Insulin

insulin-01

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.

insulin-02

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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