[1] Pharmacokinetics I (CH2)

Question 1

there are 2 types of drug administration, what are they?

Answer 1

enteral and parenteral

Question 2

what are the 3 types of enteral drug administration to remember?

Answer 2

oral
sublingual/buccal
rectal suppository

Question 3

what are the 4 types of parenteral drug administration to remember?

Answer 3

inhalation
injections (IV, IA, SC, IM, intrathecal)
topical
transdermal (patch, iontophoresis, phonophoresis)

Answer 4

most drugs, lipid soluble

Answer 5

easy and convenient to self-administer

Answer 6

• *** first pass effect (decreases amount of drug reaching blood and eventual target)
• some drugs (peptides, small proteins, etc.) are broken down by the gut, which could lead to potential irritation of the GI tract
• factors such as food, vomiting, and diarrhea may interfere

Question 7

what is the first-pass effect?

Answer 7

The first pass effect is a phenomenon where GI –> portal vein –> metabolism by liver results in a reduced concentration of the active drug in systemic circulation and eventual target site

Answer 8

nitroglycerin

Answer 9

• rapid onset of action
• absorbed through oral mucosa and hits bloodstream
• avoids first pass metabolism by liver

Answer 10

excessive dry mouth can influence absorption

Answer 11

laxative suppository

Answer 12

• avoids first pass metabolism by the liver
• may be given to pt who is unconscious or vomiting
• useful to treat local rectal condition (ie. hemorrhoids)
• useful to stimulate GI movement in cases of constipation

Answer 13

• some drugs may irritate the rectal mucosa
• may be poorly or incompletely absorbed
• pt may have trouble self-administering suppository

Question 14

things to note about parenteral routes of drug administration

Answer 14

• generally parenteral admin allows the drug to react the site of action through a more direct or “targeted” route, making the quantity of the drug when it reaches the site more predictable
• parenteral admin is not administered through the GI tract and is usually not subject to the first-pass metabolism of the liver

Answer 15

general anesthetic / asthma

Answer 16

• may be used for drugs in gaseous or volatile state
• may be used for drugs suspended as tiny droplets
• rapid onset; large SA and high blood flow (ie. lungs)
• useful to directly treat respiratory disorders

Answer 17

• some drugs can irritate the alveoli or respiratory tract
• patient may have trouble self-admin
• patient compliance

Question 18

- list all the types with their respective abbreviation

Answer 18

IV; Intravenous
IA; Intra-arterial
SC; Subcutaneous
IM; Intramuscular
Intrathecal

Question 19

- examples of each injection type along with a quick tidbit about them

Answer 19

IV: ex. analgesics … quick delivery of known amount
IA: ex. anti-cancer meds … very targeted delivery to tumor
SC: ex. insulin, anticoagulants … relatively easy route for drugs that can’t do oral
IM: ex. vaccines, botox … skeletal mm. is a large target

Intrathecal: specific site such as spinal subarachnoid space, tendon sheath,
bursa—may connect to catheter and pump

Answer 20

antimicrobials, anti-inflammatory steroids

Answer 21

• easy use for patient (applying cream or ointment to skin)
• small amounts typically do not penetrate deep enough for adverse systemic effects
• could apply topically for a systemic effect where you may get absorption into your blood (nasal spray, eye drops, topical NSAID)

Answer 22

• if large amounts are applied often enough to a large body SA, drug may be absorbed into the blood and cause adverse effects systemically

Answer 23

analgesics (acetaminophen), nicotine

Answer 24

• easy application for the patient by applying patch to skin
• we want the drug to pass through the skin and into the bloodstream for systemic effect
• the use of TD patches is expanding for issues like: angina, high BP, contraception

Answer 25

• the drug has to pass through the skin in order to work

- patients need to be reminded to take off the old patch and dispose properly

Question 26

[parenteral drug admin.]:

• what is transdermal iontophoresis
• what is transdermal phonophoresis

Answer 26

iontophoresis uses an electrical current to drive drug through skin to subcutaneous tissue

phonophoresis uses ultrasound waves to enhance the movement of the drug through the skin

Question 27

define bioavailability

Answer 27

“percentage of the drug administered that reaches the bloodstream”

Question 28

If give 100 mg of drug X (IV injection) and measure 100 mg of drug X in bloodstream, what is the bioavailability?

Answer 28

bioavailability is 100%

Question 29

If give 100mg of drug X (orally) and measure 50mg of drug X in bloodstream, what is the bioavailability?

Answer 29

bioavailability is 50%

Question 30

what can affect bioavailability?

Answer 30

• route of admin
• clearance or metabolism of drug (ie. first pass effect)
• drug ability to pass through various membranes

Question 31

what letter represents bioavailability

Answer 31

F

Question 32

for a drug given via IV, bioavailability (F) is usually …

Answer 32

100%

Question 33

what 4 factors are considered with the distribution of drugs within the body

Answer 33

– Tissue permeability
– Blood flow
– Binding to plasma proteins
– Storage in body compartments

Question 34

- a highly lipid-soluble drug may __, whereas a large nonlipid-soluble drug may __

Answer 34

Highly lipid-soluble drug may potentially reach all body compartments and enter cells, where as large nonlipid-soluble drug may remain primarily in the compartment where it is administered (e.g. GI)

Answer 35

True

Question 36

where would we find it difficult to get a drug from the blood stream to an area on the body that doesn’t get as much blood flow?

Answer 36

sinuses

Question 37

if a pt possesses a disease that reduces blood flow, what is to be expected?

Answer 37

some tissues may reduce drug delivery

Answer 38

True

some drugs may be 90% protein bound and 10% free in plasma

Question 39

[T/F]: unbound or “free” drug(s) is able to reach target tissue and exert its pharmacological effect

Answer 39

True

Question 40

what is “volume of distribution (Vd)” ?

Answer 40

Vd is just an arbitrary figure (not real volume) that reflects drug distribution relative to the TBW in a human. It is calculated as the ratio of amount of drug administered to the drug [ ] in plasma. This can be written as:

Vd = (amount) / ( [ ] plasma )

Question 41

what is the normal TBW for a male

Answer 41

42 L of TBW

Question 42

Vd for drug X < 42L

- what does this indicate?

Answer 42

indicates that drug X may be bound to plasma protein and retained in the bloodstream

Question 43

Vd for drug X > 42L

- what does this indicate?

Answer 43

indicates that drug X may be concentrated in some tissue, such as adipose/fat

Question 44

following drug admin & abs, drugs are often stored in the body in these major sites:

Answer 44

adipose/fat
bone
muscle
organs (liver, kidneys)

Question 45

what serves as a primary site for lipid-soluble drugs?

Answer 45

adipose/fat

Question 46

due to the slow nature of fat metabolism and poor blood supply, drugs tend to ___ in adipose/fat

Answer 46

due to the slow nature of fat metabolism and poor blood supply, drugs tend to [remain for long periods of time] in adipose/fat

Question 47

in what body site can some toxic heavy metals such as lead be stored in?

Answer 47

bone

Question 48

what body site may serve as a long term storage of compounds?

Answer 48

muscle

Question 49

drugs transported into [this body site] may form reversible bonds with intracellular structures

Answer 49

drugs transported into [muscle] may form reversible bonds with intracellular structures

Answer 50

True

Question 51

what are some of the adverse consequences of drug storage?

Answer 51

• tissue damage may occur when exposed to high [ ] of drugs, drug metabolites, or other toxic materials… this becomes problematic when storage sites such as adipose/fat “soak up” the drug, which could lead to a “leakage” of the drug from the site
• this ultimately prolongs the drug effect as well as extends any adverse rxns

Question 52

provide the abbreviations for the following:

• timed release
• sustained release
• extended release
• prolonged release
• controlled release

Answer 52

TR, SR, ER, PR, CR

Question 53

what perks does CR drug delivery offer

Answer 53

• slower/more prolonged absorption of drug
• decreases the # of dosages needed throughout the day
• prevents large fluctuations in plasma and maintains delivery while sleeping

Question 54

when targeting drug delivery, what 2 things are we thinking about

Answer 54

• nanoparticles… facilitate movement across membranes

- antibodies… attached to drugs that target the “antigen” on cells