Angina is caused by:

Correct Answer: D

Rationale: The correct answer is D because angina is caused by an inadequate supply of oxygen to the heart muscle, leading to chest pain. Extreme binding of noradrenaline due to upregulation can lead to increased constriction of blood vessels, reducing blood flow to the heart. This exacerbates the oxygen supply-demand imbalance, triggering angina. A: Blocking beta1 receptors with constant noradrenaline binding would decrease the effects of noradrenaline, potentially reducing heart rate and blood pressure, but it would not directly cause angina. B: Activating beta2 receptors would cause vasodilation, increasing blood flow to the heart, which is opposite to the mechanism of angina. C: Beta1 receptors not being active anymore would lead to a decrease in heart rate and contractility, but this state would not directly induce angina.

Correct Answer: C

Rationale: The correct answer is C: Inositol triphosphate. Loratadine is an antihistamine used to treat allergic conditions like urticaria by blocking histamine receptors. Histamine binds to H1 receptors on cells, leading to the activation of phospholipase C, which cleaves phosphatidylinositol 4,5-bisphosphate into inositol triphosphate (IP3) and diacylglycerol. IP3 triggers the release of intracellular calcium stores, leading to various cellular responses including allergic reactions. By blocking histamine receptors, loratadine reduces the synthesis of IP3, hence mediating its therapeutic effect. Choice A (cAMP) is incorrect because loratadine does not directly affect the cAMP pathway. Choice B (cGMP) is incorrect as it is not involved in the mechanism of action of loratadine. Choice D (Cyclooxygenase-1) is incorrect as

Correct Answer: B

Rationale: Step 1: Recognize the symptoms described in the scenario: fever, flushing, sweating, tremors, altered consciousness. These symptoms are indicative of serotonin syndrome. Step 2: Identify the patient's medications that can contribute to serotonin syndrome: paroxetine (an SSRI) and zolpidem (a CNS depressant). Step 3: Eliminate paroxetine as the trigger as the patient has been on it for a long time without issues. Step 4: Sumatriptan, a serotonin receptor agonist used for migraines, is the likely culprit. It can interact with SSRIs like paroxetine, leading to serotonin syndrome. Step 5: Summary: Acetaminophen (A) and ibuprofen (C) are unlikely to cause serotonin syndrome. Zolpidem (D) is less likely than sumatriptan to trigger serotonin syndrome in this case. Thus, the correct answer is B.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.