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Endocrinology > Diabetes Pharmacology > Flashcards

Diabetes Pharmacology Flashcards

1
Q

Which drugs have an insulin dependent action

A 
Sulphonylurea 
Incretin mimetics 
Glinides 
DPP-4 inhibitors 
Biguanides - metformin 
Thiazolidinedione
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2
Q

Which drugs have an insulin independent action

A

a glucosidase inhibitors SGLT2 inhibitors

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3
Q

How do insulin dependent drugs work

A

Can increase secretion of insulin - so need some residual B cell function
OR
Decrease insulin resiatnce and reduce hepatic glucose output

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4
Q

How do insulin independent drugs work

A

Slow glucose absorption from GI tract (α-glucosidase inhibitors)
OR
Enhancing glucose excretion by the kidney (SGLT2 inhibitors)

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5
Q

Describe how insulin is secreted from B cells in the pancreas

A

Elevated blood glucose
More glucose is moved into B cell by GLUT-2 facilitated transporter
Undergoes glycolysis etc to produce more ATP
Increased ATP closes the KATP channel causing membrane depolarisation
This opens Ca channels which moves Ca into the cell and triggers insulin release by exocytosis

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6
Q

What subunits make up the KATP channel

A

4 potassium inward rectifier Kir6.2 subunits

4 sulphonylurea receptor 1 subunits (SUR1)

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7
Q

What closes the KATP channel

A

ATP binding to the Kir6.2 subunits
Occurs when glucose is high - leads to more ATP
Triggers insulin release

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8
Q

What opens the KATP channel

A

ADP binding to the SUR1 subunits
Occurs when glucose is low
It maintains resting potential of B cell and inhibits insulin secretion

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9
Q

List examples of sulphonylureas

A

Tolbutamide
Glibeclamide
Glicazide
Glipizide

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10
Q

How do sulphonylureas work

A

Displace ADP from SUR1 subunit of KATP channel so close the channel
This stimulates insulin release by causing depolarisation and Ca influx
Requires some B cells to be effective

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11
Q

When would you use sulphonylurea

A

First-line in patients intolerant of metformin, or with weight loss
Second-line in conjunction with metformin
Third line in conjunction with metformin and thiazolidinediones, or other drugs
Only in T2DM

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12
Q

What are some negative effects of sulphonylureas

A

May cause hypoglycaemia by excessive secretion of insulin - more common with longer acting agents, in those with reduced liver/renal function and in the elderly
Cause undesirable weight gain
Avoid the long acting ones in CKD, elderly and pregnancy
Effectiveness can be reduced in late stage disease as it needs functioning B cells

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13
Q

How do glinides work

A

Similar to sulphonylureas - bind to SUR1 and close KATP channel
Also their action is related to plasma glucose level

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14
Q

How do you use glinides

A

Given orally

Use in conjunction with metformin and thiazolidinediones

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15
Q

Which is safer, glinides or sulphonylureas

A

Glinides
Less likely to cause hypoglycaemia - shorter acting
Are subject mainly to hepatic metabolism

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16
Q

When should glinides be avoided

A

In severe hepatic impairment, pregnancy and breast feeding

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17
Q

Describe the incretin effect

A

Ingestion of food stimulates released of GLP-1 and GIP from enteroendocrine cells in the small intestine
These peptides enhance insulin release from B cells and GLP-1 decreases glucagon release
This enhances glucose uptake and utilisation and also decreases new glucose production
Overall decreases blood sugar

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18
Q

Insulin response to oral glucose is greater than the response to IV glucose - true or false

A

TRUE

this is part of the incretin effect

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19
Q

How does the DPP-4 enzyme usually work

A

Rapidly terminates the actions of GLP-1 and GIP - inhibits them
Reduces the incretin effect and therefore insulin release

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20
Q

How do Gliptins work

A

Competitively inhibit DPP-4
Prolongs the actions of endogenous GLP-1 and GIP and increases plasma insulin
Overall lowers blood sugar

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21
Q

List examples of gliptins

A

Sitagliptin

Vildagliptin

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22
Q

How are glitptins normally used

A

Usually in combination with a SU or metformin
Can be employed as monotherapy
Weight neutral

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23
Q

List examples of incretin analogues

A

Extenatide

Liraglutide

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24
Q

How do incretin analogues work

A

Mimic the action of GLP-1 but are much longer lasting as they resist breakdown by DPP-4
Stimulate insulin release from B cells by binding to the GLP-1 receptors

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25
How are incretin analogues administered
Subcutaneously | Can be 2x daily, daily or weekly
26
As well as stimulating insulin secretion, what other effects do incretin analogues have
``` Supress glucagon secretion Slow gastric emptying Decrease appetie Modest weight loss Reduce hepatic fat accumulation ```
27
What are some side effects of incretin analogues
Nausea | Rarely pancreatitis
28
How does the a-Glucosidase enzyme normally work
Brush border enzyme in small intestine | Breaks down starch and disaccharides into absorbable glucose
29
How do a-Glucosidase inhibitors work
Prevent breakdown of carbs etc into glucose by inhibiting enzyme Delays glucose absorption after a meal so reduces the normal post-prandial increase
30
List examples of a-glucosidase inhibitors
Acarbose Miglitol Voglibose
31
When are a-glucosidase inhibitors used
in 2TDM patients inadequately controlled by life style measures or other drugs Infrequently used in UK
32
What are the adverse effects of a-glucosidase inhibitors
GI tract symptoms due to undigested carbs leaving small intestine: flatulence, loose stools, diarrhoea, abdominal pain, bloating
33
Which drug is the only one in the biguanide class
Metformin
34
When is metformin used
First line agent in the treatment of T2DM patients irrespective of obesity
35
How does metformin work
Reduces hepatic gluconeogenesis Increases glucose uptake and utilisation by skeletal muscle Reduced carb absorption Increases fatty acid oxidation Prevents hyperglycaemia but doesn't cause hypo
36
What are the benefits of using metformin
``` Reduces microvascular complications Can be given orally Prevents hyperglycaemia Doesn't cause hypo Causes weight loss Can be combined with other agents ```
37
What are the adverse effects of metformin
GI upset - diarrhoea, nausea and anorexia Lactic acidosis - more common with excess alcohol intake - potentially fatal Shouldn't be given to those with impaired renal and hepatic function
38
How do Thiazolidinediones work
Enhance the action of insulin at target tissues Act as agonist of a nuclear receptor PPARy which acts as a transcription factor when activated Increase the expression of several proteins involved in insulin signalling and lipid metabolism
39
What are the desirable effects of thiazolidnediones
Promote fatty acid uptake and storage in adipocytes, rather than in skeletal muscle and liver Reduce hepatic glucose output Enhance peripheral glucose uptake Do not cause hypoglycaemia
40
What are some of the adverse effects of thiazolidnediones
Weight gain Fluid retention - promotes Na reabsorption Severe hepatotoxicity Increased incidence of bone fractures - doubles risk Don't use in heart failure
41
List examples of thiazolidnediones
Pioglitazone
42
How do SGLT2 inhibitors work
They selectively block the reabsorption of glucose by SGLT2 in the proximal tubule Causes more glucose to be excreted in urine
43
As well as lowering blood glucose, what other effect do SGLT2 inhibitors have
Calorie loss which contributes to weight gain | Also helps diabetes
44
List examples of SGLT2 inhibitors
dapagliflozin, canagliflozin and empagliflozin
45
List the devices available to administer insulin
Syringe Disposable pen Reusable cartridge pen Insulin pumps
46
What are the aims of treatment in T1DM
Prevent hyperglycaemia Avoid hypoglycaemia Reduce chronic complication - micro and macrovascular disease
47
Describe the usual secretion/level of insulin in the body
Secreted at low basal rate throughout day - 50% of insulin used this way More is secreted after eating to cope with additional glucose intake
48
List some rapid acting insulins
Humalog | NovoRapid
49
List some long acting insulins
Lantus | Levemir
50
Describe the basal bolus insulin regime
seen as the “best” regime to mimic physiological insulin production take long acting insulin to act as basal level then take rapid acting with meals Much more flexible
51
Describe the twice daily insulin regime
Insulin is taken 2x per day - usually morning/evening Less flexible than basal-bolus Use intermediate insulin or a mixture of rapid and intermediate
52
What level of insulin do you normally start someone on
0.3 units/kg of body weight Adjust over time if needed Divide between 50% basal and 50% post-prandial
53
Describe advanced carbohydrate counting
This is where you synchronise the amount of insulin taken to amount of carbohydrate consumed Good for those on daily injections and insulin pumps
54
What are the benefits and limitations of finger prick blood glucose measuring
Allows for day-tday management and insulin adjustment Only provides a snap-shot
55
What are the limitations of currently available insulin treatments
Injections or pumps put insulin into SC tissue Peak too slow to stop post-meal spike Slow clearance Can be affected by temperature (absorbs faster when warm)
56
What pathology can occur at injection sites
Lipohypertrophy | More likely if you don't rotate your injection sites
57
What are the approximate blood glucose targets
Pre-prandial - 4-7 mmol Post meal <10 mmol Though are individualised
58
When might you use IV insulin
DKA HHS Acute illness Fasting patients
59
How must you monitor someone on IV insulin
Hourly blood glucose monitoring Check ketones if BG>12 Check U&Es daily
60
What is the major limitation of oral insulin
Variable absorption so not reliable
61
What type of transplants may be able to treat T1DM
Pancreas | Pancreatic islet cell
62
Which diabetes drugs are known to cause weight gain
Insulin | TZD - pioglitazone
63
What are the criteria for diabetic ketoacidosis
elevated plasma or urinary ketones | Venous bicarbonate <15 mmol/L
64
When should you suspect DKA
Anyone with type 1 DM with high blood sugar and feeling unwell
65
What is the most common cause of mortality in DKA
cerebral oedema | fluid on the brain
66
What effect does insulin have on hexokinase activity
Increases the activity of it | This increases glucose breakdown
67
What is diabetic ketoacidosis
An acute metabolic complication of diabetes characterized by hyperglycaemia, hyperketonaemia and metabolic acidosis
68
What are the symptoms of DKA
``` Nausea and vomiting Abdominal pain Tiredness Coma Polydipsia Polyuria Kussamaul breathing cerebral oedema death ```
69
What signs of diabetic ketoacidosis would show up in urinalysis
Low pH High glucose High ketones
70
List risk factors for DKA
``` Sepsis - underlying infection Poor control Pregnancy Vascular events - MI Alcohol abuse Trauma Iatrogenic - some drugs Acute pancreatitis ```
71
Name 3 ketone bodies
Acetone Beta-hydroxybutyrate Acetoacetate

Endocrinology (13 decks)

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