Oral Drug and Controlled Release Delivery Flashcards
What are the advantages of an oral drug delivery system?
It is effective, accurate, convenient and cost effective
List the shortcomings of oral drugs.
Variability in GI environment
Bioavailability
Limited drug targeting
Pediatric/ geriatric population difficulties
What are the absorption sites with oral dosages?
Stomach (limited) Small intestine(primary site) Large intestine(v. limited) Mouth (buccal and sublingual) Rectum
What are the 3 key drug properties that need to be considered in oral formulations?
Absorption
Stability
Processing
What is the most critical issue for preparation and delivery?
Solubility
What is the benefit and downside of solutions?
Increases drug absorption but is less stable
What does effect does particle size have on solubility?
Increases surface area
Faster disintegration/dissolution
How do we ensure stability in vitro?
Coating (tablets and capsules if not stable to light, moisture, etc)
Excipients
Protective packaging
How do we ensure stability in vivo?
Enteric coating
Controlled/sustained release
Site- specific release
What are some ways to increase absorption?
Improve solubility Increase disintegration and dissolution Administration strategies (w/out food: absorbed quickly and excreted quickly, better to take with food even though slower absorption)
What are some strategies to deal with metabolism?
Dose increase
Pro drugs
Enzyme inhibitors
Other administration routes
Where is drug targeting limited to in oral delivery?
The GI tract
How is drug targeting achieved?
Adhesive polymers to stomach
Sustained/controlled release to small intestine
What are 4 common mucoadhesive polymers (hydrophilic gels)?
Chitosans
Polyacrylates
Polyglucons
Hyaluronans
What do mucoadhesive polymers do?
Prolong residence
Increase contact time and bioavailability
Localization in specific residence
Who utilizes oral solutions?
Pediatrics and elderly
What are the two important considerations that must be accounted for in oral solutions?
Taste and colour
Additives(alcohol, sugar, preservatives)
Name the 3 absorptive sites of quick dissolving formulations.
Oral
Buccal
Sublingual
What are the benefits of quick dissolving formulations?
Fast drug release
Little liquid needed
Convenient administration
Why do quick dissolving drugs need special packaging?
They can’t be exposed to moisture
What are some drugs that can be found as quick dissolving and why?
Analgesics, antihistamines, migraine, antidepressants, Parkinsons
Want quick onset or there is a difficulty in taking medications
Common excipients used in quick dissolving solutions.
Mannitol, sorbitol, effervescent ingredients
What are the 4 methods of forming quick dissolving tablets?
Spray drying, molding, wet granulation, compression
What are some ways to taste mask?
Additive-dilution
Film coating
Melting with lipid-based excipients
These devices can be inserted and a slow release of drug occurs.
Controlled release
What are the benefits of controlled release?
Fewer administrations
Steady blood concentrations
Better therapeutic outcome
Improved patient compliance
What are the 3 types of controlled release drugs?
Delayed release
Controlled release
Targeted release
Release of two successive doses, initial plus replenishment.
Delayed release
Drug release over a long period of time, independent of external factors or envornment.
Controlled release
Site specific or receptor specific.
Sophisticated dosage forms, normally in Parenteral formulations
Targeted release
What are the benefits of targeted release?
Smaller drug dose, fewer dosing, less potential SE, better compliance
What are the drawbacks of controlled release?
“Dose dumping” potential
Difficult dosing termination
Variable absorption due to varying GI interactions
Increased production cost
What are three conditions that controlled release is appropriate for?
Cardiovascular
Respiratory
Mood control
What is the optimal half life of a drug to be a controlled release candidates?
2-8hrs
Any shorter and we need to increase drug dose
Any longer and there’s no need for it
Longer than 8 hrs and drug will be in large intestine (no absorption)
What is the optimal dosing range for controlled release drugs?
0.5g- 1.0g, preferably less than 0.5g
pH range of stability with controlled drugs?
1-8
What are the 4 drug release mechanisms?
Diffusion controlled
Dissolution/Diffusion controlled
Dissolution controlled
Osmotic Pressure controlled
Does diffusion or dissolution play a more significant role in drug release?
Dissolution
Describe the Reservoir System.
There is a drug core and the release rate is controlled by film properties: polymers(how fast it dissolve/how permeable to water it is)
There is a potential for toxicity if coating is accident lay destroyed.
Describe the Matrix System.
Drug and polymer is mixed, release rate is controlled by polymer. This is more of a diffusion method vs dissolution.
This system is cheaper and allows for the delivery of larger molecules but zero order delivery livery is impossible
Matrix system
This system is harder to control due to dissolution and diffusion release rates and the rates being dependant on shape of dosage form
Bioerodible System (matrix)
The release rate is controlled by the drug or the polymer?
Can be controlled by either or both.
Describe osmotic pumps.
Coated tablet with semipermeable membrane, containing unique chemical in the core that creates osmotic pressure. Drug release is independant of environment
Pressure produced by separate chemical cause what kind of order release?
Zero
What are the 4 things quality control is watching for in controlled release drugs.
Drug content
Drug uniformity
Disintegration
Dissolution
