Solution hypotonic

Ophthalmic Dosage Forms. Ophthalmic preparations can be solutions, eg, eye drops, eyewashes, ointments, or aqueous suspensions (30). They must be sterile and any suspended dmg particles must be of a very fine particle size. Solutions must be particle free and isotonic with tears. Thus, the osmotic pressure must equal that of normal saline (0.9% sodium chloride) solution. Hypotonic solutions are adjusted to be isotonic by addition of calculated amounts of tonicity adjusters, eg, sodium chloride, boric acid, or sodium nitrate. 

Some types of injections must be made iso-osmotic with blood serum. This applies particularly to large-volume intravenous infusions if at all possible hypotonic solutions cause lysis of red blood corpuscles and thus must not be used for this purpose. Conversely, hypertonic solutions can be employed these induce shrinkage, but not lysis, of red cells which recover their shape later. Intraspinal injections must also be isotonic, and to reduce pain at the site of injection so should intramuscular and subcutaneous injections. Adjustment to isotonicity can be determined by the following methods. 

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. 

D5W is a solution of free water and dextrose that provides a modest amount of calories but no electrolytes. Although it is technically isotonic, it acts as a hypotonic solution in the body. 

Hypotonic solution such as dextrose 5% and 1/2 normal saline or similar fluid... 

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... 

Any hypotonic solution containing one or more drugs can be rendered isotonic by adding appropriate quantity of sodium chloride. Following is a sample prescription that requires isotonic adjustments ... 

In this method the cells are lysed by incubation in a hypotonic solution, which leaves the nuclei intact. The cell debris and nuclei are pelleted by centrifugation leaving the cytoplasmic RNA free from DNA in the supernatant. The RNA is released from the polysomes by incubation with proteinase K and the protein extracted into phenol/chloroform. The RNA is then precipitated from the aqueous phase using ethanol. 

To isolate intact organelles, it is important for the homogenization solution to be isotonic—I e the osmotic value of the buffer has to be the same as that of the interior of the cell. If hypotonic solutions were used, the organelles would take up water and burst, while in hypertonic solutions they would shrink. 

FIGURE 2-13 Effect of extracellular osmolarity on water movement across a plasma membrane. When a cell in osmotic balance with its surrounding medium (that is, in an isotonic medium) (a) is transferred into a hypertonic solution (b) or hypotonic solution (c), water moves across the plasma membrane in the direction that tends to equalize osmolarity outside and inside the cell. 

Hypotonic solution Dissolve 560 mg of potassium chloride (KC1) in 100 mL distilled water. Prepare fresh, and keep at 37°C... 

Centrifuge the cultures at 600g, and resuspend the pellet in hypotonic solution. Incubate at 37°C for 7 min... 

Hypotonic solutions will cause a net flow of solvent into the cells to equalize the osmotic pressure. The cells will burst and die (hemolysis). Hypertonic solutions will cause a net flow of solvent out of the cells to equalize the osmotic pressure. The cells will shrink and die. 

Plain water crosses the walls of the intestine by osmotic action alone. However, if sodium and sugars are also present then the active transport mechanisms described earlier operate and water absorption can be enhanced. The effect is dependant on concentrations the maximum rate of water uptake occurs when the concentrations give a slightly hypotonic solution (200-250 mOsm/kg, cf. 287 mOsm/kg for isotonicity) (Wapnir and Lifshitz, 1985). Conversely, when the lumen contents are significantly hypertonic, water is secreted from plasma into the intestine by osmotic action this is a dehydrating effect. 

Hi) Osmolality. The majority of spoils drinks are formulated to be isotonic, i.e. to have an osmotic pressure matching that of blood serum. This is considered to optimise absorption from the intestine although, as stated earlier, water uptake is optimal with slightly hypotonic solutions. 

When the pH of a suspension of microspheres of acidic proteinoid is raised by 1-2 units, diffusion of material from the interior to the exterior, fission into two particles, and the appearance of a double layer in the boundary are observed 2 Proteinoid microspheres shrink or swell on transfer to hypertonic or to hypotonic solutions respectively. Some experiments show that polysaccharides are retained under conditions in which monosaccharides diffuse out2. Some proteinoid microspheres possess the intrinsic capacity to grow by accretion, to proliferate through budding, and to form junctions 2). The morphology and other characteristics of proteinoid microspheres are altered by the inclusion of other materials such as polynucleotides, lipids or salts. 

As you doubtlessly learned in physiology, osmosis is diffusion of water through a semipermeable membrane. The semipermeable membrane allows water to move through it, but most solute particles are either too big or too polar to make it across the membrane. The relative concentration of solutes in osmotic systems is called the tonicity. Two solutions are isotonic if they contain equal concentrations of particles. If the concentrations are not equal, the one with the greater concentration is the hypertonic solution, and the one with the lower concentration is the hypotonic solution. It is critically important to notice that tonicity is a comparative concept, and it makes no sense to call a solution hypertonic without indicating to which solution you are comparing it. For example, is a 5% NaCl solution hypotonic or hypertonic You are probably tempted to say hypertonic, because you are mentally comparing this solution to normal saline, which is 0.89% (w/w) NaCl. So, 5% NaCl is hypertonic to normal saline. However, 5% NaCl is hypotonic to 10% NaCl and isotonic with another solution of 5% NaCl. 

If we separate a 5% NaCl solution from a 1% NaCl solution by a semipermeable membrane, as illustrated in Figure 8.4, in which direction will osmosis occur Osmosis is the diffusion of water, and diffusion always spontaneously occurs in the direction from an area of high concentration to an area of low concentration. Since the concentration of water in the hypotonic solution is greater that the concentration of water in the hypertonic solution, osmosis always spontaneously occurs from the hypotonic solution to the hypertonic solution. 

Living cells, among them the red blood cells, are surrounded by semipermeable membranes. The osmolarity of most cells is 0.30 osmol. For example, a 0.89% w/v NaCl solution, normally referred to as physiological saline solution, has an osmolarity of 0.30. Thus when a cell is put in physiological saline solution, the osmolarity on both sides of the membrane is the same and therefore no osmotic pressure is generated across the membrane. Such a solution is called isotonic. On the other hand, if a cell is put in water (pure solvent) or in a solution which has lower osmolarity than the cell, there will be a net flow of water into the cell driven by the osmotic pressure. Such a solution is called hypotonic. A cell placed in a hypotonic solution will swell and eventually may burst. If that happens to a red blood cell, the process is called hemolysis. In contrast, a solution with higher osmolarity than the cell is called a hypertonic solution. A cell suspended in a hypertonic solution will shrivel there is a net flow of water from the cell into the surroundings. When that happens to a red blood cell, the process is called crenation. 

In general, however, hypotonic solutions are well tolerated in the eye and can lead to better corneal absorption of the drug due to a concentration effect on the formulation and increased permeability of the cornea (both by virtue of uptake of water from the formulation by the corneal tissue). 

Osmotic Pressure The osmolality of the lacrimal fluid is mainly dependent on the number of ions dissolved in the aqueous layer of the tear film and normally ranges between 310 and 350mOsm/kg [44], When an ophthalmic solution is instilled into the eye, it mixes with the tear fluid, resulting in an osmotic pressure that is dependent on the osmolality of the tears as well as that of the formulation and the amount of the formulation instilled. In general, hypotonic solutions are better tolerated by... 

Q2 Sweat is a hypotonic solution containing water, sodium and chloride. Loss of sweat decreases ECF volume and increases its osmolarity. If the volume lost is not great, the kidney can compensate by retaining extra sodium and water from the glomerular filtrate. But when loss of fluid via sweat is severe, the compensatory mechanisms may cause the kidney to stop producing urine for a time (anuria). 

Solutions that have identical osmotic pressures are said to be isotonic solutions. Fluids administered intravenously must be isotonic with body fluids. For example, if cells are bathed in a hypertonic solution, which is a solution having an osmotic pressure higher than that of the cell fluids, the cells will shrivel because of a net transfer of water out of the cells. This phenomenon is called crenation. The opposite phenomenon, called lysis, occurs when cells are bathed in a hypotonic solution, a solution with an osmotic pressure lower than that of the cell fluids. In this case the cells rupture because of the flow of water into the cells. 

The combination of active drug, preservative, and vehicle usually results in a hypotonic formulation (< 290 mOsm). Simple or complex salts, buffering agents, or certain sugars are often added to adjust osmolarity of the solution to the desired value. An osmolarity of 290 mOsm is equivalent to 0.9% saline, and this is the value sought for most ophthalmic and intravenous medications.The ocular tear film has a wide tolerance for variation in osmotic pressure. However, increasing tonicity above that of the tears causes immediate dilution by osmotic water movement from the eyelids and eye. Hypotonic solutions are sometimes used to treat dry eye conditions and to reduce tear osmolarity from abnormally high values. 

Subendothelial ECM is prepared from EC which had been confluent for 5-7 days. There are basically two ways of removing EC from their substrate either intact, or lysed in a hypotonic solution with a detergent. Both treatments leave the underlying matrix firmly attached to the dish. 

---