Which among the following may be used as a sedatives-hypnotic?
**Core Concept**
The question is testing the student's knowledge of the pharmacological classification of sedatives-hypnotics, which are a class of medications used to induce sleep or sedation. These medications work by modulating the activity of neurotransmitters in the central nervous system.
**Why the Correct Answer is Right**
The correct answer is a benzodiazepine, which is a class of sedatives-hypnotics that act on the GABA_A receptor to increase the activity of the inhibitory neurotransmitter GABA. This results in a calming effect on the nervous system, leading to sedation or sleep. Benzodiazepines bind to the alpha subunit of the GABA_A receptor, increasing the frequency of chloride channel opening and allowing more chloride ions to enter the neuron, leading to hyperpolarization and a decrease in neuronal excitability.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because barbiturates are a different class of sedatives-hypnotics that act on the GABA_A receptor, but they are less selective and can cause more respiratory depression than benzodiazepines. Barbiturates also have a higher risk of dependence and addiction.
**Option B:** This is incorrect because antihistamines are a class of medications used to treat allergies and itching, and they are not typically used as sedatives-hypnotics. They can cause sedation as a side effect, but this is not their primary use.
**Option C:** This is incorrect because opioids are a class of medications used to treat pain, and they are not typically used as sedatives-hypnotics. While opioids can cause sedation as a side effect, this is not their primary use.
**Clinical Pearl / High-Yield Fact**
Benzodiazepines are generally safer than barbiturates and have a lower risk of dependence and addiction. They are also more selective in their action on the GABA_A receptor, making them a preferred choice for treating anxiety and insomnia.
**Correct Answer:** C. Diazepam.