Indicate selective catechol-O-methyltransferase inhibitor which prolongs the action of levodopa by diminishing its peripheral metabolism:

Correct Answer: C

Rationale: Rationale: 1. Tolcapone inhibits catechol-O-methyltransferase (COMT), reducing levodopa peripheral metabolism. 2. By prolonging levodopa's action, it enhances its efficacy in treating Parkinson's disease. 3. Carbidopa enhances levodopa bioavailability, not directly affecting its peripheral metabolism. 4. Clozapine is an antipsychotic with no COMT inhibitory activity. 5. Rasagiline is a monoamine oxidase-B inhibitor, not a COMT inhibitor.

Correct Answer: D

Rationale: Phenothiazine derivatives like chlorpromazine possess antihistaminic, anticholinergic, and antidopaminergic activities. These properties make them effective in treating various conditions like schizophrenia. Antihistaminic activity helps with sedation, anticholinergic activity reduces side effects like tremors, and antidopaminergic activity helps manage psychotic symptoms. Therefore, the correct answer is D. Choices A, B, and C are incorrect because phenothiazines typically exhibit a combination of all three activities, not just one.

Correct Answer: A

Rationale: The correct answer is A: Amitriptyline. Amitriptyline is a tricyclic antidepressant that can worsen symptoms in patients with prostatic hypertrophy, glaucoma, coronary, and cerebrovascular disease due to its anticholinergic effects. It can cause urinary retention in prostatic hypertrophy, increase intraocular pressure in glaucoma, and exacerbate cardiovascular conditions. Paroxetine, Bupropion, and Fluoxetine are generally safer options as they have less anticholinergic effects and are less likely to exacerbate these conditions.

Correct Answer: D

Rationale: The correct answer is D, all of the above. Anxiolytic dosage reduction is recommended in patients taking cimetidine due to potential drug interactions. In patients with hepatic dysfunction, reduced metabolism can lead to increased drug levels. Elderly patients may be more sensitive to anxiolytics due to age-related changes in metabolism and increased risk of adverse effects. Therefore, all three factors (cimetidine use, hepatic dysfunction, and age) can influence anxiolytic dosing, making D the correct choice.

Correct Answer: A

Rationale: Rationale: Inhaled anesthetics and intravenous agents with general anesthetic properties directly activate GABAA receptors. GABAA receptors are inhibitory neurotransmitter receptors in the brain. Activation of GABAA receptors leads to hyperpolarization of the neuron, resulting in decreased neuronal excitability and ultimately producing the anesthetic effect. Summary: A: Direct activation of GABAA receptors is correct as it aligns with the mechanism of action of general anesthetics. B: Facilitating GABA action but not directly acting on GABAA receptors is incorrect as direct activation is necessary for the anesthetic effect. C: Reducing glutamatergic neurotransmission is incorrect as it is not the primary mechanism of action for general anesthetics. D: Increasing the duration of opening of nicotine-activated potassium channels is incorrect as it is not related to the mechanism of action of general anesthetics.