PTCB Fundamental Principles of Pharmacology

What is pharmacology?

The branch of science that studies drugs and how they interact with the body.

What two main questions does pharmacology answer?

What drugs do to the body (pharmacodynamics) and what the body does to drugs (pharmacokinetics).

What does pharmacology examine?

Origin, composition, effects, and uses of drugs in health and disease.

Why is pharmacology important for pharmacy technicians?

It provides the foundation for safe drug handling, dispensing, and patient care.

What is pharmacotherapeutics?

The study of how drugs are used to prevent or treat disease.

What is toxicology?

The study of harmful effects of drugs, overdoses, and poisonings.

What is clinical pharmacology?

The application of pharmacology principles directly to patient care.

What does ADME stand for?

Absorption, Distribution, Metabolism, Excretion.

What does pharmacodynamics study?

How drugs bind to receptors and produce biological effects.

What does pharmacokinetics study?

How drugs are absorbed, distributed, metabolized, and eliminated.

What is an indication?

The specific medical reason or condition for which a drug is prescribed.

What do indications describe?

What the drug is used to treat, prevent, or diagnose.

Who approves labeled indications in the U.S.?

The FDA.

What are approved (labeled) indications?

Official authorized uses listed in prescribing information.

What are off-label indications?

Uses not formally approved but supported by evidence or clinical experience.

Indication of acetaminophen?

Pain relief and fever reduction.

Indication of metformin?

Management of type 2 diabetes.

Indication of amoxicillin?

Bacterial infections caused by susceptible organisms.

Why are indications important for pharmacy technicians?

Ensure correct dispensing, distinguish similar drugs, and support patient counseling.

What is mechanism of action (MOA)?

The specific biochemical interaction between a drug and its target that produces a therapeutic effect.

What targets can drugs act on?

Receptors, enzymes, ion channels.

Most drugs act by doing what?

Activating (stimulating) or inhibiting natural processes.

What is an agonist?

A drug that binds to and activates a receptor.

Example of an agonist?

Albuterol (β₂-agonist).

What is an antagonist?

A drug that binds to a receptor but blocks activation.

Example of an antagonist?

Atenolol (β₁-blocker).

What is enzyme inhibition?

Blocking an enzyme to stop a reaction.

Example of enzyme inhibition?

ACE inhibitors lowering blood pressure.

What is ion channel modulation?

Opening or closing ion channels to alter electrical activity.

Example of ion channel modulation?

Local anesthetics blocking sodium channels.

What is chemical interaction?

Direct chemical reaction without receptor involvement.

Example of chemical interaction?

Antacids neutralizing stomach acid.

Why is MOA important?

Explains drug effects, predicts interactions, guides clinical use.

What is a side effect?

A predictable, often mild secondary effect of a drug.

Example of a side effect?

Drowsiness from antihistamines.

Can side effects be beneficial?

Yes (e.g., antihistamine drowsiness helping insomnia).

What is an adverse effect?

A harmful, unintended, often unpredictable reaction.

Example of an adverse effect?

Anaphylaxis from penicillin.

NSAID adverse effect?

Gastrointestinal bleeding.

Why must adverse effects be monitored?

They may require intervention or discontinuation.

What is pharmacovigilance?

Post-marketing surveillance tracking adverse effects.

Why is distinguishing side vs adverse effects important?

Enhances safety and proper patient counseling.

Pharmacokinetics definition?

What the body does to the drug.

Four stages of pharmacokinetics?

Absorption, Distribution, Metabolism, Excretion.

What is absorption?

Entry of drug into bloodstream.

What is distribution?

Movement of drug to tissues/organs.

What affects distribution?

Protein binding and fat solubility.

What is metabolism?

Chemical alteration of a drug (usually liver).

What system is major in metabolism?

CYP450 enzyme system.

What is excretion?

Removal of drug from body (mainly kidneys).

Pharmacodynamics definition?

What the drug does to the body.

What does pharmacodynamics include?

Mechanisms, receptor actions, therapeutic and toxic effects.

What is dose–response relationship?

How increasing dose changes biological effect.

What is the CYP450 system?

A family of liver enzymes that metabolize drugs.

Where are CYP450 enzymes mainly located?

Liver (also intestines, lungs, kidneys).

Most clinically significant CYP enzyme?

CYP3A4.

CYP2D6 metabolizes what types of drugs?

Antidepressants, beta-blockers, opioids.

CYP2C9 important for which drugs?

Warfarin and NSAIDs.

CYP1A2 metabolizes what?

Caffeine and certain antipsychotics.

What is a CYP inhibitor?

Substance that slows metabolism.

Example of CYP inhibitor?

Grapefruit juice.

What is a CYP inducer?

Substance that increases metabolism.

Example of CYP inducer?

St. John’s wort.

What are poor metabolizers?

Patients who metabolize drugs slowly.

What are ultra-rapid metabolizers?

Patients who metabolize drugs very quickly.

Why is CYP2D6 important for codeine?

Converts codeine to morphine (active form).

What is a drug interaction?

When one drug’s effect is altered by another drug, food, or disease.

Three types of drug interactions?

Drug–drug, drug–food, drug–disease.

Warfarin + NSAIDs risk?

Increased bleeding.

ACE inhibitors + potassium-sparing diuretics risk?

Hyperkalemia.

Opioids + benzodiazepines risk?

Respiratory depression.

Grapefruit juice effect?

Inhibits CYP3A4 → increases drug levels.

Dairy + tetracycline effect?

Decreased absorption.

Vitamin K + warfarin effect?

Reduced anticoagulant effect.

Beta-blockers + asthma risk?

Airway narrowing.

NSAIDs + hypertension risk?

Worsened blood pressure.

Corticosteroids + diabetes effect?

Increased blood sugar.

What is half-life?

Time for drug concentration to reduce by 50%.

Half-life determined by what processes?

Metabolism and excretion.

Short half-life requires what?

Frequent dosing.

Example short half-life drug?

Albuterol (3–4 hours).

Example long half-life drug?

Amiodarone (weeks).

After one half-life, 100 mg becomes?

50 mg.

After two half-lives from 100 mg?

25 mg.

After three half-lives from 100 mg?

12.5 mg.

How many half-lives to reach steady state?

4–5 half-lives.

What is steady state?

When rate of administration equals rate of elimination.

Why is half-life important in liver/kidney disease?

Impaired function prolongs half-life and increases toxicity risk.

What does half-life influence?

Dosing frequency, timing, duration, accumulation risk.

A patient picking up diphenhydramine is counseled that the medication may cause drowsiness. The patient later reports feeling sleepy but otherwise fine.
How should this effect be classified?

A. Adverse effect
B. Drug interaction
C. Side effect
D. Toxic reaction

C — Side effect
Predictable, mild, and expected.

A patient experiences throat swelling and difficulty breathing shortly after taking penicillin for the first time.
What best describes this reaction?

A. Side effect
B. Expected therapeutic response
C. Adverse effect
D. Off-label indication

C — Adverse effect
Severe, unpredictable, life-threatening.

A drug works by binding to a receptor and preventing the natural chemical from activating it.
This drug is best described as a(n):

A. Agonist
B. Partial agonist
C. Antagonist
D. Enzyme inducer

C — Antagonist
Blocks receptor activation.

A patient with asthma is prescribed atenolol. The pharmacy technician alerts the pharmacist because atenolol may worsen asthma symptoms.
This is an example of a:

A. Drug–drug interaction
B. Drug–food interaction
C. Drug–disease interaction
D. Pharmacokinetic interaction

C — Drug–disease interaction
Asthma worsened by beta-blocker.

A medication must be taken three times daily because it is cleared rapidly from the body.
Which pharmacokinetic property best explains this dosing schedule?

A. Long half-life
B. High bioavailability
C. Short half-life
D. High protein binding

C — Short half-life
Cleared quickly → frequent dosing.

A patient drinks grapefruit juice daily while taking a statin. The pharmacist warns this could raise drug levels and increase side effects.
Which enzyme system is involved?

A. CYP2D6
B. CYP1A2
C. CYP3A4
D. CYP2C9

C — CYP3A4
Grapefruit juice inhibits this enzyme.

A patient takes St. John’s wort while on oral contraceptives and later becomes pregnant.
What best explains what happened?

A. Enzyme inhibition
B. Enzyme induction
C. Poor absorption
D. Increased bioavailability

B — Enzyme induction
St. John’s wort speeds metabolism → reduced drug levels.

A drug has a half-life of 6 hours. If a patient takes a 100 mg dose, how much drug remains after 12 hours?

A. 75 mg
B. 50 mg
C. 25 mg
D. 12.5 mg

C — 25 mg
Two half-lives: 100 → 50 → 25.

Which phrase best defines pharmacokinetics?

A. How drugs bind to receptors
B. How drugs cause therapeutic effects
C. How the body absorbs, distributes, metabolizes, and excretes drugs
D. How drug doses relate to biological response

C — ADME
Classic pharmacokinetics definition.

A medication lowers blood pressure by blocking an enzyme that normally causes blood vessels to constrict.
What mechanism of action is being described?

A. Ion channel modulation
B. Enzyme inhibition
C. Chemical neutralization
D. Receptor activation

B — Enzyme inhibition
Blocking an enzyme to produce effect.

A technician notices a patient is taking warfarin and ibuprofen together.
Why should the pharmacist be alerted?

A. Risk of reduced warfarin absorption
B. Increased risk of bleeding
C. Increased metabolism of warfarin
D. Reduced NSAID effectiveness

B — Increased bleeding
Additive anticoagulant effects.