Insulin administration continuous subcutaneous

II.f.1.3. Insulin delivery. Traditionally insulin was given intramuscularly and later subcutaneously. New technology has provided devices for insulin administrations including pen-devices, air powered injectors, external insulin infusion pumps (or continuous subcutaneous insulin infusion, CSII), and implantable insulin infusion pumps. Some novel forms of insulin delivery have been introduced, for example intranasal insulin gives peak insulin concentrations at 10-20 minutes after administration, but most insulin is still administered subcutaneously. 

The standard mode of insulin therapy has traditionally been by subcutaneous injection using disposable needles/syringes. However, other routes of administration, including continuous subcutaneous insulin infusion pumps and inhalation of finely powdered aerosolized insulin, are currently being explored. 

After the administration of insulin lispro it is not necessary to delay a meal until sufficient insulin is absorbed. Insulin lispro can be given immediately before or during a meal and can be used when rapid action is important, as in outpatient treatment of ketonuria (1) or in continuous subcutaneous insulin infusion (2). Insulin lispro can be successful in patients with subcutaneous insulin resistance (3). 

Drug administration route Continuous subcutaneous insulin infusion (CSII) Recent technology has combined insulin pumps with continuous blood glucose sensors. In... 

Possible advantages of intraperitoneal versus subcutaneous insulin include the avoidance of erratic absorption (both rate and extent of absorption), convenience, avoidance of subcutaneous injection site-related complications, and prevention of peripheral hyperinsulinemia. Insulin appears to be cleared into the systemic compartment by an active transport process, or via the peritoneal lymphatics. A number of studies have demonstrated the bioavailability of intraperitoneal insufin to be about 25% to 30%, although none clearly compares the clinical effectiveness of intraperitoneal versus subcutaneous insufin in diabetes control. Insufin requirements for PD patients may be greater than in hemodialysis patients because of the continued absorption of dextrose from the peritoneal cavity. Furthermore, because of adsorption of insufin to the polyvinyl chloride bag and administration set, the intraperitoneal dose of insufin often needs to be two to three times the subcutaneous maintenance dose. 

The subcutaneous route for administration of insulin has many serious drawbacks, and alternative routes continue to attract considerable research interest. Nearly all available orifices of the human body seem to have gained attention as presenting possible noninvasive sites for insulin absorption. However, even by using modem enhancer techniques, only a small or minor fraction of the hormone becomes bioavailable when provided by most of these routes, except perhaps the pulmonary route. Key barriers to insulin absorption via the alternative routes are the resistance of those membranes to insulin penetration, the tendency of insulin to exist in associated form, and insulin proteolysis. Protection from proteolysis through some sort of encapsulation, the use of complex emulsion systems, and/or the use of protease inhibitors—association of the hormone with polymeric particles, and addition of permeation enhancers have been utilized to overcome those barriers. The absorption and enzymatic barriers to nonparenterally administered protein dmgs and the use of enhancers to modify absorption have been discussed in recent reviews (Lee, 1986 Lee e/a/., 1991a Zhou, 1994). The present review of alternative administration of insulin mainly covers investigations published since 1970. 

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