Isotonic Solution and Buffer Solution

Question 1

Osmosis

Answer 1

Movment (flux) of solvent through a semi-permeable membrane (SPM) from lower conc. to higher conc. solute in an attempt to equalize the concentration of solute on both sides of SPM

Question 2

Osmotic Pressure

Answer 2

The force that drives the flux and achieves equal osmotic pressure on both sides of SPM
- One of the Colligative Properties associated with physical chemistry of solution: depend on
– Degree of dissociation
– Concentration of solute in solution

Question 3

Colligative (collected together) Properties

Answer 3

• Osmotic pressure
• Freezing point depression- like osmotic pressure, relecant to isotonicity calculation
• Boiling point elevation
• Vapor pressure lowering
  All 4 properties depend on the # of species in solution
• Species: both ions dissociated and uncharged species(undissociated)
  – so NaCI = 1 species
  – Na + CI = 2 species

Question 4

Colligative Properties is based on

Answer 4

• Concentration of solute in solution
• The degree of dissociation (determines the number of ions and uncharged species in solution)

Question 5

Electrolyes

Answer 5

For Non-Electrolytes that dissociate to a tiny degree when dissolved in aqueous solution; the OP is a direct function of:
- The concentration of solute in solution (if we assume the DOD is zero)
For electrolytes, the OP is a function of BOTH the Conc, of solute and it’s DOD
- The greater the Conc. of Solute and the greater the DOF the greater will be the osmotic pressure.
– This is because all colligative properties are a function of # of dissociated and undissociated species in solution

Question 6

Iso-Osmotic

Answer 6

Two solution that have the same osmotic pressure. Many solution intended to come in contract with body fluids need to be iso-osmotic because:
- Reduces inflammation and associated pain and discomfort
- Enhance drug efficiency
- Reduce risk of ADRs
- Promote patient adherence

Question 7

Isotonic

Answer 7

A solution that has the same osmotic pressure as a specific physiological fluid. The body fluids to which isotonicity is referenced are:
- Blood (plasma, serum)
- Lachrymal fluids (tears)-can cause tissue necrosis

Question 8

Solutions that are Isotonic

Answer 8

When we indicate that
- 0.9% NaCl (normal saline solution)
- 5% Dextrose (D5W)
solutions are isotonic we mean that they are isotonic in blood and tears
- D10W is not Isotonic

Question 9

Hypotonic

Answer 9

• Solution have a lower osmotic pressure than physiological fluids
• Will cause hemolysis of RBC (swell and burst) and other cells
• Ex) 1L of sterile water for injection in the bloodstream => massive hemolysis => death
  (sterile water cause sever hemolysis, coma, and even death=> only when drugs are compounded Bol

Question 10

Hypertonic

Answer 10

• Solutions having higher osmotic pressure than physiological fluids
• Will cause cells to shrink (crenation)
  – Equally as bas as causing cells to swell
  Swelling in brain=> reduce water by using 3%NaCI hypertonic (be careful of how fast, how long, and how you infuse it)

Question 11

Parenteral and Ophthalmic solutions need to isotonic

Answer 11

• Less tissue irritation and discomfort
• Avoid excess tear formation in ophthalmic drops; avoid washing away API in eye drop
• Minimize hemolysis in RBCs with large volume parentera (LVP)l infusion
• Avoid electrolyte imbalance in blood

Question 12

LVP infusion precautions

Answer 12

• SWFI (sterile water for injection) in LVP volumes must be labeled “not for infusion or injection)
• Bottles, bags from 100 to 1000mL LVPs must be isotonic

Question 13

Exception to the rule that solution in contact with body fluids need to isotonic

Answer 13

• Small vol injection (SC or IM) preferable to be isotonic ut if small non repeatable vol then not a problem (less)
• Osmotic diuresis: to drain fluid from brain use HYPERTONIC solution to drawn water out of tissue or organ

Question 14

Freezing Point Depression (FPD) - Non electrolyte (doesn’t dissociate)

Answer 14

• Colligative property
• The freezing point of water is 0 C.
• The freezing point of SERUM and LACHRYMAL fluid is (-0.52 C-important) This is the FPD caused by solute that make physiological fluid isotonic
• If one gram MW of NON-ELCTROLYTE is added to 1000ml water, the freezing point is (-1.86 C)
  Ex) what % of H3BO3 (MW=61) will yield an isotonic solution
• (61.8/1.86)=(xg/0.52)=17.28g
  – (17.28g/1000ml)=(xg/100ml) 1.73g or 1.73%

Question 15

Electrolytes like NaCI

Answer 15

• Must factor degree of dissociation (the greater the DOD the fewer farms of electrolytes will be needed to produce an isotonic solution)
  Assumption: Strong electrolytes like NaCI are 80% dissociated (20% as NaCI)=> 100 molecules produce 180 particles or 1.8 X the # of molecules
• Dissociation factor = I =1.8 => Na = 80, CI = 80,NaCi = 20

Question 16

Generalized Eq

Answer 16

X=0.52(MW)/1.86I
- (i) factor for non-electrolytes 1, Electrolytes (two ions like NaCI) 1.8, Electrolytes (three ions like ephedrine sulfate) 2.6, Electrolytes (four ions like sodium citrate) 3.4