Ch. 1 Pharmacokinetics and Routes of Admin

Question 1

Definition of pharmacokinetics

Answer 1

How meds travel through the body

Question 2

Phases of pharmacokinetics

Answer 2

1. Absorption
2. Distribution
3. Metabolism
4. Excretion

Question 3

What is absorption?

Answer 3

Movement of medications from the area of administration (muscle, skin, GI tract, membranes, or subcutaneous tissue) to the blood

Question 4

What is enteral and parenteral?

Answer 4

Enteral - through the GI tract
Parenteral - by injection
(these are most common routes of administration!)

Question 5

In what ways is the medication impacted by its absorption?

Answer 5

1. Rate of absorption determines how soon the med will take effect
2. Amount of medication the body absorbs determines intensity of effects
3. Route of admin affects the rate and amount of absorption

Question 6

What are barriers to absorption for oral admin?

Answer 6

Meds need to pass through epithelial cells that line the GI tract

Question 7

Absorption pattern for oral meds

Answer 7

Varies by:
1. Stability and solubility of med
2. GI pH
3. Whether there is food in the GI tract
4. Other meds
5. Form of the med (enteric-coated pills, liquids, etc)

Question 8

Barriers to absorption for sublingual meds

Answer 8

If you accidentally swallow before it dissolves, stomach acid will destroy the med

Question 9

Absorption pattern of sublingual meds

Answer 9

Quick absorption systematically because mucous membranes are very vascular

Question 10

Barriers to absorption for rectal and vaginal suppositories

Answer 10

Presence of stool or infectious agents limits contact of the med with the tissue

Question 11

Absorption pattern of suppositories

Answer 11

Easy absorption with local and systemic effects

Question 12

Barriers to absorption and absorption pattern for inhalation

Answer 12

Effort is needed to inhale.
Meds are absorbed rapidly through alveolar capillaries.

Question 13

Barriers and absorption pattern for intradermal (topical) meds

Answer 13

Epidermal cells are very close together
Absorption is slow and primarily local but can be systematic, especially with lipid-soluble meds.

Question 14

Barriers to absorption for subcutaneous and intramuscular

Answer 14

No barrier because capillary walls have large spaces between cells

Question 15

Absorption pattern for intramuscular and subcutaneous meds

Answer 15

• whether the med is soluble in water, with higher solubility meds being absorbed faster
  -blood perfusion at the injection site

Question 16

Barriers to absorption and absorption pattern for intravenous meds

Answer 16

No barriers
Immediate absorption = enters directly into blood.
Complete absorption = reaches blood in its entirety.

Question 17

What is distribution?

Answer 17

Transport of medications to the site of action by bodily fluids

Question 18

What factors affect medication distribution?

Answer 18

1. Circulation (inhibition of blood flow = poorer distribution)
2. Permeability of cell membrane (lipid soluble meds can cross blood brain barrier and placenta)
3. Plasma protein binding

Question 19

Define metabolism.

Answer 19

Process of changing meds into more or less active forms through enzyme action.

Question 20

What factors affect metabolism?

Answer 20

1. Age
2. Increase in medication metabolizing enzymes
3. First-pass effect (liver inactivates some meds on the first pass, and if too much is inactivated a non-enteral route such as IV or sublingual is better for this particular med
4. Similar metabolic pathways (if 2 meds use the same metabolic pathway, metabolism will decrease for one or both of them and cause accumulation because less medication would be inactivated).
5. Nutritional status (malnutrition leads to decreased enzymes needed)

Question 21

What is excretion?

Answer 21

Elimination of meds from the body, mostly through the kidneys but can take place through lungs, liver, intestines, and exocrine glands (mammary)

Question 22

What is a therapeutic range?

Answer 22

Plasma concentration of medication that is non toxic and effective

Question 23

Does high or low therapeutic index require monitoring?

Answer 23

Low, because there is a narrower safety margin

Question 24

What is a half-life?

Answer 24

Time it takes for medication to drop by 50%.

Question 25

What is considered a short half-life?

Answer 25

Medication is eliminated within 4-8 hours. Short-dosing interval or MEC (minimum effective concentration, or trough) drops between doses

Question 26

What is a long half-life?

Answer 26

Takes over 24 hours for medication to leave. More time between doses without loss of therapeutic effects

Question 27

Define pharmacodynamics

Answer 27

Interactions between meds and target cells, body systems, and organs result in functional changes (this is the MOA of the med).

Question 28

What type of medication activates receptors that produce analgesia, sedation, and constipation?

Answer 28

Agonist (med binds to or mimics the receptor activity that endogenous compounds regulate).

Question 29

What type of medication blocks angiotensin II receptors on blood vessels, thereby preventing vasoconstriction (losartan)?

Answer 29

Antagonists (meds block usual receptor activity that endogenous compounds regulate or the receptor activity of other meds)

Question 30

What type of medication blocks mu receptor activity and binds to kappa receptors, causing analgesia with minimal respiratory depression at low doses (nalbuphine)?

Answer 30

Partial antagonists In this example, respiratory depression is avoided by blocking mu activity and pain relief is still obtained by facilitating kappa activity in the brain (these are opioid receptors).

Question 31

What is a disadvantage of oral medications?

Answer 31

Absorption varies greatly due to inactivation from stomach acid and by first-pass effect

Question 32

Why should you apply pressure to the nasolacrimal ducts after applying ocular medications?

Answer 32

Pressure for 30-60 seconds prevents systemic absorption

Question 33

Why should patients stay lying supine for 5 min after nasal medications?

Answer 33

This prevents the medication from running out of nose or down the throat and allows time for the med to enter the mucosal epithelium.

Question 34

What position should a patient be in for a rectal suppository?

Answer 34

Left lateral or left lying Sim's position.

Question 35

Should you shake metered dose inhalers or dry-powder inhalers?

Answer 35

Metered dose inhalers

Question 36

How should you prepare medications for NG tubes?

Answer 36

- dissolve crushed tablets and capsule contents in 15-30 mL of sterile water (do not use sublingual, enteric-coated, liquid-filled, or time-release capsules) - Flush tubing before and after each med with 15-30 mL of sterile water -Flush tubing with another 15-30 mL of warm sterile water after administering all meds.

Question 37

Where should you give a 2.5 mL IM injection?

Answer 37

Ventrogluteal site

Question 38

Where should you give a 1 mL IM injection?

Answer 38

Either deltoid or ventrogluteal site.

Question 39

What type of syringe should you use for volumes less than 0.5mL?

Answer 39

Tuberculin syringe

Question 40

What is the max volume of medication you can inject for a subcutaneous injection and what type of solution?

Answer 40

1.5 mL of water-soluble meds, such as insulin.

Question 41

What types of medications should be delivered intramuscularly?

Answer 41

1 to 3 mL of Irritating, oil-soluble, and aqueous suspensions.

Question 42

What size IV catheter should be used for trauma? For during surgery or blood administration? For children, older adults, or adults who are stable?

Answer 42

1. 16-gauge 2. 18-gauge 3. 22 to 24-gauge

Question 43

Where should you place an IV in a newborn?

Answer 43

Head, lower legs, and feet

Question 44

How is an epidural started?

Answer 44

Used for IV opioid analgesia (morphine or fentanyl). Done by a clinician - advances catheter through the needle into the epidural space at the 4th or 5th vertebra Infusion pump administers med.