Which of the following sympathomimetics acts indirectly?

Correct Answer: C

Rationale: Rationale: 1. Ephedrine acts indirectly by stimulating release of norepinephrine from nerve terminals. 2. Epinephrine (A) and norepinephrine (B) act directly on adrenergic receptors. 3. Methoxamine (D) is a direct acting alpha-1 agonist. Summary: A, B, and D directly stimulate adrejsonceptors, while only C acts indirectly by promoting norepinephrine release.

Correct Answer: D

Rationale: The correct answer is D: Propranolol. Propranolol is the preferred beta-blocker for thyroid storm due to its non-selective beta-adrenergic blockade, which helps control symptoms such as tachycardia and hypertension. It also inhibits the peripheral conversion of T4 to T3. Pindolol (A) is a partial beta-blocker with intrinsic sympathomimetic activity, not ideal for thyroid storm. Sotalol (B) is a non-selective beta-blocker with class III antiarrhythmic properties, not typically used in thyroid storm. Phentolamine (C) is an alpha-blocker, not a beta-blocker, and not indicated for thyroid storm.

Correct Answer: C

Rationale: Certainly! Ethosuximide is the correct answer because it specifically targets T-type calcium channels in thalamic neurons, effectively controlling absence seizures. Carbamazepine, Lamotrigine, and Phenytoin primarily act on sodium channels, making them ineffective in treating absence seizures. Ethosuximide's mechanism of action makes it the ideal choice for this specific type of seizure.

Correct Answer: B

Rationale: The correct answer is B because the principal aim for treating Parkinsonian disorders is to restore dopaminergic activity with levodopa and dopamine agonists. This is because Parkinson's disease is primarily caused by a deficit of dopamine in the brain. Levodopa is converted to dopamine in the brain, helping to alleviate symptoms. Choice A is incorrect because antimuscarinic drugs target the cholinergic system, not the dopaminergic system, and are not the primary treatment for Parkinson's disease. Choice C is incorrect because glutamate antagonists target a different neurotransmitter system and are not the mainstay of treatment for Parkinson's disease. Choice D is incorrect because while restoring balance between cholinergic and dopaminergic influences may be important, the primary aim is to address the dopaminergic deficit.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Strong mu receptor agonists, such as opioids, can cause hypertension due to the stimulation of mu receptors in the central nervous system. They can also increase pulmonary arterial pressure and myocardial work by affecting the cardiovascular system. Additionally, they can cause cerebral vasodilatation, leading to an increase in intracranial pressure. Therefore, all the mentioned effects are possible with strong mu receptor agonists, making option D the correct choice.