Application of Insulins

The particular insulin employed, such as human or animal, the type of formulation, the route of administration, and the frequency of administration must be chosen to suit the needs of the individual patient. The dose must also be determined for each patient, and, although a precise dose range cannot be given, a total dose in excess of about 80 units daily would be unusual and may indicate the presence of a form of insulin resistance (Martindale, 1989). 

The short-acting insulins are usually injected between 30 and 45 min before meals. The intermediate-acting insulins should be given once a day before 

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Insulin is used for the treatment of Type-I and for Type-II diabetes mellitus, when other therapeutic measures, i.e. appropriate diet and oral antidiabetics, are not sufficient to produce normoglycaemia. The physiological actions of insulin including recent advances in our knowledge on signal transduction have been discussed above (chapter 4). Since treatment of diabetes with insulin attempts only to supplement inadequate insulin secretion, this chapter will concentrate on pharmacokinetics, unwanted effects and clinical applications of insulin and its pharmaceutical preparations. 

Furthermore, microneedle systems have recently been the subject of investigation. Needles with a diameter of between 2 and 10 pm can be used to overcome the stratum corneum, leaving only very small holes that are comparable to those caused by the techniques mentioned above. The needles can be solid and sharp (solid needle), hollow and sharp (hollow needle), or hollow and blunt (hollow tubes). They have a length of about 50-100 pm, which is not long enough to reach the pain adaptors in the deeper skin. When assembled in an 3 X 3 mm array of about 400 needles, the total diameter of the microneedles is similar to a 30-G needle, and this provides a suitable application tool. Initial trials with the application of insulin have shown promising results [159]. Examples of microneedles are shown in Fig. 1.7 (from Refs. [160, 161]). 

Early applications of crystalline fructose focused on foods for special dietary applications, primarily calorie reduction and diabetes control. The latter application sought to capitalize on a signiftcandy lower serum glucose level and insulin response in subjects with noninsulin-dependent diabetes melUtus (21,22) and insulin-dependent diabetes (23). However, because fmctose is a nutritive sweetener and because dietary fmctose conversion to glucose in the hver requires insulin in the same way as dietary glucose or sucrose, recommendations for its use are the same as for other nutritive sugars (24). Review of the health effects of dietary fmctose is available (25). 

While the major application of albumin microspheres is in the area of chemotherapy, there have been studies reporting the release of such varied compounds as 1-norgestrel (97), insulin (98), and hematoporphyrins (99) from bovine serum albumin, and the antibacterial sulfadiazine from ovalbumin (100). In general, burst phenomena are found for all systems studied. However, the results from the insulin study are worthy of note in that blood glucose levels were depressed for more than 14 days following the administration of insulin-containing BSA microspheres to diabetic rats. The smaller microspheres were absorbed by day 28 and the larger particles by day 56. 

Kasicka, V., Pruslk, Z., Sazelova, P., Jiracek, J. and Barth, T., Theory of the correlation between capillary and free-flow zone electrophoresis and its use for the conversion of analytical capillary separations to continuous free-flow preparative processes. Application to analysis and preparation of fragments of insulin, ]. Chromatogr. A, 796, 211, 1998. 

Figure 22 Insulin release rate (normalized to mg/hr per 160 mg device) from insulin-loaded matrix of polyethyloxazolin-poly(methacrylic acid) complex with the application of step-function electric current in 0.9% saline solution (mean from three measurements). ( ) Current on (5mA) (O) current off. (From Ref. 47.)...

Kato, K., Hamaguchi, Y., Fukui, H., and Ishikawa, E. (1975a) Enzyme-linked immunoassay. I. Novel method for synthesis of the insulin-b-D-galactosidase conjugate and its applicability for insulin assay. /. Biochem. (Tokyo) 78, 235. 

The biopharmaceutical sector is largely based upon the application of techniques of molecular biology and genetic engineering for the manipulation and production of therapeutic macromolecules. The majority of approved biopharmaceuticals (described from Chapter 8 onwards) are proteins produced in engineered cell lines by recombinant means. Examples include the production of insulin in recombinant E. coli and recombinant S. cerevisiae, as well as the production of EPO in an engineered (Chinese hamster ovary) animal cell line. 

Reverse-phase HPLC (RP-HPLC) separates proteins on the basis of differences in their surface hydophobicity. The stationary phase in the HPLC column normally consists of silica or a polymeric support to which hydrophobic arms (usually alkyl chains, such as butyl, octyl or octadecyl groups) have been attached. Reverse-phase systems have proven themselves to be a particularly powerful analytical technique, capable of separating very similar molecules displaying only minor differences in hydrophobicity. In some instances a single amino acid substitution or the removal of a single amino acid from the end of a polypeptide chain can be detected by RP-HPLC. In most instances, modifications such as deamidation will also cause peak shifts. Such systems, therefore, may be used to detect impurities, be they related or unrelated to the protein product. RP-HPLC finds extensive application in, for example, the analysis of insulin preparations. Modified forms, or insulin polymers, are easily distinguishable from native insulin on reverse-phase columns. 

Examples of the early application of recombinant DNA technology in medicine are the development of recombinant human growth hormone human insulin human interferons, thought to have anticancer activity in addition to antiviral activity interleukins (regulatory proteins from lymphocytes that are believed to be important in the treatment of immunodeficiency diseases and cancer) tumor necrosis factor epidermal and bone marrow progenitor cell growth factors and the production of vaccines (Table 12.1). 

The scope of applicability of radioimmunoassay is rapidly expanding with the dawn of each day as RIA is being developed for newer pharmaceutical substances. It has attained wide recognition and application both in vitro and in vivo measurements of compounds of interest like insulin, gastrin, glucagon, and growth hormones on one hand whereas drugs like ... 

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