Kinetics

Question 1

What are the 3 types of variabilities of drug interaction?

Answer 1

• PHARMACOKINETIC
• PHARMACODYNAMIC
• IDIOSYNCRATIC

Question 2

•INTERACTION BETWEEN 2 OR MORE 
DRUGS THAT LEADS TO 
•ACCENTUATION/SYNERGISM 
•ATTENUATION/ANTAGONISM
•DON’T DIRECTLY INVOLVE 
ABSORPTION, DISTRIBUTION, 
METABOLISM, OR EXCRETION

Answer 2

Pharmacodynamic interaction

Question 3

\_\_\_\_\_\_ interaction
•INTERACTION THAT CHANGES THE BASIC KINETIC 
PROPERTIES
•ABSORPTION
•DISTRIBUTION
•METABOLISM
•ELIMINATION
•EXAMPLE: WARFARIN + SULFAMETHOXAZOLE

Answer 3

PHARMACOKINETIC INTERACTION

Question 4

The following drugs need to be checked for _____:
∙Warfarin
∙Digoxin
∙TCAs (amitriptyline, doxepin, nortriptyline,
desipramine)
∙Phenytoin
∙Carbamazepine
∙Lithium
∙Methotrexate / cyclosporine / tacrolimus
∙HIV medications – protease inhibitors (indinavir,
nelfinavir, ritonavir, saquinavir)
∙Rifampin

Answer 4

Negative Drug interactions

Question 5

If you give Tetracycline and antacids, how do the drugs interact?

Answer 5

antacid impairs absorption of ABX → ↓ ABX efficacy

Question 6

If erythromycin / clarithromycin /
metronidazole / ciprofloxacin /
trimethaprim-sulfamethoxazole +
warfarin interact, what happens?

Answer 6

ABX inhibit the metabolism of warfarin → ↑ serum concentration of
warfarin → ↑ risk of bleeding

Question 7

If NSAID + warfarin are combined, what happens?

Answer 7

Additive effect on ↓ platelet aggregation → additive risk for
bleeding (especially GI bleeding)

Question 8

If ASA + warfarin are combined, what happens?

Answer 8

Additive effect on ↓ platelet aggregation → additive

risk for bleeding (especially GI bleeding)

Question 9

If Tramadol +
antidepressants (DDI
highest risk for MAO-I) are combined, what happens?

Answer 9

↑ risk of serotonin syndrome (looks like malignant hyperthermia)

Question 10

If Protease inhibitors (indinavir,
nelfinavir, ritonavir, saquinavir) +
BZD are combined, what happens?

Answer 10

protease inhibitors are CYP450 3A4 inhibitors → ↓ metabolism of benzodiazepine → ↑
benzodiazepine concentrations → ↑ risk of benzodiazepine side effects (↑ sedation depth
and duration)

Question 11

How does pregnancy affect CO, renal blood flow, and albumin?

Answer 11

Increased CO
Increased renal blood flow
Decreased albumin

Question 12

What 2 things are caused due to diabetes?

Answer 12

Gastric stasis

Nephrotic syndrome

Question 13

An effect that is unrelated to clinical drug effect

• Predictable
• Dose related

Answer 13

Side effect

Question 14

An exaggeration of clinical drug effect;

• predictable
• dose related

Answer 14

Toxic reaction

Question 15

An immunologic response to a drug

Answer 15

Allergic reaction

Question 16

•WHAT THE BODY DOES TO THE DRUG

Answer 16

PHARMACOKINETICS

Question 17

•WHAT THE DRUG DOES TO THE BODY

Answer 17

PHARMACODYNAMICS

Question 18

HOW WE USE \_\_\_\_\_\_\_:
•IMPORTANT IN DRUG DEVELOPMENT AND CLINICAL TESTING, 
NEEDED TO DETERMINE OPTIMAL DOSE
•IMPORTANT IN THE CLINICAL SETTING
•TOXICOLOGY
•THERAPEUTIC MONITORING (CLINICAL EFFECT, LABS)
•DRUG INTERACTIONS
•DOSE ADJUSTMENTS
•EFFECT OF ILLNESS, ORGAN DYSFUNCTION

Answer 18

PHARMACOKINETICS

Question 19

(kinetics)
•TIME COURSE OF DRUG CONCENTRATION
DEPENDS ON

Answer 19

ADME

Question 20

KINETICS FOCUSES ON CONCENTRATIONS

OF DRUG IN ______

Answer 20

PLASMA

Question 21

What are the 2 most important things that kinetics tell us?

Answer 21

How quick it works and how long it works

Question 22

_______ = CP

Answer 22

PLASMA CONCENTRATION

Question 23

MTC

Answer 23

Minimum toxic dose

Question 24

MEC

Answer 24

Minimum effective dose

Question 25

– DETERMINES THE

MAINTENANCE DOSE-RATE

Answer 25

CLEARANCE

Question 26

–

DETERMINES THE LOADING DOSE

Answer 26

VOLUME OF DISTRIBUTION (VD)

Question 27

– DETERMINES THE TIME TO

STEADY STATE AND DOSING INTERVAL

Answer 27

HALF-LIFE

Question 28

PARAMETERS FOR A DRUG ARE
DETERMINED BY USING ___ INJECTION OR
INFUSION SINCE it is = 100%
BIOAVAILABILITY

Answer 28

IV injection

Question 29

•VOLUME OF PLASMA CLEARED OF DRUG PER UNIT
TIME
•INDEX OF HOW WELL A DRUG IS REMOVED
IRREVERSIBLY FROM THE CIRCULATION
•DETERMINES THE DOSE-RATE (DOSE/UNIT TIME) REQUIRED
TO MAINTAIN A CP

Answer 29

Clearance

Question 30

The following equations are used to calc _____:
140 – AGE / SCR
140 – AGE / SCR) X 0.85

Answer 30

Clearance

Question 31

•RATE OF ABSORPTION 
/ELIMINATION DOESN’T 
DEPEND ON THE DRUG 
CONCENTRATION
•RATE LIMITED PROCESS
•FIXED NUMBER OF ENZYMES, 
CARRIER, OR ACTIVE 
TRANSPORT PROTEINS; 
SATURATION OCCURS
•HALF LIFE (T ½ )  DECREASES 
OVER TIME
- Linear
- Saturable
•PHENYTOIN
•WARFARIN
•HEPARIN
•ETHANOL
•ASPIRIN (HIGH DOSE)
•THEOPHYLLINE

Answer 31

ZERO ORDER KINETICS

Question 32

•THE DECLINE IN CP IS NOT CONSTANT WITH TIME,
BUT VARIES WITH CONCENTRATION
•THE HALF LIFE (T ½ ) STAYS THE SAME
•CONCENTRATION DECREASES BY 50% PER EACH T ½
•MAJORITY OF DRUGS FOLLOW This
- Logarythmic

Answer 32

First order kinetics

Question 33

– FRACTION ELIMINATED PER UNIT TIME

Answer 33

•RATE CONSTANT (KE)

Question 34

•INDEX OF HOW WELL A DRUG IS REMOVED 
IRREVERSIBLY FROM THE CIRCULATION
•DETERMINES THE DOSE-RATE REQUIRED TO 
MAINTAIN A CP
•TO MAINTAIN STEADY STATE (CPSS), , 
ADMINISTRATION RATE MUST EQUAL RATE OF 
ELIMINATION
CL = KE X VD

Answer 34

Clearance

Question 35

•WHEN REPEATED DOSES OF A DRUG ARE GIVEN IN SHORT
ENOUGH INTERVALS AND ELIMINATION IS 1ST ORDER, THE CP
WILL EVENTUALLY REACH This

Answer 35

Steady staet

Question 36

How many half lives does it take to teach steday state?

Answer 36

5 half lives

Question 37

How many half lives is needed to completely eliminate a drug from body?

Answer 37

5 half lives

Question 38

•VOLUME INTO WHICH A DRUG APPEARS 
TO BE DISTRIBUTED WITH A 
CONCENTRATION EQUAL TO THAT OF 
PLASMA
•TELLS YOU WHERE THE DRUG DISTRIBUTES
•TO REACH A TARGET CP, YOU HAVE TO 
“FILL UP THE TANK”, I.E., VD

Answer 38

Volume of distrbution