Drugs in Psychiatric Disorders Practice Questions

Q: A 40-year-old patient with refractory epilepsy is on a multi-drug antiepileptic regimen. Two weeks after a dosage adjustment, he develops diffuse morbilliform rash, fever and oral mucosal erosions. Which of the following antiepileptic drugs can most saf ely be continued?

Clobazam. ***Clobazam*** - Clobazam is a **benzodiazepine** that acts as a positive allosteric modulator of GABA-A receptors, which is structurally distinct from traditional aromatic antiepileptic drugs (AEDs) like phenytoin or lamotrigine. - It is not associated with the **hypersensitivity reactions** (like DRESS syndrome or SJS/TEN) commonly triggered by the aromatic AEDs involved in the patient's current regimen. *Phenytoin* - Phenytoin is a known culprit for drug-induced **hypersensitivity reactions** (DRESS syndrome) due to its metabolites (arene oxides) that cause immune dysregulation. - It is strictly contraindicated in patients presenting with **morbilliform rashes** and systemic symptoms like fever and mucosal involvement, as continuation can lead to fatal complications. *Valproate* - Valproate is an aliphatic AED, but it can contribute to **DRESS syndrome** and also causes **hepatotoxicity**, which exacerbates the patient's systemic inflammatory response. - It is generally advised to discontinue implicated agents in a multidrug regimen to stabilize the patient, making it an unsafe drug to continue in this clinical context. *Lamotrigine* - Lamotrigine has a high potential for causing **severe cutaneous adverse reactions (SCARs)** such as **Stevens-Johnson Syndrome (SJS)** and **Toxic Epidermal Necrolysis (TEN)**, especially when titrated rapidly. - Given the presence of **oral mucosal erosions**, this drug is a highly suspicious trigger and must be discontinued immediately to prevent further progression.

Q: Which of the following ECG change is most characteristically associated with lithium therapy?

T-wave inversion. ***T-wave inversion*** - **Lithium** therapy is well-recognized for causing benign and reversible ECG changes, most characteristically **T-wave flattening or inversion**. - These changes are generally considered **non-specific** and typically do not require discontinuation of the medication unless associated with clinical cardiac symptoms or toxicity. *ST-segment elevation* - **ST-segment elevation** is much more characteristic of conditions like **acute myocardial infarction** or **pericarditis**, not lithium use. - It is not a common side effect of mood stabilizers and would necessitate a thorough investigation for **ischemic heart disease**. *ST-segment depression* - **ST-segment depression** is a classic sign of **myocardial ischemia** or **digoxin toxicity**. - This finding is not associated with lithium therapy and would indicate a different underlying pathology requiring separate investigation. *QT interval prolongation* - While **QT interval prolongation** is a serious adverse effect of many antipsychotic medications and antidepressants, it is not the primary ECG change associated with **lithium**. - Prolongation of the **QT interval** poses a risk for **torsades de pointes**, and its absence is a distinguishing feature of lithium compared to many other psychotropic agents.

Q: Which of the following drugs has the highest potential to cause metabolic syndrome?

Clozapine. **Explanation:** Metabolic syndrome—characterized by significant weight gain, hyperlipidemia, and hyperglycemia (Type 2 Diabetes)—is a major adverse effect of **Second-Generation Antipsychotics (SGAs)**. **1. Why Clozapine is correct:** Clozapine (along with Olanzapine) carries the **highest risk** of metabolic syndrome. The underlying mechanism involves potent antagonism of **H1 (histamine)** and **5-HT2C (serotonin)** receptors, which leads to increased appetite, sedation, and direct interference with insulin sensitivity. Clozapine is associated with the most profound weight gain and the highest incidence of new-onset diabetes among all antipsychotics. **2. Analysis of incorrect options:** * **Quetiapine:** Also carries a high risk of metabolic syndrome, but it is clinically ranked lower than Clozapine and Olanzapine. * **Risperidone:** Carries a moderate risk. It is more notorious for causing hyperprolactinemia (due to D2 blockade in the tuberoinfundibular pathway) than severe metabolic derangement. * **Aripiprazole:** This is a partial D2 agonist and has the **lowest risk** (metabolically neutral) along with Ziprasidone and Lurasidone. **3. NEET-PG High-Yield Pearls:** * **Hierarchy of Metabolic Risk:** Clozapine = Olanzapine > Quetiapine > Risperidone > Aripiprazole = Ziprasidone. * **Monitoring:** Patients on Clozapine require mandatory monitoring of BMI, fasting blood glucose, and lipid profiles. * **Clozapine "Must-Knows":** It is the drug of choice for **resistant schizophrenia**, but its use is limited by **agranulocytosis** (requires regular CBC monitoring) and a lowered seizure threshold.

Q: Which drug can cause psychosis?

Amfetamine. ### Explanation **Correct Option: B. Amfetamine** Amfetamine is a potent CNS stimulant that acts primarily by increasing the release of biogenic amines, particularly **Dopamine**, from presynaptic nerve terminals. According to the **Dopamine Hypothesis of Schizophrenia**, excessive dopaminergic activity in the mesolimbic pathway is linked to psychotic symptoms. High doses or chronic use of amfetamines can induce a "stimulant psychosis" that clinically mimics paranoid schizophrenia, characterized by delusions, hallucinations, and stereotypic behavior. **Analysis of Incorrect Options:** * **A. Ofloxacin:** While fluoroquinolones can occasionally cause CNS side effects like insomnia or dizziness, they are not classically associated with inducing frank psychosis. * **C. Capreomycin:** This is a polypeptide protein synthesis inhibitor used in MDR-TB. Its primary toxicities are **nephrotoxicity** and **ototoxicity** (8th cranial nerve damage), similar to aminoglycosides. * **D. Rifampicin:** A key anti-tubercular drug known for causing orange-colored secretions (urine, sweat, tears) and hepatotoxicity. It does not have psychotropic side effects. **High-Yield Clinical Pearls for NEET-PG:** * **Other drugs causing psychosis:** Levodopa (dopamine precursor), Steroids ("Steroid Psychosis"), Isoniazid (INH), Ketamine, and Cocaine. * **Drug of Choice for Amfetamine Psychosis:** Antipsychotics like **Haloperidol** (D2 blockers) are used to manage acute symptoms. * **Mechanism Recap:** Amfetamines reverse the direction of the dopamine transporter (DAT), pumping dopamine out into the synapse.

Q: Which is the recently approved drug for psychosis associated with Parkinsonism?

Pimavanserin. **Explanation:** **Pimavanserin** is the correct answer. It is a novel atypical antipsychotic specifically FDA-approved for the treatment of hallucinations and delusions associated with **Parkinson’s Disease Psychosis (PDP)**. **Mechanism of Action:** Unlike traditional antipsychotics that block Dopamine (D2) receptors—which would worsen motor symptoms in Parkinson’s—Pimavanserin acts as a **selective inverse agonist and antagonist at 5-HT2A receptors**. It has no significant affinity for D2, muscarinic, or histaminergic receptors. This allows it to treat psychotic symptoms without deteriorating motor function. **Analysis of Incorrect Options:** * **A. Lorcaserin:** A selective 5-HT2C receptor agonist previously used for weight loss (withdrawn from many markets due to safety concerns); it has no role in psychosis. * **C. Cycloserine:** An antitubercular drug (second-line) that also acts as a partial NMDA receptor agonist; it is not used for Parkinsonian psychosis. * **D. Mianserin:** A tetracyclic antidepressant that blocks alpha-2 adrenergic and 5-HT receptors; while it has sedative properties, it is not the indicated treatment for PDP. **Clinical Pearls for NEET-PG:** * **Drug of Choice for PDP:** Pimavanserin is preferred. If unavailable, **Quetiapine** or **Clozapine** (at low doses) are the traditional alternatives because they have the lowest D2 affinity among standard antipsychotics. * **Avoid:** Typical antipsychotics (e.g., Haloperidol) and certain atypicals (e.g., Risperidone) as they severely worsen Parkinsonian tremors and rigidity. * **Side Effects:** Pimavanserin can cause QT interval prolongation; monitor patients with pre-existing cardiac conditions.

Q: Which of the following drugs is known to induce parkinsonism?

Chlorpromazine. **Explanation:** The correct answer is **Chlorpromazine**. **1. Why Chlorpromazine is correct:** Chlorpromazine is a **First-Generation (Typical) Antipsychotic**. Its primary mechanism of action involves the potent blockade of **Dopamine D2 receptors** in the brain. While this helps alleviate psychotic symptoms in the mesolimbic pathway, it also blocks D2 receptors in the **Nigrostriatal pathway**. This blockade creates a functional deficiency of dopamine, leading to **Extrapyramidal Side Effects (EPS)**, of which drug-induced parkinsonism (tremors, rigidity, and bradykinesia) is a classic manifestation. **2. Why the other options are incorrect:** * **Chlorpheniramine:** An H1-receptor antagonist (antihistamine) used for allergies. It does not significantly affect central dopamine pathways. * **Chloroquine:** An antimalarial and DMARD. While it has various side effects (like retinopathy), it does not induce parkinsonism. * **Chlorhexidine:** A topical antiseptic and disinfectant used in dentistry and surgery; it has no systemic neurological activity. **3. High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of EPS":** Typical antipsychotics (like Haloperidol and Chlorpromazine) have a much higher risk of parkinsonism compared to Atypical antipsychotics (like Clozapine or Quetiapine). * **Management:** Drug-induced parkinsonism is managed by reducing the dose or adding **central anticholinergics** like **Benztropine** or **Trihexyphenidyl (PACANE)**. * **Prochlorperazine:** Another "Chlor" drug (anti-emetic) frequently tested for causing acute dystonia and parkinsonism due to D2 blockade. * **Contraindication:** Never use Levodopa to treat drug-induced parkinsonism, as it can worsen the underlying psychosis.

Q: A patient treated with haloperidol develops symptoms of Parkinsonism. What is the best treatment?

M1 muscarinic antagonist. ### Explanation **1. Why M1 Muscarinic Antagonists are Correct:** Haloperidol is a potent **D2 receptor antagonist** [1]. In the nigrostriatal pathway, there is a delicate functional balance between **Dopamine (inhibitory)** and **Acetylcholine (excitatory)**. By blocking D2 receptors, haloperidol causes a relative cholinergic overactivity, leading to Drug-Induced Parkinsonism (DIP) [1]. To restore this balance, we use **centrally acting anticholinergics (M1 muscarinic antagonists)** like **Benztropine, Trihexyphenidyl (Benzhexol), or Biperiden**. These drugs reduce the cholinergic excess, thereby alleviating tremors and rigidity. **2. Why Other Options are Incorrect:** * **A. Cholinesterase inhibitors (e.g., Donepezil):** These increase acetylcholine levels. This would worsen the cholinergic/dopaminergic imbalance and exacerbate Parkinsonian symptoms. * **B. Beta receptor antagonists (e.g., Propranolol):** These are the drug of choice for **Akathisia** (motor restlessness) induced by antipsychotics [1], but they do not treat the bradykinesia or rigidity of Parkinsonism. * **D. Alpha 1 adrenergic antagonists:** These are primarily used for hypertension or BPH. They have no role in the nigrostriatal dopamine-acetylcholine balance. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice for DIP:** Centrally acting anticholinergics (Trihexyphenidyl). * **Drug of Choice for Acute Dystonia:** Promethazine or Benztropine (IV/IM for rapid action). * **Drug of Choice for Akathisia:** Propranolol. * **Tardive Dyskinesia:** Caused by dopamine receptor supersensitivity; treatment involves switching to **Clozapine** [2] or using VMAT-2 inhibitors (Valbenazine). **Note:** Anticholinergics *worsen* Tardive Dyskinesia. * **Levodopa** is generally avoided in DIP as it can worsen the underlying psychosis [3].

Q: Stevens-Johnson syndrome is a known side effect of which of the following medications?

Carbamazepine. **Explanation:** **Stevens-Johnson Syndrome (SJS)** and its more severe variant, Toxic Epidermal Necrolysis (TEN), are life-threatening mucocutaneous reactions characterized by epidermal detachment. **Carbamazepine** is a notorious trigger for SJS, particularly in patients of Asian descent. This is strongly associated with the **HLA-B*1502 allele**; screening for this genetic marker is recommended before initiating treatment to mitigate risk. Other common psychiatric drugs causing SJS include Lamotrigine and Phenytoin. **Analysis of Incorrect Options:** * **Lithium:** Its most characteristic side effects include fine tremors, polyuria (nephrogenic diabetes insipidus), hypothyroidism, and teratogenicity (Ebstein’s anomaly). It does not typically cause SJS. * **Clozapine:** This atypical antipsychotic is most famously associated with **agranulocytosis** (requiring regular CBC monitoring), seizures, and myocarditis. * **Clonazepam:** As a benzodiazepine, its primary side effects are sedation, ataxia, and potential for dependence/withdrawal. Skin reactions are extremely rare. **Clinical Pearls for NEET-PG:** * **Lamotrigine** is the mood stabilizer with the highest risk of SJS if titrated too rapidly ("Start low, go slow"). * **HLA-B*1502** is the specific screening marker for Carbamazepine-induced SJS in Asian populations. * **HLA-A*3101** is another marker associated with Carbamazepine-induced hypersensitivity in Europeans. * If a patient on Carbamazepine or Lamotrigine develops a rash or mucosal involvement, the drug must be **stopped immediately**.

Q: Which of the following drugs causes sedation but no extrapyramidal side effects?

Clozapine. **Explanation:** The question tests the distinction between **Typical (First-generation)** and **Atypical (Second-generation)** antipsychotics regarding their side-effect profiles. **1. Why Clozapine is correct:** Clozapine is the prototype **Atypical Antipsychotic**. Its mechanism involves weak D2 receptor blockade and potent 5-HT2A antagonism. Because it has low affinity for D2 receptors in the nigrostriatal pathway and dissociates rapidly from them, it is unique for causing **virtually no Extrapyramidal Side Effects (EPS)**. However, it possesses strong H1-histaminergic and alpha-adrenergic blocking properties, leading to significant **sedation**. **2. Why the other options are incorrect:** * **Haloperidol & Fluphenazine:** These are high-potency Typical Antipsychotics. They cause strong D2 blockade in the nigrostriatal pathway, leading to a very high incidence of EPS (dystonia, akathisia, parkinsonism). While they can cause some sedation, their hallmark is motor side effects. * **Pimozide:** This is another Typical Antipsychotic (diphenylbutylpiperidine class) primarily used for Tourette’s syndrome. Like Haloperidol, it carries a significant risk of EPS and is associated with QTc prolongation. **3. High-Yield NEET-PG Pearls:** * **Clozapine Gold Standards:** It is the drug of choice for **treatment-resistant schizophrenia** and schizophrenia associated with suicidal behavior. * **Adverse Effects:** While it lacks EPS, it is notorious for **Agranulocytosis** (requires mandatory WBC monitoring), seizures (dose-dependent), myocarditis, and significant weight gain/metabolic syndrome. * **Sialorrhea:** Paradoxically, Clozapine causes excessive salivation (wet pillow sign) despite having anticholinergic properties at other sites.

Question 1

A 40-year-old patient with refractory epilepsy is on a multi-drug antiepileptic regimen. Two weeks after a dosage adjustment, he develops diffuse morbilliform rash, fever and oral mucosal erosions. Which of the following antiepileptic drugs can most saf ely be continued?

Accepted Answer

Clobazam

Answer

Phenytoin

Answer

Valproate

Answer

Lamotrigine

Question 2

Which of the following ECG change is most characteristically associated with lithium therapy?

Accepted Answer

T-wave inversion

Answer

ST-segment elevation

Answer

ST-segment depression

Answer

QT interval prolongation

Question 3

Which of the following drugs has the highest potential to cause metabolic syndrome?

Accepted Answer

Clozapine

Answer

Risperidone

Answer

Quetiapine

Answer

Aripiprazole

Question 4

Which drug can cause psychosis?

Accepted Answer

Amfetamine

Answer

Ofloxacin

Answer

Capreomycin

Answer

Rifampicin

Question 5

Which is the recently approved drug for psychosis associated with Parkinsonism?

Accepted Answer

Pimavanserin

Answer

Lorcaserin

Answer

Cycloserine

Answer

Mianserin

Question 6

Select the true statements:

Accepted Answer

Imipramine is used in the treatment of endogenous depression.

Answer

Fluoxetine causes weight gain.

Answer

Thioridazine causes less anticholinergic effects.

Answer

Benzodiazepines have the same abuse potential as barbiturates.

Question 7

Which of the following drugs is known to induce parkinsonism?

Accepted Answer

Chlorpromazine

Answer

Chlorpheniramine

Answer

Chloroquine

Answer

Chlorhexidine

Question 8

A patient treated with haloperidol develops symptoms of Parkinsonism. What is the best treatment?

Accepted Answer

M1 muscarinic antagonist

Answer

Cholinesterase inhibitors

Answer

Beta receptor antagonist

Answer

Alpha 1 adrenergic antagonist

Question 9

Stevens-Johnson syndrome is a known side effect of which of the following medications?

Accepted Answer

Carbamazepine

Answer

Lithium

Answer

Clozapine

Answer

Clonazepam

Question 10

Which of the following drugs causes sedation but no extrapyramidal side effects?

Accepted Answer

Clozapine

Answer

Pimozide

Answer

Fluphenazine

Answer

Haloperidol

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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