03_IV vs Oral

Question 1

Difference in A between an IV bolus and an oral dose?

Answer 1

IV bolus: instantaneous A

Oral dose : rise in Cp to a maximum (Cmax) at time tmax

Question 2

What does the Cp-time curve for an orally dosed drug look like?

Answer 2

The curve
A: starts at Cp = 0, rises to a Cmax at tmax,

Elimination : then falls similarly to the IV bolus curve.

Question 3

What is oral bioavailability (F)?

Answer 3

Measure of the extent to which a drug reaches the systemic circulation.

Question 4

How is F calculated?

Answer 4

Using the equation that considers differences in IV and oraldoses.

E.g: oral bioavailability of 0.75 or 75% indicates that 75% of the oral dose reaches systemic circulation.

Question 5

Why is oral absorption not 100%?

Answer 5

Various factors can reduce oral absorption:

1) poor drug solubility,
2) low membrane permeability,
3) efflux transporters pumping the drug back into the GI tract,
4) metabolism within the gut lining or liver (first-pass effect).
5) drug’s overall metabolic stability.

Question 6

What is the first-pass effect?

Answer 6

Metabolism of a drug within the gut lining (intestinal first-pass) or while passing through the liver (hepatic first-pass) BEFORE reaching the general circulation, which can significantly reduce the amount of drug available systemically.

Question 7

Why is understanding the metabolic stability of a drug important?

Answer 7

Because it affects :
1) a drug’s first-pass effect,
2) bioavailability,
3) overall exposure.

Question 8

Consequences of DRUGS (general) with low metabolic stability?

Answer 8

They show :
1) ↗ hepatic CL,
2) ↘ T1/2,
3) ↘ drug exposure

Question 9

Define Per Os?

Answer 9

Through the mouth

Question 10

If we overlay the IV bolus curve and the oral dose curve, what are the differences we can see?

Answer 10

Difference of AUC (drug exposure).

AUC of IV more exposed

Question 11

Value of F?

Answer 11

1) From (0 to 1) or %

Question 12

Equation of F?

Answer 12

F= (AUC po / Dose po) / (AUC IV / Dose IV)

Question 13

Consequences of poor metabolic stability for Oral Drugs?

Answer 13

1) low metabolic stability
2) Low A
3) Low F
4) Low exposure

Question 14

How would you define the slope of a line in mathematics?

Answer 14

In mathematics, the slope of a line represents the measure of how steep or slanted the line is. It describes the rate at which the line rises or falls as we move along the x-axis.

Question 15

Perimeter of rectangle

Answer 15

= Lenght * Width

Question 16

Circumference of a circle

Answer 16

2 π r

Question 17

Area of a circle

Answer 17

pi * r *r

Question 18

How to calculate AUC last->inf if half life is known?

Answer 18

AUC last->inf = (Cp last * T1/2) * 0.693