If two drugs with the same effect, taken together, produce an effect that is equal in magnitude to the sum of the effects of the drugs given individually, it is called as:

Correct Answer: C

Rationale: Rationale: 1. When two drugs with the same effect are taken together, and their effects sum up equally, it indicates an additive effect. 2. Additive effect means the combined effect is simply the sum of individual effects. 3. Antagonism is when the effect of one drug reduces or cancels out the effect of another. 4. Potentiation is when one drug enhances the effect of another, not equal sum. 5. None of the above is incorrect as the scenario described fits the definition of an additive effect.

Correct Answer: C

Rationale: Rationale: Scopolamine is effective for vestibular disturbances due to its central anticholinergic effects. It crosses the blood-brain barrier and blocks muscarinic receptors in the vestibular nuclei, helping to alleviate motion sickness. Atropine (A) mainly affects peripheral muscarinic receptors, not as effective. Ipratropium (B) is a bronchodilator, not used for motion sickness. Homatropine (D) is primarily used for ophthalmic purposes, not vestibular issues. Therefore, C is the correct choice.

Correct Answer: B

Rationale: The correct answer is B: Epinephrine is not synthesized in the nerve endings. It is produced in the adrenal medulla and released into the bloodstream in response to stress. It travels through the blood to target tissues where it interacts with adrenoreceptors, leading to various physiological responses. Epinephrine does not directly interact with nerve endings for synthesis or action. Choices A, C, and D are incorrect because epinephrine is indeed synthesized in the adrenal medulla, transported in the blood to target tissues, and directly interacts with and activates adrenoreceptors, respectively.

Correct Answer: B

Rationale: Rationale: 1. Xylometazoline is an alpha2-selective agonist, which means it selectively activates alpha2 adrenergic receptors. 2. This action leads to vasoconstriction and reduces nasal congestion without affecting blood pressure. 3. Phenylephrine (choice A) is an alpha1-selective agonist, causing increased blood pressure. 4. Ephedrine (choice C) is a mixed agonist affecting both alpha and beta receptors. 5. Epinephrine (choice D) is a non-selective agonist acting on both alpha and beta receptors.

Correct Answer: C

Rationale: The correct answer is C because reserpine actually causes a sympatholytic effect, not a sympathomimetic effect. Reserpine depletes norepinephrine and serotonin stores in the brain, leading to decreased sympathetic activity. Choices A, B, and D are incorrect because reserpine does inhibit the uptake of norepinephrine, decrease cardiac output and peripheral resistance, and deplete catecholamines and serotonin stores in the brain, respectively.