ipph exam 2 flash cards.txt


??Advantages of controlled release systems:


o Maintenance of optimum drug concentrationso Improved efficiency of treatment with less amount of drugo Minimized side effectso Less frequent administrationo Increased patient convenience and compliance (adherence)


Disadvantages of controlled release systems:


o Relatively high production costso Leakage of drug mass (dose dumping)- all dose is accidently released at onceo Difficulty of stopping drug releaseo Necesssity of surgical operation (sometimes)o Biocompatibility of the controlled-release device (body wants to get rid of foreign objects)


When is temporal control of drug release not needed (p.10)


" Drugs with a long half-life" Drugs which long-term effect is undesirable" Drugs which require immediate effect


What are the different delivery systems


" Diffusion-controlled systems" Dissolution-controlled systems" Erosion-controlled systems" Osmotic systems" Mechanical systems" Swelling systems


What is the release mechanism of ocusert?


diffusion reservoir system


What is the release mechanism of Tetracycline periodontal fibers?


diffusion reservoir system


What is the release mechanism ofNorplant?


diffusion reservoir system


What is the release mechanism ofConcerta tablet (OROS technology)?


Osmotic system


What is the release mechanism of Zoledex?


erosion controlled system


What is the release mechanism of Nutropin?


erosion- controlled system


What is the release mechanism of Lupron?


erosion- controlled system


What characteristics of a polymer lead to faster degradation?"


The most hydrophilic polymer degrades the fastest" Lower molecular weight polymers degrade fastest


What is the release mechanism of Gliadel wafer?


erosion- controlled system


What secretes mucus?


Goblet cells or specialized glands


What is mucus made of?


glycoproteins, lipids, inorganic salts, and 83% water


What is the range of thickness of the mucus layer?


<1 micrometer to 450 micrometers


What are the functions of mucus?


Mucus protects the mucosa in the stomach from HCL. It keeps the mucosal membrane moist. It is also a diffusion barrier for drugs.


What are the characteristics of mucin that allows polymer interactions?


Mucin is a protein that contains many systeines which are capable of forming disulfide bonds. It also has sialic acid which has a negative charge. It is a very long molecule.


How does mucoadhesion occur?


Mucoadhesion can occur by charge interaction between a positive polymer and the negative mucus. It can also be because of covalent bonding between a thiolated polymer and cysteine-rich mucin. Hydrogen bonding and polymer interpenetration can also cause mucoashesion.


what drug properties are desirable for mucosal delivery (p.28, p.29)


" Drugs delivered via oral mucosa are predominantly lipophilic. They are mostly small in molecular weight. They also may require absorption enhancers to deliver hydrophobic molecules" More lipophilic polymers are better absorbed


How should a buccal tablet be used?


" The tablet should be placed between the cheek and the gum and not bitten, chewed, or sucked


What are challanges in ocular drug delivery?


" Bioavailability is less than 10%" There are barriers which are hard to penetrate (cornea, blood-retina barrier)" Loss due to dilution in the tear film, fluid spillage, drainage" Short residence time: rapid turnover of tears and aqueous humor" Not much flexibility in formulation (pH, osmolarity, solubility)


how does a cell intraocular implant work? (p.50)


" Ocular implant is loaded with human retinal pigment epithelium cells transfected with CNTF gene to produce CNTF in situ. This uses bodily nutrients to produce proteins to retard retinal degeneration caused by retinitis pigmentosa


What region of the nose is highly vascularized with good permeability?


Respiratory region


Why is the respiratory resion important?


it allows for systemic drug delivery


How does the respiratory region allow for absorption?


It is responsible for humidification and warming of inhaled air occurs. Physical and enzymatic protection against foreign compounds (including drugs). Mucus sticks to inhaled particles or pathogens and lets them be removed by mucociliary clearance.


What is the obstacle for developing effective drugs for treating nerological diseases?


Blood brain barrier


Inertial transport


driven by momentum; increase with particle velocity, diameter, density; upper airways


How would the intranasal route help deliver drugs to the CNS?


bypassing the BBB via olfactory epithelium and olfactory bulb.


Gravitational transport


particles greater than .1 micrometer; increase with diameter and density


Diffusional transport


ultrafine particles less than .1 micrometer; lunch periphery; tent tp be exhaled without depositing


16. Factors determining particle settling in the airways (p.23)


" Vt: Terminal settling velocity" p: densities of particles" g: acceleration due to gravity" D: volume diameters" C(D): slip correction factors" k: shape factors" n: viscosity of fluid (air)" Diameter" Density" Shape (fibers, elongated particles, needles, spheres)


what is aerodynamic diameter (p.25)


" Geometric diameter (Dae) of a particle with a unit mass density (1 g/cm3) that would settle at the same velocity as the particle of interest


Why are there challanges to pulmonary delivery


the defense mechanisms of the lung


What are the mechanisms of the Upper airways:


o Filtering mechanisms in the nasal cavity trap and eliminate large particles (>10micrometers)o Reflexes: sneezing and coughing


What are the mechanisms Conducting airways:


o Mucociliary escalator, IgA (produced by plasma cells in the submucosa)


What are the mechanisms Alveoli:


o Alveolar macrophages with some interplay with and by neutrophilso Immunologic mechanisms: interplay between the alveolar macrophages and T &B lymphocytes; IgG


Pressurized metered-dose inhalers


- a small volume of pressurized drug dispersion is isolated in a metering chamber and then released through a spray orifice. As the released drug dispersion begins to equilibrate with the atmospheric pressure, it is propelled from the container forming a spray of droplets. Composed of drug, propellant, cosolvent, and surfactant.


Nebulizers-


generate droplets of a drug dispersion (usually aqueous solution or suspension) using energy from compressed air or piezoelectric ceramics. Delivered to the patients lungs on their inspiratory flow. Suitable for treatment f young and elderly patients and emergency treatment.


Dry powder inhalers-


collection of dry particles contained in an inhaler device. An aerosol of dry powder is created as it is exposed to inspiratory airflow, which then carries the small drug particles to the lung. Depending on the inspiratory flow rate, the dose deposited in the lung ranges from 5-40%.


what are particle engineering approaches to overcome particle interactions


" Ordered mixture" Co-spheronization" Large porous particles


In vivoo


Whole body or nose only exposure chambersoInstillation or insufflationoGamma- scintigraphy, single-positron-emission computer-aided tomography: to estimate the site of deposition of drugs.


In vitro


oAnderson cascade impactoroNext generation impactoroLiquid impinger


3. Some polymers that are solid at room temperature can become rubbery at the same temperature by adding?


b) a plasticizer


2. At temperatures higher than the glass transition temperature, the glassy polymer becomes?


d) rubbery


1. 'Nylon' has a special place in the polymer history, and this is because?


d) Nylon was synthesized based on the theory on polymeric nature of plastics.


6. Hydrogen bonding is dominant at?


a) Low temperature


5. Hydrophobic interaction is dominant at?


b) High temperature (e.g., 37 ?


4. Why are polymers critical in the development of controlled drug delivery systems?


c) They can control the diffusion of molecules by simple altering of the polymer structure or concentration.


7. Which one of the following is NOT an advantage of controlled release dosage forms?


d) More frequent administration


10. What is the definition of a semi-permeable" membrane?


b) A membrane that allows diffusion of water molecules but not other bigger molecules.


9. If a drug is distributed throughout a water-insoluble polymer matrix, the system is called?


d) Diffusion-controlled monolithic system


8. Which one of the following polymers is most suitable for making diffusion-controlled drug release systems?


c) Polyethylene


12. If ion-exchange resin particles are coated with ethylcellulose, the system becomes?


b) Diffusion-controlled system


11. What is the main advantage of the osmosis-controlled drug delivery systems?


d) The drug release rate is independent on both pH and temperature.