lecture 4 absorption/distribution

Question 1

what is intraosseous route of admin

Answer 1

injection into the bone

infusion into the cavity rapidly enters circulation via extensive network of sinusoidal capillaries

Question 2

what are general advantages (2) and disadvantages to (3) to injections

Answer 2

adv = reduce systemic effects, higher local concentrations
dis = risk of infection, toxicity (overdose), damage (needle)

Question 3

how is an inhaled drug/toxin dispersed throughout the body

Answer 3

Inhaled drugs and toxins are dispersed across extensive respiratory tract mucous membranes and pulmonary epithelium

Question 4

what are the advantages to inhalation

Answer 4

• Rapid absorption and systemic circulation
  
  • 7-10 seconds to reach the brain
  • Almost as fast of iv
• Not subjected to first-pass metabolism

Question 5

what happens if a drug is absorbed and deposited

Answer 5

mechanism of toxicity. there will be buildup of it in your system

Question 6

what are the 6 advantages of inhalation route of admin

Answer 6

• Rapid absorption
  
  • Access to CNS
• Convenient
• Non-invasive, does not require sterility
• Very good for local pulmonary delivery (e.g. asthma)
• Avoids first-pass metabolism
• Avoids GI enzymes and pH
  
  • Stability

Question 7

what are the 8 disadvantages of inhalation route of admin

Answer 7

• Easy access for toxins (vapours, aerosols)
• Irreversible
• Difficult to regulate amount delivered
• Elevated risk of addiction
• Can irritate pulmonary mucosa
• Can have unpleasant taste
  
  • affect taste perception
• Relatively uncommon
• Limited formulations

Question 8

what are features of the nasal cavity that make intranasal useful

Answer 8

• Nasal cavity can hold about 20 mL volume
  
  • Liquids as well as gases and aerosols
  • Very rich blood supply
  • Nasal mucosa more permeable than GI mucosa
  • Local or systemic effects
  • Rapid absorption – bypass first-pass metabolism at GI tract enzymes / pH…unless swallowed

Question 9

what are the two kinds of topical routes of admin

Answer 9

single dose cream and stuff and then patches or other devices that are placed on skin

Question 10

why does topical route of admin have limited systemic effects

Answer 10

Limited systemic effects (small SA, exposed to nature and chemicals, waxy surface, lipophilic can get in, not great blood supply. if theres a cut and you apply it then its bypassing some barriers)

Question 11

how does transdermal topical route of admin deliver to systemic circulation

Answer 11

Transdermal application (e.g. patch) delivers to systemic circulation (like infusion, more like subcutaeneous, nicotine addiction to sites where you experience withdrawal, like brain and other parts)

Question 12

what is the absorption in the skin directly proportional to

Answer 12

Skin: absorption directly proportional to the lipid solubility of the substance(s)

Question 13

why are there lower risk of side effects in topical route of admin

Answer 13

there is limited absorption into deeper tissues

Question 14

define transdermal delivery and give some examples of drugs applied via patches

Answer 14

Transdermal delivery: topically administered for systemic effects at a predetermined and controlled rate

Patches: nicotine, nitroglycerine, testosterone, fentanyl, birth control

Question 15

what are the 8 advantages of transdermal route of admin

Answer 15

• Convenient
  
  • self-administration, compliance
• Stable plasma concentration
• Non-invasive
• Allows removal of source
• Effective for substances with
  
  • short half-life
  • narrow therapeutic window
  • poor oral bioavailability
• Avoids first-pass metabolism
• Avoids GI enzymes and pH
  
  • Stability
• Emerging technologies

Question 16

what are the 4 disadvantages of transdermal route of admin

Answer 16

• Poor diffusion of large and lipophilic compounds
• Can irritate skin and mucosa
• Crystallization can lead to local toxicity
• Systemic side effects

Question 17

what is opthalmic route of admin for

Answer 17

local treatment to the eye

Question 18

what complicates dosing in opthalmic route of admin

Answer 18

• Natural spillage complicates dosing
  
  • about 80% of dose will be lost to overflow
  • ointments maintain longer contact with eye
  • Ointments cause blurring – applied at night

Question 19

rank from delivery time to blood (1 = fastest, 5= slowest)

oral, intravenous, intramuscular, inhalation, topical

Answer 19

1. intravenous
   2-3. intramuscular/inhalation. (if hydrophilic = IM, if lipophilic = inh)
2. oral
3. topical

Question 20

rank from peak delivery time to blood (1 = highest, 5= slowest)

oral, intravenous, intramuscular, inhalation, topical

Answer 20

1. IV
   2-3. IM, inh
2. oral
3. topical

Question 21

rank from potential risks (1 = most, 5= fewest)

oral, intravenous, intramuscular, inhalation, topical

Answer 21

1. IV
   2-3. IM, inh
2. oral
3. topical

Question 22

what is the preferred route of admin for drugs (top 3)

Answer 22

1. oral (65%)
2. injectable (20%)
3. topical (5%)

Question 23

what are the 3 physical factors influencing absorption

Answer 23

1. substance properties
2. matrix properties
3. route of exposure/administration

Question 24

what is the importance of available blood flow for absorption

Answer 24

> blood flow = > absorption
- > absorption from intestine
- > absorption from muscle than subcutaneous tissue

Question 25

what is the importance of available surface area and time for absorption

Answer 25

> surface area = > absorption - E.g. length and microvilli of intestine provide surface area 1000-fold greater than that of stomach; stomach empties faster - > absorption from intestine than stomach