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PHA332 > Wk 10: Anti-diabetic drugs > Flashcards

Wk 10: Anti-diabetic drugs Flashcards

1
Q

What is the mechanism of action of glucose when releasing insulin?

A
  • Glucose attaches to GLUT-2 receptor on pancreatic cell surface
  • Glucose metabolised by mitochondria
  • Generates ATP, inactivates K = depolarisation
  • Activates calcium channel, influx of calcium
  • Releases insulin
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2
Q

What is the mechanism of action of insulin?

A
  • Insulin binds to insulin receptor
  • Receptor phosphorylated
  • Activates cell signalling
  • Releases glucose transporter 4 (GLUT4 )
  • GLUT4 imports glucose into cell
  • Lowers blood glucose
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3
Q

What do you add/do during insulin preparation to delay absorption?

A
  • Zinc: zinc-insulin hexamer: Inc stability + delays abs
  • Protamine: prolong release
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4
Q

Give examples of 3 available rapid acting insulin

A
  • Lispro
  • Aspart
  • Glulisine

5-15 mins before meal

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5
Q

How does lispro differ from normal human insulin?

A
  • AA proline at B28 replaced by lysine
  • AA lysine at B29 replaced by proline
  • Prevents dimer/hexamer formation
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6
Q

Short acting insulin

A
  • 30-45 mins before meal
  • IV admin: managing diabetic ketoacidosis
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7
Q

Give examples of insulin sensitisers

A
  • Biguanides: Metformin
  • Thiazolidinediones/glitazones: pioglitazone
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8
Q

What is the action of biguanides?

A
  • Dec hepatic gluconeogenesis
  • Improves insulin sensitivity
  • Stimulates tissue uptake of glucose esp muscle
  • Antihyperglycemic effect
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9
Q

When is metformin used?

A

First line in T2DM for overweight patients

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10
Q

What is the mechanism of action of metformin?

A
  • OCT1 transports metformin into cell
  • Once in liver, interacts w/ mitochondrial electron compex 1
  • AMP inc, detected by AMPK
  • AMPK triggers inc of conversion of NADH to NAD + inc lactate into cell
  • Lactate inc, pyruvate dec, dec hepatic glucose prod
  • AMPK also dec gluconeogenesis gene prod -> dec hepatic glucose prod
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11
Q

What is the mechanism of action of pioglitazone?

A
  1. Activation of PPARy (fat, muscle + liver cells) -> restoration of target genes:
    - Dec interleukin-6
    - Inc adiponectin + insulin sensitising
  2. Inc GLUT 1 + 4 expression -> glucose uptake into peripheral tissues
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12
Q

Does pioglitazone require insulin?

A

Yes

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13
Q

What are the adverse effects of glitazones?

A
  • Weight gain
  • Liver dysfunction
  • HF
  • Bladder cancer
  • Fracture risk
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14
Q

When is glitazones used?

A

3rd line therapy after metformin + sulfonylureas

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15
Q

Give examples of insulin secretagogues

A
  • SU
  • Meglitinides: Repaglinide
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16
Q

What is the mechanism of action of sulfonylurea?

A
  • Sulfonylurea binds to SUR1 + blocks k channel causing depolarization
  • Activates calcium channel causing influx in calcium
  • Triggers insulin secretion
17
Q

When is the use of sulfonylureas drugs ineffective?

A

No insulin prod:

  • T1DM
  • Post-pancreatectomy
18
Q

What are the adverse effects of sulfonylurea?

A
  • GI disturbance
  • Hypo
  • Weight gain
  • Renal impairment
19
Q

What is the mechanism of action of meglitinides?

A

Bind to SUR1 receptor on b cells stimulating insulin release

20
Q

When should meglitinides be used?

A
  • Poor renal function
  • Irregular eating habits
21
Q

What are the adverse effects of meglitinides?

A
  • Hypo
  • Visual disturbance
  • Di + vom
22
Q

Give examples of agents that mimic incretin

A
  • DPP4 inhibitors: gliptins
  • GLP-1 agonist (mimetics): exantatide
23
Q

What are incretin hormones?

A

Hormones that release GLP-1 + GIP following food

  • Activate cell
  • Stim cAMP
  • Stim EPAC2
  • Activates pathways, secreting insulin
24
Q

When should GLP-1 be used?

A

3rd line - in place of insulin, glitazones + DPP4 inhibitors

25
Q

What are the adverse effects of GLP-1 agonists?

A

Acute pancreatitis

26
Q

Exenatide

A
  • Injectable
  • Lowers blood glucose
  • Excreted by kidney but don’t use if GFR <30
27
Q

What is the role of DPP4?

A

Inactivates + degrades incretin hormones

28
Q

What is the mode of action of gliptins?

A
  • Competitive inhibitor of DPP-4: binds directly to DPP-4 enzyme
  • Red inactivation of GLP-1 + GIP
  • Prolongs GLP-1 + GIP activity to help red glucose levels
29
Q

What are the unwanted effects of gliptins?

A
  • GI
  • Pancreatitis
  • Dec apetite
30
Q

Give an example of a drug that slow intestinal absorption of glucose

A

A-glucosidase inhibitor (acarbose)

  • Competes w/ dietary oligosaccharides for a-glucosidase enzymes
  • Postprandial peak of blood gluc red + conc more stable
31
Q

What is the adverse effects of acarbose?

A

Diarrhoea + Flatulence

32
Q

Give an example of an agent that inhibits glucose reabsorption in the kidney

A

SGLT2 inhibitor (glifozins)

  • Competitive reversible inhibitors of SGLT2
  • Red glucose absorption from tubular filtrate + inc urinary glucose
  • Insulin independent
33
Q

When is SGLT2 inhibitors not recommended + ineffective?

A
  • Not recommended: GFR <60ml/min
  • Ineffective: GFR <30ml/min
34
Q

What are the adverse effects of SGLT2?

A
  • Rapid weight loss
  • UTI

PHA332 (34 decks)

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