Which of the following hypnotic drugs is more likely to cause cumulative and residual effects?

Correct Answer: C

Rationale: The correct answer is C: Phenobarbital. Phenobarbital is a long-acting barbiturate that can lead to cumulative and residual effects due to its long half-life and potential for drug accumulation in the body over time. This can result in prolonged sedative effects and increased risk of side effects. Zolpidem (A), Temazepam (B), and Triazolam (D) are shorter-acting hypnotic drugs with less potential for cumulative and residual effects compared to Phenobarbital.

Correct Answer: B

Rationale: The correct answer is B: Clozapine. Clozapine is an atypical antipsychotic that can help counteract the behavioral complications of levodopa therapy, such as hallucinations and psychosis, without compromising the efficacy of levodopa. Tolkapone (A) is a COMT inhibitor used to prolong the effect of levodopa, not counteract behavioral complications. Carbidopa (C) is a dopa decarboxylase inhibitor that enhances levodopa's effectiveness but does not address behavioral complications. Pergolide (D) is a dopamine agonist used to treat Parkinson's disease symptoms, but it does not specifically target levodopa's behavioral complications.

Correct Answer: C

Rationale: Buprenorphine is a partial mu receptor agonist, meaning it activates the mu receptors but to a lesser extent compared to full agonists like morphine. Buprenorphine's unique pharmacological profile includes partial agonist activity at mu receptors, along with antagonist activity at kappa receptors. This combination results in a ceiling effect on respiratory depression and a lower risk of abuse potential compared to full agonists. Methadone is a full mu receptor agonist, morphine is a full mu receptor agonist, and sufentanyl is a potent full mu receptor agonist but is not a partial agonist like buprenorphine.

Correct Answer: B

Rationale: The correct answer is B: Clozapine. Clozapine is considered an atypical antipsychotic due to its unique mechanism of action targeting serotonin and dopamine receptors. It is commonly used for treatment-resistant schizophrenia. Haloperidol (A) is a typical antipsychotic. Thioridazine (C) and Thiothixene (D) are also typical antipsychotics. They primarily target dopamine receptors and are associated with more side effects compared to atypical antipsychotics like Clozapine.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Tricyclic antidepressants like Amitriptyline have all three effects. Antimuscarinic action leads to dry mouth, constipation. Antihistaminic action causes sedation. Alpha adrenoreceptor-blocking action results in orthostatic hypotension. These side effects are common with tricyclic antidepressants due to their pharmacological properties.