A48-year-old woman suffering from allergic urticaria started a treatment with loratadine. The decreased synthesis of which of the following substances most likely mediated the therapeutic effect of the drug in the patient's disease?

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: 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.

Correct Answer: A

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

Correct Answer: C

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