A 55-year-old male with chronic back pain is prescribed oxycodone. Oxycodone works primarily by:

Correct Answer: B

Rationale: The correct answer is B: Binding to opioid receptors in the central nervous system. Oxycodone is an opioid analgesic that exerts its effects by binding to opioid receptors in the brain and spinal cord, which modulates pain perception. This mechanism of action is how oxycodone provides pain relief. A: Blocking sodium channels in peripheral nerves is incorrect because this mechanism is associated with local anesthetics, not opioids like oxycodone. C: Increasing the release of serotonin is incorrect as oxycodone does not directly affect serotonin levels. D: Inhibiting the reuptake of norepinephrine is incorrect as this is a mechanism seen in certain antidepressants, not opioids like oxycodone.

Correct Answer: C

Rationale: The correct answer is C: Inhibiting potassium channels in the heart. Amiodarone works by prolonging the action potential duration and refractory period by inhibiting potassium channels. This helps to stabilize the heart's rhythm in atrial fibrillation. Choices A, B, and D are incorrect because amiodarone does not directly affect sodium channels, beta-adrenergic receptors, or calcium influx into the myocardium. Sodium channel blockers are class I antiarrhythmics, beta-blockers target beta-adrenergic receptors, and drugs that increase calcium influx are typically used for other indications like heart failure.

Correct Answer: B

Rationale: The correct answer is B: Phenytoin. Phenytoin is an antiepileptic drug commonly used to manage seizures in patients with epilepsy. It works by stabilizing the neuronal membranes and inhibiting the spread of seizure activity. Aspirin (A) is a pain reliever and anti-inflammatory drug, not used for seizures. Metformin (C) is used for diabetes, not seizures. Furosemide (D) is a diuretic used for treating fluid retention, not seizures. Therefore, Phenytoin is the correct choice for managing seizures in patients with epilepsy.

Correct Answer: C

Rationale: The correct answer is C: "Do not use near heat or flame." Albuterol is a bronchodilator inhaler, and using it near heat or flame can lead to the risk of fire due to its flammable nature. This instruction is crucial for patient safety. A: "Do not use this medication more than once a day" is incorrect because the frequency of albuterol inhaler use is typically based on the individual's condition and prescribed by the healthcare provider. B: "Rinse your mouth after every use to avoid infection" is not directly related to albuterol inhaler use. Rinsing the mouth is more commonly recommended with steroid inhalers to prevent oral thrush. D: "Take it with food to reduce GI discomfort" is not necessary for albuterol inhaler use as it is not typically associated with significant gastrointestinal side effects.

Correct Answer: A

Rationale: The correct answer is A: Inhibiting sodium reabsorption in the kidneys. Furosemide is a loop diuretic that acts on the ascending loop of Henle in the kidneys to inhibit the reabsorption of sodium and chloride ions. This leads to increased excretion of water and electrolytes, reducing fluid volume and relieving congestion in heart failure patients. Choice B is incorrect because furosemide does not directly inhibit aldosterone. Choice C is incorrect because furosemide does not affect myocardial contractions but rather fluid balance. Choice D is incorrect because furosemide's primary mechanism of action is not related to relaxing vascular smooth muscle.