Insulin Flashcards
Instability of insulin
Drug instability may be advantageous to certain individuals, e.g., insulin
Numerous accidental insulin overdoses
Prolonged hypoglycemia light threatening
Less frequent agent of suicide in both diabetics and non-diabetics
Insulin used as an instrument of homicide
Rare occurrence
Marks review of the literature found only 66 cases worldwide
Conviction only 31 cases, with the additional weapon used in 11 of the cases
Nurse Kenneth Barlow
1st. case of murder facilitated by insulin in england
“You could commit a perfect murder with insulin. It cannot be traced”
Wife was pregnant and neither wanted a baby
Gave her injections to “induce an abortion”
Found “drowned”…
Pathologist noted four injection sites in her buttocks
Excised for analysis
Insulin detected; not a diabetic, thus no need for insulin
Barlow gave wife insulin, instead of abortifacient, to make her stuporous and complaisant
Placed her comatose in the tub – slide under the water and drowned
Martha sharp crawford von bulow
Known as Sunny von Bulow
American heiress, socialite, and philanthropist
o Found in coma
o Husband, Claus von Bulow
Convicted of attempting murder to her (1980) by insulin overdose
o Second trial found him not guilty
Experts opined that there was no insulin injection
Symptoms attributed to over-use of Rx drugs
o Sunny von Bulow lived almost 28 years in a persistent vegetive state until her
death in a New York nursing home on dec 6, 2008
proinsulin
o Two peptide chain molecules (insulin) linked by connecting peptide [C-peptide]
o Synthesized by the B-cells of the pancreas
what do you see when you increase glucose
Causes a proteolytic cleavage of the proinsulin molecule
o T=yields the active insulin molecule and the inactive c-peptide in a molar ratio
of 1:1
C-peptide
C-peptide is produced simultaneously with insulin in the insulin precursor – proinsulin
In proinsulin, C-peptide is located as if connection insulin A and B chains
So, it is called “c(onnecting) peptide”
plasma half life
Plasma half-life of insulin is ~5-8 minutes
o Degraded by red-cell proteolytic enzymes, in kidney and liver
C-peptide half life
10-20minutes
degraded by kidneys
what can happen if patient previously exposed to exogenous insulin
may develop antibodies to insulin
degrade degration
leads to falsely high or low values
what is the main difference between endogenous and exogenous insulin
Major difference between commercial insulin and endogenous insulin is the absence of
C-peptide
what do you expect with large dose of exogenous insulin
elevated insulin and suppressed C-peptide
o Suppression of C-peptide due to negative feedback system
Stops cleavage
o Hypoglycemic effect of insulin potentiated by alcohol
IS insulin stable
fairly stable at 4C
significant degaration notes at 37V four to five days
normal ranges of insulin
serum: 0-22
C-peptide.08-4.6
normal fasting regions for insulin
5-75
fatal insulin ranges
800-3200