Cumulative Exam Review

Question 1

What is meant by the term pharmacokinetics?

Answer 1

Pharmacokinetics studies the time course of a particular drugs action

Absportion, distribution, metabolism, elimination –> Bioavailabilty

Question 2

What is the difference between enteral and parenteral routes of administration?

Answer 2

Enteral routes involve the gastrointestinal (GI) tract and the Parenteral routes do not

Enteral: Orally, rectally

Parenteral: injection, inhalation, skin, mucous membranes

Question 3

What characteristics must a drug be in order to be administered orally?

Answer 3

G.I Resistant - sustains stomach acid

Lipid soluble

Question 4

How is a drug absorbed into the blood when administered orally?

Answer 4

A drug taken orally must pass through the stomach into the intestine. Once in the upper intestine absorption occurs though passive diffusion (must be lipid soluble) into the hepatic portal system. The portal system carries nutrients that have been absorbed into the capillary network to the liver to store and metabolize. Drugs that are not absorbed directly by the liver are sent into systemic circulation

Question 5

Discuss some advantages and disadvantages of the various methods of administering drugs

Answer 5

Orally - Stomach discomfort, variable levels of absorption, insult from stomach acid

Rectal - poor absorption, recital membrane irritation

Inhalation - Is very rapid and can be difficult to intervene if taken a toxic drug

Muscus membrane - irritates membrane

Transmembrane patch - allows for contiious controlled release

Injection - very rapid, unable to response to adverse reaction, must be sterile, essentially irreversible

Question 6

Why would someone administer a drug rectally?

Answer 6

When the person is unconscious or unable to swallow

Question 7

How do drugs reach the blood when they are inhaled?

Answer 7

When you administer through inhalation your lung tissues have a large SA with a lot of blood flow that allow rapid absorption. The drug is absorbed into the pulmonary capillaries and carried to the pulmonary veins which leads to the left side of the heart

Question 8

When snorting a substance it goes directly to your brain.

True or False

Answer 8

False. Your mucous membrane absorbs the drug into your blood, which is taken to your heart and then lungs for oxygen before being sent back to your heart and then brain

Question 9

Which 4 ways can drugs be injected?

Answer 9

1. Intravenous (vein)
2. Intramuscular
3. Subcutaneous (under skin)
4. Spinal/epidural

Question 10

Only a very small portion of the total amount of a drug that is in your body interacts with its target receptors.

True or False

Answer 10

True. There is limited receptors and this wide distribution account for side effects

Question 11

Describe first-pass metabolism

Answer 11

First-pass metabolism is drug metabolizing enzymes in the cells of the GI tract or liver (CYP3A) that markedly reduce the amount of drug that reaches the blood stream. Some drug molecules that are absorbed through the intestine and carried to the liver via hepatic portal system are metabolized immediately and not sent into general systemic circulation.

Question 12

Discuss the BBB as a limitation to drug transport

Answer 12

The BBB consist of tightly bound capillaries that are covered by a glial sheath (fatty)

There are no pores so passage depends on size and lipid solubility

Large molécules that are not lipid soluble pass poorly. They must be carried by social transport systems

Question 13

Which 4 membranes affect drug distributions?

Answer 13

Cell membres

Capillary vessels

BBB

Placental barrier

Question 14

What is a phospholipid bilayer?

Answer 14

A phospholipid bilayer makes up a membrane of a cell

It consists of a hydrophilic head (polar/water loving) and hydrophobic tail (non polar/water hating)

Question 15

What is the function of a capillary vessel?

Answer 15

A capillary vessel is a small blood vessel with pores that allow passive diffusion. They exchange material between blood and tissues.

Drugs entry into body tissue depends on the rate of blood through through capillary and drugs ability to pass through pores

Question 16

Describe the basic characteristics of CSF in the brain

Answer 16

It circulates nutrients, removes waster products, and transports hormones

It keeps the brain suspended to reduce weight, pressure, and provides protection against impact

Question 17

How do drugs cross the placental barrier?

Answer 17

Passive diffusion from projected villi from the placenta to fetal capillaries

Lipid soluble substances diffuse rapidly

Question 18

Which ways can a drug exit the body?

Answer 18

Kidney excretion (urine), lungs, bile, and skin

Question 19

Why must a psychoactive drug be altered metabolically in the body before it can be excreted?

Answer 19

Drugs that are too lipid soluble to be passively excreted through urine must be transformed to metabolites that are smaller, more water soluble, and less biologically active.

This is called biotransformation

Question 20

Describe the role of the kidneys, liver and hepatic enzyme system in drug elimination

Answer 20

Neprons are located on the outer portion of the kidneys. They contain a glomerulus - a knot of capillaries that is surrounded by the Bowman’s capsule. Blood flows from the renal artery to renal vein through these capillaries. Pressure on the glomerulus results in a release of fluid from the capillaries into the Bowman’s capsule. This fluid flows into a collecting duct. This collected fluid is passed trough the ureters and into the urinary bladder (99.9% of fluid is reabsorbed before reaching the bladder - these being lipid soluble molecules)

The reabsorbed fluid is picked up by hepatocytes (liver cells) and biotranformed into metabolites that are less fat soluble. It is then returned to the bloodstream and taken to the liver by the artery.

The process is repeated

Question 21

What is a half life? How does it apply to steady state?

Answer 21

A half-life is the length of time required for half the drug to be metabolized

It is said to take 6 half-lives before a drug is ‘out’ of the body, known as a steady state

Question 22

If a drug has a half-life of 10 minutes how long does it take to be essentially eliminated from the body?

Answer 22

1 hour (10 x 6)

Question 23

What are the goals of therapeutic drug monitoring?

Answer 23

TDM can track patient compliance, prevent drug induced toxicity, enhance therapeutic response (sweet spot), manage addition potential, and provide better patient care

Question 24

What is meant by the terms therapeutic drug monitoring and therapeutic window?

Answer 24

TDM is the measurement of plasma concentration of a drug.

The therapeutic window is the well-defined range of blood vessel associated with optical clinical response

Question 25

What is drug tolerance and why does it occur?

Answer 25

Drug tolerance is a sate of progressively decreasing responsiveness to the same dose of drug.

It occurs because of 3 mechanisms:
1. Metabolic tolerance - increased production of CP450 enzyme

2. Pharmacodynamic tolerance - neurons adapt to excess drug by either reducing the number of receptors available (down-regulation) or reducing their sensitivity
3. Contingent tolerance - behavioural conditioning, environmental triggers

Question 26

Contrast tolerance and dependence

Answer 26

Tolerance is the decreasing responsiveness to the same dose of drug.

Dependence is the physical requirement to obtain the drug to avoid withdrawal symptoms

Question 27

What are the functions of the 4 brain lobes?

Answer 27

Frontal lobe - motor function, memory, language, emotion

Temporal lobe - auditory, memory, visual perception

Parietal lobe - body info, touch, muscle-stretch, somatosensory representation

Occipital lobe - visual

Question 28

What is saltatory conduction?

Answer 28

Saltatory conduction is the movement of electrical signals down the length of a myelinated neuron. Myelination is a fatty sheath and does not allow depolarization and thus action potentials can only occur at nodes of ranvier.

Saltatory conduction causes the action potential to jump between nodes, increasing speed and decreases energy required

Question 29

Explain how an action potential moves down an axon

Answer 29

The cell membrane of a neuron contains channels. During the resting state these channels are closed and the inside is more negative than the outside (polarized). The AP causes voltage gated Na+ channels to open and since the charge is more positive on the outside of the cell it drives Na+ into the cell.

The inside now becomes temporarily more positive (depolarized) and voltage gated K+ cells open allowing K+ to exit the cell, repolarizing the cell.

Na+ ions diffuse down the membrane to the nodes of ranvier and causes a change of voltage, opening the Na+ channels and repeating the process.

The Na+/K+ pump (removes 3 Na+ and brings in 2 K+) rests the polarity once the AP has propagated down the axon

Question 30

Summarize the process involved in synaptic transmission. How is synaptic transmitter action terminated?

Answer 30

The AP is transmitted down the axon to the presynaptic terminal. It triggers the Ca2+ ion channels to open and for Ca2+ to enter the cell.

Calcium causes synaptic vesicles to fuse with the terminal membrane, open, and release transmitter molecules

NTs bind to the postsynaptic receptors, causing ion flow in/out of the postsynaptic cell creating either an inhibitory or excitatory postsynaptic potential

Enzymes in the cleft break down some NTs, others are taken back into the neuron to be repackaged in vesicles for future use (transporter), and some bind to the presynaptic cell (auto receptor)

Question 31

Which NTs are catecholamines?

Answer 31

Dopamine, Norepinephrine, and epinephrine

Question 32

Which NTs are biogenic amines?

Answer 32

Serotonin and histamine

Question 33

Contrast Glutamate and GABA

Answer 33

Glutamate is the major excitatory NT and GABA is the major inhibitory NTs

Question 34

Which major brain structures are associated with the neural pathways that release NE, DA, and 5-HT?

Answer 34

NE - in the brain stem mainly in the locus coreuleus in the pons

DA - originate in the brain stem and send axons rostral (forwards - to brain) and caudal (back - to spinal cord)

5-HT - upper brain stem particularly in the raphe nuclei in the pons and medulla

Question 35

Distinguish between the terms pharmacodynamics and pharmacokinetics

Answer 35

Pharmacodynamics is the biochemical and physiological effects of drugs and the mechanisms of drug action. Whereas, pharmacokinetics is the time course of particular drug action.

Question 36

What is a drug receptor? What are the major types and how do they differ?

Answer 36

A drug receptor is a membrane-spanning protein that moves molecules across a membrane.

Ion channels - forms a channel that opens/closes with the binding of a NT

Carrier/Transporter proteins - Small bowl shaped basin that are open to the synaptic cleft. When a molecule binds to the ‘hairpins’ (binding site) it becomes trapped and is then released into the presynaptic cell

G Protein-Coupled Receptors - Once binded a G protein is activated which produces a second messenger chemical which opens a receptor channel

Question 37

Contrast down-regulation and up-regulation

Answer 37

Both of these are potential receptor effects.

Down-regulation (desensitization) occurs when the number of receptor sites decrease (blocked by agonist) and sensitivity decreases, which accounts for tolerance

Up-regulation (super sensitivity) occurs when the number of molecules available at the postsynaptic receptor decrease because they are blocked by an antagonist, causing an increase of sensitivity

Question 38

What is a dose-response curve and what does it indicate?

Answer 38

A dose-response curve is function that describes the relationship between the dose of a drug and the magnitude of the drug’s effect

It indicates:
- Potency: absolute # of drug molecules required to elicit an effect

• Efficacy: maximum effect attainable
• Variability: individual differences in drug response

Question 39

What does drug-receptor specificity mean?

Answer 39

When there is high drug-receptor specificity there is a good fit (lock and key) which mean the response will be more potent and can lead to less side effects

Question 40

What does the therapeutic index indicate?

Answer 40

The therapeutic index is the ratio of the LD (lethal dose) to the ED (effective dose)

Is the ED is 50 - it provides a therapeutic response in 50% of the population

Ideally, you don’t want your LD and ED to overlap - you want it to be 100% effective without killing anyone

Question 41

Define the terms full and partial agonist; and antagonist

Answer 41

An agonist initiates a similar or identical reaction exerted by the transmitter

• Full agonists are capable of eliciting the maximum response
• Partial agonists are unable to induce maximal activation

An antagonist binds to the receptor and blocks the transmitter from binding

Question 42

What is the difference between a competitive and noncompetitive antagonist ?

Answer 42

A competitive antagonist binds to the receptor in a reversible way - both agonists and antagonists bind bit the antagonist can be kicked out by multiple agonists

A irreversible/non-competitive antagonist cannot be overridden regardless of dose

Question 43

Define the placebo effect. Discuss the history and factors that influence it.

Answer 43

A placebo is any agent/procedure that produces an effect in a patient because of its therapeutic intent and not its physical/chemical nature

There has been an increase in placebo effectiveness because 1) there is more faith in health care and 2) we have more access to information and can self-diagnose (even when were wrong - these people respond better to placebos)