Exam 1 -- Drug Dosage Regimens

Question 1

steady-state plasma concentration (Css)

Answer 1

the point at which the drug’s intake rate equals its elimination rate, resulting in a stable concentration of the drug in the blood stream during repeated dosing

Question 2

ineffective range

Answer 2

refers to drug concentrations in the bloodstream that are too low to produce a therapeutic effect

Question 3

therapeutic range

Answer 3

concentration range of a drug in the bloodstream that produces desired therapeutic effect without causing toxicity or adverse effects

Question 4

What aer pharmacokinetic variables?

Answer 4

• bioavailability
• volume of distribution
• clearance
  determine concentration-time relationships of drug in plasma

Question 5

bioavailability (F)

Answer 5

the fraction of administered drug reaching the systemic circulation in itsactive form

Question 6

Which route of administration has the highest bioavailability?

Answer 6

intravenous = 1
* all other routes are lower and somewhere between 0 to 1

Question 7

minimum effective concentration

Answer 7

the line of plasma concentration that separates the ineffective range from the therapeutic range

Question 8

apparent efficacy

Answer 8

the observed effectiveness of a drug in producing a desired therapeutic effect in clinical practice
* drugs may have a lower efficacy than seen lab when used in real-world conditions

Question 9

onset of action

Answer 9

the point where the dose crosses into the therapeutic range from the ineffective range

Question 10

duration of action

Answer 10

the amount of time spent in the therapeutic range during a dose

Question 11

rate of availability

Answer 11

rate at which drug enters systemic circulation
* effects onset of action
* can affect apparent efficacy and duration of action

Question 12

What factors affect the rate of availability?

Answer 12

• dissolution of drug into absorbable form
• blood flow

Question 13

volume of distribution (Vd)

Answer 13

the apparent body volume in which a drug distributes

Question 14

How is volume of distribution determined?

Answer 14

Vd = Amount of drug in body / plasma concentration

Question 15

What factors affect Vd?

Answer 15

body weight and body composition

Question 16

clearance (CL)

Answer 16

elimination of active drug from the plasma after its distribution
* CL includes elimination by excretion as well as metabolism

Question 17

How is clearance determined?

Answer 17

CL = rate of elimination / plasma concentration

Question 18

Factors the affect clearance?

Answer 18

body weight and blood flow to clearance organs

Question 19

Clearance increases as plasma concentration…?

Answer 19

increases

Question 20

Css occurs when amount fo drug coming into the body (dose x bioavailabilty) = …?

Answer 20

amount of drug going out of the body (clearance)

Question 21

Maintenance dose (Dm)

Answer 21

maintains Css by replacing loss due to elimination
* Dm = ((Css * CL) / F) * dosing interval
* maintenance dose is dependent on clearance

Question 22

Loading dose (DL)

Answer 22

quickly reaches Css by quickly filling Vd
* DL = (Css * Vd) / F
* loading dose is dependent on Vd

Question 23

half-life

Answer 23

time for plasma concentration of drug to decrease by half

Question 24

plateau effect

Answer 24

Css is achieved in about 4-5 * half-lifes

Question 26

zero-order elimination

Answer 26

refers to a pharmacokinetic process in which a drug is eliminated from the body at a constant rate, regardless of it concentration

Question 27

first-order elimination

Answer 27

refers to a pharmacokinetic process in which the rate of drug elimination from the body is proportional to its concentration