Solution isotonic

Sports drinks provide water to the body in the form of an isotonic solution (one having the same total molar concentration of solutes as human blood). These drinks contain electrolytes such as NaCI and KCI as well as sugar and... 

Osmotic pressure plays an important role in biological chemistry because the cells of the human body are encased in semipermeable membranes and bathed in body fluids. Under normal physiological conditions, the body fluid outside the cells has the same total solute molarity as the fluid inside the cells, and there is no net osmosis across cell membranes. Solutions with the same solute molarity are called isotonic solutions. 

In isotonic solution, red blood cells are spherical top). At higher ion concentration center), osmotic flow removes water from the cell interior, shrinking the cell. At lower ion concentration, osmotic flow pumps water into the cell and may cause it to burst bottom). 

Red blood cells are particularly susceptible to these potentially damaging concentration changes because they are suspended in the aqueous medium of the blood. Consequently, solutions used for intravenous feeding must be isotonic. Example deals with isotonic solutions. 

Isotonic solutions, by definition, exert equal osmotic pressure. Therefore, for blood is the same as I I for the glucose solution. We can calculate from Equation after converting the concentration moles per liter —MRT and... 

Eye lotions are isotonic solutions used for washing or bathing the eyes. They are sterilized... 

Fluids can be classified further according to their tonicity. Isotonic solutions (i.e., normal saline or 0.9% sodium chloride [NaCl]) have a tonicity equal to that of the ICF (approximately 310 mEq/L or 310 mmol/L) and do not shift the distribution of water between the ECF and the ICF. Because hypertonic solutions (i.e., hypertonic saline or 3% NaCl) have greater tonicity than the ICF (greater than 376 mEq/L or 376 mmol/L), they draw water from the ICF into the ECF. In contrast, hypotonic solutions (i.e., 0.45% NaCl) have less tonicity than the ICF (less than 250 mEq/L or 250 mmol/L) leading to an osmotic pressure gradient that pulls water from the ECF into the ICF. The tonicity, electrolyte content, and glucose content of selected fluids are shown in Table 24—3. 

Sterility, freedom from pyrogens, and acceptably low level of extraneous particulate matter are critical quality attributes of all injectable products. Additional critical quality attributes depend on the clinical use of the product. For example, for IV, IM, and SC routes, isotonicity and physiological pH (7.4) are always desirable in order to minimize potential irritation upon injection. Other factors may preclude this, however. If the required dose of drug must be administered in a small volume, it may not be feasible to formulate an isotonic solution. Likewise, solubility or stability considerations may preclude formulation at physiological pH. This explains why formulation pH for injectable drugs varies from about pH 2 to about pH 11. 

HSA is used therapeutically as an aqueous solution it is available in concentrated form (15-25 per cent protein) or as an isotonic solution (4-5 per cent protein). In both cases, in excess of 95 per cent of the protein present is albumin. It can be prepared by fractionation from normal plasma or serum, or purified from placentas. The source material must first be screened for the presence of indicator pathogens. After purification, a suitable stabilizer (often sodium caprylate) is added, but no preservative. The solution is then sterilized by filtration and aseptically filled into final sterile containers. The relative heat stability of HSA allows a measure of subsequent heat treatment, which further reduces the risk of accidental transmission of viable pathogens (particularly viruses). This treatment normally entails heating the product to 60 °C for 10 h. It is then normally incubated at 30-32 °C for a further 14 days and subsequently examined for any signs of microbial growth. 

Adding an isotonic solution to the extracellular fluid (ECF) does not change intracellular volume. Adding a hypertonic solution to the ECF decreases cell volume, whereas adding a hypotonic solution increases it (Table 78-1). 

In the eye, hypertonic solutions may cause drawing of water towards the site of application whereas hypotonic solutions may cause water to move from the topical application site through the tissues of the eye. When instilled into the eye, isotonic solutions cause no contraction or swelling of the tissues with which they come in contact, and cause no discomfort. Therefore, it is very important to adjust the isotonicity of topical ophthalmic products. Isotonic adjustments are also important for nasal and aural preparations, parenteral products, and irrigating solutions. In a given product, all the... 

In the prescription above, 1% atropine sulfate is ordered. The sodium chloride equivalent of atropine sulfate is 0.13 (refer to Table 8.2). This means that 1% solution of atropine sulfate has same osmotic pressure as that of 0.13% solution of sodium chloride. This solution is hypotonic. Addition of 0.77 g (i.e., 0.9 - 0.13 = 0.77) of sodium chloride per 100 mL of the 1% solution of atropine sulfate results in an isotonic solution. To determine the amount of sodium chloride required to render a given solution isotonic, the following steps may be used ... 

White and Vincent2 provided a method for readily finding the correct volume of water in which to dissolve a drug to produce a solution iso-osmotic with tears, followed by the addition of an isotonic vehicle to bring the solution to the final volume. The volume (V) of isotonic solution that can be prepared from any given drug is obtained by the equation ... 

If more than one ingredient is contained in an isotonic preparation, the volumes of isotonic solution, obtained by mixing each drug with water, are additive. If that is the case, V can be calculated as follows ... 

The volume (V) of isotonic solution that can be prepared from 0.6 g of the drug ... 

In order to make isotonic solution, 0.6 g of procaine hydrochloride is dissolved in purified water to make 14 mL of an isotonic solution, and the preparation is adjusted to a volume of 60 mL by adding isotonic vehicle such as NSS (normal saline solution). 

On the basis of freezing point depression values, the USP includes a method for rapidly adjusting isotonicity of ophthalmic solutions. Since depression of freezing point depends upon the number of particles of solute(s) in solution, a proportion can be set up to solve for the volume of isotonic solution... 

The volumes of isotonic solutions prepared in milliliters from a gram of selected drug substances are listed in Table 8.3. 

TABLE 8.3. Volume of Isotonic Solutions Prepared (in Milliliters) from 1 g of Drug Substance. 

The freezing point of a 5% solution of boric acid is -1.55°. How many grams of boric acid should be used in preparing 100 mL of an isotonic solution ... 

Ephedrine sulfate 2% Sodium chloride q.s. Isotonic solution 40 mL... 

Dissolve 0.4 g of epinephrine sulfate in purified water to make 10.2 mL of an isotonic solution, and adjust the preparation to a volume of 40 mL with isotonic NaCl (0.9%) solution. 

Most of the early work on membranes was based on experiments with erythrocytes. These cells were first described by Swammerdam in 1658 with a more detailed account being given by van Leeuwenhoek (1673). The existence of a cell (plasma) membrane with properties distinct from those of protoplasm followed from the work of Hamburger (1898) who showed that when placed in an isotonic solution of sodium chloride, erythrocytes behaved as osmometers with a semipermeable membrane. Hemolysis became a convenient indication of the penetration of solutes and water into the cell. From 1900 until the early 1960s studies on cell membranes fell into two main categories increasingly sophisticated kinetic analyses of solute translocation, and rather less satisfactory examinations of membrane composition and organization. 

---