Pharmacology

Question 1

What is the definition of pharmacology?

Answer 1

Pharmacology is the study of drugs and how they interact with living organisms.

Question 2

True or False: Pharmacotherapeutics focuses on the use of drugs to treat diseases.

Answer 2

True

Question 3

What is the term used to describe the study of how drugs are administered, absorbed, distributed, metabolized, and eliminated by the body?

Answer 3

Pharmacokinetics

Question 4

Fill in the blank: Pharmacodynamics is the study of the ________ of drugs on the body.

Answer 4

effects

Question 5

Which branch of pharmacology focuses on the study of drug interactions with specific receptors?

Answer 5

Pharmacodynamics

Question 6

What is the term for a substance that binds to a receptor and causes a biological response?

Answer 6

Agonist

Question 7

True or False: Antagonists prevent the action of agonists by binding to the same receptor.

Answer 7

True

Question 8

What is the term for the amount of drug required to produce a therapeutic effect?

Answer 8

Minimum effective concentration

Question 9

Fill in the blank: The ________ refers to the range between the minimum effective concentration and the toxic concentration of a drug.

Answer 9

therapeutic window

Question 10

Which term describes the study of how genetic factors influence an individual’s response to drugs?

Answer 10

Pharmacogenomics

Question 11

What is the term for the study of how drugs are used in different populations, such as children or the elderly?

Answer 11

Pharmacotherapy

Question 12

True or False: Adverse drug reactions are always predictable based on the drug’s known pharmacology.

Answer 12

False

Question 13

Which term describes the process by which a drug is broken down and removed from the body?

Answer 13

Metabolism

Question 14

Fill in the blank: Drug ________ can lead to decreased drug effectiveness or increased risk of toxicity.

Answer 14

interactions

Question 15

What is the term for the study of how drugs move across cell membranes to reach their target sites?

Answer 15

Pharmacokinetics

Question 16

True or False: Drug metabolism primarily occurs in the kidneys.

Answer 16

False

Question 17

Which branch of pharmacology focuses on studying the safety and efficacy of drugs in humans?

Answer 17

Clinical pharmacology

Question 18

Fill in the blank: Drug ________ is the process by which a drug is absorbed into the bloodstream.

Answer 18

absorption

Question 19

What term describes the use of drugs to prevent disease or maintain health?

Answer 19

Prophylaxis

Question 20

A reason for administering a medication

Answer 20

Indication

Question 21

A reason for administering a medication Incorrect! Correct answer:indication
The amount of a drug administered that is actually available to produce a therapeutic effect

Answer 21

Bioavailability

Question 22

A serum concentration that is enough to produce the beneficial clinical response

Answer 22

Therapeutic level

Question 23

The observed clinical effects of a drug from the body

Answer 23

Drug effects

Question 24

An undesirable drug action that can occur in the body and which is often harmful

Answer 24

Adverse drug reactions

Question 25

A reason for not administering a medication

Answer 25

Contraindication

Question 26

Pharmacodynamics

Answer 26

Pharmacodynamics is “the study of the biochemical and physiological effects of medications, the study of medications’ mechanisms of action, and what medications do to the body”

Question 27

There are three major mechanisms of action:

Answer 27

Chemical reaction. Drugs in this category change the chemical composition of a body fluid, for example antacids (e.g., Mylanta) neutralise stomach acidity;

Physical action. Drugs in this category change the environment of the body cells, for example laxatives which osmotically attract fluid into the gut;

Binding to a receptor (as an agonist or antagonist). Drugs in this category bind to receptors (usually proteins) on cell membranes and alter cellular physiology, for example digoxin binds to receptors on myocardial cells and increases calcium influx, which increases myocardial force of contraction

Question 28

Mechanism of action (Metoprolol)

Answer 28

Metoprolol, the active substance of Lopresor, is relatively cardioselective beta-blocker, i.e. it acts on beta1-receptors mainly located in the heart at lower doses than thosed needed to influence the beta2-receptors mainly located in the bronchi and peripheral vessels.

Metoprolol has little membrane stabilising effect, nor does it display partial agonist activity, i.e. intrinsic sympathomimetic activity (ISA), at doses required to produce beta-blockade.

Lopresor belongs to a group of medicines called beta-blockers. It works by affecting the body’s response to some nerve impulses, especially in the heart. As a result, it decreases the heart’s need for blood and oxygen and reduces the amount of work that the heart has to do. It also widens the blood vessels in the rest of the body.

Question 29

Agonists

Answer 29

Agonists are molecules that bind to specific receptors and cause a process in the cell to become more active, they can be natural (within the body such as endorphins) or artificial (introduced into the body such as morphine) (Christie, 2016). The agonist medication mimics the natural agonist so it can bind to and have the same effect on the receptor e.g. like a key, the agonist fits into the receptor (the lock) and exerts an effect (like opening the door with the key) (Christie, 2016).

Question 30

Mechanism of action (Morphine)

Answer 30

Morphine is the principal alkaloid of opium. Morphine acts as an agonist, binding to receptors in the brain, spinal cord and other tissues. These sites have been classified as mu receptors and are widely distributed throughout the central nervous system being present in highest concentration in the limbic system.

Morphine exerts its primary effects in the central nervous system and organs containing smooth muscle.

Morphine produces many effects, including analgesia, decreased gastrointestinal motility, respiratory depression, drowsiness, changes in mood and alterations of the endocrine and autonomic nervous systems.

Nausea and vomiting may occur through direct stimulation of the chemoreceptor trigger zone (CTZ). Urinary retention may occur due to increased bladder sphincter tone.

Question 31

Antagonists

Answer 31

are medications that act against agonists, they bind to specific receptors and block the action of the natural agonist (Christie, 2016). Using the key analogy, the antagonist (the key) fits into the receptor (the lock) however it does not have the right properties to trigger an effect but remaining in position prevents the agonist (proper key) from fitting into the receptor and working (Christie, 2016). If a patient had been administered too much morphine, an antagonist (e.g. Naloxone) could be administered to prevent morphine from binding to the opioid receptors

Question 32

Mechanism of action (Naloxone)

Answer 32

Naloxone is essentially a pure opiod antagonist, it has little or no agonostic activity. Naloxone is thought to act as a comptetitive antagonist at mu, kappa, and sigma opioid receptors in the central nervous system (CNS), although the precise mechanism of action has not been fully determined.

Naloxone prevents or reverses the effects of opioids, including respiratory depression, sedation and hypotension. Naloxone can also reverse the psychotomimetic and dysphoric effects of agonist-antagonists such as pentazocine, but higher doses are required. One milligram of naloxone intravenously completely blocks the effects of 25 milligrams of diacetylmorphine (heroin).

Question 33

A drug that binds to a receptor but does not activate it

Answer 33

Antagonist

Question 34

The mechanism when a drug that changes the chemical composition of a body fluid

Answer 34

Chemical reaction

Question 35

The mechanism when a drug changes the environment of the body cells

Answer 35

Physical action

Question 36

A medicine or other substance that stimulates a receptor

Answer 36

Agonist

Question 37

Pharmacokinetics

Answer 37

four important processes: Absorption, Distribution, Metabolism and Excretion (ADME)

Question 38

Absorption

Answer 38

Absorption is the first process. Medication passes from the source of administration into the blood stream. At a cellular level, absorption takes place by both active and passive transport. There are a number of physiological factors that influence the absorption of medication. These include:

Lipid solubility: Cell membranes mainly consist of lipid materials, therefore lipophilic substances are able to cross through easily and rapidly.

Surface Area: When admitting patients and often throughout their hospitalisation, obtaining a surface area measurement especially on the paediatric patient, significantly affects the dosage decision. The adult patient’s body weight measurement will often suffice, (though not always) when prescribing the dosage.

Blood flow at administration sites: If only a few cells separate the drug from the systemic circulation, absorption occurs rapidly. The drug quickly becomes effective.

Age: There are many age related changes that may affect the action of a drug. All medications should be given with caution to the elderly or very young patient.

Organ health: It is now becoming common practice in health facilities for the clinical pharmacist to be part of the multidisciplinary team during medical ‘rounds’. Input from both physician and pharmacist allows closer observation and monitoring of the health status of the patient. Prescribing medication is ‘fine-tuned’ when each patient is assessed individually.

Question 39

Distribution

Answer 39

Once a medication is in the body its distribution is dependent on blood flow. Organs with a large supply of blood such as the heart, liver and kidneys receive the medication quickly. Distribution to skin, fat, muscle, and other internal organs is slower.

Distribution is also reliant upon the ability of the drug to cross the cell membrane and that depends on whether the drug is lipid soluble (which cross easily), or water soluble (can’t cross the cell membrane). Lipid soluble drugs are able to cross the blood brain barrier and enter the brain.

The third factor affecting distribution of drugs is associated with drugs coming into contact with proteins. The drug can remain free or bind with the protein. Only the portion of the drug that remains free or unbound can remain active (i.e able to do its job).

Question 40

Metabolism

Answer 40

Drug metabolism, also known as biotransformation, refers to the body’s ability to change a drug from its dosage form into a water soluble form which can then be excreted.

Metabolites (products of metabolism) usually become inactive prior to excretion. Some drugs however may be converted to metabolites which are active and are excreted from the body unchanged e.g. chemotherapy agents.

Most drugs are metabolised in the liver, however metabolism can occur in the plasma, kidneys and membranes of the intestines. Some drugs compete or inhibit enzyme metabolism, resulting in an accumulation of the drugs occurring if they are given together. This increases the potential for an adverse drug reaction or drug toxicity occurrence.

Question 41

Excretion

Answer 41

Drug excretion refers to the elimination of drugs from the body. Most drugs are excreted by the kidneys however the lungs, exocrine glands (salivary, sweat and mammary glands), skin and intestinal tract also facilitate excretion.

An important concept associated with drug administration is an understanding of the term ‘half-life’. Scott and McGrath (2009) tell us that the half-life of a drug is the amount of time it takes for half of that drug to be eliminated by the body. Knowing the half-life of a drug assists the prescriber in determining the frequency that a drug should be given. Absorption, distribution, metabolism and excretion all affect the half-life of a drug (Bullock & Manias, 2013).

Question 42

Metabolism and the hepatic first pass effect

Answer 42

When a drug gets metabolized, it can result in a reduced concentration of the active drug reaching its intended site of action or the systemic circulation. This effect is usually associated with the liver (as the liver is a major site of drug metabolism) and is thus referred to as the hepatic first pass effect (Herman & Santos, 2022). The hepatic first pass effect is only relevant for medications administered orally.

Question 43

Excretion: Measuring medication action by drug ‘half-life’

Answer 43

For example, if the elimination half-life of a medication was four hours, the following would be observed:

initial amount of medication in body = 100%
amount remaining after 4 hours = 50%
amount remaining after 8 hours = 25%
amount remaining after 12 hours =12.5%
amount remaining after 16 hours = 6.25%.

Question 44

Drug-receptor interaction

Answer 44

Brain receptors become more sensitive,
making psychoactive drugs very potent.

Question 45

Circulation

Answer 45

Vascular nerve control is less stable. Antihypertensives, for example, may overshoot, dropping blood pressure too low. Digoxin, for example, may slow the
heart rate too much.

Question 46

Metabolism

Answer 46

Liver mass shrinks. Hepatic blood flow and enzyme activity decline. Metabolism drops
to 1/2 to 2/3 the rate of young adults. Enzymes lose ability to process some
drugs, thus prolonging drug half-life.

Question 47

Excretion

Answer 47

In kidneys, renal blood flow, glomerular filtration rate, renal tubular secretion and reabsorption, and number of functional nephrons decline. Blood flow and waste removal slow. Age-related changes
lengthen half-life for renally excreted drugs. Antidiabetic drugs, among others, stay in
the body longer.

Question 48

Absorption

Answer 48

Gastric emptying rate
and gastrointestinal motility slow. Absorption capacity of cells and active
transport mechanism decline.

Question 49

Distribution

Answer 49

Lean body mass falls. Adipose stores increase. Total body water declines, raising the concentration of water-soluble drugs, such as digoxin, which can cause heart dysfunction. Plasma protein diminishes, reducing sites available for protein-bound drugs
and raising blood levels of free drug.

Question 50

The percentage of body water is higher in children than it is in adults.

Answer 50

True - Correct. This answer is true. The percentage of body water is higher in children than it is in adults. In children, water as a percentage of bodyweight ranges from 80% at birth to approx 60% at 12 months; for adults it is 55% of bodyweight.

Question 51

Paediatric doses can be based on body surface area, age and bodyweight.

Answer 51

True - Correct. This answer is true. Paediatric doses can be based on body surface area, age and bodyweight.

Question 52

Administration of medications via the parenteral route is preferred in children.

Answer 52

False - Correct. This answer is false. In children, intramuscular injections are generally avoided because of pain and the possibility of unpredictable absorption. This occurs due to differences in absorption by site of injection (intramuscular or subcutaneous) and the variability of muscle mass and depth of injection (too deep or too shallow)

Question 53

Acute illness in the older patient can lead to a decline in renal function and may affect the elimination of drugs

Answer 53

True - Correct. This answer is true. Acute illness can impair renal functioning and this may alter the elimination of the drug If elimination is reduced and the drug stays in the body longer, half-life increases. This can increase the effect of the drug and the possibility of toxicity

Question 54

Older people may experience difficulty reading and understanding the directions for taking their medications.

Answer 54

True - Correct. This answer is true. Older adults’ declining eyesight can further make it difficult for them to read/understand labels on medication containers, resulting in dosage errors – this in turn may influence pharmacokinetics.