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Pharmacology and effectiveness of the prescribed medication and what the…
Pharmacology and effectiveness of the prescribed medication and what the GP could have done better.
Aspirin
Aspirin is prescribed to those who have had a cardiovascular disease such as a Heart attack and it is used to reduce the risk of blood clots forming.
It does this by inhibiting the circulating blood cells known as platelets. Aspirin (acetylsalicyclic acid) works by disrupting the production of prostaglandins throughout the body by targeting COX-1 and COX-2.
The inhibition of platelet aggregation occurs because of its interference with thromboxane A2 in platelets caused by COX-1 inhibition. Thromboxane A2 is an important lipid responsible for platelet aggregation which can lead to clot formation and future risk of heart attack or stroke.
For those affected by cardiovascular disease, long term treatment with low doses of Aspirin, usually 75 mg gives an antiplatelet effect explaining the dosage administered to George.
The OD stands for every day and is consistent with a long term treatment plan to reduce the likelihood of blood clots. The route PO, stands for oral administration by pill, this must be specified as Aspirin can be administered by oral, rectal or intravenous route.
Whilst Aspirin is widely considered to be effective for those who have had a heart attack, there are some risks associated with low dose Aspirin. It can irritate the stomach lining and can trigger gastrointestinal upset, ulcers and bleeding and can be dangerous for people who are at a higher risk of bleeding. Therefore it is important to keep an eye on the patient as George will have these drugs administered to him over a long period of time.
Bisoprolol
Bisoprolol is used alone or together with other medicines to treat high blood pressure (hypertension). High blood pressure adds to the workload of the heart and arteries. High blood pressure increases the risk of heart attacks but these problems may be less likely to occur if blood pressure is controlled.
Bisoprolol is a beta blocker and works by affecting the response to nerve impulses in certain parts of the body, like the heart. As a result, the heart beats slower and decreases the blood pressure.
It is a cardioselective beta 1-adrenergic blocking agent used to treat high blood pressure. It is considered a potent drug that has a long half life which is used once daily to reduce the need for multiple doses of antihypertensive drugs.
It is a well tolerated drug due to its beta 1 – adrenergic receptor selectivity. Whilst the full mechanism of action is not fully understood, it is thought that therapeutic effects are achieved through the antagonism of beta-1 adrenoreceptors to result in a lower cardiac output decreasing heart rate (chronotropy) and contractility (inotropy).
Bisoprolol is also thought to reduce the output of renin in the kidneys, which normally increases blood pressure. Part of its effectiveness is it ability to be well absorbed in the GI tract. As a result of this, its bioavailability is about 90% due to the minimal first pass effects. Absorption is also unaffected by food intake.
According to the Nice guidelines, the dosage is 2.5mg every day and orally administered for a week. Tolerance is then noted over time, and it may be increased to 3.75, then 5, then 7.5, then 10 in successive weeks. 10g is the max.
Atorvastatin
Statins help lower low density-lipoprotein (LDL) cholesterol in the blood. They draw cholesterol out of plaque and stabilise plaque. Plaque is a waxy substance consisting mainly of cholesterol deposits that can build up within the walls of the arteries, interfering with blood flow to and from the heart and leading to heart attack.
Atorvastatin is an HMG- CoA reductase inhibitor used to lower lipid levels. It is an oral antilipemic agent that reversibly inhibits HMG-CoA reductase. It lowers total cholesterol, low density lipoprotein-cholesterol, apolipoprotein B, non-high density lipoprotein-cholesterol and triglyceride plasma concentrations. High concentrations of all of these are associated with increased risk of atherosclerosis and cardiovascular disease.
Atorvastatin is effective and clinical studies have shown that Atorvastatin reduces LDL-C and total cholesterol by 36-53%. It is a competitive inhibitor of the enzyme HMG-CoA reductase, which catalyses the conversion of HMG-CoA to mevalonate, an early rate-limiting step in cholesterol biosynthesis.
Atorvastatin acts mostly in the liver, where decreased hepatic cholesterol concentrations stimulate the upregulation of hepatic low-density lipoprotein receptors, which increases hepatic uptake of LDL. 20 mg are administered orally every day, which is the recommended dosage by the NICE guidelines for adults in the primary prevention of cardiovascular events. This can be then increased if necessary.
Glyceryl Trinitrate
GTN spray (or glyceryl trinitrate) is a type of medicine called a nitrate used to treat angina. It is a vasodilator drug used for the treatment of chest pain and high blood pressure. It causes the relaxation of vascular smooth muscles, causing arteriolar and venous dilatation. It reduces cardiac preload and afterload and reduces coronary artery spasm, decreasing systemic vascular resistance as well as systolic and diastolic blood pressure.
Nitroglycerin is converted by mitochondrial aldehyde dehydrogenase (mtALDH) to nitric oxide, an active substance which then activates the enzyme guanylate cyclase. The activation of this enzyme is followed by the synthesis of the cyclic guanosine 3',5' monophosphate (cGMP), activating a cascade of protein kinase-dependent phosphorylation events in smooth muscles.
This process eventually leads to the dephosphorylation of the myosin light chain smooth muscles, causing relaxation and increased blood flow in veins, arteries and cardiac tissue. These processes then lead to decreased work of the heart, decreased blood pressure, relief of anginal symptoms, and increased blood flow to the myocardium.
Nitroglycerin is also quite effective as it is rapidly absorbed meaning it can quickly provide relief from the chest pain associated with angina. In Georges case, the medication is taken PRN or 'pro re nata' which means that the administration of medication is not scheduled and the medication is taken as needed. It is also taken sublingually. 2 puffs are used and it is designed to be short acting (usually around 20-30 minutes).
Actions of GP
Looking at Georges first attendance to the GP, his symptoms were more indicative of angina and the GP had George started on some treatment for this. But in the case 2 scenario, George experiences symptoms that more closely mirror a heart attack. The symptoms of a heart attack include: ongoing pain in the chest that wont go away and nausea both of which George was experiencing so he was right to ring the paramedics straight away as a possible myocardial infarction is serious and requires immediate treatment.
We know that the symptoms George presented with in the visit to the surgery were more similar to an angina attack, but the GP would know that with this comes the risk of an eventual heart attack. The GP in this case would give him advice on preventing heart attacks and prevention is best achieved through lifestyle changes such as diet management and reducing consumption of saturated fat.
Whilst it does not say what treatment the GP had George on before the heart attack, it is likely to be some form antiplatelet, most likely aspirin. All in all, the GP should inform George of the inherent risks of a heart attack that come with suffering cardiovascular problems such as angina. The GP should also inform him that if the pain gets more severe and wont go away after a few minutes and the feeling of nausea gets worse, it is vital to receive treatment and call an ambulance as quickly as possible.