Sept. 21 - Controlled Release

1. 1Conventional therapy (solutions, suspensions, capsule, tablet, injection)
   • What are the three problems with concerned with conventional therapy?
   • 1). [blank_start]Produces peaks[blank_end] and [blank_start]valleys[blank_end]
   • 2). Patient [blank_start]incompliance[blank_end] possible- resulting in [blank_start]failure[blank_end]
   • 3). Drug level may not be [blank_start]therapeutic range[blank_end] at [blank_start]early times[blank_end]
   

   1. AProduces peaks
   2. Bvalleys
   3. Cincompliance
   4. Dfailure
   5. Etherapeutic range
   6. Fearly times
2. 2• Oral drug absorption characteristics?
   • Most common route
   • Safest??
   • Most [blank_start]convenient[blank_end]
   • Most [blank_start]economical[blank_end]
   • Requires patient cooperation
   • First-pass metabolism-[blank_start]highly variable[blank_end] “survival” of drug between subject
   

   1. Aconvenient
   2. Beconomical
   3. Chighly variable
3. 3• What are the 5 factors that affect absorption?
   • [blank_start]Dose form[blank_end]
   • Solution vs tablet
   • [blank_start]Physiochemical properties[blank_end] (eg. Solubility)
   • [blank_start]First pass effect[blank_end]
   • Co-administration with food
   • [blank_start]Gastric emptying rates[blank_end]
   • Absorption occurs in the [blank_start]small intestine[blank_end].
   

   1. ADose form
   2. BPhysiochemical properties
   3. CFirst pass effect
   4. DGastric emptying rates
   5. Esmall intestine
4. 4• What are the 7 causes of irregular absorption?
   • 1). Depends on [blank_start]stomach contents[blank_end]- gastric emptying time
   • 2). Altered stomach [blank_start]pH[blank_end] due to food
   • 3). Increased splanchnic [blank_start]blood flow[blank_end] after eating
   • 4). Complex formulation of drug with food product
   • 5). Competition between food and drug for transporters, enzymes etc.
   • 6). [blank_start]Gastrointestinal irritation[blank_end] (Nausea, vomiting)
   • 7). [blank_start]Low pH[blank_end] may inactivate certain drugs
   - Penicillins, erythromycin, digoxin

   1. Astomach contents
   2. BpH
   3. Cblood flow
   4. DGI irritation
   5. ELow pH
5. 5• How does the motility (physiology) affect absorption (5 things)?
   • Motility pattern:
   • 1). Fastest gastric emptying occurs with a [blank_start]fasted[blank_end] stomach
   • 2). [blank_start]Women[blank_end] and [blank_start]elderly[blank_end] have slower gastric emptying
   • 3). Smaller sizes emptying
   • 4). Intestinal motility increased by [blank_start]fibre[blank_end] in diet
   • 5). Enterohepatic cycling: recycling by liver and bile system for some

   1. Afasted
   2. BWomen
   3. Celderly
   4. Dfibre
6. 6• How does food affect absorption?
   • Can keep dose form in the stomach
   • May interfere with the absorption of [blank_start]Ca[blank_end] 2++ or [blank_start]metabolism[blank_end]
   • [blank_start]Microbes[blank_end] in the gut can [blank_start]metabolize[blank_end] some drugs.
   

   1. ACa
   2. Bmetabolism
   3. Cmetabolize
   4. DMicrobes
7. 7• What 4 things promotes gastric emptying?
   • [blank_start]Hunger[blank_end] (fasted state)
   • Lying on the [blank_start]right[blank_end] side
   • Drugs (metoclopramide)
   • [blank_start]Liquid[blank_end] Intake
   

   1. AHunger
   2. Bright
   3. CLiquid
8. 8• What 4 things slow down (retard) gastric emptying?
   • [blank_start]Meals[blank_end] (fat, bulky, viscous)
   • Lying on the [blank_start]left[blank_end] side
   • Disease states (ulcer, hypothyroidism)
   • Drugs (tricyclic anti-depressants, anticholinergics)
   

   1. AMeals
   2. Bleft
9. 9• What are the 5 qualities that make a suitable candidate for extended release products?
   • 1). Exhibit neither very slow nor very fast rates of absorption and excretion
   • 2). [blank_start]Uniformly absorbed[blank_end] from gastrointestinal tract.
   • 3). Administered in relatively [blank_start]small doses[blank_end].
   • 4). Good margin of [blank_start]safety[blank_end]
   • 5). [blank_start]Chronic disease[blank_end] conditions rather than acute.
   

   1. AUniformly absorbed
   2. Bsmall doses
   3. Csafety
   4. DChronic disease
10. 10• What's the pk behind sustained release?
    • The ideal of providing an exact amount of drug at the site action for a precise time period is usually approximated by most systems. This approximation is achieved by creating a [blank_start]constant concentration[blank_end] in the body or an organ over an extended time.
    • Rate in= Rate out = kel * Cp * Vd
    

    1. Aconstant concentration

11. 11• What are the three goals behind extended release systems?
    • 1). [blank_start]Maximizes[blank_end] therapeutic efficacy of drug
    • 2). [blank_start]Reduced costs[blank_end] due to optimal administration
    • 3). Reduction in [blank_start]side effects[blank_end]
    

    1. AMaximizes
    2. BReduced costs
    3. Cside effects
12. 12What are the requirements for oral ER systems?
    4 different Biological factors:
    • Half-life
    • Therapeutic window
    • Absorption (high-moderate absorption rate)
    - Active vs passive
    - GI transit time
    - [blank_start]Floating systems[blank_end]
    - Bioadhesives
    - [blank_start]Penetration enhancers[blank_end]
    - Permeability throughout the GI tract
    • Metabolism (moderate elimination otherwise to high dose required for ER)
    

    1. APenetration enhancers
    2. BFloating systems
13. 13ER systems: 4 different physiochemical factors:
    • Dose size ([blank_start]0.5[blank_end] -[blank_start]0.1[blank_end]g)
    • [blank_start]Ionization[blank_end], pKa, and aqueous solubility
    • Solubility less [blank_start]0.01 mg/ml[blank_end] (digoxin, griseofulvin)
    • [blank_start]Partition Coefficient[blank_end]
    • Stability
    

    1. A0.5
    2. B0.1
    3. CIonization
    4. D0.01 mg/ml
    5. EPartition Coefficient
14. 14What are the 5 advantages of zero-order release?
    •1). [blank_start]Extreme peaks[blank_end] and [blank_start]troughs[blank_end] of drug plasma levels are [blank_start]avoided[blank_end]
    •2). The period of release of single dose can be [blank_start]extended[blank_end]
    •3). The required dose of a drug to obtain the desired effect might be [blank_start]reduced[blank_end]
    •4). The need for [blank_start]patient compliance[blank_end] is minimized or removed (less doses per day)
    •5). Extend [blank_start]patent protection[blank_end] and marketing
    

    1. AExtreme peaks
    2. Btroughs
    3. Cavoided
    4. Dextended
    5. Ereduced
    6. Fpatient compliance
    7. Gpatent protection
15. 15• Absorption in the GI tract
    o [blank_start]Convenience[blank_end] of administration
    o Patient compliance
    o [blank_start]Cost[blank_end]
    

    1. AConvenience
    2. BCost
16. 16• Sophisticated system:
    - Enteric coatings for the protection of drugs from [blank_start]degradation[blank_end] within the [blank_start]GI tract[blank_end] or protection of the stomach from the irritating effects of the drug.
    - Delivery of drugs to [blank_start]absorption windows[blank_end] or specific targets within the GI tract, particularly the colon.
    

    1. Adegradation
    2. BGI tract
    3. Cabsorption windows
17. 17Diffusion systems – [blank_start]matrix devices[blank_end], [blank_start]reservoir[blank_end] (depot), non- biodegradable)
    • Two examples
    • What are reservoir devices?
    • How do they work? What are they made of?
    • They characterized by a core of a drug, the reservoir surrounded by a [blank_start]polymeric membrane[blank_end]. The nature of the membrane determines the rate of release of the drug from the system.
    • Matrix is involved
    

    1. Amatrix devices
    2. Breservoir
    3. Cpolymeric membrane
18. 18• What are the 2 advantages of the reservoir system?
    • 1). [blank_start]Zero-order[blank_end] delivery is possible
    • 2). Release rate variable with [blank_start]polymer type[blank_end]
    

    1. AZero order
    2. Bpolymer type
19. 19• What are the 4 disadvantages of the reservoir system?
    • 1). System will not [blank_start]dissolve[blank_end]
    • 2). Removal of system from [blank_start]implants[blank_end], see other devices
    • 3). [blank_start]Cost[blank_end]
    • 4). [blank_start]Potential toxicity[blank_end] if system fails
    

    1. Adissolve
    2. Bimplants
    3. CCost
    4. DPotential toxicity
20. 20• How do matrix devices work?
    • Consists of drugs [blank_start]dispersed homogenously[blank_end] throughout a [blank_start]polymer matrix[blank_end]
    • Drug in the outside layer is exposed to the bathing solution is dissolved and diffuses out of the matrix
    • This process continues with the interface between the bathing solution and the solid drug moving toward the interior.
    • What are they composed of?
    • [blank_start]Polyethylene[blank_end], [blank_start]polyvinyl acetate[blank_end], polymethylacrylate
    

    1. Adispersed homogenously
    2. Bpolymer matrix
    3. CPolyethylene
    4. Dpolyvinyl acetate
21. 21• What are the 2 advantages of the matrix diffusion system?
    • 1). Easier to produce than [blank_start]reservoir devices[blank_end]
    • 2). Can deliver [blank_start]high molecular weight[blank_end] compounds
    

    1. Areservoir devices
    2. Bhigh molecular weight
22. 22• What are the 2 disadvantages of the matric diffusion system?
    • 1). Cannot obtain [blank_start]zero-order[blank_end] release
    • 2). Removal of [blank_start]remaining matrix[blank_end] is necessary for implanted systems or natural recovery.
    

    1. Azero order
    2. Bremaining matrix
23. 23•Bioerodible and combination diffusion and dissolution systems
    What is this system? What are the 3 characteristics?
    • Bioerodible devices constitute a group of systems for which mathematical descriptions of release can be complex.
    • The complexity of the system arises from the fact that, as the polymer dissolves, the diffusion path length for the drug may change
    - This usually results in a moving-boundary diffusion system.
    - True zero-order release normally only occurs if [blank_start]surface erosion[blank_end] occurs and the [blank_start]surface area[blank_end] does not change with time.
    

    1. Asurface erosion
    2. Bsurface area
24. 24• What are the 2 advantages of the bioerodible matrix system?
    • 1). All the advantages of [blank_start]matrix dissolution system[blank_end]
    • 2). [blank_start]Removal[blank_end] is not necessary
    

    1. Amatrix dissolution system
    2. BRemoval
25. 25• What are the two disadvantages of the bioerodible system?
    • 1). Difficult to [blank_start]control kinetics[blank_end] due to multiple processes of release
    • 2). Potential [blank_start]toxicity[blank_end] of [blank_start]degraded polymer[blank_end]
    • 3). [blank_start]Dose dumping[blank_end]
    

    1. Acontrol kinetics
    2. Btoxicity
    3. Cdegraded polymer
    4. DDose dumping
26. 26• How do osmotically controlled systems work?
    • Osmotic pressure provides the driving force to generate [blank_start]controlled release[blank_end] of drug.
    • System has a semi permeable membrane that is permeable to [blank_start]water[blank_end], but not to the drug.
    • When this device is exposed to water or any body fluid, water will flow into the system owing to the osmotic pressure difference.

    1. Acontrolled release
    2. Bwater
27. 27• What are the 3 advantages of osmotically controlled systems?
    • [blank_start]Zero order[blank_end] release is obtainable
    • [blank_start]Reformulation[blank_end] is not required for different drugs
    • Release of drug is [blank_start]independent[blank_end] of environment of the system
    

    1. AZero order
    2. BReformulation
    3. Cindependent
28. 28• What are the 3 disadvantages of osmotically controlled systems?
    • Systems can be very [blank_start]expensive[blank_end]
    • [blank_start]Quality control[blank_end] is more extensive
    • Used for nifedipine, phenylpropanolamine, prazosin, salbutamol, KCL
    

    1. Aexpensive
    2. BQuality control
29. 29Ion exchange/Gel-system:
    • What is resin?
    • Water [blank_start]insoluble[blank_end] materials containing [blank_start]salt-forming[blank_end] groups
    • Prolonged and sustained release over [blank_start]8[blank_end] to [blank_start]12[blank_end] hours into the GI tract
    • What is drug release?
    • pH, electrolyte, property of resin
    

    1. Ainsoluble
    2. Bsalt forming
    3. C8
    4. D12
30. 30• What is ion-exchange?
    • What are they available as (two drugs)?
    Are available as capsules or suspensions
    • [blank_start]Biphetamine capsules[blank_end]
    • [blank_start]Tussionex suspension[blank_end]
    

    1. ABiphetamine capsules
    2. BTussionex suspension
31. 31• What are the steps of making an ion-exhange/Gel-system?
    • Preparation
    - Preparation by mixing the [blank_start]resins[blank_end] with a [blank_start]drug solution[blank_end]
    • By repeated exposure of the resin to the drug in a [blank_start]chromatographic column[blank_end]
    • By [blank_start]prolonged[blank_end] contact of the resin to the drug.
    

    1. Aresins
    2. Bdrug solution
    3. Cchromatographic column
    4. Dprolonged
32. 32For ion-exchange/gel-system:
    • Rate of diffusion
    - Controlled by the area of diffusion, diffusional path length and the amount of cross-linking agent ([blank_start]rigidity[blank_end] of the resin)
    - Modified by [blank_start]coating[blank_end] the drug-resin complex
    - By the Microencapsulation process
    • Polystyrol resin for oral depot preparation of alkaloids such as ephedrine and amphetamine.
    - [blank_start]Alkaline exchange[blank_end] resin= prolonged release rate
    

    1. Arigidity
    2. Bcoating
    3. CAlkaline exchange
33. 33Other Depot dosage forms
    • Vaginal inserts
    • Gel, ring devices, stick
    • Examples of different types of vaginal inserts
    - Cervidil
    - Bioadhesive
    - Estradiol
    • [blank_start]Subdermal implants[blank_end]- there is a risk of sudden drug release. Ex. 5 years levonorgestrel

    1. ASubdermal implants

Descripción

361 PHARMACEUTICS II MIDTERM Test sobre Sept. 21 - Controlled Release , creado por Crystal Yu el 25/09/2018.

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Crystal Yu

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Creado el 25 sep 2018 · actualizado el 26 sep 2018

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361 pharmaceutics ii midterm

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