex
- Two drugs may compete for the same binding sites, with the drug having the stronger bonding attraction for the site generally prevailing
- Already bound moleules of the more weakly bound drug may be displaced from the binding site and left free in the circulatory system
The key purpose of the clinical trials is to:
Establish a safe and effective dose
What are the criteria for the safe and effective dose established during clinical trials?
- Characteristics of the drug substance
- Dosage form and its route of admin
- Patient’s: age, body weight, general health status, pathologic conditions, concominant drug therapy, sex, race
In a normal distribution sample, a drug dose will provide:
- Little effect in a portion
- Average effect in most individuals
- Greater than average effect in another portion
The dose that would produce the desired effect in most individuals is considered
- The drug’s usual adult dose
- The likely starting dose for a patient
What is the minimum effective concentration (MEC)?
When there is a correlation between blood serum concentration and the presentation of drug effects
An average blood serum concentration that represents the minimum concentration that can be expected to produce the drug’s desired effects in a patient
What is the minimum toxic concentration (MTC)
When there is a correlation between blood serum concentration and the presentation of drug effects
Second level of serum concentration of drug.
Drug serum concentrations above this level would be expected to produce dose-related toxic effects in the average individual
For what reason are drugs manufactued in a dosage form?
So that one dose is in a managable size
* Most current drugs are very potent, of low dosage, and administered in milligrams
* When the dose of the drug is small, additionnal ingredients may be needed to make the drug larg enough to pick up
Name some common families of non-medicinal ingredients found in tablet formulations
- Diluents
- Binders
- Disintergants
- Lubricants
- Glidants
- Colouring agents
- Flavouring agents
What is the use of:
Diluents?
Increase bulk
What is the use of:
Binders?
Hold powders together
What is the use of:
Disintergrants
Aid in breaking up the tablet
What is the use of:
Lubricants
Decrease adhesion to punch/die
Decrease friction to punch/die and facilitate tablet ejection
Recuce punch/die wear
What is the use of:
Glidants
Improve flow properties of powders
What is the use of:
Colouring agents
Impart colour
What is the use of:
Flavouring agents
Desired flavour
How are formulations protected from destruction by atmospheric oxygen or humidity?
Use of coated tablets or sealed ampuls
How are drugs protected from the destructive influence of gastric acid after oral admin?
Enteric-coated tablets
How are biterness, saltyness or offensive flavours or odors of a drug substance concealed?
Use of capsules, coated tablets of flavored syrups
What are the three types of stability considered when making a drug?
- Chemical
- Physical
- Microbiological
What does chemical stability of a drug entail?
The drug retains its chemical structure throughout its shelf life. Drugs in solution are more susceptible to structure altering chemical reactions
What does physical stability of a drug entail?
The product retains the original physical characteristics especially in the initial appearance and uniformity. Avoid precipitation and settling for a suspended drug, which may be difficult to re-disperse
What does microbiological stability of a drug entail?
The dosage form must be sterile and resist microbial growth
What is a first-order rate reaction?
When the loss of drug is directlt proportional to the concentration remaining with respect to time (units are reciprocal time, time^-1
How is the stability projection for shelf life (t90) calculated?
Time required for 10% of the drug to degrade with 90% of the intact drug remaining
To enhance the stability of drugs, we increase the stability against what types of reaction?
- Hydrolysis
- Oxidation
To help prevent hydrolysis
How do we reduce or eliminate water from the pharmaceutical system?
Use of solid dosage form:
* Apply water-proof protective coating
* Keeping drug in a tightly closed container
Use of liquid dosage form:
* Replace water with glycerin, propylene glycol and alcohol
* Use anhydrous vegetable oils
* Suspending drug in a non-aqueous vehicle
* Drug supplied to pharmacist in a dry from and reconstituted by adding a specified volume of purified water just before dispensing
What is a route of administration? How are they categorized?
Route by which a drug is administered
Categorized according to the general location of the intended effect to be produced