HUMULIN “ONE STEP AHEAD OF INSULIN” BY – SUBHAJIT HAZRA(3RD YEAR, 6TH SEMESTER) PHARMACEUTICAL ENGINEERING (BACHELOR OF PHARMACY)

CONTENTSI. Introduction.II. Insulin Biosynthesis.III. Need for genetically engineered

Insulin(Humulin).IV. Humulin.V. Humulin synthesis.VI. Clinical Pharmacology of Humulin.VII. Advantage and disadvantage of humulin

I. INTRODUCTION Diabetris Mellitus – Diabetes, often referred to by doctors as diabetes mellitus, describes a group of

metabolic diseases in which the person has high blood glucose (blood sugar). Patients with high blood sugar will typically experience polyuria (frequent urination), they will become increasingly thirsty (polydipsia) and hungry (polyphagia).

Types: Type 1 Diabetes - the body does not produce insulin.

Approximately 10% of all diabetes cases are type 1. Type 2 Diabetes - the body does not produce enough insulin

for proper function. Approximately 90% of all cases of diabetes worldwide are of this type.

Symptoms: hyperglycemia,increasedurination,thirst,hunger,weight loss, weakness. These can be managed by various treatments, one of which is insulin treatment.

II. INSULIN PRODUCTION . Insulin is produced by the β cells of islets of langerhans of pancreas. The gene(Human Insulin Gene) responsible for this protein synthesis is located on chromosome 11. The insulin mRNA is translated as a precursor called preproinsulin, removal of its signal peptide

during insertion into the endoplasmic reticulum generates proinsulin. Proinsulin consists of three domains: an amino-terminal B chain, a carboxy-terminal A chain and a

connecting peptide in the middle known as the C peptide. Within the endoplasmic reticulum specific endopeptidases excise the C peptide, thereby generating the mature form of insulin.

Insulin and free C peptide are packaged in the Golgi apparatus which accumulate in the cytoplasm. When the beta cell is appropriately stimulated, insulin is secreted from the cell by exocytosis and

diffuses into islet capillary blood. C peptide is also secreted into blood, but has no known biological activity.

β cells preproinsulin translocation proinsulin (rough ER)

insulin golgi apparatus

FIG 1 – MECHANISM OF INSULIN BIOSYNTHESIS

III. NEED FOR GENETICALLY ENGINEERED INSULIN (HUMULIN).

In the 1920s ,physicians began giving insulin purified from the pancreas of pigs(porcine) and cows(bovine) to the diabetic patients as porcine and bovine insulin were similar to human insulin.

As their was a slightly difference in the human and animal produced insulin it resulted in the production of antibodies against the animal’s insulin in the patient’s body,

This in turn resulted in inflammatory responses at the site of injection.

Thus evidenced from various clinical cases led researchers to synthesize humulin(Genetically Engineered Insulin).

IV. HUMULIN It was 1st prepared by Eli Lily &Co.(Humulin N / R). Humulin R® U-500 is a polypeptide hormone structurally identical

to human insulin synthesized through rDNA technology in a special non-disease-producing laboratory strain of Escherichia coli bacteria.

Humulin R® U-500 is a sterile, clear, aqueous and colorless solution that contains human insulin (rDNA origin)

Humulin R U-500 is for subcutaneous injection only and should not be used intravenously or intramuscularly.

Humulin

short acting intermediate acting(takes 30 min.to act) (takes 2 to 4 hr. to act)e.g: Humulin S Humulin N(Neutral Protamine Hagedorn)

V. HUMULIN SYNTHESIS Synthesis of Humulin is a 2 Step Reaction –

Step 1 of Synthesis – Synthesis of r-dna and its introduction in vector.

At first, the DNA chains carrying the nucleotide sequences specifically for A & B chains, are synthesized chemically.

This requires 63 nucleotides to synthesize A chain , 90 nucleotides for B chain and a terminator codon to terminate synthesis when required.

Also,an anticodon methionine , which is added at the beginning of the sequence to distinguish humulin from the other bacterial proteins is required.

The synthetic A &B chain are then separately inserted into the plasmid.

Step 2 of Synthesis – Clonning of r-dna in host (E.coli )

The r-plasmids are then introduced into the E.coli cells,where the insulin gene is expressed as it replicates with the enzyme in the cell undergoing mitosis.

The protein which is formed, consists partly of β galactosidase, joined either to A or B chain of insulin, from where the A &B chains are extracted and purified.

The two chains are mixed and reconnected in a reaction that forms the disulphide cross bridges, resulting in pure humulin.

Due to the complexity in it’s (humulin’s) purification technique from the bacteria, now a days we use yeast cells (eukaryotic) as the vector which secreate the whole humulin molecule with perfect 3D structure.

FIG 2 - STEP 1 OF SYNTHESIS – SYNTHESIS OF R-DNA AND ITS INTRODUCTION IN VECTOR.

STEP 2 OF SYNTHESIS – CLONNING OF R-DNA IN HOST (E.COLI )

VI. CLINICAL PHARMACOLOGY OF HUMULIN. Administered insulin, including Humulin R U-500, substitutes for inadequate

endogenous insulin secretion and partially corrects the disordered metabolism and inappropriate hyperglycemia of diabetes mellitus, which are caused by either a deficiency or a reduction in the biologic effectiveness of insulin.

When administered in appropriate doses at prescribed intervals to patients with diabetes mellitus, Humulin R U-500 restores their ability to metabolize carbohydrates, proteins and fats.

As with all insulin preparations, the duration of action of Humulin R U-500 is dependent on dose, site of injection, blood supply, temperature, and physical activity.

The time course of action of any insulin may vary considerably in different individuals or at different times in the sameindividual.

VII.ADVANTAGES & DISADVANTAGES OF HUMULIN

Advantage: a) Humulin could be created in large amounts and at relatively low

cost.b) It doesn’t produces inflammatory response in diabetic patients.

Disadvantage:a) Some patients have claimed that on switching to human insulin

from animal insulin, resulted in increased risk of hypoglycemia.b) But, research study have found no significant difference in the

frequency of hypoglycemia between users of two different types of insulin.

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