Lecture 4 Modified Release

Question 1

What does MEC stand for?

Answer 1

median effective concentration

Question 2

What does MTC stand for?

Answer 2

median toxic concentration

Question 3

The large the distance between the MEC and the MTC, the greater safety of the drug. T/F

Answer 3

True

Question 4

What are the advantages of modified-release dosage forms?

Answer 4

less fluctuation in blood levels, reduced dosing frequency, enhanced convenience and compliance, reduce adverse side effects, and overall reduction in health care costs (due to enhanced compliance).

Question 5

What are the disadvantages of modified-release dosage forms?

Answer 5

Potential that all of drug may be released at once, may not be an option for some populations, takes longer to clear out of system, not enough variation available, can not crush.

Question 6

What makes a good candidate for modified release products?

Answer 6

They exhibit neither very slow nor very fast rates of absorption and excretion. (too fast - huge tablet, too slow - doesn’t need modified release)They are uniformly absorbed from the GI tractThey are administered in relatively small dosesThey process a good margin safetyThey are used in the treatment of chronic rather than acute diseases. (the need to adjust in acute disease makes modified-release dosage forms unpractical)

Question 7

What are the important variables relevant to modified release formulation?

Answer 7

route of drug administration, type of delivery system, disease being treated, patient, length of therapy, drug properties(biological properties ADME, solubility permeability)

Question 8

What is a modified-release form

Answer 8

Release features based on time, course, and/or location that are designed to accomplish therapeutic or convenience objectives not offered by conventional or immediate-release forms.

Question 9

What is an extended-release form?

Answer 9

Reduced frequency of dosage

Question 10

What is a delayed-release form?

Answer 10

Releases the drug from the dosage from at a time other than promptly after administration.

Question 11

What is a repeat action form?

Answer 11

Usually contain two single doses of medication, one for immediate release and the second for delayed release.

Question 12

What are different types of extended-release forms?

Answer 12

Delayed release, repeat action, and targeted release(might not be extended).

Question 13

What is a targeted-release form?

Answer 13

Directed toward isolating or concentrating a drug in a body region, tissue, or site for absorption or for drug action.

Question 14

How can you control drug release through dissolution?

Answer 14

By controlling access of biologic fluids to the drug through the use of barrier coatings.

Question 15

How can you control drug release through diffusion rates?

Answer 15

Reservoir devices - drug release is governed by Fick’s first law of diffusionMatrix devices - Pseudo steady(state is maintained during release) and release medium is perfect sink at all times.

Question 16

How can you control drug release through chemical reactions?

Answer 16

Chemical reaction or interaction between the drug substance or its pharmaceutical barrier and site-specific biological fluids.

Question 17

What are the three ways you can control drug release?

Answer 17

Dissolution, Diffusion, and chemical reactions

Question 18

How can drug release be controlled using coated beads, granules, or microspheres?

Answer 18

Variation in coat thickness affect rate at which fluids can penetrate the coating to dissolve the drug.

Question 19

How can multitablet systems be used to control drug release?

Answer 19

Small spherical compressed tablets with varying drug release characteristics can be placed within gelatin capsule shells.

Question 20

What is microencapsulation?

Answer 20

Process of enclosing solids, liquids, or gasses within microscopic particles by forming thin coatings of wall material around the substance.

Question 21

How does embedding a drug in slowly eroding or hydrophilic matric system affect drug release?

Answer 21

Drug substance is combined and made into granules with an excipient material that slowly erodes in body fluids, progressively releasing the drug for absorption.

Question 22

How does embedding drug in inert plastic matrix affect drug release?

Answer 22

Drug is granulated with an inert plastic material and the granulation is compressed into tablets; drug is slowly released from the matrix by diffusion.

Question 23

What is a complex formation?

Answer 23

Chemical combination of drug substance with other agents to form complexes that may be only soluble in body fluid, depending on the pH of the environment.

Question 24

What is an ion-exchange resin?

Answer 24

Resin-drug complex is prepared and may be tableted, encapsulated or suspended in aqueous vehicle. Drug release depends on pH and electrolyte concentration in the GI tract.

Question 25

What is an osmotic pump?

Answer 25

System composed of a core tablet surrounded by a semi-permeable membrane coating having a 0.4 mm diameter laser-produced hole through which drug is released by osmotic pressure.

Question 26

What are types of coating materials used in modified dosage forms?

Answer 26

Don’t memorize just be familiar with these!Hydroxypropyl methylcelluose, methylhydroxy ethylcellulose, ethylcellulose, polyvinylpyrrolidone(PVP), sodium carboxymethylcellulose, polyethylene glycols.

Question 27

What are enteric coating materials?

Answer 27

Cellulose Acetate Phthalate (CAP) and Eudragits

Question 28

What should patients be advised of when using modified dosage forms?

Answer 28

Dose and dosing frequency, don’t use them interchangeably with IR, do not crush or chew, NG an PE tube patients, Nonedible plastic matrix shells and osmotic tablets remain intact in the stool.