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Insulin is not a cure for diabetes; it is a treatment. It enables the diabetic to burn sufficient carbohydrates, so that proteins and fats may be added to the diet in sufficient quantities to provide energy for the economic burdens of life. — Sir Frederick Grant Banting'Diabetes and Insulin', Nobel Lecture, 15 September 1925. In Nobel Lectures: Physiology or Medicine, 1922-1941 (1965), 68.
Laughter is the best medicine - unless you're diabetic, then insulin comes pretty high on the list. Jasper Carrott
Introduction Is a protein Synthesised from the beta cells of islets of langerhans. Deficiency causes DIABETES MELLITUS. Gene located on chromosome 11. Name 'insulin'by J de meyer .-1907. Insulin –first hormone for which radioimmunoassay was developed. Name ''insulin'' is derived from word insula—meaning island---a latin word. Connaught initial name Novo nordisk –since 1923
History 1869---Paul Langerhans–two distinct group of cells in pancreas –acinar cells ,islets. 1889---Minkowski---pancreactomized dogs—diabetes mellitus. 1921—Frederick Grant Banting–insulin secreted was destroyed by proteolytic digestion Charles .H.Best, a fourth year medical student –ligated the pancreatic ducts Leonard Thompson, a 14 yr old was the first person to receive insulin .---11 JAN 1922 J.M.Collip-who purified epinephrine,purified insulin also. Purified and crystallized –Abev Aminoacid sequence by Sanger—1960 Complete synthesis of protein-1963 3 dimensional structure—Hodgkins-1971 NOBEL PRIZE in medicine or physiology-1923-Banting and Best,Mcleod and Collip
Secretion of insulin Β cells of islets of langerhans in the pancreas—secrete 110 AA chain ,single chain—PREPROINSULIN. Rough endoplasmic reticulum---24 AAterminal( NH2)of preproinsulin is cleaved off—PROINSULIN During formation of PROINSULIN,the molecule folds,disulfide bonds are formed Converted to INSULIN-golgi complex. During conversion –4 basic AA are removed,remaining connector or C peptide removed byproteolysis. Insulin formed is stored in vesicles. Bound to zinc atoms. Exist in hexamer form.
Structure of insulin 51 amino acids 5808 daltons 2 peptide chains A and B One intrasubunit and two intersubunit disulphide bonds A-21 AA,B-30 AA Slight difference in structure in species Porcine-one AA Bovine—3 AA C peptide differs in all.
Equimolar amounts of C peptide,insulin are released into the circulation. C peptide has no biological function. It is useful index of insulin secretion. Proinsulin-insulin by 2 Ca endopeptidases PC2 lysine arginine—C-A PC3 argininearginine –C-B
Structure of insulin Conserved portions of insulin—3 disulfide bonds Both ends of A chain C terminal residues of B chain
Genetics of insulin Single insulin gene –chromosome 11 Close to IGF-1 Single protein product in most species 2 genes encode—rat,mice---two molecules differ from each other by 2 AA residuesin B chain. Several helical regions in both A and B chains. Proinsulin –INS gene
Existence of insulin Isolated chains of insulin are inactive. In acid solution –dimers At neutral Ph—exist as hexamers and with Zn. Insulin in solution exists as monomer,dimer,hexamer Intermediate,long acting insulins have hexamers are common 2 molecules of zn are incorporated in hexamer . Zn plays a role in crystallization. Monomer is active.
Pharmacology of insulin Introduction of insulin of human insulin,proinsulin gene into organisms—e.coli,yeast-recombinant DNA technology. Insulin ppt at ph—5.4—soluble at 2-3 1 U of insulin -38.5 ug of substance 40 U and 100 U –40u/ml,100u/ml 10 U for infants T1/2—40 min
NN= SaccharomycesCerevisiae Eli lilly= non-disease producing strain of E.Coli Sanofi= non-disease producing strain of E.Coli
Insulin receptor Insulin binds to N and C terminal of subunit of the receptor. cysteine rich region in alpha subunit. Affinity towards receptor-effect on glucose metabolism. Insulin is a member of IGF s. IGF1,IGF2 –are similar to proinsulin ,concerned with growth,Cpeptides are not removed. IGF1 –somatomedin,growth promoting actions of insulin. Proinsulin has 2% metabolic potency of insulin,50% as potent for mitogenesis---atherosclerosis
Regulation of insulin secretion Prinicipal stimulus for insulin secretion is the glucose. Sugar is more effective in provoking insulin secretion when taken orally than when taken IV –inc vagal activity. Stimulants—various nutrients-glucose,AA,FA,ketones. GI hormones pancreatic hormones autonomic neuro transmitters 2 adrenergic receptor—inhibits insulin receptor. Β2 adrenergic receptor,vagal—release. Hypoxia,hypothermia,surgery,severe burns—suppress insulin secretion. 2 antagonists—increases insulin B2 antagonists—decreases insulin HORMONES—GLP-1,GIP-inc insulin Similarly gastrin,secretin,cholecystokinin,VIP,GRP,enteroglucagon
Insulin secretion is BIPHASIC. First phase—peak at 1-2 min,short lived. Second phase-delayed onset,long duration. Depends on intracellular calcium Intracelular Ca—increased by phospholipase C by Ach,cholecystokinin Inc c AMP-b adenylcyclase---GLUCAGON. Insulin circulates in blood as monomer. Distributed in ECF.. Aminoacid which causes secretion of insulin –arginine. Glucokinase acts as glucose sensor. Glucose conc <90mg/dl—no insulin release
Rate of secretion in fasting—1U of insulin /hr into portal vein Conc of insulin 2-4 ng/ml.50-10031U/ml-portal vein Peripheral circulation—0.5ng/ml,12U/ml. Goal of insulin therapy is to mimic this pattern –diificult to achieve with SC injection. T1/2-insulin 5-6 min in normal subjects Increased in diabetes Proinsulin -17 min C peptide -30 min serves as a marker of insulin secretion
degradation Liver,kidney,muscle 50% insulin that reaches liver is destroyed. It is filtered by glomeruli-reabsorbed by tubules –degrade it Renal function impairement appears to affect the rate of disappearance of circulating insulin to a greater extent than hepatic disease Degraded in endosomes of liver. Thiolmetalloproteinases in liver,muscle,kidney,brain insulinase
Functions of insulin Globally— Control of cellular intake of certain substance-glucose in muscle,adipose tissue. Increase of DNA replication and protein synthesis Modification of activity of numerous enzymes.
Types of insulin 20types of insulin products available in four basic forms,each with a different time of onset and duration of action. Which to choose is individulaised Choosing insulin depends on Onset-how soon it starts working peak time-when it works the hardest Duration-how long it lasts in the body. Obesity affects the work of insulin in the body.extra fat tissue –more resistant to insulin.
Types of insulin Five different types Some are clear in appearance .,some are cloudy RAPID ONSET-FAST ACTING INSULIN-novo rapid (insulin Aspart) humalog (Lispro) SHORT ACTING INSULIN—actrapid,Humulin,hypurin neutral(bovine) INTERMEDIATE ACTING INSULIN-cloudy—protamine or zinc added Protamine—protaphane,humulinNPH.hypurinisophane MIXED INSULIN—RAPID/INTERMEDIATE—novomix 30,humalog mix 25,mixtard 30/70,mixtard 20/80 30/70—30% is short acting,70% long acting LONG ACTING INSULIN-lantus-(glargine).levemir(detemir)
Insulin sliding scale Not recommended for subcutaneous injection 50U -50 ml NS Every one hour until the blood glucose level stabilises Rate of infusion adjusted as per blood sugar. <120mg/dl-no insulin 120-200---2U/hr 200-300—3U/hr 300-500---5U/hr >500---7U/hr -JAPI october 2007
Somoygi phenomenon Somogyi effect is a rebounding high blood sugar that is a response to low blood sugar. It is due to counteracting hormones release –glucagon,adrenaline,cortisol Frequent monitoring of blood glucose Night dose to be low compared to morning dose.
Dawns phenomenon Early morning hyperglycemia without nocturnal hypoglycemia. It is due to counter regulatory hormones No need of insulin dose change.
Increasing requirements Infection,stress,puberty,pregnancy,acromegaly,cushings syndrome. Lipohypertrophy at the site of injection Malignancies Compliance of the patient
Decreaesing requirements Impending renal failure Honeymoon phase in type 1 Hypothyroidism Addisons disease Hypopituitarism Remission of diabetes
In renal disease Half of the sliding scale of insulin dose to be given As insulinase enzyme does not function The duration of insulin action increases.
Indications for insulin therapy Type 1 diabetes Women with diabetes who become pregnant or are breastfeeding Transiently in type 2 diabetes in special situations- renal & hepatic disease, pancreatitis, HHS, during surgery, infections etc. In type 2 diabetes, inadequately controlled on OADs
Side effects of insulin use Hypoglycemia Weight gain Locally-allergy infection abscess anaphylaxis
Insulin devices Insulin syringes Delivery pens Insulin pumps Insulin syringes—10ml insulin vials 30 unit—0.3 ml,50 unit-0.5 ml,100 unit-1ml Needles -8mm to 13mm Use each syringe only once. Insulin pen-insulin catridge-3ml-300units fits into the device Disposable, reusable Durable pens are—Novopen3,Novopen demi,Innovo and HumaPen Pre filed disposable devices –innolet,flexpen and Novolet.
Insulin pumps-reservoir of insulin-infusion set worn outside the body—abdomen Only short or rapid acting insulin are used—mimics physiological pattern Inhaled insulin
Mode of administration Subcutaneous Intravenous Inhaled Intramuscular
Sites Rotation of injection site to prevent lipohypertrophy. Within one area. Abdomen has fastest rate of absorption Exercise increases lipohypertrophydecreasees Rate of absorption after IM is faster.
Timing of insulin 30 min prior to meals Not to exceed 30 min in case of rapidly acting insulins Intermediate acting insulin –bed time.
Insulin injection Cloudy insulin gently rolled in between Pen needs to be rotated upside down for at least ten times before using Air of volume equal to dose of insulin should be injected in vial. No use of alcohol may destroy silicon coating. 90 angle—thin 45 Routine aspiration not needed Embedded for 5 sec after complete depression--pens
Alternative routes—failed Jet injectors—deliver high pressure stream of insulin. Useful in lipoatrophy. Transdermal Iontophoresis Low frequency ultra sound Transferomes—phosphatidylcholine vesicles 50% SC efficiency
Intranasal Bioavailability is 8-15% Nasal irritation is common High rates of treatment failure. Gelified nasal insulin Oral Enteric—limited bioavailability Too large,hydrophilic Only 0.5% reaches circulation Buccal—aerosol solution
Regular insulin Clear solution at neutral pH 0.4% zinc added-hexamers Phenol or cresol-prevent growth of microorganisms Onset of action within 15-30 min after SC max activity-120 -150 min Action -6-8 hrs Insulin to be given 30-40 min prior to meals
indications In case of type1 DM ,type 2 DM –DKA,HONK,Pregnancy,patients being taken up for surgery,acute illness. Controls post prandial blood glucose levels when used with long acting insulins.
NPH or isophane insulin At hagedorn university in 1940. Protamine added in 1:6 ratio to regular insulin Phosphate buffer for neutral ph Zinc ,cresol. Peak of action at 5-7 hrs Action lasts for 12-15 hrs. Bed time to control FBS. Cloudy.
Lente insulin Zinc in amounts 10 times to NPH Acetate as buffer Insoluble zinc insulin complexes Semilente---amorphous,biphasic absorption Ultralente—long acting crystalline suspension Can’t be mixed with regular insulin.
Premixed formulations 30:70 50:50 25:75 Regular and NPH insulin
Rapidly acting insulins—insulin analogues Analogous to keep insulin in monomeric form Only change in aminoacid sequence at a particular point. Action starts within 15 min after SC injection. Peaks at 60-90 min Over by 4 hrs Post prandial excursions curtailed No delayed hypoglycemia.
Aspart by Novo Nordisk as Novolog or Novorapid B28 ---proline is substituted by aspartic acid residue. Increased charge repulsion—no hexamers Components- zinc-metal ion19.6g/ml buffer-disodium hydrogen phosphate dihydrate1.25 mg/ml Preservative-- m cresol 1.72mg/ml Phenol 1.50mg/ml Isotoncity agent –glycerin and Nacl ph 7.2-7.6
NovoRapid (Insulin Aspart ) Pro Phe Gly Arg Phe Asp Tyr Glu B20 Thr Gly Asp Cys Lys B28 B30 Thr Val Asn Cys A21 Tyr Leu A1 Gly Asn Tyr Ile Glu Leu Val Leu Ala Glu Gln Glu Gln Tyr Val Leu Cys Ser Cys Leu Ile Ser Thr Cys His Ser Gly Cys Leu B1 His Gln Asn Val Phe
Lispro Marketed by Eli Lilly—HUMALOG First insulin analogue. Penultimate lysine and proline residues on the Cterminal end of B chain are reversed---no change in receptor binding. No formation of hexamers Post prandial excursions are controlled.
Glargine Marketed by sanofiaventis—Lantus Resembles basal insulin secretion of non diabetic pancreatic beta cells. Controls fast blood glucose. Glycine for asparagine at A21 and two arginine added to carboxy terminal of B chain. Formulated at acid pH—4.0 Hexamers at pH-7.4 Can be injected with I port
Glargine In 2009 there was conflicting and confusing data regarding the link of glargine insulin and cancer developing risk. ADA –the avaailable data does not provide a cause for concern and that changes to the prescribing advice are therefore not necessary.
C14 fatty acid chain (Myristic acid) Phe Gly Phe Arg Glu Tyr Thr Gly Pro Cys Lys Val Thr Lys Cys Asn A21 B29 Leu Tyr Gly A1 Asn Tyr Ile Glu Leu Val Leu Ala Glu Glu Gln Gln Tyr Val Cys Leu Leu Cys Ser Ser Thr Cys Ile His Ser Gly Cys Leu Gln His Asn Val Phe B1 Design of Insulin Detemir - 1 LysB29(N-tetradecanoyl)des(threonine)human insulin Des-threonine myristic(mir) acid
Detemir Marketed by Novo Nordisk –LEVEMIR Fatty acid myristic acid is bound to lysine aminoacid at B29. quickly absorbed—binds to Albumin—complex Better control of blood glucose levels Appreciable decrease in HbA1c levels--
levemir Albumin binding: Makes Levemir therapy with a smooth and peakless profile throughout the day
Time-action profile Up to 24 hours Predictability lower within-patient variability than NPH and glargine Glycaemic control Better glycaemic control Hypoglycaemia Lesser hypoglycaemia compared with NPH & glargine Weight No undesirable weight gain shown in all studies
Strength of insulin 40 U /ml –most widely used WHO—all insulin across the globe to be U 100. Storage Refrigerated <2 and >30 C Excess agitation avoided Used for > 1 month –may lose potency. Away from sunlight.
Mixing insulins glargine is not mixed with any other insulin.
Problems with syringes / vials Cumbersome procedure Difficult to transport and carry around Inaccuracy in withdrawing the correct amount of insulin Difficulty in mixing insulin Insulin wastage Stigma of injections and hence suggestion of ill-health Needle passes a rubber membrane and losses sharpness-more pain
Advantages with Devices Simplicity - Simple to operate and inject Accuracy - A new superior standard in dose accuracy Reliability - High quality materials and finish Discreeteness - Non-medical, non-syringe design All-in-one - Pen + insulin cartridge + needles Portability - Small & compact, robust carrying case - with space for extra needles and cartridge
Prefilled pen Contain a built-in, single-use insulin cartridge Loading Require no loading by patient Ease of use Portable, durable, & lightweight delivery systems patients who have difficulty handling the cartridges in reusable pens persons with busy schedules short - term therapy = GDM, Post-Surgery Ease of disposal are made of non-polluting plastic it breaks down into naturally occurring substances when burned industrially it can be safely landfilled
Design Characteristic of FlexPen The FlexPen is a disposable, prefilled insulin delivery device— there is no insulin cartridge to change. The FlexPen is simply thrown away when the last of the insulin has been used, or at the end of the in-use time.
FlexPen Prefilled syringes are available with three insulin analog preparations: Levemir, NovoRapid, and NovoMix 30. Each FlexPen is named for the insulin it contains and is color branded for easy identification.
NovoMix 30 FlexPen = identified by Blue push button
NovoRapidFlexPen = identified by orange push button
Durable pen Patient has to insert an insulin cartridge into pen's delivery chamber Flexibility Allows greater flexibility for some patients Changing types of insulin without needing to buy another pen if prescription changes Ease of use Durable and easy to use Designed for longer duration of use. With individual use - risk of infection is minimized
Insulin dose calculation Calculate total daily insulin TDI 0.5 *WEIGHT (KG) or sum of current doses Ex—60 kg---30U. Total meal time insulin—lispro,aspart,regular 60% 0f TDI 18U-----three divided doses—breakfast,lunch.dinner Total basal insulin—NPH,glargine,ultrlente 40% of TDI 12U---bed time insulin
Insulin dosage DKA Bolus dose—IV 0.1U/kg IM-0.3U/kg Then 0.1U/kg/hr Mild episodes of DKA—short acting insulin analogues IV regular insulin to be used in infusion until acidosis resolves 0.05-0.1U/kg/hr.
Pre prandial insulin dose INSULIN /CARBOHYDRATE ratio 1-1.5 U/10 gm of carbohydrate Supplemental or correcting insulin—1Uof insulin for every 50mg/dl of glucose over the preprandial glucose target. Ex A 60kg male has FBG 0f 250 mg/dl,desired is 100mg/dl,the insulin dose is 60*(250-100)/1500 60(150/1500-----60*150/1500----6U
Twice daily regimens Long acting insulinNPH.regular insulin –morning,bed time. 2/3 of insulin in the morning 1/3 of insulin at bed time To prevent nocturnal hypoglycemia. FBG-prior evening long acting insulin Pre lunch glucose—morning short acting insulin Pre supper glucose-morning long acting insulin’ Bed time—pre supper short acting insulin. Not an optimal regimen for 1 DM
Continuous subcutaneous insulin infusion CSII Very effective insulin regimen for type 1 DM To the basal infusion,,a pre prandial insulin bolus is delivered by the device based on instructions from the patient—who uses an individualized algorithm incorporating the preprandial plasma glucose and anticipated carbohydrate intake. Sophisticated device Advantages: programmed dose basal infusion rates altered during exercise different doses of insulin can be matched based on meals reqiures education of the patient and frequent interactions Disadvantages---infection,hyperglycemia,DKA Short acting insulin analogues are used. SBMG
SEP 2006-OCT 2007 Powdered form of recombinant human insulin Effective but no better than short acting insulin. Discontinued because of poor sales. Marketed by pfizer. 1mg-3U Increment is not linear 1mg given subsequently is more insulin than 3 mg given once. 3mg—8U May be associated with lung cancer not Cost effective Mannkind --AFREZZA