osmolarity, is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) .

1. AL-QUDS UNIVERSITY
COLLEGE OF GRADUATE STUDIES
PHARMACEUTICAL TECHNOLOGY (8038675)
OSMOLALITY AND OSMOLARITY
Professor : Dr. Numan Malkieh
Student preparation : Hanibal Mousa Mansour .
1
Jerusalem-Palestine
2020

2. OUTLINE
2
1. Introduction
2. Classification of drug solution
3. Osmotic of drug solutions
4. Osmotic pressure
5. Clinical relevance of osmotic effects
6. Osmotic properties of Pharmaceutical solution
7. Preparation of isotonic solution
8. Calculation of Osmolarity of Solution
9. References

3. Introduction
 when two different solutions are separated by a membrane that
is impermeable to the dissolved substances, fluid shifts
through the membrane from the region of low solute
concentration to the region of high solute concentration until
the solution are of equal concentrations.
 This diffusion of water causes by a fluid concentration
gradient is known as osmosis.

4. Introduction
The Osmolarity and Osmolality of a solution
 Osmolarity and Osmolality are units of Solute concentration that
are often used in reference to biochemistry and body fluids
 The concentration of osmotically active particles in that solution .
The term Osmolarity refers to the number of particles of solute per
liter of solution which is the measure of osmoles of solute per liter
of solution (Osm/L)

5. Introduction
 Measurements of osmolarity are temperature dependent
because the volume of solvent varies with temperature (i.e.,
the volume is larger at higher temperatures) .
 The term osmolality refers to the number of particles of
solute per kilogram of solvent. Which is the measure of
osmoles of solute per kilogram of solvent (Osm/kg).
 osmolality, which is based on the mass of the solvent, is
temperature independent

6. Classification of Solutions
Solutions Classified by Route of Administration :
 Oral solutions
 Topical solutions
 Rectal solutions
 Vaginal solution
 Otic solutions
 Nasal solutions
 Ocular solution
 Parenteral solutions
 Inhalations

7. Osmotic of drug solutions
 Properties that are dependent on the number of molecules in
solution in this way are referred to as colligative properties,
and the most important of such properties from a
pharmaceutical viewpoint is the osmotic pressure .
Colligative properties :
vapor pressure
osmotic pressure
boiling point
freezing point

8. Osmotic pressure
 Whenever a solution is separated from a solvent by a
membrane that is permeable only to solvent molecules, there
is a passage of solvent across the membrane into the solution.,
then a pressure differential develops across the membrane,
which is referred to as the osmotic pressure .

9. Osmotic pressure
 Solvent passes through the membrane because of the
inequality of the chemical potentials on either side of the
membrane. Since the chemical potential of a solvent molecule
in solution is less than that in pure solvent, solvent will
spontaneously enter the solution until this inequality is
removed .

10. Clinical relevance of osmotic
effects
 Osmotic effects are particularly important, the red blood cell membrane,
behave in a manner similar to that of semipermeable membranes.
 Solutions that have the same tonicity as blood serum are said to be isotonic
with blood. Solutions with a higher tonicity are hypertonic and those with
a lower tonicity are termed hypotonic solutions.

11. Clinical relevance of osmotic
effects
• Similarly, in order to avoid discomfort on administration of solutions to the
delicate membranes of the body, such as the eyes, these solutions are made
isotonic with the relevant tissues.
It is important for a solution to be isotonic with a bodily fluid to prevent
irritation and cell damage, and to maximize drug efficacy.

12. Osmotic properties of Pharmaceutical
solution
 Osmotic properties, plays an important role in formulation and preparation
of parenteral solutions, especially those prepared for ophthalmic, nasal,
rectal administration.
 Administration of solution (i.e. injection) to delicate membranes of body (i.e.
eyes): isotonic solution avoid discomfort feeling
 For preparing of isotonic solution, osmotic pressure is usual to use the freezing
– point depression

13. Preparation of isotonic solution
 Body fluids such as blood plasma and lachrymal secretions
have a freezing point of 0.52 C° due to different solutes
present in them. 0.9% solution of NaCI (isotonic solution)
also has freezing point of - 0.52 C . Hence, all solutions which
freeze at 0.52 C° will be isotonic with these fluids.
:
Based on freezing point

14. Preparation of isotonic solution
 With a solution of a drug, it is not of course possible to alter the
drug concentration in this manner, and an adjusting substance must
be added to achieve isotonicity.
 The quantity of the adjusting substance needed for making the
solution isotonic with blood may be calculated below :
 Amount of adjusting substance required = 0.52 - a /b
 Where, a = freezing point of 1% solution of un-adjusted solution
b = freezing point of 1% solution of adjusting substance

15. Preparation of isotonic solution

16.  The unit used to measure osmotic concentration is the milliosmole
(mOsmol)
 Osmotic pressure is proportional to the total number of particles in
solution, the unit used to measure osmotic concentration must reflect the
total number of particles in solution .
 Millosmolar weight can then be used as a conversion between milligram
and milliosmoles as follows :
Calculation of Osmolarity of Pharmaceutical
solutions

17. Calculation of Osmolarity of Pharmaceutical
solutions
 According to the United States Pharmacopeia, the ideal
osmolar concentration may be calculated according to the
equation :
For example, the ideal osmolarity of 0.9% sodium chloride injection is:

18. Calculation of Osmolarity of Pharmaceutical
solutions
 The total number of particles in solution depends on the degree of dissociation of
the substance in question. Assuming complete dissociation :
 1 mmol of NaCl represents 2 mOsmol (Na+ + Cl-) of total particles .
 1 mmol of CaCl2 represents 3 mOsmol (Ca+ + 2Cl- ) of total particles,
 1 mmol of sodium citrate (Na3C6H5O7) represents 4 mOsmol (3Na+ +
C6H5O7-) of total particles

19. Calculation of Osmolarity of
Solution

20. Calculation of Osmolarity of
Solution

21. References
 Ingham, A., & Poon, C. Y. (2013). Tonicity, Osmoticity, Osmolality,
Osmolarity. Remington, 277
 Helle, K. B., Reed, R. K., Pihl, K. E., & Serck‐Hanssen, G. (1985). Osmotic
Properties Of The Chromogranins And Relation To Osmotic Pressure In
Catecholamine Storage Granules. Acta Physiologica Scandinavica .
 ZATLOUKAL, Z. (2009). Conversion Between Osmolality And Osmolarity Of
Infusion Solutions. Scientia Pharmaceutica, 77(4), 817-826 .
 Zhang, Z., Kleinstreuer, C., & Kim, C. S. (2006). Isotonic And Hypertonic Saline
Droplet Deposition In A Human Upper Airway Model. Journal Of Aerosol
Medicine, 19(2), 184-198.
 Florence, A. T., & Attwood, D. (1988). Physicochemical Properties Of Drugs In
Solution. In Physicochemical Principles Of Pharmacy (Pp. 47-80). Palgrave,
London