Fundamentals Of Drugs

Question 1

Solution

Answer 1

Homogenous mixture of 2 or more substances

Question 2

Solute

Answer 2

Substance present in smaller amount

Question 3

Solvent

Answer 3

Substance present in the larger amount

Question 4

Solubility

Answer 4

The number of parts of solvent (by volume) that will dissolve one part of solute (by weight)

Question 5

Unsaturated solution

Answer 5

More solute dissolves
No solid remains in flask
Solubility not reached yet

Question 6

Saturated solution

Answer 6

No more solute dissolves
Undissolves solid remains in flask
Maximum limit of solubility is reached

Question 7

Supersaturated solution

Answer 7

More solute than is normally possible
Becomes unstable crystals form
Maximum limit of solubility is exceeded

Question 8

Absorption

Answer 8

Process of movement of drug from the site of administration to systemic circulation

Question 9

Drugs with low aqueous solubility

Answer 9

Present problems related to formulation and bioavailability

Question 10

Why is aqueous solubility important?

Answer 10

Drugs must be molecularly dispersed before being absorbed through biological membranes

Question 11

Drug release and dissolution

Answer 11

1. Disintegration
2. Dissolution of shell
3. Deaggregation
4. Dissolution
5. Drug in solution
6. Absorption

Question 12

Disintegration

Answer 12

Solid dosage form broken down into smaller fragments by disintegrants, which help facilitate the process

Question 13

Dissolution of shell

Answer 13

The shell must dissolve first to expose the active pharmaceutical ingredient

Question 14

Deaggregation

Answer 14

Smaller granules or particles further break down into finer particles
Increases the surface area available for dissolution, improving drug solubility

Question 15

Dissolution

Answer 15

The active pharmaceutical ingredient dissolves in the surround gastrointestinal fluids
Dissolution rate depend on the drug’s solubility, formulation properties and pH

Question 16

Why must the drug be in solution?

Answer 16

Available for solution
Passive or active transport across biological membranes

Question 17

Cosolvency

Answer 17

Solubility of poorly soluble drugs can be improved by the addition of water miscible solvents in which the compound is soluble

Question 18

pH adjustment

Answer 18

Most drugs are weak acids or weak bases
Proportion of ionised fraction for weak acids will increase by increasing the pH of the medium
Weak bases, it will increase by lowering the pH

Question 19

pH manipulation

Answer 19

Membrane irritation at extremes pH values
Formulation compatibility’s
Formulation- container compatibility

Question 20

Solubilisation

Answer 20

The addition of surfactant may be used as a strategy to solubilise poorly soluble drugs

Question 21

What must a surfactant be?

Answer 21

Non toxic
Miscible with the solvent system
Compatible with the other ingredients and the container
Free from bad odour
Free from bad taste

Question 22

Chemical modification

Answer 22

Drug may be chemically modified to reduce a water soluble derivative
E.g sodium phosphate salt of hydrocortisone

Question 23

Salt formation

Answer 23

Salt of weak acid/base have much higher aqueous solubility than the free acid or base
If the drug can be given as a salt the solubility can be increased and the dissolution can be improved

Question 25

Particle size control

Answer 25

Smaller particles increase the surface area, leading to better dissolution

Question 26

Temperature

Answer 26

Solubility of the majority of drugs in endothermic and subsequently increasing temperature enhances the solubility

Question 27

What does a drug do other than bind to its target?