INI-CET 2025 — Pharmacology
17 Previous Year Questions with Answers & Explanations
Sodium thiopentone is regarded as an ultrashort-acting drug due to
Which of the following psychoactive substances is a new, rapidly acting antidepressant?
Imipramine and Diphenhydramine are given together to a patient. Why is this combination considered irrational?
Which of the following statements regarding Thalidomide is correct? a. It acts as an antimetabolite and is useful as an immunosuppressant b. It is used in the treatment of multiple myeloma c. It is used in the management of Type 2 lepra reaction (ENL) d. It is teratogenic
According to the Drugs and Cosmetics Rules, match the following medications with their corresponding schedules: 1. Insulin, 2. Hepatitis B vaccine, 3. Morphine, 4. Veterinary drugs. Schedules: A. Schedule H, B. Schedule Z, C. Schedule G, D. Schedule X.
Which of the following statements is incorrect?
For benzodiazepines and barbiturates, which of the following is true?
A male patient with a history of MSM presents with urethral discharge. There is penicillin resistance on testing. Which drug should be given?
Carbamazepine and erythromycin were given to a patient, and he presented with ataxia and dizziness. Which of the following is the reason for the symptoms?
Loading dose of an oral drug depends on all of the following except?
INI-CET 2025 - Pharmacology INI-CET Practice Questions and MCQs
Question 1: Sodium thiopentone is regarded as an ultrashort-acting drug due to
- A. Short elimination half-life
- B. Metabolism
- C. Excretion
- D. Rapid redistribution (Correct Answer)
Explanation: ***Rapid redistribution*** - The ultrashort action of **thiopentone** is primarily due to its rapid **redistribution** from the central compartment (brain) to peripheral tissues (muscle and fat). - This rapid drop in plasma and brain concentration leads to swift termination of the drug's hypnotic effect. *Metabolism* - While thiopentone is metabolized primarily by the **liver**, its metabolic clearance is relatively slow, contributing to its long elimination half-life rather than its quick onset/offset. *Excretion* - Thiopentone is only minimally excreted unchanged by the **kidneys**; renal excretion is not the reason for the ultrashort duration of action. *Short elimination half-life* - Thiopentone actually has a **long elimination half-life** (around 10–12 hours) because of its high lipid solubility, long protein binding, and slow systemic metabolism. - The duration of action is governed by redistribution, not by the elimination half-life.
Question 2: Which of the following psychoactive substances is a new, rapidly acting antidepressant?
- A. Ketamine (Correct Answer)
- B. Bupropion
- C. Haloperidol
- D. Cannabinoids
Explanation: ***Ketamine*** - It is an **NMDA receptor antagonist** that produces a rapid and often sustained antidepressant effect, typically within hours, making it a new class of rapidly acting antidepressants. - **Esketamine** (a derivative) is specifically approved for **treatment-resistant depression** and acute suicidal ideation. *Bupropion* - This is a traditional antidepressant classified as a **Norepinephrine and Dopamine Reuptake Inhibitor (NDRI)**. - Like most conventional antidepressants (SSRIs, SNRIs), Bupropion has a **delayed onset of action**, usually requiring weeks for clinical efficacy. *Haloperidol* - This substance is a typical or first-generation **antipsychotic** used primarily to treat conditions involving psychosis, such as schizophrenia and acute mania. - Its primary function involves potent blockade of **Dopamine D2 receptors**, and it is not used in the management of primary depression. *Cannabinoids* - These agents primarily modulate the **endocannabinoid system (CB1 and CB2 receptors)**, and while they have CNS effects, they are generally not used as primary, rapid-acting antidepressants. - Research into cannabinoids for mood is complex, and they may sometimes lead to dysphoria or **anxiety/psychosis exacerbation**.
Question 3: Imipramine and Diphenhydramine are given together to a patient. Why is this combination considered irrational?
- A. Both have anticholinergic action (Correct Answer)
- B. Both cause serotonin syndrome
- C. Both cause hypotension
- D. Both cause increased sedation
Explanation: ***Both have anticholinergic action*** - Imipramine, being a **Tricyclic Antidepressant (TCA)**, possesses significant **anticholinergic properties** (Muscarinic receptor blockade). - Diphenhydramine, a first-generation antihistamine, is also a highly effective **anticholinergic agent**; their co-administration leads to severe, potentially fatal, additive anticholinergic effects (e.g., acute confusion, severe urinary retention, paralytic ileus). *Both cause serotonin syndrome* - While Imipramine is a weak **Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**, Diphenhydramine does not directly contribute significantly to **serotonin toxicity**. - The primary and most hazardous interaction is the severe risk of **anticholinergic crisis**, not Serotonin Syndrome. *Both cause hypotension* - Imipramine can cause **orthostatic hypotension** due to its **alpha-1 adrenergic blockade** effects. - Although side effects include hypotension, the combined risk of severe **anticholinergic side effects** (delirium, ileus) is the overwhelming reason this combination is irrational. *Both cause increased sedation* - Both drugs are highly sedating, which is a valid concern for driving and daily function, mediated by **H1 receptor antagonism**. - However, while increased sedation is a risk, the combination is specifically deemed irrational because of the risk of life-threatening **anticholinergic toxicity**, which is a more critical pharmacological interaction than simple additive sedation.
Question 4: Which of the following statements regarding Thalidomide is correct? a. It acts as an antimetabolite and is useful as an immunosuppressant b. It is used in the treatment of multiple myeloma c. It is used in the management of Type 2 lepra reaction (ENL) d. It is teratogenic
- A. a, b, d
- B. a, b, c
- C. a, c, d
- D. b, c, d (Correct Answer)
Explanation: ***b, c, d*** - Statements b, c, and d are correct: Thalidomide is an **Immunomodulatory Drug (IMiD)** used effectively in the treatment of **multiple myeloma**, it is the drug of choice for **Erythema Nodosum Leprosum (ENL)** (Type 2 lepra reaction), and it is historically significant for causing **phocomelia** (teratogenicity). - Its mechanism involves downregulation of **pro-inflammatory cytokines** like TNF-alpha, which underlies its use in ENL, and anti-angiogenic/anti-proliferative effects against myeloma cells. *a, b, c* - Statement 'a' is incorrect because Thalidomide is an **Immunomodulatory Drug (IMiD)**, not an **antimetabolite** (a class of drugs that inhibit DNA/RNA synthesis). - Inclusion of the incorrect mechanism ('a') invalidates this set, despite 'b' (multiple myeloma) and 'c' (ENL) being correct clinical applications. *a, c, d* - This combination is incorrect primarily because it includes statement 'a', which wrongly defines Thalidomide as an **antimetabolite**. - Crucially, this option omits statement 'b', which is a major, current indication for Thalidomide in **multiple myeloma**. *a, b, d* - This combination wrongly includes the factual error of statement 'a' (it is not an **antimetabolite**). - It also misses statement 'c', which is the prominent use of Thalidomide in **Type 2 lepra reaction (ENL)**.
Question 5: According to the Drugs and Cosmetics Rules, match the following medications with their corresponding schedules: 1. Insulin, 2. Hepatitis B vaccine, 3. Morphine, 4. Veterinary drugs. Schedules: A. Schedule H, B. Schedule Z, C. Schedule G, D. Schedule X.
- A. 1-D, 2-B, 3-A, 4-C
- B. 1-C, 2-D, 3-B, 4-A
- C. 1-B, 2-A, 3-D, 4-C
- D. 1-C, 2-A, 3-D, 4-B (Correct Answer)
Explanation: ***1-C, 2-A, 3-D, 4-B*** - **Insulin** (1) is properly categorized under **Schedule G** (C), specifying drugs that must be taken only under the supervision of a registered medical practitioner. - The **Hepatitis B vaccine** (2) falls under **Schedule H** (A - general prescription drugs), **Morphine** (3) is correctly placed under **Schedule X** (D - narcotics/psychotropics), and **Veterinary drugs** (4) are covered by **Schedule Z** (B - proprietary veterinary medicines). *1-C, 2-D, 3-B, 4-A* - This option incorrectly assigns the **Hepatitis B vaccine** (2) to Schedule D (which deals with standards of imported drugs) instead of Schedule H. - It incorrectly places **Morphine** (3) under Schedule B (fees for tests and analysis) instead of the appropriate Schedule X. *1-B, 2-A, 3-D, 4-C* - This option incorrectly assigns **Insulin** (1) to Schedule B (fees for test or analysis by the Central Drugs Laboratory) instead of Schedule G. - It incorrectly places **Veterinary drugs** (4) under Schedule C (which deals with biological products intended for parenteral administration). *1-D, 2-B, 3-A, 4-C* - This option incorrectly assigns **Insulin** (1) to Schedule D (rules regarding the importation of drugs) and **Morphine** (3) to Schedule A (forms of application for licenses). - It also incorrectly links the **Hepatitis B vaccine** (2) to Schedule B (fees for tests rather than a drug category).
Question 6: Which of the following statements is incorrect?
- A. Alcohol in low dose causes brain stimulation and in higher doses, causes brain suppression
- B. Cannabis use can result in self-driven, repetitive behaviours (Correct Answer)
- C. Opioids are very effective analgesics
- D. Volatile inhalational agents (when abused) are mostly toxic to humans
Explanation: ***Cannabis use can result in self-driven, repetitive behaviours*** - This statement is **incorrect**. Repetitive, purposeless, or **stereotyped behaviors** (**stereotypies**) are typically associated with chronic use or intoxication with **stimulants** (e.g., cocaine, amphetamines/methamphetamine), not cannabis. - Cannabis (THC) primarily acts as a depressant/hallucinogen, often causing symptoms like impaired coordination, anxiety, paranoia, altered time perception, and the **amotivational syndrome**, rather than stimulant-like stereotypies. ***Alcohol in low dose causes brain stimulation and in higher doses, causes brain suppression*** - This statement is **correct**. In low doses, alcohol causes **disinhibition** and euphoria due to selective suppression of inhibitory neurons (apparent stimulation). - In higher doses, alcohol progressively depresses the entire Central Nervous System (CNS), leading to sedation, coma, and **respiratory suppression**. ***Opioids are very effective analgesics*** - This statement is **correct**. Opioids act by agonizing **mu-opioid receptors** in the CNS, spinal cord, and peripheral nerves, causing profound **analgesia**. - They are considered the gold standard for managing severe, acute, and chronic pain, though their use is limited by addiction potential and side effects. ***Volatile inhalational agents are mostly toxic to humans*** - This statement is **correct** for recreational/abused inhalational agents (like toluene, butane, nitrites). - Abuse of these agents can cause severe immediate toxicity (e.g., **sudden sniffing death**) and long-term damage, particularly to the brain (encephalopathy), liver, and kidneys.
Question 7: For benzodiazepines and barbiturates, which of the following is true?
- A. Flumazenil is the antidote for barbiturate
- B. Cause additive sedation with alcohol
- C. Thiopentone has short duration of action due to metabolism
- D. Both have effect on GABA-A chloride channel (Correct Answer)
Explanation: ***Both have effect on GABA-A chloride channel*** Both benzodiazepines and barbiturates act as **positive allosteric modulators** of the **GABA-A receptor**, a **ligand-gated chloride channel**, leading to increased frequency (BZDs) or duration (Barbiturates) of channel opening [1]. This enhancement of the inhibitory neurotransmitter GABA results in **CNS depression**, which is the basis for their anxiolytic, sedative, and hypnotic effects [1].***Flumazenil is the antidote for barbiturate*** **Flumazenil** is a competitive antagonist used specifically to reverse the effects of **benzodiazepines** by blocking their binding site on the GABA-A receptor [1]. There is **no specific pharmacological antidote** for barbiturate overdose; management involves supportive care like airway protection and respiratory support.***Cause additive sedation with alcohol*** Although both drugs cause severe **synergistic CNS depression** when combined with alcohol, this is a property shared by many CNS depressants, not unique to this pair, whereas their shared molecular target (D) is a fundamental defining characteristic. The combination of either BZDs or barbiturates with ethanol significantly **potentiates sedation** and increases the risk of respiratory depression and coma.***Thiopentone has short duration of action due to metabolism*** The ultra-short action of **thiopentone** following a single intravenous dose is primarily due to rapid **redistribution** out of the brain into highly perfused tissues (muscle and fat) since it is highly lipid-soluble [1, 2]. While it is eventually metabolized by the liver, **hepatic metabolism** is not the factor responsible for the swift onset and termination of its hypnotic effect [1].
Question 8: A male patient with a history of MSM presents with urethral discharge. There is penicillin resistance on testing. Which drug should be given?
- A. Ceftriaxone (Correct Answer)
- B. Amoxiclav
- C. Tetracycline
- D. Vancomycin
Explanation: ***Ceftriaxone*** - **Ceftriaxone** (a third-generation cephalosporin) is the current primary treatment for uncomplicated **gonorrhea**, especially due to rising penicillin and fluoroquinolone resistance globally. - Given the patient's presentation (urethral discharge in an **MSM** patient) strongly suggesting gonorrhea, and documented **penicillin resistance**, ceftriaxone remains the drug of choice. *Amoxiclav* - **Amoxicillin/clavulanic acid** (Amoxiclav) is ineffective for the treatment of *Neisseria gonorrhoeae* due to widespread $\beta$-lactamase production and insufficient coverage against resistant strains. - It is more commonly used for community-acquired respiratory tract infections or skin infections. *Tetracycline* - **Tetracyclines** (like doxycycline) are the preferred treatment for co-occurring **Chlamydia trachomatis** infection, but are not the primary single agent for resistant gonococcal infection. - Although historically used, tetracyclines have limited efficacy against many contemporary **gonococcal strains** and are not recommended as monotherapy for resistant gonorrhea. *Vancomycin* - **Vancomycin** is a glycopeptide antibiotic primarily used for serious infections caused by **Gram-positive** bacteria, particularly **MRSA** and *Clostridium difficile*. - It has no meaningful role or efficacy in treating **Gram-negative** infections like **gonorrhea**.
Question 9: Carbamazepine and erythromycin were given to a patient, and he presented with ataxia and dizziness. Which of the following is the reason for the symptoms?
- A. Toxicity of carbamazepine (Correct Answer)
- B. Toxicity of erythromycin
- C. Erythromycin speeds up carbamazepine metabolism
- D. Sub-therapeutic carbamazepine levels causing seizures
Explanation: ***Toxicity of carbamazepine*** - Erythromycin is a potent inhibitor of the hepatic **CYP3A4 enzyme**, which is primarily responsible for the metabolism and subsequent clearance of carbamazepine. - Inhibition of carbamazepine metabolism leads to increased plasma concentration, resulting in **CNS side effects** such as **ataxia, dizziness**, nystagmus, and drowsiness. *Toxicity of erythromycin* - Erythromycin toxicity typically presents with **gastrointestinal symptoms** (e.g., nausea, vomiting, diarrhea) or cardiac issues like **QT prolongation**. - The described symptoms, ataxia and dizziness, are classic manifestations of **anticonvulsant toxicity**, not macrolide toxicity. *Erythromycin speeds up carbamazepine metabolism* - This statement is incorrect; erythromycin **inhibits** CYP3A4, thus slowing down carbamazepine metabolism and resulting in drug accumulation. - If metabolism were sped up (i.e., enzyme induction), the patient would likely experience sub-therapeutic carbamazepine levels, increasing the risk of **seizure recurrence**. *Sub-therapeutic carbamazepine levels causing seizures* - Recurrent seizures are caused by **sub-therapeutic levels** of carbamazepine, often due to enzyme induction (e.g., by phenytoin, carbamazepine itself) or non-compliance. - The symptoms of ataxia and dizziness indicate **supratherapeutic levels** (toxicity), which is the opposite of the low levels that cause breakthrough seizures.
Question 10: Loading dose of an oral drug depends on all of the following except?
- A. Volume of distribution
- B. Half-life (Correct Answer)
- C. Plasma concentration
- D. Bioavailability
Explanation: ***Correct Answer: Half-life*** - **Half-life** primarily determines the **maintenance dose** and **dosing interval**, not the loading dose - The **loading dose (LD)** is calculated to rapidly achieve the desired therapeutic **plasma concentration** using the formula: **LD = (Cp × Vd) / F** - Half-life determines how long it takes to reach steady state (4-5 half-lives) and how frequently maintenance doses should be given - The loading dose bypasses the waiting time by immediately achieving therapeutic levels *Incorrect: Volume of distribution* - **Vd** is a mandatory parameter in the calculation of the loading dose formula - It determines how widely the drug distributes in the body relative to the target plasma concentration - A higher **Vd** necessitates a higher loading dose to saturate tissue binding sites and achieve therapeutic plasma levels quickly *Incorrect: Plasma concentration* - The loading dose is specifically calculated to quickly achieve the desired therapeutic **steady-state plasma concentration (Cp)** - The target concentration (Cp) is central to the loading dose calculation and appears in the numerator of the formula - The goal of the loading dose is to bypass the time required to reach this concentration with maintenance doses alone *Incorrect: Bioavailability* - **Bioavailability (F)** represents the fraction of the administered drug that reaches systemic circulation - It is crucial for oral drugs where absorption may be incomplete due to first-pass metabolism or incomplete absorption - The loading dose formula includes **F** in the denominator (LD = (Cp × Vd) / F) to adjust for incomplete absorption