4. Absorption

Question 1

Absorption

Answer 1

The transfer of a drug from its site of administration to the blood stream

Most drugs dissolve in stomach and are absorbed in small intestine

Question 2

Enteric-coated (EC) drugs / delayed release (DR) drugs

Answer 2

Specifically formulated with polymer matrix that prevents drug from being dissolved in the stomach and dissolves in the small intestine

Protect stomach from drugs: aspirin can be very acidic and break down mucosa of stomach

Protect drugs from stomach: stomach acidic/hostile for more basic drugs

To release drug after stomach: site of action is small intestine

Question 3

Delayed release (DR) vs extended release (ER)

Answer 3

Delayed release (DR) dosed 2-3 times a day= enteric coated (EC) all drug is released at once

BUT these are not the same as extended-release (ER, X-RAY, XL) - slow release over a period of time - dosed once daily

Question 4

Most drugs are absorbed via ________ in the _______.

Answer 4

Passive transport, small intestine

Small intestine: a lot of surface area great place for absorption

Passive transport: increase concentration in gut vs bloodstream

Question 5

Factors that effect rate and extent of drug absorption - related to DRUG

Answer 5

Molecular weight

Lipid/water soul ability

Degree of unionization

Particle size

Dosage form

Concentration

Question 6

Factors that effect rate and extent of drug absorption - related to BODY

Answer 6

Gastric mobility

Intestinal transit time

pH

Blood flow absorption site

Surface area

Food

Question 7

Vancomycin

Answer 7

Large, hydrophilic molecule = very poor absorption in gut so we have an IV formulation

We also have a pill form: site of action is gut- no absorption just released in gut

Question 8

Take medication with/without food

Answer 8

With food: required for absorption, sometimes high fat, protect stomach mucosa, prevent nausea/vomiting, for efficacy

Without food: required for absorption- sometimes specific cations can interfere and hinder absorption. Avoid dairy and multivitamins

Question 9

P-glycoproteins

Answer 9

Effluent pump that pumps drugs back into GI lumen

Protection mechanism, works to decrease drug absorption

Question 10

CYP3A4

Answer 10

Enzyme that breaks down drugs in enterocytes of the small intestine

Another mechanism to decrease drug absorption

Question 11

First-Pass Effect/Metabolism

Answer 11

Drug concentration is greatly reduced before reaching systemic circulation

Gut wall enzymes, hepatic enzymes

Can greatly reduce bioavailability (F)

Question 12

Bioavailability (F)

Answer 12

The fraction of the drug absorbed into the systemic circulation after administration

In IV medication =100%

Question 13

Absorption based on Oral Route

Answer 13

First-pass effect may be significant

Question 14

Absorption based on Sublingual Route

Answer 14

By-pass first-pass effect, rapid absorption

Question 15

Absorption based on Transdermal Route

Answer 15

Bypass first pass, slow absorption

Question 16

Absorption based on Rectal Route

Answer 16

Less first-pass effect then oral

50% goes to liver
50% does not

Question 17

Absorption based on IV Route

Answer 17

F=100%, most rapid onset

Question 18

Absorption based on Intramuscular Route

Answer 18

Absorption depends on injection site, blood flow

Question 19

Absorption based on Subcutaneous Route

Answer 19

Constant, slow absorption

Question 20

Area Under the Curve (AUC)

Answer 20

Represents total drug exposure over time

Question 21

Cmx

Answer 21

The maximum or peak concentration of drug in the blood

Question 22

Brand name vs generic name drugs

Answer 22

Need to prove bioequivalence or similar rate/extent of absorption

Inactive ingredients may be different

Max, AUC similar

Same active ingredient, same strength, dosage form, route of administration

Some medications you may not want to switch such as seizure medications