Pharmacokynetics V300 in Aesthetics

Question 1

Term

Answer 1

Definition

Question 2

What are the 4 phases of pharmacokinetics?

Answer 2

Absorption, Distribution, Metabolism, Excretion (ADME)

Question 3

What is bioavailability?

Answer 3

The fraction of an administered dose that reaches systemic circulation unchanged.

Question 4

What is first-pass metabolism?

Answer 4

Drug metabolism that occurs in the liver after oral administration, reducing bioavailability.

Question 5

What affects drug absorption?

Answer 5

Route of administration, gastric pH, food, formulation, and blood flow to the absorption site.

Question 6

What factors influence drug distribution?

Answer 6

Lipid solubility, plasma protein binding, blood flow, and tissue permeability.

Question 7

What is the volume of distribution (Vd)?

Answer 7

A theoretical volume that relates drug amount in the body to plasma concentration.

Question 8

What is drug metabolism and where does it occur?

Answer 8

Chemical alteration of drugs; mainly in the liver via cytochrome P450 enzymes.

Question 9

What are the two phases of metabolism?

Answer 9

Phase I: Oxidation, reduction, hydrolysis. Phase II: Conjugation (makes drug more water-soluble).

Question 10

What is drug clearance?

Answer 10

The volume of plasma from which a drug is completely removed per unit time.

Question 11

What is half-life (t½)?

Answer 11

Time taken for plasma concentration of a drug to reduce by half.

Question 12

How is elimination affected in renal impairment?

Answer 12

Decreased renal function slows elimination, requiring dose or interval adjustment.

Question 13

Which patient factors influence pharmacokinetics?

Answer 13

Age, weight, renal/hepatic function, pregnancy, genetics, drug interactions.

Question 14

What is zero-order kinetics?

Answer 14

Drug is eliminated at a constant rate regardless of concentration (e.g., alcohol).

Question 15

What is steady state?

Answer 15

When drug input equals elimination; usually achieved after 4–5 half-lives.

Question 16

Why is pharmacokinetics important for prescribing?

Answer 16

It guides safe dosing, route, timing, and choice of drug – essential for patient safety.

Question 17

What is therapeutic drug monitoring (TDM)?

Answer 17

Measuring drug levels in blood to maintain efficacy and avoid toxicity, especially for drugs with a narrow therapeutic index.

Question 18

Define the therapeutic index (TI).

Answer 18

Ratio of toxic dose to effective dose: TI = TD50 / ED50.

Question 19

How do you calculate loading dose?

Answer 19

Loading dose = (Target concentration × Vd) / Bioavailability.

Question 20

What is the formula for maintenance dose?

Answer 20

Maintenance dose = (Clearance × Target concentration) / Bioavailability.

Question 21

Why are elderly patients at higher risk of adverse drug reactions?

Answer 21

Reduced renal/hepatic function, polypharmacy, altered distribution, slower metabolism.

Question 22

How does renal failure affect drug dosing?

Answer 22

Drugs may accumulate due to impaired excretion; adjust dose or dosing interval.

Question 23

What is protein binding and why does it matter?

Answer 23

Only unbound drug is pharmacologically active; high binding affects distribution and elimination.

Question 24

Name a drug that is highly protein bound.

Answer 24

Warfarin (approx. 99% protein bound).

Question 25

How can drug-drug interactions affect metabolism?

Answer 25

Inhibitors increase drug levels; inducers reduce drug levels by altering enzyme activity.

Question 26

What is a prodrug?

Answer 26

An inactive compound metabolized into an active drug in the body (e.g., codeine → morphine).

Question 27

Why are lipid-soluble drugs more widely distributed?

Answer 27

They cross membranes more easily and accumulate in fatty tissues.

Question 28

How do pregnancy and lactation alter pharmacokinetics?

Answer 28

Increased plasma volume, altered enzyme activity, and renal clearance affect drug levels.

Question 29

What is the significance of half-life in dosing schedules?

Answer 29

It determines how frequently a drug should be administered to maintain therapeutic levels.

Question 30

How many half-lives does it take to reach steady state?

Answer 30

Approximately 4 to 5 half-lives.

Question 31

What is the clinical significance of enzyme polymorphisms?

Answer 31

Genetic differences in metabolism affect drug response and risk of side effects or failure.

Question 32

How is botulinum toxin absorbed?

Answer 32

Injected intramuscularly; remains localized with minimal systemic absorption.

Question 33

How are dermal fillers distributed in the body?

Answer 33

Remain at injection site; no significant systemic distribution.

Question 34

What affects topical anaesthetic absorption?

Answer 34

Skin integrity, occlusion, site of application, and surface area.

Question 35

How are amide anaesthetics like lidocaine metabolized?

Answer 35

Metabolized in the liver.

Question 36

How are ester anaesthetics like procaine metabolized?

Answer 36

Metabolized by plasma cholinesterases.

Question 37

What is the clinical risk with large-area use of topical lidocaine?

Answer 37

Systemic toxicity due to increased absorption.

Question 38

How is hyaluronic acid (filler) broken down?

Answer 38

By hyaluronidase and local tissue metabolism.

Question 39

Why is adrenaline added to local anaesthetics?

Answer 39

To reduce absorption rate, prolong effect, and decrease bleeding.

Question 40

What are signs of local anaesthetic systemic toxicity (LAST)?

Answer 40

Tinnitus, confusion, seizures, and cardiovascular collapse.

Question 41

What is the safe dose limit for lidocaine without adrenaline?

Answer 41

3 mg/kg.

Question 42

What is the safe dose limit for lidocaine with adrenaline?

Answer 42

7 mg/kg.

Question 43

Why must you aspirate before injecting in aesthetic procedures?

Answer 43

To avoid intravascular injection and systemic complications.

Question 44

How does blood flow affect drug uptake in aesthetic sites?

Answer 44

High perfusion areas (e.g., face) may increase absorption and effect onset.