A nurse is preparing to administer phenylephrine as a vasopressor to treat a patient for hypotension. The desired therapeutic effect of phenylephrine in this context is:

Choice A reason: This is correct. The liver is the main organ responsible for drug metabolism. The enzymes that the body uses to metabolize drugs are present throughout the body but are most abundant in the liver. The liver can transform drugs into more polar and water-soluble compounds, which can then be excreted by the kidneys or the biliary system.

Choice B reason: This is incorrect. The lungs are not primarily responsible for drug metabolism, although they can play a minor role in some cases. The lungs can metabolize some drugs that are inhaled, such as anesthetics, or drugs that circulate through the pulmonary blood vessels, such as propranolol. However, the lungs have a lower capacity and a lower variety of enzymes than the liver.

Choice C reason: This is incorrect. The heart is not responsible for drug metabolism, although it can be affected by it. The heart is the organ that pumps blood throughout the body, delivering oxygen and nutrients to the tissues and organs. The heart can be influenced by the pharmacokinetics and pharmacodynamics of drugs, which are the processes of drug absorption, distribution, metabolism, and excretion, and the effects of drugs on the body, respectively.

Choice D reason: This is incorrect. The kidney is not primarily responsible for drug metabolism, although it is important for drug excretion. The kidney is the organ that filters the blood and removes waste products and excess fluid as urine. The kidney can excrete drugs that are water-soluble or that are not reabsorbed by the tubules. The kidney can also metabolize some drugs, such as aspirin, but to a lesser extent than the liver.

Choice A reason: This is correct. Nausea, vomiting, and diarrhea are the most common side effects of metformin, especially when the drug is started or the dose is increased. These side effects occur because metformin can interfere with the absorption of glucose and other nutrients in the intestines, causing osmotic diarrhea. The nurse should advise the client to take metformin with food, start with a low dose and gradually increase it, and drink plenty of fluids to prevent dehydration. The nurse should also monitor the client for signs of lactic acidosis, a rare but serious complication of metformin that causes severe diarrhea, abdominal pain, muscle cramps, and difficulty breathing.

Choice B reason: This is incorrect. Palpitations are not a common side effect of metformin. Palpitations are the sensation of a rapid, irregular, or pounding heartbeat, which can be caused by various factors, such as stress, anxiety, caffeine, nicotine, or heart problems. Metformin does not affect the heart rate or rhythm directly, but it can lower the blood sugar levels, which can trigger the release of adrenaline, a hormone that can cause palpitations. The nurse should check the client's blood sugar levels and advise the client to eat regular meals and snacks, avoid alcohol and caffeine, and report any chest pain or shortness of breath.

Choice C reason: This is incorrect. Headaches are not a common side effect of metformin. Headaches are the pain or discomfort in the head, scalp, or neck, which can be caused by various factors, such as stress, dehydration, or sinus infection. Metformin does not cause headaches directly, but it can lower the blood sugar levels, which can cause headaches as a symptom of hypoglycemia. The nurse should check the client's blood sugar levels and advise the client to eat regular meals and snacks, drink plenty of water, and take painkillers as needed.

Choice D reason: This is incorrect. Heartburn is not a common side effect of metformin. Heartburn is the burning sensation in the chest or throat, which is caused by the reflux of stomach acid into the esophagus. Metformin does not cause heartburn directly, but it can worsen it if the client already has gastroesophageal reflux disease (GERD), a condition where the lower esophageal sphincter is weak or relaxed and allows the acid to flow back. The nurse should advise the client to take metformin with food, avoid spicy or fatty foods, elevate the head of the bed, and take antacids as needed.