Which of the following effects is related to direct beta1-adrenoreceptor stimulation?

Correct Answer: C

Rationale: The correct answer is C: Tachycardia. Direct beta1-adrenoreceptor stimulation leads to an increase in heart rate by enhancing the conduction of electrical impulses in the heart. Beta1 receptors are primarily located in the heart, particularly in the sinoatrial node, atria, and ventricles. This stimulation results in an increased rate of depolarization, leading to tachycardia. Choices A and B are incorrect because beta2 receptors are responsible for bronchodilation and vasodilation, respectively. Choice D is incorrect because bradycardia is not associated with direct beta1-adrenoreceptor stimulation.

Correct Answer: D

Rationale: The correct answer is D because all three options (A, B, and C) are used in the treatment of insomnia. Benzodiazepines, such as diazepam, help induce sleep. Imidazopyridines, like zolpidem, also aid in sleep. Barbiturates, such as phenobarbital, have sedative effects. Therefore, all of the above options are valid treatments for insomnia.

Correct Answer: C

Rationale: The correct answer is C: Clonazepam. Clonazepam is a benzodiazepine commonly used for myoclonic seizures due to its ability to enhance the inhibitory neurotransmitter GABA in the brain, reducing seizure activity. Primidone (A), Carbamazepine (B), and Phenytoin (D) are more commonly used for other types of seizures like focal or generalized tonic-clonic seizures, not specifically for myoclonic seizures.

Correct Answer: A

Rationale: The correct answer is A because levodopa, as a precursor of dopamine, can cross the blood-brain barrier and be converted to dopamine in the brain, while dopamine itself cannot cross the blood-brain barrier when administered peripherally. Choice B is incorrect because dopamine-induced psychotic reactions are not the main reason for choosing levodopa. Choice C is also incorrect as levodopa is metabolized in the periphery before reaching the brain. Therefore, the correct choice is A as it addresses the main reason for using levodopa over dopamine.

Correct Answer: D

Rationale: The correct answer is D: Meperidine. Meperidine is the preferred opioid analgesic for relieving acute severe pain of renal colic due to its rapid onset of action and short duration of effect. It is particularly useful in this scenario as it provides quick pain relief without causing excessive sedation or respiratory depression. A: Morphine is a strong opioid analgesic but is not the preferred choice for renal colic due to its slower onset of action. B: Naloxone is an opioid antagonist and is used to reverse opioid overdose, not for pain relief. C: Methadone is a long-acting opioid analgesic and is not typically used for acute severe pain relief such as in renal colic.