Pharmacology of Diabetes Medications

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Questions and Answers

What is the mechanism of action of glyceryl trinitrate (GTN) in treating angina pectoris?

GTN is converted to nitric oxide (NO), which stimulates guanylate cyclase, increasing cGMP and causing vasodilation.

List two common side effects associated with glyceryl trinitrate administration.

Flushing and headache.

Describe the function of GLP1 agonists like Liraglutide in obesity management.

GLP1 agonists mimic endogenous GLP1 released from L cells, promoting insulin secretion and reducing appetite.

What are the common side effects of Liraglutide treatment?

Nausea, vomiting, diarrhea, and injection site reactions. Signup and view all the answers

Why is glyceryl trinitrate administered sublingually for angina treatment?

It is administered sublingually to avoid first-pass metabolism in the liver. Signup and view all the answers

Explain how glucagon-like peptides (GLP) are activated in response to digestion.

GLP1 is released from L cells in response to the digestion of carbohydrates, fats, and proteins. Signup and view all the answers

What is one rare but serious side effect associated with GLP1 agonists like Liraglutide?

Pancreatitis. Signup and view all the answers

How does the action of glucagon-like peptides influence the vagus nerve?

GLP1 agonists bind to GLP1 receptors on the vagus nerve, which affects appetite and insulin secretion. Signup and view all the answers

What is the primary mechanism of action for Prazosin?

Prazosin binds to and inhibits vascular ɑ1 adrenoceptors, leading to vasodilation. Signup and view all the answers

What significant side effect is associated with the first dose of Prazosin?

The first dose of Prazosin can cause hypotension. Signup and view all the answers

Describe the role of Yohimbine and its target receptor.

Yohimbine is an antagonist of ɑ2 adrenoceptors, which can increase noradrenaline release. Signup and view all the answers

How does Botulinum toxin affect acetylcholine release?

Botulinum toxin blocks the release of acetylcholine (Ach) at the neuromuscular junction. Signup and view all the answers

What is an atypical antidepressant that targets ɑ2 adrenoceptors?

Mirtazepine is an atypical antidepressant that targets ɑ2 adrenoceptors. Signup and view all the answers

What is a common side effect of drugs that inhibit adrenoceptors, like Phentolamine?

Drugs like Phentolamine can cause postural hypotension as a side effect. Signup and view all the answers

What effect does Mianserin have in the treatment of depression?

Mianserin acts as an antagonist at ɑ2, histamine, and serotonin receptors, promoting antidepressant effects. Signup and view all the answers

What therapeutic use is associated with drugs that target cholinesterase inhibition?

Cholinesterase inhibitors are commonly used in the treatment of glaucoma. Signup and view all the answers

What is the primary mechanism of action for Biguanides in treating Type II diabetes?

Biguanides increase insulin-mediated glucose uptake and reduce hepatic glucose production. Signup and view all the answers

Describe one major side effect of Sulfonylureas?

Hypoglycemia is a major side effect of Sulfonylureas. Signup and view all the answers

How do SGLT-2 inhibitors affect glucose levels in patients?

SGLT-2 inhibitors increase glucose excretion in urine by inhibiting glucose reabsorption in the kidneys. Signup and view all the answers

What gastrointestinal side effects are commonly associated with α-glucosidase inhibitors?

Flatulence, abdominal discomfort, and loose stools are common side effects. Signup and view all the answers

What role does exogenous insulin play in diabetes management?

Exogenous insulin is used to increase insulin levels to physiological levels. Signup and view all the answers

What is the effect of Methylphenidate on neurotransmitter levels in the brain?

Methylphenidate increases synaptic concentrations of dopamine and norepinephrine by blocking their reuptake. Signup and view all the answers

Identify one potential issue of combining Sulfonylureas with other diabetes medications.

Combining Sulfonylureas with insulin can lead to synergistic hypoglycemia. Signup and view all the answers

Why are α-glucosidase inhibitors contraindicated in patients with inflammatory bowel disease?

These inhibitors work in the gastrointestinal tract and can exacerbate abdominal issues in such patients. Signup and view all the answers

What is a common side effect of using SGLT-2 inhibitors in elderly patients?

Diuretic effects are a common side effect, leading to increased urination. Signup and view all the answers

Discuss one potential drug interaction with exogenous insulin.

Beta blockers can mask the symptoms of hypoglycemia when used with exogenous insulin. Signup and view all the answers

What influences the clearance of Sulfonylureas in patients with renal dysfunction?

The metabolism and excretion of Sulfonylureas can be impaired in patients with renal dysfunction. Signup and view all the answers

What is the mechanism of action for dopamine reuptake inhibitors like Methylphenidate?

Dopamine reuptake inhibitors block the reuptake of dopamine and norepinephrine, increasing their availability. Signup and view all the answers

What metabolic impact does metformin (a Biguanide) have on cholesterol levels?

Metformin reduces LDL cholesterol and triglyceride levels. Signup and view all the answers

What are the risks associated with the administration of exogenous insulin and alcohol consumption?

Alcohol inhibits hepatic glucose synthesis and gluconeogenesis, increasing the risk of hypoglycemia. Signup and view all the answers

Study Notes

Biguanides

Increase insulin mediated glucose uptake
Reduce hepatic glucose production by activating AMP activated protein kinase in the liver to inhibit gluconeogenesis
Decrease carbohydrate absorption
Reduce LDL cholesterol and triglyceride levels
GI disturbances are common side effects
Oral absorption, short half life
Excreted unchanged via kidney
Can cause lactic acidosis if improperly prescribed

Sulfonylureas

Mimic the rapid peak in insulin that is present in type II diabetes
Act on β cells to stimulate insulin secretion
Bind to K+ ATP channel to reduce K+ permeability and prevent K+ efflux
This causes membrane depolarization which triggers opening of Ca2+ channels for Ca2+ entry and insulin release into the bloodstream
Oral absorption, long half life
Metabolised by the liver and excreted via the kidney
Clearance can be impaired in patients with renal or liver disease
Hypoglycemia
Weight Gain

Na+ - Glucose Cotransporter 2 (SGLT-2) Inhibitors

Increase the excretion of glucose
Passive Na+ movement via transporter causes glucose to also be transported due to a decline in [Na+]
Inhibits SGLT2, decreasing the resorption of blood glucose from the the proximal convoluted tubule (PCT) and increases glucose excretion
Oral absorption, long half life
Metabolised in the liver and excreted via the kidneys
Diuretic effect in the elderly
Hypoglycemia when combined with insulin
Thrush, polyuria, weight loss, UTI, thirst

ɑ-Glucosidase Inhibitors

Inhibits intestinal α-glucosidase which is involved in the digestion of carbohydrates
Delays carb absorption
Decreases post-prandial rise in glucose
Flatulence and abdominal discomfort
Loose stool
Contraindicated in patients with inflammatory bowel disease
No systemic absorption required as it works in the gastrointestinal tract

Exogenous Insulin

Increases insulin to physiological levels
Hypoglycemia
Drug interactions:
- Beta-blockers mask indicators of low blood glucose
- Corticosteroids oppose the actions of insulin
- Diuretics overwork the kidneys
- Alcohol inhibits hepatic glucose synthesis and gluconeogenesis

Dopamine Reuptake Inhibitors

Methylphenidate (Ritalin) and Atomoxetine (Strattera)
Increase synaptic concentrations of dopamine and noradrenaline (NA) by blocking reuptake
Used to treat ADHD
Few side effects
Atypical antidepressant

Selective NA Reuptake Inhibitors

Reboxetine
Used for treating depression
Few side effects
Atypical antidepressant

Modafil (Provigil) (Verapamil)

Used to treat learning difficulties
Exact mechanism unknown
Phenylalkylamine
Flushing
Headache

Glyceryl Trinitrate (GTN)

Used to treat angina pectoris
GTN is a prodrug that is converted into nitric oxide (NO)
Stimulates guanylate cyclase in vascular smooth muscle to increase cGMP levels
This increases vasodilation which improves oxygen supply and decreases oxygen demand
Usually administered sublingually to avoid first pass metabolism
Vasodilation of collateral vessels
Reflux tachycardia and increased vascular tone, venodilation may cause venous pooling and postural hypotension, flushing and headache

Glucagon-like Peptide (GLP) 1 Agonists

Liraglutide
Used for treating obesity
GLP1 is released from L cells in response to the digestion of carbohydrates, fats and proteins
GLP1 agonists mimic the effects of endogenous GLP1, binding to the GLP1 receptors on the vagus nerve
Subcutaneous injection
Nausea, vomiting, diarrhoea, injection site reactions, pancreatitis (rare)

α-Adrenoceptor Antagonists

Prazosin (α1)
Used as an antihypertensive
Binds to and inhibits vascular α1 adrenoceptors
Inhibits NA mediated vasoconstriction
Decreases total peripheral resistance (TPR)
Decreases blood pressure
1st dose hypotension
Nasal decongestion due to α1 adrenoceptor mediated constriction of nasal mucosa arteries
Postural hypotension
Initial reflux tachycardia (baroreceptor reflex)

α2 Adrenoceptor Antagonists

Yohimbine
Phentolamine (α1 and α2)
Mianserin (α2, histamine and serotonin antagonist)
Mirtazepine (α2)
Used for treating depression
Few side effects
Atypical antidepressant

Drugs Targeting ACh Release

Botulinum
Used for paralyzing muscles for cosmetic purposes
Blocks the release of ACh
Progressive motor paralysis

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Description

This quiz focuses on the pharmacology of various diabetes medications, including Biguanides and Sulfonylureas. You will learn about their mechanisms of action, side effects, and physiological impacts. Test your knowledge on how these drugs influence glucose metabolism and insulin secretion.