Lecture 5: Sterile Liquid Formulations Flashcards
Isotonicity
-maintaining and possessing a uniform tension or tone of cell membrane/tissues
over time, concentrations tend to
equilize
Equilibrium can happen in 2 ways:
- diffusion
- osmosis
Diffusion
-permeable membrane
-solute moves from high to low
Osmosis
-SEMIpermeable membrane
-water moves high to low
-membrane does not allow solute to move so it brings in water to dillute it
-concentration is equal but volume changes
Parenteral vehicles have the ability to
-shrink
-burst open blood and venous epithelial cells
Cell membranes are
semipermeable
semipermeable
-somethings can or cant cross
-viable cell
Impermeable membrane
-cell starves
permeable membrane
-cell dies as empty shell
RBCs
-semipermeable
-only water can move in/out via osmosis
-has no capacity to expand = bursts
Hypotonic vehicles
-doesnt have to be water
-can be anything relatively dilute
Osmometer
-measures osmolarity and osmolality of preparations
-uses colligative properties
Colligative properties
-properties of solutions that depend on quantity of molecular paricles in solution rather than the chemical nature of the dissolved materials
Measurable Colligative properties
-freezing point depression
-lowerning of vapor pressure
-OSMOTIC pressure!
-elevation of boiling point
Any solute dissolved has the same effect as something else
-penicillin = sodium
-chemical property doesnt matter
-what matters is how it effects concnentration
Osmolarity and osmolality are determined by
-total concentration of solutes dissolved
-including the drug
Molarity vs Osmolarity
Molarity eq
mols solute/L of solution
Osmolarity eq
Osmoles solute/L of solution
a/a+b
= Molarity * (m-particles/1molecule)
1 molecule of NaCl yields
-2 ions
-2 m-particles
-2 osmols
1 molecule dextros yields
-1 molecule
-1 particle
-1 osmole
Salt particles
-dissociate in solution
-inc # of particles
-NaCl = Na + Cl
Molality
amt of solute/amt of SOLVENT
Osmolality
osmoles of solute/ kg of SOLVENT
a/b
When are osmolarity and osmolality similar?
-LOW concentrations
-DO NOT USE INTERCHANGEABLY in high concentrations
70% concentration dextrose ???
Iso-osmotic vs isotonic
iso means equal
-equal to BLOOD SERUM
-osmolarity is a number (concentration)
-tonicity looks at EFFECT (concentration of good stuuf or bad stuff)
Serum osmolality range
275-310 mOsmol/kg
Tonicity
-refers to EFFECT on cells
-sulfuric acid and NS can have same osmolarity but sulfuric acid is NOT isotonic bc it will kill cell
If a solution is isoTONIC it must be
isoOSMOTIC
mix iso-osmotic solutions yields
iso-osmotic mixed solution
-recall colligative properties
mix isotonic solutions yields
-isotonic mixed solution
-all non-damaging
Normal saline and D5W
-isotonic
-NOT always interchangable
-wont damage cell but might damage drug
-always check monograph
compatibility
-separate issue that must be checked every time
using an iso-OSMOTIC solution to dissolve large amt of drug results in
=hyperosmotic solution
-presence of drug adds to total osmolarity
HYPOosmotic solution can
-BURST cells
-hemolysis
HYPERosmotic solution
-SHRINKS cells
-lesser of two evils
-better to be HYPER if it cannot be ISO
