Chapter 1

Question 1

Drug

Answer 1

Drug: Any substance which brings about a change in biological function through its chemical action.
Come in many forms
Solids, e.g pills, tablets
Liquids and gels, e.g. syrup, ointments, creams
Vaporized liquids, e.g. inhalers, nose spray
Gaseous, e.g. anesthesia gas during surgery
Oxygen is a potent drug!!

Question 2

Drug Routes

Answer 2

Oral – abbreviated “po” (pronounced: “pee-oh”)
Intravenous - abbreviated “IV” (pronounced: “eye-vee”) – injected directly into the vein – very rapid onset
Subcutaneous - abbreviated “SQ” – (pronounced: “sub-Q”) – injected into the subcutaneous fat layer of the skin. Ex: insulin; onset: depends on the medication.
Sublingual - abbreviated “SL” – under the tongue, absorbed by the large vessels in the floor of mouth. Ex: nitroglycerin for chest pain
Transdermal – absorbed through the skin – slow release. Ex: estrogen patch, nicotine patch, opioids (narcotic patch)
Intramuscular - abbreviated “I.M.” – “a shot”; med injected into the muscle; onset = 20-40 minutes; ex: flu vaccine

Question 3

Pharmacokinetics versus Pharmacodynamics

Answer 3

Pharmacokinetics = Actions by the BODY on the drug.

Pharmacodynamics = Actions by the DRUG on the body.

Question 4

Pharmacokinetics

Answer 4

Pharmacokinetics = the drug’s actions within the body and how the drug moves to and from the site of action
Actions by the BODY on the drug.

Question 5

Bioavailability

Answer 5

Bioavailability: The extent to which the active drug or metabolite enters the general circulation, thereby permitting access to the site of action.
Most important concept: protein binding.
Most meds are bound to proteins in the blood, can travel along with the plasma protein in an inactive state, until it reaches its target organ or the body activates the medication.
Diseases that decrease amount of plasma/blood proteins: malnutrition, renal or hepatic problems
Note: all plasma proteins are made in the liver

Question 6

Pharmacokinetics: 4 processes

Answer 6

Absorption: movement of a drug from the site of administration
Distribution: transport of a drug in the bloodstream
Metabolism: alteration of a drug in the body
Excretion: elimination of the drug or its compound from the body

Question 7

Absorption

Answer 7

Absorption: the process of drug movement from the site of administration to the systemic circulation.
Many factors influence absorption: acidity of stomach; how fast GI tract is moving (e.g. fast with diarrhea  less time for absorption); interference from other meds that may neutralize the drug.

Question 8

Distribution

Answer 8

The reality: once a drug is in the body, the drug can go throughout the body. Hopefully, the drug will cause the desired action in the desired tissue or organ (Ex:  pain). Other organs and body systems may also be affected: causing side-effects (e.g. nausea) or harmful/adverse reactions (e.g. low blood pressure or allergic reactions).
I.V. meds distribute rapidly & cause rapid responses
So, once the drug is in the body, you can’t take it out!

Question 9

Metabolism

Answer 9

Metabolism: alteration of a drug in the body
The body must metabolism (break down) medications or the med’s actions will last longer than desired or build up to toxic/dangerous levels.
Most metabolism of medications is done in the liver.
Other sites for metabolism: Skeletal muscle, Kidneys, Lungs, Plasma, and Intestinal mucosa
Hepatic (Liver) “Cytochrome P-450” enzyme system: Most medications are broken down through these many enzymes. Cytochrome P-450 is frequently mentioned during discussion of medications and their bioavailability.

Question 10

Excretion

Answer 10

Excretion: elimination of the drug or its compound from the body
Most excretion of medications is done in the kidney.
Other sites for excretion: the lungs (exhalation), the skin (sweating), the GI tract (defecation)
Drugs are excreted in many forms: doesn’t matter if the drug is an original compound, (parent compound), an active or an inactive metabolite –
Patients with renal (kidney) failure will not be able to excrete drugs efficiently
Drug levels will increase → Patients may experience more adverse effects and toxicity

Question 11

Dosing: how often should a med be given?

Answer 11

Dosing – factors to consider: onset of action, peak concentration level (highest effective level in the body at that time), duration of action, and half-life.
The range of drug concentration in the blood lies between minimally effective level and a toxic level.
Half-life
The time required to change the amount of drug in the body by one half
Useful to determine the time to attain 50% of steady state; short half-life: wears off faster and give more often

Question 12

Half Life

Answer 12

The time required to change the amount of drug in the body by one half
Rule: 5 half lives = 97% of drug elimination
Example: med with 4-hour half-life
4h 50%
8h 25%
12h 12.5%

Question 13

Pharmacodynamics

Answer 13

Pharmacodynamics: the science of the effect of meds on the body and their mechanisms of actionor Actions by the DRUG on the body

Question 14

Receptors

Answer 14

RECEPTORS are the classic “Lock and Key” mechanism: actions are activated or inhibited when the chemical (or med) interacts with the receptor site; the chemical (med) “turns the key” producing an effect or “blocks the key.”
AGONIST: a chemical/med that binds to receptor activates the receptor → Causes action;
A drug can CAUSE a reaction = AGONIST
ANTAGONIST: Binds to receptor but does not bring about a change and/or blocks other molecules (meds) from binding to the receptor site → Inhibits action;
A drug can PREVENT a reaction = ANTAGONIST

Question 15

Agonists and Antagonists

Answer 15

Both Agonists and Antagonists are used in drug
therapy
AGONIST: A drug can CAUSE a reaction
Epinephrine/Adrenalin: binds to receptors in the heart (and many other areas) to increase heart rate and force of contraction
ANTAGONIST: A drug can PREVENT a reaction
Naloxone (Narcan): selectively binds and blocks opiate/narcotic receptors in the brain; given I.V. to reverse narcotic overdoses and respiratory arrest from narcotics

Question 16

Medication Effects �

Answer 16

Therapeutic Effect: the desired response from the medication with as few side-effects as possible
The med did its job and everyone is happy.
Adverse Effects: often serious and potentially lethal effects; not intended or desired. (No one is happy)
How can this happen? Many, many reasons. Some:
Interactions with other medications, including over-the-counter, non-prescription meds!
Patient has other physical problems, e.g. bad heart or kidneys, and reacts negatively to the medication (common!); poor monitoring by staff of pt’s condition�Dose related reactions
Small dose produces no effect; Higher dose (range) produces therapeutic/desired effect; Dose in excess of desired produces no more effect as well as adverse reactions. Know the therapeutic “margin of safety” dosage range.
Allergic or Sensitivity Reactions: Often unpredictable; ranges from minor to anaphylactic/ allergic shock. Check for allergies BEFORE the procedure. Monitor for signs of allergic reactions, e.g. shortness of breath, hives, rash, loss of consciousness.
Toxic reactions
Too much med for that particular person. Example: normal dose to a person with renal failure → unable to excrete/metabolize med and
Some drugs have a very narrow range between therapeutic and toxic
Digoxin (heart med) and Gentamycin (antibiotic) are
examples of drugs commonly monitored with blood levels
Allergic or Sensitivity Reactions: Often unpredictable; ranges from minor to Anaphylactic/ allergic shock. Check for allergies BEFORE the procedure. Monitor for signs of allergic reactions, e.g. shortness of breath, hives, rash, loss of consciousness.

Question 17

Solution Concentration

Answer 17

Solution concentration: a certain amount of a medication in a certain amount of fluid
Example: Lidocaine 1Gm in 250 ml of saline
Amount of med: Lidocaine 1Gm
Amount of fluid: 250 ml of saline

Question 18

Creatinine (serum level)

Answer 18

Patients with renal (kidney) failure will not be able to excrete drugs efficiently
Drug levels will increase → Patients may experience more adverse effects and toxicity
Labs for renal function: creatinine
Creatinine is produced by the continual breakdown of muscle.
Serum Creatinine – a common blood test
Normal range = 1.0 mg/dl [0.8-1.2 mg/dl]
Increased serum creatinine levels indicate that the kidneys are not filtering out the creatinine and the creatinine [as well as other by-products of metabolism and medications cleared by the kidneys] are building up.

Question 19

Contraindications

Answer 19

Contraindications
Meds are not given due to the patient’s history and physical condition
Examples: allergy to the medication; pregnancy

Question 20

Incompatibilities:

Answer 20

Incompatibilities: If two specific medications are given together, e.g. in same syringe or same IV fluid, they neutralize or destroy each other. Often the clear IV fluid will become milky white when the two incompatible meds mix! Alert the RN and other staff immediately if this occurs!