Isophane

Therapeutic Function Hypoglycemic Chemical Name Isophane insulin Common Name Isophane insulin injection 

Trade Name Manufacturer Country Year Introduced 

This is a crystalline product of insulin and an alkaline protein where the protein/insulin ratio is called the isophane ratio. This product gives a delayed and uniform insulin action with a reduction in the number of insulin doses necessary per day. Such a preparation may be made as follows 1.6 g of zinc-insulin crystals containing 0.4% of zinc are dissolved in 400 ml of water, with the aid of 25 ml of 0.1 N hydrochloric acid. To this are added aqueous solutions of 3 ml of tricresol, 7.6 g of sodium chloride, and sufficient sodium phosphate buffer that the final concentration is As molar and the pH is 6.9. 

Trade Name Manufecturer Country Year Introduced 

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NPH Isophane Human Insulin Suspension. NPH isophane insulin, also called Humulin N, Insulatard NPH Human, or Novolin N is an intermediate-acting form of human insulin produced by recombinant DNA techniques. Mixtures Humulin 70/30 and Novolin 70/30 contain 70% NPH isophane and 30% regular, whereas Humulin 50/50 contains 50% NPH isophane and 50% regular. It is adrninistered subcutaneously and should not be given intravenously. Absorption is delayed because the insulin is conjugated with protamine in a complex of reduced isoelectric solubiUty. Therapeutically, this preparation is probably comparable to purified porcine NPH insulin. However, human NPH insulin may have a slightly shorter duration of action than comparable purified porcine products. 

METHODS OF ADMINISTERING INSULIN. Several methods can be used to administer insulin. The most common method is the use of a needle and syringe Use of microfine needles has reduced the discomfort associated with an injection. Another method is the jet injection system, which uses pressure to deliver a fine stream of insulin below the skin. Another method uses a disposable needle and special syringe The syringe uses a cartridge that is prefilled with a specific type of insulin (eg, regular human insulin, isophane [NPH] insulin, or a mixture of isophane and regular insulin). 

A patient is required to take 10 units of U-40 isophane insulin suspension and 18 units of U-100 protamine zinc insulin. What volume, in milliliters, of each type will provide the desired dosage ... 

A medication order in the hospital setting calls for isophane insulin suspension to be administered to a 152-lb patient on the basis of 1 unit per kg per 24 hours. How many units of isophane insulin suspension should be administered daily ... 

Insulin suspensions. When the hormone is injected as a suspension of insulin-containing particles, its dissolution and release in subcutaneous tissue are retarded (rapid, intermediate, and slow insulins). Suitable particles can be obtained by precipitation of apolar, poorly water-soluble complexes consisting of anionic insulin and cationic partners, e.g the polycationic protein protamine or the compound aminoqui-nuride (Surfen). In the presence of zinc and acetate ions, insulin crystallizes crystal size determines the rate of dissolution. Intermediate insulin preparations (NPH or isophane, lente or zinc insulin) act for 18 to 26 h, slow preparations (protamine zinc insulin, ultralente or extended zinc insulin) for up to 36 h. 

ISOPHANE INSULIN SUSPENSION (NPH insulin combined with protamine and zinc) ... 

Isophane insulin preparations containing equimolar quantities of insulin and protamine in order to prolong its duration of action... 

Biphasic insulins are fixed dose combinations of a short-acting and intermediate-acting insulin in various proportions. Examples are Humulin, a biosynthetic human insulin (rDNA origin) suspension with respectively 20%, 30% and 40% regular and 80%, 70% and 60% isophane insulin and Mixtard, a biphasic biosynthetic human insulin suspension with respectively 10%, 20% and 40% soluble and 90%, 80% and 60% isophane insulin. 

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