Insulin
Mechanism of action:Insulin acts by binding with
insulin receptor.Insulin receptor (IR) is a glycoprotein of 3,50,000 MW.It has
2 subunits:
[A]2
α-subunites:Lying outer aspect of cell membrane.
[B]2 β-subunits:Which are transmembranous.Tyrosine kinase
is related to β-subunit.
Steps:
Binding of insulin with α-subunite
of insulin receptor
↓
Auto-phosphorylation of β-subunit
↓
Activation of β-subunit
↓
Stimulation of some enzyme in the
cell and they perform all the activities of insulin.
Pharmacological effects/Adverse effects:
Type of metabolism
|
Liver
|
Skeletal muscle
|
Adipose tissue
|
Carbohydrate metabolism
|
↑Glycogenesis.
↑Glycolysis.
↓Glycogenolysis.
↓Gluconeogenesis
|
↑Glucose uptake
↑Glycolysis
↑Glycogenesis
↓Glycogenolysis
|
↑Glucose uptake
↑Fatty acid synthesis
↓Lipolysis
|
Protein metabolism
|
↑Amino acid uptake
↑Protein synthesis
|
||
Fat metabolism
|
↑Glycerol synthesis
↑Synthesis of triacylglyceride
↓Liolysis
|
Indications:
1)
IDDM.
2)
NIDDM-When OHA fail.
3)
DM associated with complications:
·
DM+Ketoacidosis.
·
DM+Nephropathy.
·
DM+Retinopathy.
·
DM+Gangrene(Sever infections)
4)
DM in pregnancy(because OHA can cross placenta &
teratogenic)
5)
DM pt during(before 1 day)and after surgery.
6)
Hyperkalaemia.
Insulin is administered:
1)
Sub.cutaneous→
hour before breakfast to prevent sever
hypoglycemia.
2)
I.V→in case of emergency.
Preparations of insulin:
1)
Bovine insulin(from cow)
2)
Procine insulin(from pork)
3)
Human insulin(from man)
Adverse effects/Complication of insulin/Hazared of insulin:
1)
Hypoglycemia:Hypoglycaemic reaction,hypoglycaemic shock.
2)
Insulin allergy.
3)
Lipodystrophy.
4)
Insulin edema.
5)
Rebound hyperglycemia.
6)
Insulin resistance.
7)
Obesity.
8)
Hypokalaemia.
9)
Alopecia.(Loss of hair)
Contraindications:
1)
Hypertension taking β blocks.
2)
Insulin resistance case.
3)
Hypersensitizing to insulin.
Classify anti-diabetic drugs:
[A]According
to onset & duration of a action:
Types
|
Example
|
Onset of action
|
Duration of action
|
Route of adm
|
1.Rapid acting insulin(soluble insulin)
|
*Insulin lispro
*Insulin aspart
*Insulin glulisine
|
Within 15-60 min
|
3-5 hours
|
IV
|
2.Short acting insulin(Soluble insulin)
|
*Regular insulin
*Natural insulin
|
Within 30 min
|
5-8 hours
|
IV
|
3.Termediate acting insulin
|
*NPH or Isophane
*Insulin zinc suspension (Lente)
|
Within 1-2 hours
|
12-24 hours
|
Subcutaneous
|
4.Long acting insulin
|
*Crystalline insulin zinc suspension
*Protamine zinc insulin suspension
*Insulin glargine
|
4-6 hours
|
>24 hours
|
Subcutaneous
|
5.Mixture of insulin:(Biphasic insulin)
|
*Soluble(25%)+ Crystalline(75%)
*Crystalline+Isophane
*Soluble(50%)+Isophane(50%)
|
1 or 2 hours
|
24 hours
|
Subcutaneoous
|
[B]According to source:
1)
Mixed species insulin:70% bovin + 30% porcine insulin(&
other combination)
2)
Monospecies insulin(Porcine):
·
Actrapid.
·
Monotard.
·
Semitard.
3)
Newer insulin preparation:
·
Human insulin:
ü Enzyme modified porcine
insulin(EMP).
ü
Chain recombinant bacterial insulin(CRB).
·
Human proinsulin.
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