ISOTONIC SOLUTIONS Flashcards
pharmaceutical solutions that are meant for application to delicate membranes of the body should also be adjusted to approximately the ____ with the body fluids
SAME OSMOTIC PRESSURE
- Causes no swelling or contraction of tissues
- Produce no discomfort in the eye, nasal tract, blood or body tissues
- Has the same salt concentration, hence same osmotic pressure as the RBC
ISOTONIC SOLUTIONS
Causes outward passage (Shrinkage/Crenation)
HYPERTONIC SOLUTIONS
Causes swelling, which leads to bursting (Hemolysis)
HYPOTONIC SOLUTIONS
Hypertonic Solutions
greater than 0.9% NaCl
Hypotonic Solutions
<0.9% NaCl
NSS
normal saline solution
Methods of Adjusting Tonicity
NaCl or other substance is added
1) Cryoscopic Method
2) Sodium chloride Equivalent Method
CLASS I METHODS
Refers to the concentration of aqueous NaCl solution having the same colligative properties as the solution in question
ISOTONICITY VALUE
Methods of Adjusting Tonicity
water is added to the drug, followed by sufficient
isotonic solution
1) White-Vincent Method
2) Sprowls Method
CLASS II METHODS
Measurement of Tonicity
Based on the appearance of RBC suspended in solutions
HEMOLYTIC METHOD
Measurement of Tonicity
Based on slight differences in vapor pressure, freezing point or boiling point
COLLIGATIVE PROPERTIES
HEMOLYTIC METHOD:
Hypotonic → ____
liberates oxyHgB
Methods of Adjusting Tonicity
CLASS I METHODS
1) Cryoscopic Method
2) Sodium chloride Equivalent Method
- a.k.a. “tonicic equivalent” of a drug
- the amount of NaCl that is equivalent to 1 gram of the drug
SODIUM CHLORIDE EQUIVALENT (E)
Liso VALUES
non electrolytes
1.9
Methods of Adjusting Tonicity
CLASS II METHODS
1) White-Vincent Method
2) Sprowls Method
SODIUM CHLORIDE EQUIVALENT (E)
g NaCl / 1g of drug
Liso VALUES
weak electrolytes
2.0
Liso VALUES
di-divalent electrolytes
2.0
Liso VALUES
uni-univalent electroylytes
3.4
Liso VALUES
uni-divalent electrolytes
4.3
Liso VALUES
di-univalent eelctrolytes
4.8
Liso VALUES
uni-trivalent electrolytes
5.2
Liso VALUES
tri-univalent electrolytes
6.0
Liso VALUES
tetraborate electrolytes
7.6
sucrose, glycerin, urea, camphor
nonelectrolytes
boric acid, cocaine, phenobarbital
weak electrolytes
magnesium sulfate, zinc sulfate
di-divalent electrolytes
sodium chloride, cocaine hydrochloride, sodium phenobarbital
uni-univalent electrolytes
sodium sulfate, atropine sulfate
uni-divalent electrolytes
zinc chloride, calcium bromide
di-univalent electrolytes
sodium citrate, sodium phosphate
uni-trivalent electrolytes
aluminum chloride, ferric iodide
tri-univalent electrolytes
sodium borate, potassium borate
tetraborate eelctrolytes
Sodium Chloride Equivalent Method
if NaCl is the tonicity agent
FORMULA
step 1: NaCldrug = Edrug x gdrug
or NaCldrug = Edrug x %drug/100 x mLsoln
step 2: NaCltotal = 0.009 x mLsoln
step 3: NaClneeded = NaCltotal - NaCldrug
Methods of Adjusting Tonicity
If water and isotonic diluting agent are used, the volume in mL of isotonic solution that may be prepared by mixing drug with water, followed by isotonic diluting agent to the required volume
WHITE VINCENT METHOD
WHITE VINCENT METHOD formula
V = w x E x 111.1
or
V = %drug / 100 x mLsoln x E x 111.1
Diffusion of water across a semi-permeable membrane
osmosis
- Relative solute concentrations of two environments separated by a semi-permeable membrane
- The concentration of only the solute that cannot cross a membrane
TONICITY
Sodium Chloride Equivalent Method
If NaCl is not the tonicity agent
FORMULA
step 1: NaCldrug = Edrug x gdrug
or NaCldrug = Edrug x %drug/100 x mLsoln
step 2: NaCltotal = 0.009 x mLsoln
step 3: NaClneeded = NaCltotal - NaCldrug
step 4: gagent = NaCl needed / E agent
