Lecture 10

Question 1

isotonic (iso-osmotic)

Answer 1

solutions containing the same concentration of particle

Question 2

exceptions to the rules of pH and osmolarity

Answer 2

certain isotonic, pH neutral infusates cause phlebitis
example - erythromycin, oxacillin, chemotherapeutic drugs

Question 3

concentrations

Answer 3

tend to equalize over time through diffusion or osmosis

Question 4

diffusion

Answer 4

permeable membrane
solute moves from the region of higher concentration to the region of lower concentration

Question 5

osmosis

Answer 5

water moves from the region of higher concentration to the region of lower concentration
semipermeable membrane

Question 6

isotonicity

Answer 6

parenteral vehicles have the ability to shrink or burst open blood and venous endothelial cells

Question 7

impermeable

Answer 7

cell starves
nothing goes through

Question 8

permeable

Answer 8

cell ends as an empty shell, dead again
everything goes through

Question 9

semipermeable

Answer 9

viable cell
somethings can cross

Question 10

hemolysis

Answer 10

cell bursts open due to increased water flow in the cell

Question 11

water dilution

Answer 11

water will move into the more concentrated side to dilute the solution (the solute cannot move through in a semipermeable membrane)
any hypotonic vehicle could do the same

Question 12

how can we measure the risk of any given preparation?

Answer 12

by knowing the osmolarity/osmolality of the preparation through an instrument (osmometer)
practical use of colligative properties

Question 13

colligative properties examples

Answer 13

freezing point depression
lowering of vapor pressure
osmotic pressure
elevation of boiling point

Question 14

colligative properties

Answer 14

properties of solutions that depend on the quantity of molecule particles (m-particles) in solution rather than the chemical nature of the dissolved materials

Question 15

osmolarity/osmolality determinants

Answer 15

by the total concentration of solutes dissolved (aka m-particles) including the drug

Question 16

NaCLl (solid) –> Na+ + Cl- (solution)

Answer 16

1 molecule of NaCL
2 m-particles of Na+ and Cl-

Question 17

Molarity vs osmolarity

Answer 17

osmolarity is molarity multiplied by the number of m-particles in the solution
example - salts would be multiplied by 2 as they dissociate

Question 18

osmolarity equation

Answer 18

number of osmoles / volume of solvent and solute
g/L

Question 19

osmolality equation

Answer 19

number of osmoles / weight (in Kg) of only the solvent
g/kg

Question 20

interchangeable of osmolarity/osmolality?

Answer 20

often used but only at low concentrations
very dangerous at high concentrations (example - TPN dextrose solutions)

Question 21

osmolarity/osmolality

Answer 21

a number, a concentration value, measured by an instrument (osmometer)

Question 22

osmometer

Answer 22

will not distinguish between NaCl and sulfuric acid (a living cell will)

Question 23

tonicity

Answer 23

effect on living cells

Question 24

iso-osmotic vs isotonic example

Answer 24

a solution of sulfuric acid gives the same osmolarity value as NS
the two solutions are iso-osmotic (= same concentration of m-particles)
only NS is isotonic (=compatible with living cells)

Question 25

iso-osmotic/isotonic

Answer 25

iso-osmotic is a rectangle isotonic is a square all isotonic solutions are iso-osmotic but not all iso-osmotic solutions are isotonic

Question 26

iso-osmotic mixed solution

Answer 26

recall colligative properties

Question 27

isotonic mixed solution

Answer 27

all non-damaging solutes

Question 28

normal saline and D5W

Answer 28

both isotonic not always interchangeable so always check the drug monograph/package insert compatibility with the product is a separate issue that must be checked every time

Question 29

hyperosmotic solution

Answer 29

the presence of the drug adds to the total osmolarity when an iso-osmotic solution is used to dissolve a large amount of drug will shrink cells not as bad

Question 30

hypo-osmotic solution

Answer 30

will result in hemolysis (cell burst) worse than hyperosmotic ones