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P A R T 6
Drugs acting on the endocrine system
Past
Subcutaneous insulin injection
. The delivery of insulin
by subcutaneous injection was introduced in the 1920s
and changed the way that diabetic people were managed
clinically, giving them a chance for a normal lifestyle.
Research is ongoing to find more efficient and acceptable
ways to deliver insulin to diabetic people.
Present
Subcutaneous insulin injection
. This remains the primary
delivery system.
Insulin jet injector
. This cylindrical device shoots a fine
spray of insulin through the skin under very high
pressure. Although it is appealing for people who do
not like needles or have problems disposing of needles
properly, it can be very expensive.
Insulin pen
. This syringe-like device looks like a pen. It has
a small needle at the tip and a barrel that holds insulin
(Figure 38.1). The person “dials” the amount of insulin
to be given and injects the insulin subcutaneously by
pressing on the top of the pen. This is advantageous for
people who need insulin two or three times during the
day but cannot easily transport syringes and needles.
It is a subtle way to give insulin, and is popular with
students and business people on the go. It is important
to rotate the syringe 15 to 20 times before injecting the
insulin to disperse it. People often forget this point after
using the pens for a while, and as a result, may inject far
too much or too little insulin when it is needed. Periodic
reinforcement of the administration instructions is
important.
External insulin pump
. This pump device can be worn on a
belt or hidden in a pocket and is attached to a small tube
inserted into the subcutaneous tissue of the abdomen.
The device slowly leaks a base rate of insulin into the
abdomen all day; the person can pump or inject booster
doses throughout the day to correspond with meals and
activity. The device does have several disadvantages. For
example, it is awkward, the tubing poses an increased
risk of infection and requires frequent changing, and
the person has to frequently check blood glucose levels
throughout the day to monitor response.
Long-acting insulin
. The year 2001 brought the release
of a subcutaneous insulin that lasts two to three times
longer than NPH insulin. This should decrease the need
for multiple injections and may increase glucose control,
especially for people with erratic glucose levels during
the night. Long-term effects of this type of insulin
therapy are not yet known.
Future
Implantable insulin pump
. This pump is surgically
implanted into the abdomen and delivers base insulin
as well as insulin boluses as needed directly into the
abdomen to be absorbed by the liver, just as pancreatic
insulin is (Figure 38.2). The disadvantages are risk of
infection, mechanical problems with the pump and lack
of long-term data on its effectiveness. This method is not
yet available for general use.
Insulin patch
. The patch is placed on the skin and delivers
a constant low dose of insulin. When the person eats
a meal, tabs are pulled on the patch to release more
insulin. The problem with this delivery method is that
insulin does not readily pass through the skin, so there is
tremendous variability in its effects. This route is not yet
commercially available.
Inhaled insulin
. The lung tissue is one of the best sites for
insulin absorption. An aerosol delivery system has been
developed that delivers a powdered insulin formulation
directly into the lung tissue. Research has been very
promising, suggesting that this may be a more reliable
method of delivering insulin in the future.
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BOX 38.5
Insulin delivery: Past, present and future
FIGURE 38.1
Pre-filled insulin syringe. (From Farrell, M. &
Dempsey, J. (2014).
Smeltzer & Bare’s Textbook of Medical-
Surgical Nursing
(3rd edn). Sydney: Lippincott Williams & Wilkins.)
SEL
ACT
FIGURE 38.2
Person wearing an insulin pump. (From Dempsey, J.,
Hillege, S. & Hill, R. (2014).
Fundamentals of Nursing and
Midwifery
(2nd edn). Sydney: Lippincott Williams & Wilkins.)
