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802 > Lecture 14 (Cut off for Exam 4) > Flashcards

Lecture 14 (Cut off for Exam 4) Flashcards

Modified Release

1
Q

Extended Release

A

Slow release of drug over extended period of time (slow or sustained release)

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2
Q

Targetted Release

A
  • Enteric/colonic delivery
  • Gastroretentive systems (stays in stomach and releases from there)
  • Taste masking
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3
Q

Therapeutic Window

A

Concentration of plasma between the minimum effective and minimum toxic concentration

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4
Q

Immediate Release

A
  • Rapid release
  • High peak concentration
  • Short time in the therapeutic window
  • Less time in therapeutic window leads to more frequent dosing
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5
Q

Sustained Release

A
  • Slower onset
  • Lower peak concentration
  • Longer time in the therapeutic window
  • Lower peak concentration leads to less dose-dependent side effects
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6
Q

Delayed Release

A
  • Same aspects as immediate release but initial release is delayed
  • Released AFTER leaving stomach
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7
Q

Sustained-Release Advantages (4)

A
  • Enhanced patient compliance/convenience (decreased dosing frequency)
  • Reduction in blood level fluctuations
  • Reduction in adverse effects
  • Reduction in healthcare costs
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8
Q

Sustained-Release Disadvantages (3)

A
  • Potential for dose dumping - larger quantity in one dosage unit, releasing all at once has potential for toxicity/overdose
  • Requires more formulation skills
  • More expensive to produce
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9
Q

Drug Restrictions for Sustained Release (5)

A
  • Should exhibit neither fast or slow absorption or excretion
  • Should be uniformly absorbed from GI Tract
  • Administered in relative small doses
  • Should possess good margin of safety (wide therapeutic window)
  • Used in treatment of chronic conditions over acute
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10
Q

Methods to Achieve Sustained-Release (6)

A
  1. Film coating
  2. Osmotic Pump
  3. Eroding Matrices
  4. Microencapsulation
  5. Ion-exchange resins
  6. Inert plastic matrices
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11
Q

Selecting Method of SR

A
  • Based on desired release profile
  • Physio-chemical properties of API
  • Available equipment, expertise, and patient issues
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12
Q

Reasons to Coat Drugs (6)

A
  • Improve aesthetic appearance
  • Mask taste or odor
  • Prevent inadvertent contact with active
  • Facilitate swallowing
  • Protection from decomposition in air/humidity
  • Alter release characteristics (depends on coating solubility)
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13
Q

Are sugar coatings utilized in controlled drug release?

A

No.

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14
Q

Sugar-Coating Advantages (4)

A
  • Protection from atmospheric oxygen and moisture
  • Masks taste and odor
  • Enhances attractiveness
  • Reduces dust
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15
Q

Sugar-Coating Disadvantages (3)

A
  • Extensive time to apply
  • “Art” & “Science”
  • Increase in size and weight of tablet
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16
Q

Sugar-Coating Process

A
  1. Waterproofing and Sealing
  2. Subcoating
  3. Smoothing and Final Rounding
  4. Finishing and Coloring
  5. Polishing

-Similar process to candy coating. Same type of equipment and coating core

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17
Q

Waterproofing and Sealing

A

Shellac or other agent in alcohol solution utilized

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18
Q

Subcoating

A
  • 3-5 coats of sugar based syrup in PVP or gelatin

- Sprinkle with dusting powder

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19
Q

Smoothing & Final Rounding

A
  • 5-10 coats of thick syrup

- Dusing powder may or may not be used

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20
Q

Finishing & Coloring

A

Several coats of thin syrup

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21
Q

Polishing

A

Utilize wax-lined pans (carnuba and/or beeswax)

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22
Q

Gelatin-Coated

A

-Layer of gelatin surrounding tablet core

Applied by:

  • Dipping Technique - each side dipped
  • Enrobing Technique - similar to SGC process
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23
Q

Gelatin-Coated Advantages (4)

A
  1. Taste/odor masking
  2. Easier to swallow - gelatin itself helps and can compress more as a tablet than in a capsule
  3. Protect from light and oxygen (not water)
  4. Tamper resistant
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24
Q

Gelatin-Coated Disadvantages (2)

A
  • Same concerns with capsules - control water and humidity

- Can’t use for controlled release

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25
Q

Polymer Coated Solids

A
  • Think polymeric films surrounding a solid core

- Solid core can be tablets, pellets, beads, granules, powders

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26
Q

Polymer Coated Advantages (3)

A
  • *Compared to Sugar Coatings**
  • Can be used to alter release (depending on coating’s aqueous solubility)
  • No significant increase in size or weight of tablet
  • Faster and easier to apply
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27
Q

Polymer Coated Formulations

A
  • Polymer - cellulose and acrylic
  • Plasticizer - flexibility and decreases cracking
  • Solvent - water or organic
  • Optional Additives - Anti-sticking agents (during coating/storage), surfactant (increases spreadability), colorants/opacifiers (dyes, lakes, iron oxides), flavors and sweeteners.
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28
Q

Water Soluble Polymers

A
  • Protects drug from atmospheric oxygen and moisture
  • Protect from light if opacifiers included
  • Masks taste and/or odor
  • Improves appearance

Not used for altering drug release

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29
Q

Water Insoluble Polymers

A
  • Allows for slow release of drug
  • Drug slowly diffuses through film
  • Aqueous solubility of API and the thickness of film influences the release rate

EX: Ethyl cellulose, Eudragit RS 30 D

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30
Q

Polymer Drug Release Mechanism

A
  • Coating hydrates and swells
  • Water penetrates coating and dissolves the drug
  • Drug diffuses out
31
Q

Thickness of Film + Release Rate

A

Thicker films cause increased tortuous diffusion path and slows the release of the drug.

32
Q

pH-Dependent Solubility

A
  • Delays drug release until after product passes the stomach
  • Small intestine and colon are the targets
  • Mechanism - ionizable functional groups that only are soluble at higher pH
  • Ex: CAP, PVAP, Eudragit L
33
Q

Reasons to Use Enteric Coatings (4)

A
  1. Acid Liable Drugs
  2. Targetting small intestine or colon
  3. Drug irritates stomach mucosa
  4. Drug degrades by gastric enzymes
34
Q

Enteric Coating Drug Release Mechanism

A
  • Coating DOESN’T stay intact

- At lower pH, the coating dissolves and the drug is released to enter solution

35
Q

Reverse Enteric System

A
  • Another example of a pH-Dependent Solubility
  • Form of delayed release, but only delays in mouth
  • Ionizable groups that dissolve at low pH of the stomach but not the higher pH of saliva
  • Taste-masking applications
36
Q

Equipment Used for Coating (3)

A
  1. Conventional coating pans - used for tablets, are like sugar coating
  2. Perforated coating pans - used for tablets, more efficient solvent evaporation then conventional
  3. Fluidized Bed Apparatus (with Wurster insert) - “popcorn” machine, used for beads, pellets, and granules
37
Q

Similarities between Coating Equipment

A
  • Atomization of polymer liquid (solution or suspension)
  • Heat to evaporate solvent (water or organic)
  • Movement of substrate
38
Q

Coating Process

A
  • Coating formulation (liquid) is sprayed
  • Comes into contact with substrate and spreads
  • Solvent evaporates
  • Coalescence and polymer chains intertwine
39
Q

Coated Beads/Granules/Pellets Uses

A
  • Filled into capsules (Prilosec, Eryc)
  • Compressed into tablets (PCE) - coated particles need to stay intact, the compression pressure shouldn’t fracture them
  • Combine uncoated and coated particles (IR+SR)
40
Q

Non-Pareil Beads

A
  • Have a polymer layer and a rate controlling layer on top
  • Think of a peanut M&M for structure
  • Alternative to wet granulation
  • Use a water soluble polymer
41
Q

Film Coating Problems (5)

A
  1. Edgewear
  2. Orange Peel
  3. Sticking
  4. Picking and cratering
  5. Bridging of imprinted design on tablet
42
Q

Gelatin Coating Application Problems

A
  • Gelatin softens during spraying process
  • Shell becomes brittle due to water evaporation
  • Problems with adhesion
43
Q

Hard Shell Capsule Problem

A

Separation of cap and body

44
Q

SGC Problem

A

Stability issues stemming from dynamic nature of capsule.

45
Q

OxyContin

A
  • Film-coated
  • Slowly releases over 12 hours when swallowed whole
  • When crushed, dose dumping, a “high”, and fatal overdosing can occur
46
Q

How to Decrease OxyContin Abuse

A
  • Include sequestered antagonist in tablet so when they are crushed the antagonist is released along with the active ingredient
  • When swallowed whole the sequestered antagonist wouldn’t be released
47
Q

Other Abuse Determinants

A
  • Viscosity Modifiers - not syringable (decreases dissolution)
  • High melting points - resists heat and injection
  • Taste modifiers - reduces snorting
  • Waxy excipients - decreases snorting and makes more crush resistant
48
Q

Arthrotec

A
  • Example of a multiple layer drug
  • Combination of Misoprostol and Diclofenac
  • 1st Layer = Misoprostol, IR and outer soluble coating
  • 2nd Layer = Diclofenac, DR and tablet core with EC
49
Q

Dry Powder Coating

A
  • Currently under investigation
  • Polymers applied as powders rather than solution or suspension
  • Eliminates potential interactions between substrate and coating (ex: migration of active into coating). No water used so can coat water sensitive products too
  • Eliminates pollution, explosion, and toxicity with organic solutions
50
Q

Electrostatic Coating

A
  • Example of dry powder coating
  • Unique and precise coating - thickness and different polymers on different parts of the tablet
  • Continuous process
51
Q

Osmotic Pump

A

-Used for SR
Structure
-Bilayer tablet core with a drug and “push” layer
-Semipermeable membrane (polymer) with a small hole

-Push layer expands to moisture as water enter through membrane, this pushes drug solution out of hole into body from increased osmotic pressure
-Creates a more stead, sustained release throughout the day
-“Snickers” structure
Example: Ditropan XL, Procardia XL, Glucotrol XL

52
Q

Osmotic Pump + EC

A
  • Example = Covera HS
  • ER Verapamil HCl osmotic pump overcoated with EC
  • Taken at bedtime to get a morning surge release of drug
53
Q

Eroding Matrix

A
  • Hydrophilic matrix tablets
  • Drug mixed with polymer(s) and compressed into tablets
  • Dry polymer hydrates to form an outer “gel” layer
  • Drug releases by diffusion through gel layer OR erosion of gel layer depending on the drug solubility
  • Examples: Slow-K, Sinemet CR
54
Q

Microencapsulation

A

-Can be used to modify release
Types:
-Microencapsule - reservoir, “regular M&M” structure
-Microsphere - Matrix, “Krackel” bar structure

  • Particle size is micron (VERY small)
  • Filled into capsules, compressed into tablets, suspended in liquids
55
Q

Wall/Matrix Materials

A

-Dictates release properties

Examples

  • Gelatin - first used to create carbonless carbon paper
  • Synthetic polymers - ethylcellulose
  • Biodegrabable Polymers - polylactic and glycolic acid

**Numerous processes used to create particles

56
Q

Xtampza ER

A
  • Oxycodone ER capsule with microspheres

- Microspheres have ER and substance abuse deterrent properties

57
Q

Ion-Exchange Resin

A

-Used for MR or taste masking
-Cationic drug complexed into anionic resins or anionic drug complexed into cationic resins
-Resin is insoluble and porous
-Drug-resin complex formed when equilibriated with drug solution
-Can be tableted, encapsulated, suspended in aqueous solution
Examples: Tussionex, Ionamin, Delsym

58
Q

Ion-Exchange Resin

A
  • Drug attached to resin

- After ingestion, an anion or cation replaces the drug on the resin (which it is depends on the charge of the drug)

59
Q

Inert Plastic Matrix

A

-Non-eroding, used for SR
-“Krackel” bar structure before ingestion and swiss cheese structure after ingestion
-Drug granulated with inert plastic matrix (polyethylene, polyvinyl acetate)
Examples: Desoxyn Gradumet Tablets

60
Q

Inert Plastic Matrix Mechanisms (3)

A
  • Drug on surface dissolves
  • Body fluids create pores of channels
  • Drug leaches out in body fluids
61
Q

Hot Melt Extrusion

A
  • Used for SR
  • Matrix where drug dissolved/suspended in low melting carrier
  • Achieve SR by selecting appropriate carrier - wax matrix or suitable polymer
62
Q

Gastric Retentive Systems (6)

A
  1. Floating - low density, CO2 production
  2. Sinking
  3. Bioadhesion
  4. Swelling
  5. Expanding
  6. Magnetic

All used for SR

63
Q

Are SR systems good to use with drugs with narrow windows of absorption?

A

No, conventional SR systems are ineffective with these drug types.

64
Q

Colon Drug Delivery

A

-Drug release controlled for local effects
-Treat specific disease states like IBS, Crohn’s Disease, and Ulcerative Colitis
-No substantial absorption
Example: Pulsin Capsule - EC and capsule dissolved in small intestine and hydrogel plug swells and ejects to release drug in colon

65
Q

Rupture-Type

A
  • Creates a “lag” time to target colon
  • Comprised of drug core, swellable coating, and insoluble/permeable coating
  • Mechanism: water diffusion causes inner coating to swell and the increase pressure causes the outer, insoluble coating to rupture
66
Q

Rupture-Type

A
  • Creates a “lag” time to target colon, controlled by permeability and mechanism properties of coatings
  • Comprised of drug core, swellable coating, and insoluble/permeable coating
  • Mechanism: water diffusion causes inner coating to swell and the increase pressure causes the outer, insoluble coating to rupture
67
Q

CODES

A
  • Example of drug exploiting natural bacteria in colon to trigger release
  • EC dissolves in stomach, acid soluble/slightly permeable coating goes through small intestine
  • Dissolution and release of polysaccharides in colon then allows bacteria to feed on polysaccharides and drop the pH to cause the drug to release
68
Q

In-Vitro Tests

A
  • Dissolution

- Disintegration - basket, paddle, Method III (reciprocating cylinder)

69
Q

In-Vitro for Micro-flora Medications

A
  • More challenging tests
  • Use of animal caecal contents - diluted to pH of 7
  • Stimulated human intestinal microbial ecosystem (SHIME) - incubation of delivery system with bacteria common to colon
  • Provide some indication of in vitro performance
70
Q

Enteric/Colonic/Gastroretentive In Vitro Tests

A
  • Human and animal studies
  • Pharmacokinetics (drug levels in blood)
  • Gamma imaging - non-invasive imaging when drug is labeled with gamma-emitting isotope. Allows for real-time GI observations with gamma camera to visualize the disintegration of the product
71
Q

Repeat Action Forms

A
  • Behaves like 2 doses of drug from 1 tablet
  • Initial drug release from tablet shell and the second dose from the inner core of tablet
  • Barrier coating between the two layers
  • Graph looks like two IR doses release over time
  • Example: Repetabs
72
Q

Repeat Action Drug Requirements

A
  • Low dosage
  • Treat chronic conditions
  • Regular absorption patterns
  • Fairly rapid absorption and excretion
73
Q

Dosage Forms to NOT Chew

A
  • Sublingual
  • Buccal
  • Enteric coatings
  • Extended Release
  • Products with carcinogenic release
74
Q

What controls Osmotic Pump drug release? (3)

A
  1. Size of Hole
  2. Thickness and nature of coatings
  3. Surface Area

802 (14 decks)

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