Central Nervous System Pharmacology — MCQs

Q: What is the drug of choice for managing status epilepticus?

Lorazepam. ***Lorazepam*** - **Lorazepam** is the preferred first-line agent for status epilepticus due to its rapid onset of action and relatively long duration of anticonvulsant effect (12-24 hours), making it highly effective in stopping ongoing seizures. - Its **lipophilicity** allows it to quickly cross the blood-brain barrier while having less redistribution than diazepam, providing sustained seizure control. - Dose: **0.1 mg/kg IV** (typically 4 mg) administered at 2 mg/min. *Propofol* - **Propofol** is an anesthetic agent used in **refractory status epilepticus** when first and second-line agents have failed. - It carries risks of **hemodynamic instability**, **propofol infusion syndrome** with prolonged use, and requires ICU monitoring with intubation. - Reserved for third-line therapy, not appropriate as initial management. *Thiopentone* - **Thiopentone** is a barbiturate used for **refractory status epilepticus** as a third-line agent. - It has a longer half-life and recovery time compared to benzodiazepines, with significant **cardiovascular depression** and respiratory suppression. - Requires ICU setting with mechanical ventilation and hemodynamic support. *Phenytoin* - **Phenytoin** (or fosphenytoin) is a **second-line agent** used after benzodiazepines if seizures persist. - It has a **slower onset of action** (15-30 minutes) compared to benzodiazepines and requires cardiac monitoring due to risk of arrhythmias. - Loading dose: **20 mg/kg IV** at maximum rate of 50 mg/min to avoid cardiovascular complications.

Q: Which of the following statements about ramelteon is false?

Has high addiction liability. ***Has high addiction liability*** - Ramelteon is a **melatonin receptor agonist** that does not bind to GABA receptors, distinguishing it from benzodiazepines and Z-drugs (zolpidem, eszopiclone, zaleplon). - Its mechanism of action leads to a **very low risk of abuse and dependence**, contrary to the statement. *Is a substrate of CYP1A2* - Ramelteon is extensively metabolized in the liver, primarily by **CYP1A2**, which is accurate. - This metabolic pathway can lead to drug interactions if co-administered with **CYP1A2 inhibitors** (e.g., fluvoxamine), which can significantly increase ramelteon concentrations. *Approved for treatment of insomnia* - Ramelteon is indeed indicated for the **treatment of insomnia**, particularly for difficulties with **sleep onset**. - It works by mimicking the action of **melatonin**, promoting the regulation of the sleep-wake cycle. *Agonist at MT1 and MT2 receptors* - Ramelteon acts as a **selective agonist** at the **melatonin MT1 and MT2 receptors** in the suprachiasmatic nucleus. - Activation of these receptors helps to modulate the **circadian rhythm**, thereby promoting sleep.

Central Nervous System Pharmacology — MCQs

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