Central Nervous System Pharmacology Practice Questions

Q: All the following drugs are used for Absence seizures except -

Phenytoin. ***Phenytoin*** - Phenytoin is primarily effective in treating **tonic-clonic seizures** and **focal seizures** by blocking voltage-gated sodium channels. - It can actually exacerbate **absence seizures** or have no therapeutic effect on them. *Valproate* - **Valproate** is a broad-spectrum antiepileptic drug effective against various seizure types, including **absence seizures**. - It works by blocking **voltage-gated sodium channels**, enhancing GABAergic transmission, and inhibiting T-type calcium channels. *Ethosuximide* - **Ethosuximide** is the **first-line drug** for treating **absence seizures** due to its selective action. - It primarily acts by blocking **T-type calcium channels** in the thalamic neurons, which are crucial for generating absence seizures. *Clonazepam* - **Clonazepam**, a benzodiazepine, is effective for treating **absence seizures** by enhancing **GABAergic inhibitory neurotransmission**. - It can be used as an **adjunct or alternative** when other drugs are not effective or tolerated, though it has more sedative side effects.

Q: In treatment of Parkinsonism with Levodopa dose limiting toxicity is

Choreiform movements. ***Choreiform movements*** - **Choreiform movements** (dyskinesias) are a common dose-limiting toxicity of **levodopa** in Parkinson's disease, occurring as the cumulative dose increases over time. - These involuntary, dance-like movements are largely due to **pulsatile stimulation** of dopamine receptors, eventually leading to their hypersensitivity. *Giddiness* - **Giddiness** or **orthostatic hypotension** can occur with levodopa, especially early in treatment, but it is typically managed by dose titration or adjunct therapies rather than being a primary dose-limiting toxicity that necessitates stopping the drug. - While it can be a side effect, it rarely limits the continuation of levodopa therapy in the long term as much as dyskinesias do. *Vomiting* - **Nausea and vomiting** are common initial side effects of levodopa, particularly without a **decarboxylase inhibitor** like carbidopa. - These symptoms are usually managed by administering levodopa with food or by adding carbidopa, and are not typically the primary factor limiting chronic high-dose therapy. *Tardive dyskinesia* - **Tardive dyskinesia** is primarily associated with **long-term use of dopamine receptor blockers** (e.g., antipsychotics), not typically with levodopa. - While levodopa can cause dyskinesias, the term "tardive dyskinesia" is specifically reserved for neuroleptic-induced movement disorders.

Q: All are vasodilators except –

Cocaine. ***Cocaine*** - Cocaine is unique among local anesthetics because it causes **vasoconstriction** rather than vasodilation. - This vasoconstrictive effect is due to its blocking of **norepinephrine reuptake** at adrenergic nerve terminals, leading to an accumulation of norepinephrine and subsequent adrenergic stimulation. *Lidocaine* - Lidocaine is a common **amide-type local anesthetic** known for its vasodilatory properties that contribute to its systemic absorption. - Its vasodilatory effect can lead to a **flushing** sensation and increased blood flow in the area of injection. *Procaine* - Procaine is an **ester-type local anesthetic** that causes vasodilation, which results in a relatively short duration of action. - This vasodilation increases **local blood flow**, speeding up the systemic absorption and metabolism of the drug. *Bupivacaine* - Bupivacaine is an **amide-type local anesthetic** with longer duration of action compared to lidocaine, and like most local anesthetics, it causes vasodilation. - The vasodilatory effect of bupivacaine can lead to increased **systemic absorption** and potential for systemic toxicity if not managed carefully.

Q: Drug of choice in treatment of partial complex seizures

Carbamazepine. ***Carbamazepine*** - **Carbamazepine** is a **first-line agent** for **focal (partial) onset seizures**, including complex partial seizures, due to its efficacy in stabilizing neuronal membranes. - It works by blocking **voltage-gated sodium channels**, reducing abnormal electrical activity in the brain. *Sodium valproate* - **Sodium valproate** is a **broad-spectrum anticonvulsant** effective against both **generalized and focal seizures**, but it is generally considered **first-line for generalized seizures**, especially absence and myoclonic. - While it can be used for partial seizures, carbamazepine or oxcarbazepine are usually preferred as initial therapy for focal seizures. *Phenytoin* - **Phenytoin** is an effective anticonvulsant for **focal (partial) and generalized tonic-clonic seizures**, blocking sodium channels to prevent seizure propagation. - However, its use is limited by a **narrow therapeutic index**, significant drug interactions, and dose-related side effects such as **gingival hyperplasia**, nystagmus, and hirsutism. *Ethosuximide* - **Ethosuximide** is the **drug of choice** specifically for **absence seizures** (pyknolepsy) by inhibiting T-type calcium channels in the thalamus. - It has **no significant efficacy** against partial complex seizures or generalized tonic-clonic seizures.

Q: Antagonist of benzodiazepine is?

Flumazenil. ***Flumazenil*** - **Flumazenil** is a competitive antagonist at the **GABA-A receptor**, where benzodiazepines exert their effects. - It is used to reverse the sedative and respiratory depressant effects of **benzodiazepine overdose** or to aid in recovery from general anesthesia induced with benzodiazepines. *Buspirone* - **Buspirone** is an anxiolytic agent that acts primarily as a **selective serotonin 5-HT1A receptor partial agonist**, with no direct benzodiazepine receptor activity. - It is used for generalized anxiety disorder but does not reverse benzodiazepine effects. *Zolpidem* - **Zolpidem** is a **non-benzodiazepine hypnotic** (Z-drug) that selectively agonizes the **alpha-1 subunit of the GABA-A receptor**, exhibiting hypnotic effects. - While it acts on the GABA-A receptor, it is an agonist, not an antagonist, and thus exaggerates rather than reverses benzodiazepine-like effects. *Ramelteon* - **Ramelteon** is a **melatonin receptor agonist** that acts on MT1 and MT2 receptors in the suprachiasmatic nucleus. - It helps regulate the sleep-wake cycle and is used for insomnia, but it has no interaction with the benzodiazepine receptor.

Q: Angel dust is:

Phencyclidine. ***Correct: Phencyclidine*** - **Phencyclidine (PCP)** is commonly known by the street name **"angel dust"** - It is a **dissociative anesthetic** with hallucinogenic and neurotoxic effects - Acts primarily as an **NMDA receptor antagonist** *Incorrect: LSD* - **LSD (lysergic acid diethylamide)** is a classic hallucinogen with the street name "acid," not angel dust - It primarily affects **serotonin receptors (5-HT2A)** and causes profound alterations in perception and thought - Chemically and pharmacologically distinct from PCP *Incorrect: Cannabis* - **Cannabis** is a psychoactive drug derived from the *Cannabis* plant, commonly known as marijuana or weed - Its active compound **THC (tetrahydrocannabinol)** produces euphoric and relaxing effects through cannabinoid receptors - Not related to the street name "angel dust" *Incorrect: Morphine* - **Morphine** is a potent **opioid analgesic** used for pain relief - Acts as a **CNS depressant** through mu-opioid receptors - Unlike PCP's dissociative and stimulant effects, morphine produces sedation and analgesia

Q: A boy is planning to travel by bus. Which of the following drugs can be used to prevent motion sickness in this person?

Promethazine. **Promethazine** - **Promethazine** is an **H1 antihistamine** with significant **anticholinergic** properties that effectively blocks muscarinic receptors in the **vestibular system**, making it highly effective for preventing motion sickness. - Its **sedating effects** are also beneficial in relieving the discomfort associated with motion sickness. *Fexofenadine* - **Fexofenadine** is a **second-generation H1 antihistamine** that is **non-sedating** and has minimal anticholinergic activity. - While effective for allergies, its lack of central nervous system penetration and anticholinergic action makes it **ineffective for motion sickness**. *Loratadine* - **Loratadine** is another **second-generation H1 antihistamine**, known for being **non-sedating** and having limited entry into the central nervous system. - It does not possess the significant anticholinergic properties necessary to prevent the **vestibular disturbances** that cause motion sickness. *Cetirizine* - **Cetirizine** is a **second-generation H1 antihistamine** that has **moderate sedative effects** (more than other second-generation agents) and some CNS penetration, but lacks the significant **anticholinergic activity** required for motion sickness prevention. - It is primarily used for allergies and is **not recommended** for the prevention or treatment of motion sickness.

Q: Which of the following drugs is used for smoking cessation?

Varenicline. ***Varenicline*** - **Varenicline** is a **partial agonist** at the **α4β2 nicotinic acetylcholine receptor**, reducing cravings and withdrawal symptoms while decreasing the rewarding effects of nicotine [2]. - It is a first-line pharmacotherapy for **smoking cessation**, often initiated a week before the target quit date. *Gabapentin* - **Gabapentin** is primarily an **anticonvulsant** and is also used to treat **neuropathic pain**. - It is not indicated for **smoking cessation** and acts by modulating **GABAergic neurotransmission**, unrelated to nicotine dependence. *Acamprosate* - **Acamprosate** is used to maintain **abstinence from alcohol** in patients with alcohol dependence. - Its mechanism involves restoring the balance between **excitation and inhibition** in the brain, which is not directly applicable to nicotine dependence. *Nalmefene* - **Nalmefene** is an **opioid system modulator** used for reducing **alcohol consumption** in adults with alcohol dependence [1]. - It acts as an **opioid receptor antagonist**, a mechanism distinct from the neurotransmitter systems involved in nicotine addiction [1].

Q: Which of the following is not an ESTER?

Bupivacaine. ***Bupivacaine*** - Bupivacaine is an **amide-type local anesthetic** because it contains an amide linkage in its chemical structure. - Amide-type local anesthetics are metabolized in the liver, generally having a **longer duration of action** and a lower risk of allergic reactions compared to esters. *Benzocaine* - Benzocaine is an **ester-type local anesthetic**, characterized by an ester linkage that connects the aromatic ring and the amine group, though it lacks a tertiary amine. - It is typically used for **topical applications** due to its poor water solubility and rapid metabolism by plasma esterases. *Amethocaine* - Amethocaine (also known as tetracaine) is an **ester-type local anesthetic**, identifiable by its ester bond. - It has a relatively **long duration of action** for an ester and is often used for spinal anesthesia and topical applications. *Procaine* - Procaine is an **ester-type local anesthetic**, containing the characteristic ester linkage in its chemical structure. - It was one of the first local anesthetics discovered and has a **short duration of action** due to rapid metabolism by plasma pseudocholinesterase.

Q: True about MDMA:

Ecstasy is another name for it. Ecstasy is another name for it - MDMA (3,4-methylenedioxymethamphetamine) is widely known by its street name, Ecstasy [1]. - This name refers to its profound empathogenic effects and sense of well-being it often induces. It is a cocaine congener - MDMA is an amphetamine derivative and acts primarily on serotonin, dopamine, and norepinephrine systems, distinct from cocaine's primary action as a reuptake inhibitor [1], [2]. - While both MDMA and cocaine are stimulants, their chemical structures and primary mechanisms of action are different; MDMA is a substituted amphetamine [1]. Methadone is used to treat withdrawal symptoms - Methadone is an opioid agonist primarily used in the management of opioid dependence and withdrawal symptoms [3]. - MDMA withdrawal symptoms are typically managed with supportive care, focusing on symptom relief and psychological support, as there is no specific pharmacological treatment like methadone for MDMA withdrawal [3]. Causes parkinsonism like syndrome - While MDMA can cause neurotoxicity, particularly affecting serotonergic neurons, it is not typically associated with a direct parkinsonism-like syndrome [2]. - Parkinsonism is primarily linked to dopaminergic system damage, often seen with certain neuroleptics or drugs like MPTP, not MDMA.

Question 1

All the following drugs are used for Absence seizures except -

Accepted Answer

Phenytoin

Answer

Valproate

Answer

Ethosuximide

Answer

Clonazepam

Question 2

In treatment of Parkinsonism with Levodopa dose limiting toxicity is

Accepted Answer

Choreiform movements

Answer

Giddiness

Answer

Vomiting

Answer

Tardive dyskinesia

Question 3

All are vasodilators except –

Accepted Answer

Cocaine

Answer

Lidocaine

Answer

Procaine

Answer

Bupivacaine

Question 4

Drug of choice in treatment of partial complex seizures

Accepted Answer

Carbamazepine

Answer

Sodium valproate

Answer

Phenytoin

Answer

Ethosuximide

Question 5

Antagonist of benzodiazepine is?

Accepted Answer

Flumazenil

Answer

Buspirone

Answer

Zolpidem

Answer

Ramelteon

Question 6

Angel dust is:

Accepted Answer

Phencyclidine

Answer

LSD

Answer

Cannabis

Answer

Morphine

Question 7

A boy is planning to travel by bus. Which of the following drugs can be used to prevent motion sickness in this person?

Accepted Answer

Promethazine

Answer

Fexofenadine

Answer

Loratadine

Answer

Cetirizine

Question 8

Which of the following drugs is used for smoking cessation?

Accepted Answer

Varenicline

Answer

Gabapentin

Answer

Acamprosate

Answer

Nalmefene

Question 9

Which of the following is not an ESTER?

Accepted Answer

Bupivacaine

Answer

Benzocaine

Answer

Amethocaine

Answer

Procaine

Question 10

True about MDMA:

Accepted Answer

Ecstasy is another name for it

Answer

It is a cocaine congener

Answer

Methadone is used to treat withdrawal symptoms

Answer

Causes parkinsonism like syndrome

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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