Diabetes Pharmacology and Guidelines Flashcards
(135 cards)
Describe the chemical (primary) structure of insulin:
Two peptide chain
Chain A: 21 a.a residues
Chain B: 30 a.a residues
Chains linked by disulphide bridges between (A7 and B7) and (A20 and B19)- tertiary
Chain A is also internally bridged between A6 and A11
What are the different types of insulin and their differences and which ones are used now?
Bovine
Porcine
Human
Very similar but different a.a residues on A8, A10 and B30
Describe the physical (secondary) structure of insulin:
Alpha helix
Three segments
Intramolecular H-bonding between amide groups
Describe the physical (tertiary) structure of insulin:
Disulfide bridges
Describe the Dimer (quaternary) structure of insulin:
In solution exists as dimers
Anti-parallel B sheet formed between B23 and B30, with B28 proline which is important in weak hydrophobic interactions stabilised by H-bonding involving R24 and R26
Describe the Hexamer (quaternary) structure of insulin:
Two Zn ions and three insulin dimers
Globular, not soluble
Interior is mainly non polar a.a side chains
Exterior is mainly polar a.a side chains
What are the two forms of conformation of the B chain in insulin?
T (extended B1 to B8)
R (alpha helix B1 to B8)
Which one of the conformation of the B chain in insulin is more predominant and stable?
R state found in presence of phenol or cresol
R state is more stable
What does insulin need to be in order to be absorbed?
Dissolved
What are the physical properties of insulin?
White powder
Can be amorphous or crystalline
Practically insoluble in water, ethanol and ethers
Dissolves in dilute mineral acids
Dissolves and decomposes in dilute solutions of alkali hydroxides
Which structure of insulin will dissolve faster?
Amorphous
What is the process in obtaining natural insulin?
Pig or cow, insulin from pancreas
Needs to be free from transmissible spongiform encephalopathies (TSF)
Long and involved purification process: extraction, purification, analysis
Describe semi-synthetic human insulin?
Chemically identical to human insulin
Enzymatically modified porcine insulin
Label must state ‘emp’
How is semi-synthetic human insulin made?
Generate purified porcine insulin as normal and then change the B30 residue from alanine to threonine by action of an enzyme
What does ‘emp’ stand for on an insulin label?
Enzymatically modified porcine
Describe biosynthetic human insulin:
Chemically identical to human insulin
Recombinant DNA tech
Label must contain the method of preparation :
‘Prb’ ‘Crb’ ‘Pyr’
How is biosynthetic human insulin made?
Identify gene codes for insulin in humans
Insert gene into the plasmid of a bacterial or fungal vector
Grow the modified bacterium/fungus
Harvest and purify the human insulin
What does ‘Prb’, ‘Crb’ and ‘Pyr’ stand for on an insulin label?
Prb and Crb= purified recombinant bacterial
Pyr= purified yeast recombinant
What is one unit equivalent to in human insulin?
0.0347mg
How is insulin administered?
Normally Subcutaneously
Occasionally IM
IV in emergencies
Where is the absorption of insulin fastest when it is injected and what can also increase the rate of absorption?
Fastest at abdominal wall
Exercise and heat will increase rate
Name the five types of insulin formulations:
Soluble insulin (neutral insulin)
Insulin Zinc suspension
Isophane insulin (NPH-neutral protamine hagedorn)
Protamine zinc insulin
Biphasic isophane insulin
Describe soluble insulin:
Insulin is all in solution in the dimer form, fast acting and clear
Describe Insulin zinc suspension:
Crystalline/ amorphous/ mixed (70:30 C:A)
Insulin is all as solid particles so it takes time to go from hexamers to dimers as in complex