This document discusses isotonic and buffered solutions. It defines key terms like isotonic, hypertonic, and hypotonic in relation to cell membranes and tissues. Solutions need to be isotonic to avoid irritation when applied to or administered into the body. Normal saline and lactated ringers are considered isotonic with blood, while 5% dextrose is hypotonic. The document provides guidelines for fluid replacement based on the type of fluid and volume deficit. It also discusses considerations for ophthalmic and parenteral medications and maintaining proper tonicity.

1. Ref :
Physical Pharmacy by Myrtin., Chapter 09., Buffered and Isotonic
Solutions., Page No 209 onward.
&
The Science and practice of pharmacy “Remingtons” Ed 21st 17th Chapter
., part 2, page no 250 onward.

2.  A solution is a homogeneous mixture of two or
more substances. One of the substances is
called a solvent (a substance in which other
substance or substances are dissolved). The
substances dissolved in a solvent are called
solutes.

 A solution can exist in a solid, liquid or gas
form depending on mixed substances and
external conditions such as temperature and
pressure.

3.  Solutions to be applied to tissues or administered
parenterally are liable, to cause irritation if their pH is
greatley different from the normal pH of the relevant
body fluid.
 Consequently the pharmacist must consider this point
when formulating OPTHALMEIC SOLUTIONS,
parenteral products and fluids to abraded surfaces.
 Tissue Irritation due to large pH differences b/w the
solution being applied/administered will be minimal ;
if the said Solution {to be applied} is ISOTONIC IN
NATURE.

4.  IN_VIVO_Buffer such as Blood., Lacrimal
Fluids having capacity to manage pH of the
relevant biological fluids.

5.  Tonicity is a measure of the osmotic pressure (as defined by the water
potential of the two solutions) of two solutions separated by a
semipermeable membrane.
 It is commonly used when describing the response of cells immersed in
an external solution.
 Like osmotic pressure, tonicity is influenced only by solutes that cannot
cross the membrane, as only these exert an osmotic pressure.
 Solutes able to freely cross the membrane do not affect tonicity because
they will always be in equal concentrations on both sides of the
membrane.
 Osmotic pressure is the pressure that must be applied to a solution to
prevent the inward flow of water across a semipermeable membrane.

6.  Hypertonicity
A hypertonic solution is a solution having a greater solute concentration
than the cytosol.
A hypertonic solution is used in osmotherapy[1] to treat cerebral
hemorrhage.
 Hypotonicity
 A hypotonic solution is a solution having a lesser solute concentration than
the cytosol.
Isotonicity
 A condition or property of a solution in which its solute concentration is the
same as the solute concentration as in CYTOSOL or another solution with
which it is compared.
 .

7.  Terms isotonic, hypertonic and hypotonic are usually used
when a reference to cell of a living organizm is made, but it
can be generally used to compare concentration of a solute
in two solutions.
 Isotonic solutions
 Isotonic solutions are two solutions that have the same
concentration of a solute.
 Hypertonic solution
 Hypertonic solution is one of two solutions that has a higher
concentration of a solute.
 Hypotonic solution
 Hypotonic solution is one of two solutions that has a lower
concentration of a solute.

14.  A solution that has no effect on the volume of
tissues and cells. Thus, a cell, when placed in
an isotonic solution tends neither to gain or
lose water.
 Isotonic sports drinks have the same
concentration as the body fluids.

15.  Red blood cell membrane is not impermeable to all drugs; that is, it is not
a perfect semipermiable membrane.
 Thus, it will permit the passage of not only water molecules, but also
solutes such as UREA., Ammonium Chloride., Alcohol and Boric Acid.
 A 2% BORIC ACID SOLUTION HAS SAME OSMOTIC PRESSURE AS THE
BLOOD CELLS CONTENTS. Such solution called as ISOSOMATIC
SOLUTION with Blood.
 The molecule of Boric acid can pass through the Erythrocyte membrane easily.
 It is interesting here that the mucous lining of the EYE acts as a true
semipermiable membrane to boric acid in solution.
 2% BORIC ACID SOLUTION SERVES AS AN ISOTONIC
OPTHALMIC PREPRATION.

16.  Husa suggested that the term isotonic solution
should be restricted to solutions having equal
osmotic pressure w.r.t a particular membrane.
 Goyan and Reck introduced a new term as
“ISOTONICITY VALUE” defined as
concentration of an Aqueous sodium chloride
solution having the same colligative properties
as solution in question.
 0.9g of NacL per 100 ml of solution needed not necessarily be
isotonic with respect to the living membrane concerned. {Roughly
Isotonic}

17.  Normal saline solution (0.9% NaCl) is
considered isotonic with blood (although it actually has a slightly
higher degree of osmolality).
 Ringers lactate is also considered
isotonic.
 5% Dextrose solution is also considered
hypotonic compared with blood, because although it is isotonic
while infusing, the dextrose is metabolized and free water is left,
which is hypotonic.

18.  ISOTONIC SOLUTION(s)
 0.9% NaCl (normal saline) isotonic
Lactated Ringer's solution isotonic
Hypo TONIC SOLUTION(s)
 0.25% NaCl hypotonic
0.45% NaCl hypotonic
2.5% dextrose hypotonic
D5W (acts as a hypotonic solution in body)
 Hyper TONIC SOLUTION(s)
 D5 NaCl hypertonic
D5 in Lactated Ringer's hypertonic
D5 0.45% NaCl hypertonic

19.  Isotonic Fluid Volume Deficit Type of Loss:
 solute and water loss.,serum sodium level is decreased to 125-150 mEq/L.
 The cause of the fluid loss is GI fluid loss, urine loss and decreased oral intake.
Clinical signs:
 poor skin;
 cold, dry dusky skin;
 sunken eyes; dry mucous membranes;
 rapid pulse; low B/P; irritability or lethargy
Fluid Replacement Guidelines:
Initially, a bolus of 0.9% sodium chloride or Ringer's lactate is given followed by 5%
Dextrose in water and 0.45% sodium chloride.
Half of the deficit should be replaced in the first 8 hours and the remaining half over the
next 16 hours

20.  Hypertonic Fluid Volume Deficit Type of Loss:
 There is greater water loss than solute loss. Volume moves from the ICF to the ECF.
 Sodium levels are maintained at over 150 mEq/L.
 The cause is GI fluid loss with hypertonic oral intake,
 diabetes insipidus, fever and hyperventilation.
 Clinical Signs: Include cold, thick and doughy skin; sunken eyes; a moderately rapid pulse;
moderately low blood pressure; hyperirritability; high-pitched crying in babies; seizures.
 Fluid Replacement Guidelines:
 5% Dextrose in water and 0.225% or 0.45% sodium chloride. If the patient is hypertensive
Ringer's lactate should be given at a rate of 20mL/kg over one hour.
 Fluid replacement should be given slow and gradual over 48 hours. 2 to 3 mEq/kg of potassium
should be given per 24 hours.
 At least 2 mEq/L/hour of sodium should also be included in the IV fluids that are used.

23.  Ophthalmic Medication
 Ophthalmic prep’s are intended for the administration into cul-de-sac of
the eye must be isotonic to avoid any irritation.
 Abnormal tonicity of the CONTACT LENSE solutions can cause the lens
to adhere to the eye and or cause burning or dryness/photophobia.
 Parenteral Medication
 Solution differ in Osmoticity/tonicity w.r.t serum may
cause irritation_pain at the site of injection_Electrolyte
Shifts., the severity depends upon the degree of variation
from TONICITY.

24.  Alcohol  21.7 ml of H20
 Ascorbic Acid 6.0 ml of H2o
 Boric Acid 16.7 ml of H2o
 Dextrose Anhydrous  6.0 ml of H2o
 Ephedrine Hcl  10.0 ml of H2o
 Glycerin  11.7 ml of H2o
 Penicillin G Na and K  6.0 ml of H2o
 Silver Nitrate  11.0 ml of H2o
 Zinc Chloride  20.3 ml of H2o

25.  The term osmolality express the OSMOLAL
Concentration.
 Emphasis on w/w relationship.
 Not influenced by temperature.
 A solution has an osmolal concentration of one
when it contains 1 osmol of solute/kg of water.

26.  The term osmolarity express the OSMOLAR
Concentration.
 Emphasis on w/v relationship.
 influenced by temperature.
 A solution has an osmolar concentration of one
when it contains 1 osmol of solute/liter of water.
 0.9 % w/v solution of Nacl in water contains 9
gram of sodium chloride in 996.5 gram of wtaer
equivalent to 0.309 osmolal value.

27.  Class I Methods
 Cryoscopic Method
 Sodium Chloride Eq Method
 Freezing Point Depression Method
Class II Methods
 White –Vincent Method
 The Sprowls Methods