The calcium channel blockers have direct negative inotropic effects because they reduce the inward movement of calcium during the action potential This consideration is:

Correct Answer: A

Rationale: The correct answer is A: TRUE. Calcium channel blockers reduce the inward movement of calcium during the action potential in cardiac muscle cells, leading to a decrease in the intracellular calcium concentration. This results in a direct negative inotropic effect by reducing the force of contraction of the heart muscle. Choices B and D are incorrect because calcium channel blockers do indeed have direct negative inotropic effects. Choice C is incorrect as well because not all choices are correct; only choice A is accurate based on the mechanism of action of calcium channel blockers in cardiac muscle cells.

Correct Answer: D

Rationale: The correct answer is D because many hormones actually exert their effects by interacting with specific receptors on the cell membrane rather than acting directly on subcellular membranes. This interaction triggers a series of intracellular events that lead to a cellular response. Option A is true as hormones indeed interact with specific receptors on cell walls. Option B is true as cyclic AMP is a common second messenger system utilized by hormones. Option C is true as many hormones stimulate adenylcyclase enzyme as part of their signaling pathway.

Correct Answer: A

Rationale: The correct answer is A, Repaglinide (Prandin), as it is not a biguanide but a meglitinide used for managing type 2 diabetes by stimulating insulin release. Metformin is a biguanide commonly used as a first-line treatment for type 2 diabetes due to its efficacy and safety profile. Phenformin is a biguanide that was withdrawn from the market due to its association with lactic acidosis. Glipizide is a sulfonylurea, not a biguanide, and works by stimulating insulin release from the pancreas. Therefore, A is the correct answer as it is not an oral hypoglycemic biguanide.

Correct Answer: B

Rationale: The correct answer is B: FALSE. COX-1 is constitutively expressed and involved in homeostatic functions, while COX-2 is inducible during inflammation to facilitate the inflammatory response. COX-1 is responsible for maintaining normal physiological functions, such as protecting the stomach lining and regulating blood flow, while COX-2 is primarily involved in producing prostaglandins during inflammation. Therefore, COX-1 is not induced during inflammation, and COX-2 is not homeostatic. Choice A is incorrect because COX-1, not COX-2, is homeostatic. Choice C is incorrect because there is a clear distinction between the functions of COX-1 and COX-2. Choice D is incorrect because not all options are correct; only option B is accurate based on the roles of COX-1 and COX-2 in the body.

Correct Answer: C

Rationale: The correct answer is C: GI disturbance. Cyclosporine A is known to cause gastrointestinal (GI) disturbances as a common side effect, including nausea, vomiting, abdominal pain, and diarrhea. This is due to its impact on the digestive system. Choice A (Diarrhea) is too specific and not the most common side effect. Choice B (Headache) is not a typical side effect of cyclosporine A. Choice D (Immunosuppression) is the intended therapeutic effect of cyclosporine A, not a side effect. Therefore, C is the correct choice based on the common side effects associated with cyclosporine A.