Introductory Pharmacology Short Answer Essays

I completed Introductory Pharmacy online which I found to be easy for this unit. We had to write four short answer essays, only two of which would be submitted for grading. I ended up having to submit Essays A and B, my marks were 10/12 for A and 11/12 for B. I will also add here the pdf files I created with the questions and answers to the multiple choice questions for our quizzes, these are a good study tool!

Please note my writings are published for educational purposes only, all of my works have been submitted to Turnitin so please do not copy and paste or you will be flagged for plagiarism.

ESSAY A 10/12
The terms first generation and second generation refer to drug classes. Drug classes are groups of medications that work the same way as each other or have similar chemical properties. To be classed as a second generation drug a medication must have significant benefits over the first generation drug or decreased side effects.

The two main ways that medications work in the body are by binding to receptors and acting as agonists or antagonists or by inhibiting an enzyme. Agonists bind to a receptor and act in the same way as the original substrate would whereas an antagonist binds to a receptor and blocks the original substrate from binding and thus blocking the action the original substrate would cause. Enzyme inhibitors prevent an enzyme from catalysing a reaction by binding to the enzyme and slowing down or stopping the enzyme’s reaction.

Histamine is a neurotransmitter that binds to the H1 receptors in the periphery and brain in response to an allergen. In the periphery histamine causes itchiness, runny nose, and watery eyes, while in the brain histamine can cause motion sickness from irritation to the vestibular nerve and impair cognition and awareness.
Antihistamines bind to the H1 receptors and prevent histamine from binding, thus decreasing the effects of histamine. However, as histamine is not the only neurotransmitter that works in the brain, there is another receptor that antihistamines can bind to. This neurotransmitter is acetylcholine and the binding of an antihistamine to the acetylcholine receptor can cause anticholinergic effects such as drowsiness and decreased cognitive awareness in the brain, and urinary retention, dry mouth, decreased GIT motility and blurred vision in the periphery.

Loratadine is a selective antagonist that binds only to the histamine 1 receptors in the peripheral nervous system that is used to treat allergic rhinitis, conjunctivitis and urticaria. Loratadine stays in the periphery and because of this selectivity does not cause the side effects seen with first generation antihistamines such as drowsiness, dizziness, dry mouth. Because loratadine does not go into the brain, it also does not have the ability to bind to acetylcholine and thus does not produce the anticholinergic side effects. Because of this lack of crossover effects, Loratadine is good antihistamine to use if you are required to drive or use heavy machinery and need to stay alert.
Diphenhydramine is a first generation medication that has potential crossover effects and side effects due to its lack of selectivity. Diphenhydramine is indicated for allergic rhinitis, conjunctivitis, urticaria and short term sedation. Diphenhydramine not only binds to the histamine 1 receptors in both the peripheral nervous system and in the brain, it also allows some binding to take place on the acetylcholine receptors. This nonselective binding creates anticholinergic side effects in the brain such as drowsiness, cognitive impairment, and decreased memory. Heavy usage of diphenhydramine has been linked to an increased risk of dementia. Binding to receptors in the periphery can cause side effects such as dry mouth, GIT problems, decreased urination, and blurry vision. Thus, this medication is not indicated for people who work in industries where they are required maintain levels of awareness and alertness. However due to these anticholinergic effects may be useful for people experiencing insomnia. Diphenhydramine is also beneficial to treat motion sickness as it blocks muscarinic receptors in the vestibular and vomiting centres.

ESSAY B (11/12)
The sympathetic nervous system is responsible for the flight or fight response in the body. It is a very important system in the use of medications which make use of the selectivity of receptors to produce a desired response while reducing the potential for experiencing undesired side effects. Adrenaline acts on Alpha 1, Beta 1 and Beta 2 receptors to produce varying actions according to the location of those receptors.

Alpha 1 receptors are located in the peripheral blood vessels where adrenaline acts to constrict them and increase blood pressure, in the eye to dilate pupils and allow more light in, and in the urinary sphincter and prostate to contract these and cause urinary retention.

Beta 1 receptors are located in the heart where adrenaline causes increased heart rate and contractions; and in the kidneys to stimulate renin release, increased angiotensin and increased blood pressure.

Beta 2 receptors are located mainly in the lungs where adrenaline acts on the smooth muscles to dilate the bronchi and increase air flow to the alveoli, with some also located in the gastrointestinal tract and the liver. Binding of an agonist to the beta 2 receptors in the GIT decreases motility and slows down digestion and decreases salivation causing dry mouth, while in the liver results in increased production of glucose.

Prazosin is an alpha 1 adrenergic antagonist that was commonly prescribed to treat hypertension and benign prostatic hyperplasia (BPH). Prazosin works by blocking the effect of adrenaline on the prostate, bladder, urethra and ureters to dilate the blood vessels to allow blood to flow better while also improving urination. Because of this, it can also cause the side effect of lowering blood flow in the brain upon standing up and thus is not indicated in patients with orthostatic hypotension. Other side effects include nasal congestion and runny nose, making prazosin unsuitable for those with conditions like allergic rhinitis. In BHP patients, prazosin acts to improve urinary retention by relaxing the smooth muscles of and widening the urethra to allow urine to flow freely. There are now medications that are more selective for prostate enlargement and more selective for hypertension. However, prazosin works well for and is still prescribed for patients with both hypertension and BPH.

Atenolol is a second generation beta blocker, which means it is a selective antagonist for beta 1 receptors. It is very commonly prescribed to treat hypertension, angina and congestive heart failure. However, although atenolol is one of the most prescribed medications for hypertension, it is no longer the recommended treatment as other newer generation beta blocker medications that are safer and more effective have been developed. Atenolol binds to beta 1 receptors in the heart and causes the heart rate and force of contractions to decrease resulting in lowered blood pressure. Common side effects include symptoms of dizziness upon standing as well as slow heart rate, tiredness and vertigo. Atenolol is not recommended for a patient with orthostatic hypotension and has been found to increase the risk of developing diabetes type 2.

ESSAY C (ungraded)
The renin-angiotensin aldosterone system is responsible for maintaining blood pressure regulation and fluid balance. Renin is released from the kidneys in response to reduced blood pressure, sympathetic stimulation of the beta adrenoreceptors in the renal juxtaglomerular apparatus or a reduction of sodium delivered to the distal convoluted tubule. Renin acts on angiotensinogen to convert it to angiotensin I, which is then converted to angiotensin II by the angiotensin converting enzyme (ACE). Angiotensin II acts on blood vessels to vasoconstrict them to increase blood pressure, on nerves to increase thirst and the need for sodium and promote the release of hormones to retain fluid. Angiotensin II acts on the adrenal glands to stimulate production of aldosterone to retain sodium and excrete potassium from the kidneys, and in the kidneys Angiotensin II changes the way blood is filtered through the kidneys, increasing sodium retention and water reabsorption to increase blood pressure and volume. Drugs ending in the suffix PRIL are ACE inhibitors that suppress the ACE enzyme from converting Angiotensin I to Angiotensin II, while drugs ending in the suffix SARTAN are angiotensin II receptor blockers that block Angiotensin II from being able to bind to their receptors.

ACE inhibitor drugs also inhibit the production of bradykinin, an inflammatory enzyme that vasodilates the blood vessels, causing a dry, persistent cough and angioedema. Angioedema and cough are the two most common adverse effects of ACE inhibitors, thereby making an Angiotensin II Receptor Blocking (ARBs) drug like Candesartan a preferred treatment for hypertension. Candesartan is an Angiotensin II receptor blocker that selectively binds to the angiotensin II type 1 (AT1) receptor in a number of tissues including the adrenal gland and vascular smooth muscles to block the binding of Angiotensin II. This selective binding prevents Angiotensin II from being able to produce aldosterone-secreting and vasoconstricting effects. Candesartan is indicated for hypertension and heart failure, and helps to prevent heart attacks, kidney problems and strokes. Precautions for the use of Candesartan include patients with heart or renal failure or impairment, hypovolemia, hypotension or hypokalemia. Candesartan should not be taken during pregnancy where possible and women of childbearing age should be made aware of the risks. Common side effects of Candesartan include dizziness, back pain, headaches, and flu like symptoms like nasal congestion and sore throat. Serious adverse effects that warrant immediate medical attention include symptoms of muscle weakness, heart rhythm changes, facial swelling, feeling ill, tiredness and shortness of breath. These symptoms could indicate kidney problems, hypotension, hyperkalemia, or allergic reaction.

While Candesartan is an angiotensin II receptor blocker that relaxes the blood vessels, hydrochlorothiazide is a diuretic that works by decreasing the amount of fluid in the body. Active reabsorption of sodium, primarily in the distal kidney tubules, is inhibited by hydrochlorothiazide and promotes sodium, chloride, and water excretion. Hydrochlorothiazide lowers the amount of plasma and extracellular fluid and decreases blood pressure and cardiac output. Administered together these medications are far more effective than if administered on their own. Common side effects of candesartan and hydrochlorothiazide fixed pill combinations include upper respiratory tract infection, back pain, cold or flu symptoms, dizziness, cough, itching and rash and are generally mild. Conditions that are contraindicated for this combination of drugs include diabetes, gout, liver problems/failure, kidney impairment, pregnancy, and breastfeeding. Patients taking this medication should be regularly monitored for fluid and electrolyte imbalances as it can cause either hyperkalemia or hypokalemia.

ESSAY D (ungraded)
Insulin is a hormone produced in the pancreas that is responsible for regulating the metabolism of carbohydrates, proteins and fats by promoting glucose absorption from the blood into cells. When cells in body fat, muscles and the liver stop responding to insulin, the body becomes insulin resistant. The hormone insulin allows to glucose to move from the blood vessels into the cells to provide fuel for the body. When glucose cannot move into the cells due to insulin resistance, it is then deposited in fat cells of the body to be stored as body fat which then causes weight gain. Long term excess blood glucose increases the likelihood of insulin resistance developing. Examples of how insulin resistance occurs include eating large amounts of foods regularly, excess weight located around the middle section of the body, excess consumption of fructose, sucrose and free fatty acids and a sedentary lifestyle. Healthy changes to diet and lifestyle including regular exercise can prove effective in reversing the effects of insulin resistance. There are two main oral agents used in the treatment of Diabetes Mellitus Type 2, and they come from the drug classes sulphonylureas and biguanides.

Glimepiride is an Australian sulphonylurea medication that works by increasing levels of insulin in two ways – stimulating the release of insulin from the pancreas and reducing the breakdown of insulin in the liver. The main side effect from this is an increase in insulin known as hyperinsulinemia that can lead to hypoglycaemia. Patients prescribed with Glimepiride need to be educated about the signs of hypoglycaemia which include rapid onset excessive hunger, fatigue, and confusion. Other signs include sweating, fainting, dizziness, and nausea. Sulphonylurea medications are also associated with weight gain and an increased risk of developing PCOS. As some NSAIDs also induce hypoglycaemia, their use should be restricted while also taking sulphonylurea as taking these medications together increases the risk. Side effects of sulphonylureas include skin rashes, weight gain, GIT complaints and jaundice. In rare cases blood disorders can develop from taking Glimepiride, these include thrombocytopaenia, leukopenia and haemolytic anaemia.

The biguanide Metformin is the only biguanide currently available in Australia and is considered the number one treatment for Diabetes Mellitus Type 2. Metformin works by decreasing the production of glucose in the liver, a process known as gluconeogenesis. Decreased glucose production can have the side effect of increasing the risk of lactic acidosis, although this is rare. Lactic acidosis can be avoided by monitoring liver and kidney function and checking alcohol consumption. Metformin is not recommended for people suffering liver or kidney malfunction or for people who consume alcohol. Metformin does not cause weight gain and may improve PCOS symptoms. Though Metformin is typically well tolerated, common side effects include diarrhea, nausea and abdominal pain which are generally lessened if the medication is taken with food. Both Metformin and Glimepiride as oral agents are contraindicated during pregnancy as insulin therapy is the recommended treatment.

As Glimepiride is associated with weight gain and an increased risk of PCOS symptoms, added to the fact that Metformin has less side effects and interactions with other drugs, Metformin would be the best medication to prescribe for treatment.

Feel free to download my pdf files I have created 🙂

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