Hypoglycaemics Flashcards
Metformin:
Undergoes liver metabolism
False. Metformin is not metabolised and is excreted unchanged in the urine. It is undetectable in plasma at 24 hours after a single dose.
Metformin:
Is effective in overweight diabetics
True. It does not cause weight loss but decreases weight gain in combination with lifestyle modifications.
Metformin:
Overdose can lead to lactic acidosis
True
Metformin:
Has a half life of 6 hours
True. Peak concentrations are reached within one to three hours, but it’s duration of action is between 8 & 12 hours, and is therefore administered up to 3 times a day.
Metformin:
Causes ketonuria
True
Biguanides:
Stimulate pancreatic insulin secretion
False. Biguanide action involves decreased gluconeogenesis, increased glycolysis & decreased intestinal glucose reabsorption.
Biguanides:
Are teratogenic
False. They are not recommended in pregnancy, though are not teratogenic.
Biguanides:
Are used in all ages of diabetics
False. Ketonuria can occur in young diabetics treated with Insulin & Biguanides, and so Metformin is usually only used in adult onset diabetes.
Biguanides:
Metformin has an oral bioavailability of 50-60%
True
Biguanides:
Metformin is highly protein bound
False. Metformin has negligible protein binding.
Sulphonylureas:
Are used in adult onset diabetes
True
Sulphonylureas:
Can cause hypoglycaemia
True. Sulphonylureas, such as Gliclazide, unlike Metformin, can cause hypoglycaemic episodes and blood sugars must be checked regularly.
Sulphonylureas:
Cause lactic acidosis in toxicity
False. Unlike Metformin, they do not cause lactic acidosis.
Sulphonylureas:
Act by increasing insulin release
True. They also enhance Insulin’s effect of taking up glucose into muscle & fat. Other examples include glibenclamide, tolbutamide &, the older preparation, chlopropramide.
Sulphonylureas:
Act by increasing insulin production
False. They act by increasing insulin release (not production) from the pancreatic beta cells, by binding to specific receptors.
Sulphonylurea hypoglycaemics:
Tend to cause weight loss
False
They act by binding to a receptor coupled to increased Calcium entry into the pancreatic beta cells, which enhances Insulin secretion.
Sulphonylurea hypoglycaemics:
Can be used to treat ketoacidosis
False. Oral hypoglycaemics have no role in the management of acute diabetic ketoacidosis.
Sulphonylurea hypoglycaemics:
Are safe for use in pregnancy
False
Sulphonylurea hypoglycaemics:
Are potentiated by Sulphonamides
True
Sulphonylurea hypoglycaemics:
Have shorter half lives than Biguanides
False
Sulphonylureas:
Have a hypoglycaemic effect potentiated by thiazide diuretics
False. Sulphonylureas’ hypoglycaemic effect is antagonised by thiazide diuretics.
Sulphonylureas:
Are highly protein bound
True
Sulphonylureas:
Displace bound Insulin from pancreatic islet 13 cells
True. Act by displacing bound Insulin from the pancreas &, therefore, they are only effective if endogenous insulin still exists (i.e. not absolute insulin loss/pancreatic beta cell destruction, as in type 1 DM).
Sulphonylureas:
Include the drug Phenformin
False. Phenformin is a Biguanide similar to Metformin.
Sulphonylureas:
Include the drugs Chlorpropramide & Metoclopramide
False. Despite the identical suffix (-pramide), Metoclopramide is a Benzamide anti-emetic.
Sulphonylureas:
Are effective orally & parenterally
False. Sulphonylureas are only effective when administered orally. There is no IV preparation.
Sulphonylureas:
Can cause pancytopenia
True. Tolbutamide & Chlorpropramide can cause leucopenia, agranulocytosis and thrombocytopenia in rare cases.
Sulphonylureas:
Chlorpropramide is metabolised & excreted by the kidneys
False. Chlorpropramide undergoes no significant metabolism & is excreted, very slowly, largely unchanged in the urine.
Sulphonylureas:
Gliclazide protects pancreatic beta cells from hyperglycaemic damage
True
Sulphonylureas:
Gliclazide reduces atheromatous build up
True
Insulin:
Neutral insulin has a pH of 7
True
Insulin:
Different preparations exist lasting from less than 2 hrs to more than 36 hours
True
Insulin:
60 - 80% of insulin can be lost due to binding to the IV fluid container & tubing
True
Insulin:
80% of the secreted insulin is degraded by the liver & kidneys
True. The liver enzyme, hepatic glutathione transhydrogenase breaks the insulin molecule down into it’s constituent peptide chains.
Insulin:
Half life of endogenous insulin is 45 mins
False. Endogenous insulin has a very short half life of 10 - 20 mins and is fixed to many tissues, except RBCs & brain.
Regarding insulin:
It’s action involves a second messenger system
True
Insulin decreases cAMP in the liver
Regarding insulin:
It is a polypeptide formed of 4 chains
False. It is formed of 2 chains, A and B.
Regarding insulin:
It increases cAMP levels in the liver
False
Insulin decreases cAMP in the liver
Regarding insulin:
Insulin increases potassium uptake into cells
True
Regarding insulin:
Insulin increases protein synthesis in ribosomes
True
It also inhibits hormone sensitive lipase, increases protein synthesis in ribosomes and increases glucose uptake in the peripheral tissues.
Insulin facilitates glucose uptake into:
The pituitary
True
Insulin facilitates glucose uptake into:
Red Blood Cells
False
Insulin facilitates glucose uptake into:
Peripheral tissues inc. muscle & fat
True
Insulin facilitates glucose uptake into:
Fibroblasts
True
Insulin facilitates glucose uptake into:
Intestinal mucosa
False. It decreases reabsorption in the intestine, which can lead to glycosuria.
Insulin secretion:
Can be blocked by Atropine
True
whereas the anticholinergics, including Atropine, can block it’s release.
Insulin secretion:
Is inhibited by the hormone Somatostatin
True
Insulin secretion:
Is inhibited by the phosphodiesterase inhibitor Theophylline
False. Theophylline stimulates Insulin secretion but Somatostatin opposes it’s secretion.
Insulin secretion:
Is stimulated by leucine
True
Insulin secretion:
Is increased by Beta 2 adrenergic receptor activation
True. The Sympathetic nervous system has conflicting effects on Insulin release, Alpha 2 agonists decrease Insulin release, whilst Beta 2 agonists increase it’s secretion.
