Foundations of Pharm Principles

Question 1

Pharmacokinetics

Answer 1

What the body does to the drug

How the drug concentration/dosage in the plasma changes over time

AMDE: Absorption, distribution, metabolism, elimination

Question 2

Pharmacodynamics

Answer 2

What the drug does to the body

Relationship between drug concentration and effect

Question 3

Drug names

Answer 3

Chemical name: describes the drug’s chemical composition

Generic name: name recognized by Health Canada under FDA

Trade name: registered trademark and restricted by the drug’s patent owner

Question 4

Pharmacotherapeutics

Answer 4

The use of drugs and the clinical indications for drugs to prevent and treat diseases

Question 5

Pharmaceutics

Answer 5

Study of how various drug forms influence pharmacokinetic and pharmacodynamic activities

Question 6

Routes and drug administration

Answer 6

Routes can affect how quickly and how much drug enters the systemic circulation
- Important to determine peak plasma concentration

Drugs are administered as a formulation due to route, time course, and active drug concentration

Question 7

Excipients

Answer 7

Non-medicinal ingredients (fillers, colorants, coatings, flavourings and sweeteners)

Question 8

Enteral administration

Answer 8

Entry via gastrointestinal tract. Most happens in the stomach/small intestine.

Absorption usually <100% depending on drug comp and GI functioning

Benefits: easiest, safest, cheapest. No need for sterility.

Drawbacks: acid-sensitive and protein drugs are unstable, must be conscious and cooperative, upper GI irritation, bioavailability

Question 9

Parenteral administration

Answer 9

Not by the GI tract (eg. inhalers)

Question 10

Topical administration

Answer 10

Absorbed through the skin

Question 11

First pass effect

Answer 11

Pre-systemic elimination

Blood supply from the small intestine enter the hepatic system first to go into the liver, then exits the liver into systemic circulation. The liver metabolizes the drug before it can reach systemic circulation

Question 12

Enteral Administration - Rectal

Answer 12

Absorbed through the rectal mucosa

Benefits: rapid absorption, cheap and easy, useful with swallowing, less first pass effect

Drawbacks: absorption is often incomplete, many drugs cause irritation of mucosal lining

Question 13

Formulations for Enteral Admin

Answer 13

Tablets

Capsules (powder in a gelatin coating) - faster absorption

Caplets (capsule shape tablets) - more easily swallowed

Liquids (even faster absorption) - aqueous, suspensions or emulsions

Question 14

Sublingual EA

Answer 14

Under the tongue

Advantages: relatively rapid absorption, no first-=ass effect, suitable for acid-sensitive drugs, fast easy and cheap

Disadvantages: taste

Question 15

Parenteral Administrations - Transdermal

Answer 15

Through the skin
Usually for local effects
Benefits: cheap and wasy, simple local admin, no first pass effect

Drawbacks: not suitable for many drugs (fat insoluble), affected by skin hydration

Formulations: creams, gels, ointments, controlled release patches, topical aerosol spray

Question 16

Parenteral Admin - Inhalation

Answer 16

Inhaled into airways

Advantages: local action, no first pass effect, useful for gasses

Disadvantages: limited absorption for large proteins, possible irritation of lung lining

Formulations: gasses or gas mixtures, inhalers (particulate, powders, nebulized (mist)

Question 17

Parenteral Admin - Subcutaneous Injection (SC)

Answer 17

Injected under skin

Advantages: rapid effect, useful for local drug delivery (local anesthetics), drug absorption into circulation is controlled

Disadvantages: requries sterile drug, patient preference, absorption affected by blood flow

Question 18

PA - Intramuscular Injection (IM)

Answer 18

Drug injected into skeletal muscle

Advantages: into a large muscle mass, easy self admin, absorption into systemic circulation

Disadvantages: can be painful

Question 19

PA - Intravenous (IV)

Answer 19

Drug injected into vein

Advantages: rapid distribution, can come close to 100% bioavailability, large drug volumes

Disadvantages: requires skilled administration and close monitoring, drug must be sterile, greater cost

Question 20

Topical Routes

Answer 20

Skin, eyes, ears, nose, vagina

Question 21

Choosing a route

Answer 21

Enteral
- Convenient but first pass effect

Parenteral

• Bypasses the liver
• More drug reaches the circulation

Question 22

Drug Absorption

Answer 22

Entry to drug into circulatory system
Can be active or passive
Passive: movement of drug with the concentration gradient. Most drugs are absorbed this way.

Question 23

Chemical factors affecting drug absorption

Answer 23

Drug size: smaller = more absorption
Lipid solubility: does it prefer fatty or liquid environment
Drug charge: prefers to be in watery environment

Question 24

Physical factors affecting drug absorption

Answer 24

1. Blood flow to the site of absorption - intestine favoured
   In shock, extremities have less blood so subcutaneous admin is less effective
2. Total surface area for absorption - high surface area in intestine
3. Contact time - greatly affected by diarrhea or constipating drugs
4. Drug formulation - particle size

Question 25

Bioavailability

Answer 25

The proportion of drug that passes into systemic circulation after admin
Often much less than 100%

Affected by first pass effect

Question 26

Bioequivalence

Answer 26

Two related drugs that show comparable bioavailability, pharmacokinetics and biological effects

Question 27

Distribution

Answer 27

Determined by 3 factors

1. Blood flow to tissues
2. Exiting the vascular system
3. Entering cells

Affected by

1. Fat solubility of the drug - drug accumulation
2. Plasma protein binding

Question 28

Plasma Protein Binding

Answer 28

% of drug bound to protein can be quite high (90% or more)

Albumin - major carrier or drugs
When a person has lower albumin, lower the drug dose because it will have a great affect

Only free drugs can have effects

Question 29

Drug Metabolism

Answer 29

Occurs in the liver, gut, kidney, lungs, plasma and placenta

Drugs more water soluble - renal elimination

Variation between individuals
Grapefruit juice can inhibit P450s

Enzyme induction - cells stimulated to make more enzymes

Question 30

Drug Excretion

Answer 30

Occurs mostly through the kidney - GI tract, sweat, breast milk

Drug excretion depends on
- plasma protein binding and drug fat solubility/charge

Most drugs have to be metabolized before excretion - less fat soluble

Question 31

Which drugs can be excreted in an unaltered form?

Answer 31

Some antibiotics

Question 32

Steady state

Answer 32

When there is a consistent level of a drug in the body that corresponds to maximum therapeutic benefits

The time taken to reach a steady state is dependent on the drug’s half life
- usually 4-5 T 1/2

Question 33

Half life T1/2

Answer 33

The time required for the amount of drug in the body to decrease by 50%

Question 34

How does liver disease effect dosages?

Answer 34

You could lower dosage or extend the period of time between doses

Depends on situation

Question 35

Drug Target

Answer 35

Drugs usually bind to specific targets (mostly protein receptors or cell membranes)

Protein targets are “receptors”

Drugs should interact only with their target molecule, cell or tissue

Question 36

Affinity

Answer 36

Binding of drug depends on the “stickiness” of a drug fro tis target

Question 37

Agonist

Answer 37

Drug A + Receptor = Drug A–Receptor = Response

Question 38

Antagonist

Answer 38

Drug B + Receptor = Drug B–Receptor = No response

Prevents other drugs/chemcials from reacting (antihistamine or beta blockers)

Question 39

MEC

Answer 39

Minimum effective concentrtion is the plasma drug level that must be reached for therapeutic effect

Question 40

What is the difference between a low and a high therapeutic index?

Answer 40

The lower the therapeutic index, the small the amount of the drug it takes to lead to a toxic response

Higher the therapeutic index, the safer the drug

Question 41

Contraindication

Answer 41

A characteristic of the patient, especially a disease state, that makes the medication dangerous to the patient

Question 42

Tolerance

Answer 42

A decrease response to repetitive drug doses

Question 43

Dependence

Answer 43

A physiological/psychological need for a drug

Question 44

Idiosyncratic reactions

Answer 44

Unusual reaction to a drug

Question 45

Teratogenic

Answer 45

Drug that crosses the placenta and can affect embryo/fetus l

Question 46

Mutagenic

Answer 46

Can cause permanent genetic changes

Question 47

Carcinogenic

Answer 47

Causes cancer