Pharmacology 3

Question 1

What are the main routes of administration of drugs?

Answer 1

IV
IM
SC
Inhalation (Inhaler= They land on surface of airways and are topically absorbed through the surface of the skin).

Question 2

What are the advantages and disadvantages of taking orally?

Answer 2

A- Socially acceptable.
D- Slow onset, varied absorption, gastric acid may destroy drug and “first pass metabolism”. Lipid solubility and ionisation, drug formulation, GI motility, interactions with other substances in the gut, GI tract disease.

Question 3

Where does all blood drain to?

Answer 3

All blood drains to the hepatic portal vein (this vein drains to the liver) except the rectal veins and the sublingual veins. The drug only reaches the systemic circulation after passing through the liver once.

Question 4

Liver can inactivate (GTN) and activate (valaciclovir to aciclovir) a drug.

Answer 4

.

Question 5

What are the disadvantages and advantages of non-oral drug administration?

Answer 5

A- bypasses first pass metabolism and it has predicable plasma levels.
D-allergic reactions are more severe, cost is higher and you would need to self medicate..

Question 6

Define bioavailability.

Answer 6

Proportion of an ingested drug that is available for clinical effect.

Question 7

What modifies bioavailability.

Answer 7

Dosage form, destruction in the gut, poor absorption and first pass metabolism.

Question 8

Define volume of distribution.

Answer 8

How much of the body the drug diluted in.

Question 9

What is the problem with taking warfarin and aspirin?

Answer 9

Warfarin and aspirin binds to plasma proteins. If you then take aspirin (higher affinity), warfarin becomes more available in palsma and effect becomes greater- blood might not clot at all.

Question 10

What are the phases of drug metabolism?

Answer 10

Phase 1= oxidation, reduction and hydrolysis.

Phase 2= conjugation (targeting drug to enzyme that we want to excrete and it will increase drug excreted from body).

Question 11

Proportion of drug in breath is directly proportionate to drug in blood eg. drink breath test and drug test.

Answer 11

.

Question 12

Renal Disease
  Chronic renal failure
  Drug doses must be reduced
  Liver disease
  Liver failure
  Drug doses must be reduced

Answer 12

.

Question 13

What is the single and two compartment model?

Answer 13

Single- drug behaves as if it is evenly distributed throughout the body.

Two- drug behaves as it is in equilibrium with different tissues in the body.

The drug goes to where the highest blood flow is first.

Question 14

What is first order kinetics?

Answer 14

When drug elimination or absorption is by passive diffusion only. Drug removal is promotional to drug concentration (more the drug the faster it is eliminated). Log graph of elimination is a straight line.
“A constant percentage of drug is eliminated per unit time”.

Question 15

What is zero order kinetics?

Answer 15

Drug elimination is an active process and can be saturated by high drug concentrations. Linear graph of drug elimination (Paracetamol, more than we want, more than the enzyme system can remove, diff enyme systm kicks in- causes damage to liver).
“A constant amount of drug is eliminated per unit time”.

Question 16

Dosing schedules- impact of too in/frequent.

Answer 16

Dosing Schedule
 Carefully worked out for each drug
TOO FREQUENT will result in plasma levels that may be toxic
 Depends upon the drug’s THERAPEUTIC INDEX
TOO INFREQUENT will result in sub- therapeutic plasma levels and no clinical effect.