Pharmacokinetics

Question 1

ADME?

Answer 1

Absorption - route of administration to blood stream. Mostly happens in stomach by weak acids and in small intestine and/or large intestine. Ostomy/GI = dec. surface area absorption.
-oral/intradermal/SQ/IM/topical/ NOT IV because this goes directly to bloodstream before getting absorbed.
Not

Question 2

Distribution

Answer 2

where will it go? transporters from blood to target tissue think protein bound and albumin…lipid soluble are easier to cross membrane. This happens through blood stream by Systemic Circulation.
Disorder effecting plasma protein…
-Intravascular –> intracellular/interstitial/fat.
ISSUES: Low levels of protein or high levels of fat (lipophilic drugs will get stuck in fat)

Question 3

Metabolism

Answer 3

How is it broken down?? LIVERRRR. Drugs get broken down, changed, and usually changed from lipophilic to hydrophilic. Liver disease = inc. risk of toxicity.

Question 4

Excretion

Answer 4

How does drug leave body? Better if its hydrophilic…this is why metabolism was so important. This happens through the kidneys and urine. If someone has kidney problems, inc. risk for toxicity.

Question 5

Drug Variability

Answer 5

Why a drug is given once a day versus 3x a day. Something we don’t need to know. BUT we need to know patient variability…how will patient respond.

Question 6

Bioavailability

Answer 6

Amount of drug that is available for body to use.

Question 7

Systemic Circulation

Answer 7

how a drug is circulated through body.

Question 8

Enteral VS Parenteral

Answer 8

Enteral enters GI system (usually oral/sort of sublingual which has higher bioavailability) while parenteral (IV, subQ, IM). A drug which goes directly to target tissue is FASTER and has HIGH bioavailability (inhaler, ear drops, eye drops)

Question 9

First-Pass Effect

Answer 9

Part of absorption of oral meds. Why there is a dec. bioavailability for oral meds = they go to hepatic portal vein before they go to systemic circulation.
*hepatic portal vein, liver, systemic circulation

Question 10

How does an empty stomach effect drugs?

Answer 10

Food = Inc. GI motility, Inc. Acid… thus, food in stomach DECREASES absorption. So an empty stomach increases absorption.

Question 11

Empty Stomach

Answer 11

2 hours after last meal and 1 hour before a meal

Question 12

Enteric Coating is…

Answer 12

Protects stomach from drug and protects drug from stomach. Goal = breaks down more in intestine versus stomach.

Question 13

Diffusion

Answer 13

• Smaller drugs cross membranes easier.
• Non-ionized drugs cross easier
• Lipophilic same thing as hydrophobic…and easier to cross membranes (or hydrophilic and lipophobic are the same)

Question 14

the nurse has administered a drug that requires energy to move the drug molecules into the cells that they are intended to affect. The nurse should recognize the presence of:

Answer 14

Active transport

Question 15

Factors that affect absorption

Answer 15

Route, Drug concentration, GI tract environment, perfusion to absorption site… dec. blood flow!, drug ionization, drug interactions, surface area (surgery)

Question 16

what most commonly occurs first when an oral drug is being absorbed

Answer 16

The drug moves from the small intestine directly into the portal venous system.

Question 17

The nurse is admin. ….. PO4 times daily to a client sith gonorrhea. The nurse should plan to take which action to enhance absorption of this medication.

Answer 17

Give a drug on an empty stomach with a full glass of water.

Question 18

Factors that affect distribution

Answer 18

• Perfusion to tissues,
• Drug solubility (size, polarity, lipid soluble)…need drugs that are small, non/ionized/lipophilic.
• Tissue Storage; trapping common in adipose tissue
• drug-protein binding- albumin in blood. Risk for toxicity.
• special barriers (BBB, fetal/placental barrier is not very effective)

Question 19

The nurse has administered a drug that is known to be lipid soluble. This drug’s solubility will primarily affect what aspect of pharmacokinetics?

Answer 19

DISTRIBUTION…solubility affects distribution.

Question 20

the culture and sensitivity testing of a patient’s wound exudate indicates that a specific antibiotic is necessary for treatment. The drug in question is 96% protein bound. What are the implications of this fact??

Answer 20

Dosages of the drug must be large in order to be effective.

Question 21

Enzyme Substrates

Answer 21

The drug acted upon

Question 22

Enzyme inducers and enzyme inhibitors

Answer 22

either cause toxicity or subtherapeutic levels.

Question 23

Sub-therapeutic Level

Answer 23

Level of drug in the body is too low to have an effect on the body.

Question 24

Long 1/2 life

Answer 24

• higher protein binding
• higher dosing interval
• higher enterohepatic recirculation