Phamacological Principles - Pharmacokinetics

Question 1

Pharmacokinetics

Answer 1

How the body interacts with administered drugs until it leaves the body

Question 2

Absorption

Answer 2

Movement of drug from site of administration into the bloodstream. Once it is in the bloodstream, it can circulate throughout the body

Question 3

What is the enteral route of administration?

Answer 3

Route of administration through the oral cavity and will go through the GI tract

Question 4

First-Pass-Effect

Answer 4

The metabolism of a drug leading to lower concentration of active drug in the circulatory system and thus target tissues. It inactivates >90% of orally administered drugs and very minimally will it activate a drug

Question 5

What are the 2 types of enteral route?

Answer 5

1. Mouth - its absorption site is the mucosa of stomach, small intestine, or large intestine. Its metabolism site is the liver via portal vein. It undergoes the First-Pass-Effect
2. Sublingual/Buccal - its absorption site is the vascularized tissue of oral mucosa. It does not have a metabolism site, therefore, FPE doesn’t occur

Question 6

What 5 factors affect absorption in the enteral route?

Answer 6

1. Stomach acidity
2. Stomach motility
3. Changes in intestinal mucosa
4. Blood flow to the stomach or intestine
5. Food and liquid

Question 7

Bioavailability

Answer 7

The amount of active drug absorbed into the circulatory system and thus target tissue

Question 8

What is the clinical implication of FPE and bioavailability?

Answer 8

A high FPE indicates a higher dose of the medication to allow for better availability

Question 9

What is the purpose of enteric coating? What happens if the stomach is too acidic?

Answer 9

It protects the stomach wall and allows for dissolution and absorption of drugs to take place in the intestine

If the stomach is too acidic, decreased absorption in the intestine occurs

Question 10

Advantages and disadvantages of the oral route (enteral) and their clinical implications

Answer 10

Advs:
- Easier and more convenient to administer
- Safer than injection and easier to reverse accidental ingestion

Disadvs:
- Variable absorption
- Inactivation of some drugs by stomach acid

Nursing Considerations:
- Involves a variety of dosage forms (ex. liquids, solutions, tablets, enteric-coated)
- Some need to be taken with food, others not
- What other medications is the patient taking?

Question 11

Advantages and disadvantages of the sublingual/buccal route (enteral) and their clinical implications

Answer 11

Advs:
- Absorbed more rapidly from oral mucosa than oral route
- More rapid onset of action
- No breakdown of drug by stomach acid
- No FPE

Disadvs:
- Patient may accidentally swallow pill as it needs to be dissolved under tongue/cheek
- Need salivary secretions

Nursing Considerations:
- Sublingual: needs to be placed under the tongue
- Buccal: needs to be placed between the cheek and gum

Question 12

What is the parenteral route of administration?

Answer 12

Any route of administration other than the GI tract

Question 13

What are the 4 types of parenteral route?

Answer 13

1. Intravenous (IV) injection - injected directly into the circulatory system
2. Intramuscular (IM) injection - absorption through the vasculature of the muscles
3. Subcutaneous (SC) injection - absorption through the vasculatur of the SC tissue
4. Intradermal injection - absorption through the vasculature of the dermal tissue

No method undergoes the FPE

Question 14

What 4 factors affect absorption in the parenteral route?

Answer 14

1. Temperature
2. Messaging
3. Blood pressure
4. Peripheral circulation

Question 15

What are the clinical implications of the parenteral route?

Answer 15

• Great for when the patient cannot take a drug orally (ex. nausea and vomiting, or lack of swallowing reflex)
• Fastest route of absorption; great for immediate effects
• Requires immediate and close monitoring of both positive and negative drug impacts

Question 16

Advantages and disadvantages of the IV route (parenteral) and their clinical implications

Answer 16

Advs:
- Rapid onset
- Able to directly control drug level in blood
- Allows for larger fluid volume
- Avoid FPE

Disadvs:
- Higher cost
- Inconvenience
- Fluid overload (too much volume in body, affecting perfusion)
- Risk of infection
-Possibility of air embolism
- Difficulty to reverse drug effect

Nursing Considerations:
- If continuous infusion, need frequent monitering
- Need to always check for compatibility
- Need to always monitor for site of administration

Question 17

Advantages and disadvantages of the SC route (parenteral) and their clinical implications

Answer 17

Advs:
- Allows for slow, sustained absorption. Allows for prolonged effect

Disadvs:
- Discomfort of injection
- Inconvenience
- Bruising

Nursing Considerations:
- Need to landmark site of administration

Question 18

Advantages and disadvantages of the IM route (parenteral) and their clinical implications

Answer 18

Advs:
- Absorption can be longitudinal
- Onset of action will differ

Disadvs:
- Discomfort of injection
- Inconvenience
- Bruising

Nursing Considerations:
- Need to landmark site of administration

Question 19

What is the topical route of administration?

Answer 19

Administration through body surfaces

Question 20

What are the 7 types of topical route?

Answer 20

• The skin, eyes, ears, nose, lungs, and vagina all have their absorption site in the capillaries that feed into the tissue. No FPE
• The rectum has its absorption site in the capillaries that feed into the tissue and/or the capillaries that feed the portal vein. Has mixed FPE and non-FPE absorption and metabolism

Question 21

What factor affect absorption in the topical route?

Answer 21

Perfusion to the site

Question 22

Distribution and what 4 factors is it impacted by?

Answer 22

The journey of the drug through the bloodstream until it reaches the target tissues and cells

Impacted by:
1. Plasma proteins (ie. albumin). Drugs bound by albumin are inactive as it cannot enter cells. This impacts the conc. of active drugs
2. Competing drugs
3. BBB
4. Blood-placental barrier

Question 23

Clinical implications of plasma proteins (ie. albumin)

Answer 23

• Drugs bound to albumin are pharmacologically inactive
• Low levels of albumin means increased concentration of pharmacologically active drugs, thereby increasing possibility of drug toxicity
• Low levels of albumin may be due to liver dysfunction, malnourishment, and severe burns
• Albumin is made by the liver

Question 24

Metabolism

Answer 24

The process by which the drugs are modified (bio-transformed) from its original form to either:
- A more soluble compound
- An inactive metabolite
- A potent metabolite
- Less active metabolite by enzymes

Question 25

Excretion and the 4 types of excretion that could occur

Answer 25

It is how the drug is eliminated from the body. The kidney is the most dominant organ for excretion; kidney function is very important

4 types of excretion:
1. Exhalation
2. Sweating
3. Urination
4. Defecation

Question 26

Half-life

Answer 26

The time required for serum drug levels to be reduced by one-half (50%) during the elimination phase. By approx. 5 half-lives, 97% of most drugs are effectively removed from the body

Question 27

Steady state and the clinical implications of half-life

Answer 27

Steady state is the physiological state in which the amount of drug removed via elimination is equal to the amount of drug absorbed with each dose. Reaching SS is considered maximum therapeutic effects

Half-life can affect decisions around dosing schedule. The longer the half-life, the longer time to steady state

Question 28

Describe the onset of action, peak-effect, and duration of action of a drug

Answer 28

Onset of action - time required for the drug to elicit a therapeutic response

Peak-effect - time required for the drug to reach its maximal therapeutic response

Duration of action - the length of time that the concentration of a drug is sufficient enough (w/o more doses) to elicit a therapeutic response