Parenteral preparations should be isotonic with human plasma to avoid tissue damage. However, not all drugs in the recommended doses are isotonic with blood, so an osmotic pressure regulator needs to be added to the formulation. The most commonly used regulator is glucose, while others such as glycerol and sodium chloride are less commonly used. Other commonly used osmotic pressure regulators are glycerin and mannitol. CD Formulation has professional production equipment and management experience, as well as professionals with rich professional knowledge. We can also custom osmotic pressure regulator with different specifications and quality requirements, and produce corresponding products according to customer needs.
Maintaining the osmotic pressure of plasma is not only necessary for cell survival, but also related to maintaining the body's water balance. Therefore, the osmotic pressure of injections should be as equal as possible to plasma. Any solution with the same osmotic pressure as plasma and tear fluid is called isotonic solution, such as 0.9% sodium chloride solution and 5% glucose injection. When the hypertonic solution is injected, the red blood cells will shrink due to the exudation of water. However, the body has a certain function of regulating osmotic pressure. As long as the input volume is not too large and the speed is not too fast, it will not produce adverse effects. Therefore, intravenous injection of 10%, 50% glucose and other hypertonic solutions is harmless in clinical practice. However, injecting a large amount of hypotonic solution may cause hemolysis, which must be avoided. 0.45% sodium chloride solution can cause hemolysis, and 0.35% sodium chloride solution can completely hemolyze. Intravertebral injection, isotonic solution must be used.
Commonly used osmotic pressure regulators: glucose, sodium chloride, phosphate or citrate, etc.
Fig.1 Osmotic Pressure Regulators - Glucose
The most commonly used calculation methods for adjusting isotonicity: freezing point reduction data method and sodium chloride isotonic equivalent method.
(1) Freezing point reduction data method: The freezing point of plasma is -0.52 °C, and for any solution, the freezing point is reduced to -0.52 °C, which is isotonic with plasma.
(2) Sodium chloride isotonic equivalent method: Sodium chloride isotonic equivalent refers to the isotonic effect of 1 g drug equivalent to the number of grams of sodium chloride.
(3) Isotonic solution and isotonic solution: Isotonic solution: a solution whose osmotic pressure is equal to the osmotic pressure of plasma. Some isotonic solutions (boric acid, ephedrine hydrochloride, cocaine hydrochloride, ethylmorphine hydrochloride) cannot keep the volume and shape of red blood cells normal. Isotonic solution: A solution that has the same tension as the red blood cell membrane. The red blood cells in the isotonic solution can maintain normal volume and shape, and hemolysis will not occur.
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