Module 2 Absorption

Question 1

Absorption

Answer 1

• Movement of drug from administration site into blood
• Speed of drug effects

Question 2

Affecting Factors of Absorption

Answer 2

• Rate of dissolution
• Surface area
• Blood flow
• Lipid solubility
• pH partitioning
• Activity of transport proteins

Question 3

Rate of Dissolution

Answer 3

• Speed of dissolving in solution
• Determines speed of onset

Question 4

Surface Area

Answer 4

• Larger area provides faster absorption

Question 5

Blood Flow

Answer 5

• Concentration gradient drives absorption
• Exercise increases absorption
• High blood flow = fastest absorption

Question 6

Lipid Solubility

Answer 6

• Ability to cross cell membrane
• Faster absorption

Question 7

pH Partitioning

Answer 7

• pH gradient between site of administration & ionized in blood

Question 8

Transport Protein Activity

Answer 8

• Uptake transporters increase absorption
• Efflux transporters decrease absorption

Question 9

Routes of Administration

Answer 9

• Oral
• Sublingual
• Transdermal
• Rectal
• Intravenous (V)
• Subcutaneous (SC)
• Intramuscular (IM)
• Pulmonary

Question 10

External Route

Answer 10

• GI Tract

Question 11

External Route Examples

Answer 11

• Oral
• Rectal

Question 12

Parenteral Route

Answer 12

• Everything EXCEPT GI tract

Question 13

Parenteral Route Examples

Answer 13

• Intravenous
• Intramuscular
• Subcutaneous

Question 14

Stomach Absorption Factors

Answer 14

• Small surface area
• Thick mucous layer

Question 15

Small Intestine Absorption Factors

Answer 15

• Large surface area

Question 16

Pharmaceutical Phase

Answer 16

• After tablet is swallowed
• Disintegration of tablet
• Dissolution of drug

Question 17

Gastric Emptying

Answer 17

• Movement from stomach into intestine

Question 18

Increase Gastric Emptying

Answer 18

• Empty stomach
• Cold water
• Lying on right side
• Tube feeding (high osmolality)
• Prokinetic drugs (increase motility)

Question 19

Decrease Gastric Emptying

Answer 19

• High fat
• Heavy exercise
• Lying on left side
• Inhibiting vagus nerve (anticholinergic)

Question 20

Enteric Coating

Answer 20

• Prevent dissolution in acidic conditions (stomach)
• Dissolves in alkaline duodenum

Question 21

Bioavailability

Answer 21

• Fraction of dose reaching circulation unchanged

Question 22

Affecting Factors of Bioavailability

Answer 22

• Drug formulation
• Route of administration
• Degree of metabolism

Question 23

Sublingual Absorption

Answer 23

• Dissolve under tongue
• Absorbed across oral mucosa
• Venous drainage to superior vena cava
• Lipophilic & uncharged drugs only

Question 24

Transdermal Absorption

Answer 24

• Dissolve in extracellular fluid
• Lipophilic to penetrate epidermis
• Hydrophilic to dissolve

Question 25

Transdermal Considerations

Answer 25

- Patches, sprays, ointments - Constant levels - Drug free periods to avoid tolerance

Question 26

Affecting Factors of Transdermal Absorption

Answer 26

- Thickness of skin - Hydration - Hair follicles - Application area - Skin barrier integrity

Question 27

Skin Thickness

Answer 27

- Inversely proportional absorption

Question 28

Hydration

Answer 28

- Increased absorption when well hydrated

Question 29

Hair Follicles

Answer 29

- Bypass epidermis barrier - More follicles = better absorption

Question 30

Application Area

Answer 30

- Surface area increases absorption

Question 31

Skin Barrier Integrity

Answer 31

- Damaged barrier increases absorption

Question 32

Rectal Absorption

Answer 32

- Situations of vomiting/loss of consciousness - Bypass liver

Question 33

Disadvantages of Rectal Absorption

Answer 33

- Incomplete absorption - Irritation of rectal mucosa

Question 34

Intravenous (IV) Absorption

Answer 34

- Injection into peripheral vein - Bolus or IV drip

Question 35

IV Bolus

Answer 35

- Single dose - Short time period

Question 36

IV Drip

Answer 36

- Continuous infusion - Long time period - Diluted solution

Question 37

Advantages of IV Absorption

Answer 37

- No barriers - 100% bioavailability - Control of dosage & duration - Dilution increases solubility - Irritants slowly injected

Question 38

Disadvantages of IV Absorption

Answer 38

- Expensive - Invasive - No mechanism of removal - Infection/fluid overload risk - Risk of improper formula

Question 39

Subcutaneous Absorption

Answer 39

- Subcutaneous tissue injection - Capillary wall only barrier

Question 40

Affecting Factors of Subcutaneous Absorption

Answer 40

- Blood flow - Water solubility - Irritant drugs cause adverse effects

Question 41

Intramuscular (IM) Absorption

Answer 41

- Muscle tissue injection - Pass fenestrations of capillary wall

Question 42

Advantages of IM Absorption

Answer 42

- Useful for poorly soluble drugs - Depot preparations (long time period)

Question 43

Disadvantages of IM Absorption

Answer 43

- Pain/discomfort - Tissue/nerve damage

Question 44

Affecting Factors of IM

Answer 44

- Blood flow - Exercise (increase flow & absorption) - Heart failure/hypotension (decrease flow)

Question 45

Pulmonary Absorption

Answer 45

- Gaseous & volatile drugs - Inhaled & absorbed via pulmonary epithelium - Rapid absorption (lung surface area) - Delivered to site of action (asthma)