Plasma protein binding is more pronounced than tissue binding

V_d indicates that this drug is highly metabolized in the tissue

The drug does not leave the plasma

Not at all bound to tissue proteins

Drug is able to cross membranes

2. Mark whether the following statements are True or False ( 5 points)

The hepatic clearance of a high extraction drug will increase if the hepatic blood flow is decreased.

The oral bioavailability of a low extraction drug is 70%-100%.

Drugs having a high extraction ratio undergo significant hepatic metabolism

Is the fraction of an oral dose that reaches the general (systemic)circulation.

The maximum volume of distribution possible for a drug which does not show tissue and plasma protein binding is that of the volume of the body.

3. A 10 year old 25 kg patient suffering from Status Asthmaticus was given an iv bolus of theophylline (400 mg). When the serum concentrations were measured at 0 and 5 hours after injection, drug levels were found to be 35 and 14.4 m g/ml, respectively. Assume a therapeutic range of 10-20 m g/ml for theophylline.

a. Calculate the volume of distribution in this patient.

b. Calculate k_e and t_1/2 in this patient.

c. Calculate the clearance in this patient.

4. The distribution of drugs A into the brain is driven by permeability limitations. The distribution of drug B into the brain is driven by perfusion limitations. Which of the two drugs will enter the brain faster (short explanation) (10 pts)

5. Liposan is a highly lipophilic drug. It shows a very low extraction ratio. This drug has a very low extraction ratio and we would predict that the oral bioavailability would be relatively high since F=1-E. However, it has a low oral bioavailability. Discuss the potential reason. (10 pts)

6. Explain in your own words what the volume of distribution describes. (no equations). (10 points)

7. Drugs that induce the hepatic P-450 system are likely to increase the plasma clearance of high extraction drug propranolol (a drug metabolized by these enzymes). Is this statement correct. Explain and provide your reasoning. (10 points)

8. A drug is given as an IV bolus injection. The initial plasma concentration (Cpo) was 100 m g/ml. 4 hours later the plasma concentration was 50 mg/ml. What is the plasma concentration 8 hours after dosing if (10 pts)

a) the elimination is first order?

b) the elimination is zero-order?

9. Discuss the advantages and disadvantages of pulmonary delivery. (10 pts)

10. Discuss why quite often tablets are taken with a full glass of water. (10pts)

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