Most commonly abused opioid -
Which anaesthetic agent is neither metabolised by liver nor by kidney?
Which local anesthetic is known for its vasoconstrictive properties?
Which of the following is the prototypical sympathomimetic agent with both alpha and beta-adrenergic activity?
What is the effect of adding epinephrine to lignocaine (a local anesthetic)?
Which amino acid-derived neurotransmitter is primarily targeted in the pharmacological treatment of depression?
Midazolam does not cause which of the following?
Drug of choice for Pneumocystis jirovecii in pregnancy?
What is the drug of choice for malaria in pregnancy?
All of the following occurs because of prostaglandin use except?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 81: Most commonly abused opioid -
- A. Morphine
- B. Diacetylmorphine (Correct Answer)
- C. Oxycodone
- D. Buprenorphine
Explanation: ***Diacetylmorphine*** - **Diacetylmorphine**, commonly known as **heroin**, is synthetically derived from **morphine** but is significantly more potent and lipid-soluble, allowing it to cross the **blood-brain barrier** rapidly [1, 3]. - Its rapid onset of action and intense euphoric effects contribute to its high potential for **abuse** and addiction, making it one of the most commonly abused opioids globally, particularly through intravenous injection [1]. *Morphine* - While **morphine** is a potent opioid and has a high potential for abuse, it is often prescribed in clinical settings for severe pain. - Its slower onset and less intense "rush" compared to **heroin** make it less frequently the **primary opioid of abuse** in illicit street drug markets [1]. *Oxycodone* - **Oxycodone** is a highly abused prescription opioid, especially in the form of controlled-release formulations like **OxyContin**, but its abuse is primarily linked to prescription drug diversion rather than being the most common illicitly manufactured opioid of abuse. - While it contributes significantly to the opioid crisis, **heroin** (diacetylmorphine) remains the most commonly abused opioid in the illicit market due to its widespread availability and potency [1]. *Buprenorphine* - **Buprenorphine** is a **partial opioid agonist** used in the treatment of opioid dependence (opioid replacement therapy) due to its ceiling effect on respiratory depression and ability to block the effects of other opioids. - Although it can be abused, particularly in combination with naloxone (Suboxone) via intravenous injection, its primary role is in **medication-assisted treatment**, making it less commonly abused as a standalone illicit opioid compared to **heroin**.
Question 82: Which anaesthetic agent is neither metabolised by liver nor by kidney?
- A. Vecuronium
- B. Pancuronium
- C. Rocuronium
- D. Atracurium (Correct Answer)
Explanation: ***Atracurium*** - **Atracurium** undergoes **Hofmann elimination**, a non-enzymatic chemical degradation in plasma, and also **ester hydrolysis** by non-specific plasma esterases [2]. - This unique metabolism makes its elimination largely independent of **liver** and **kidney function**, making it a good choice for patients with organ dysfunction [2]. *Vecuronium* - Primarily metabolized by the **liver** into active and inactive metabolites [1]. - Its elimination can be prolonged in patients with **hepatic impairment** [1]. *Pancuronium* - Undergoes significant **hepatic metabolism** and subsequent **renal excretion** of both parent drug and metabolites [1]. - Its duration of action is significantly affected by both **liver** and **kidney dysfunction** [1]. *Rocuronium* - Primarily eliminated unchanged via **biliary excretion** (liver) [1]. - Its duration of action is prolonged in patients with **hepatic impairment** [1].
Question 83: Which local anesthetic is known for its vasoconstrictive properties?
- A. Lidocaine
- B. Chlorprocaine
- C. Procaine
- D. Cocaine (Correct Answer)
Explanation: ***Cocaine*** - Cocaine is unique among local anesthetics for its inherent **sympathomimetic** properties, leading to **vasoconstriction**. - This vasoconstriction is due to its ability to block the reuptake of **norepinephrine** and other catecholamines at adrenergic nerve terminals. *Procaine* - Procaine is an **ester-type** local anesthetic that typically causes **vasodilation**, which can lead to rapid systemic absorption and a shorter duration of action. - It does not possess any inherent vasoconstrictive properties. *Lidocaine* - Lidocaine, an **amide-type** local anesthetic, generally causes **vasodilation** at clinical concentrations. - Due to this vasodilatory effect, **epinephrine** is often added to lidocaine preparations to prolong its action and reduce systemic absorption. *Chlorprocaine* - Chlorprocaine is another **ester-type** local anesthetic known for its rapid onset and short duration of action. - It primarily causes **vasodilation**, similar to procaine, and has no intrinsic vasoconstrictive effects.
Question 84: Which of the following is the prototypical sympathomimetic agent with both alpha and beta-adrenergic activity?
- A. Epinephrine (Correct Answer)
- B. Isoproterenol
- C. Norepinephrine
- D. Dopamine
Explanation: ***Epinephrine*** - Epinephrine (adrenaline) is a potent direct-acting **sympathomimetic** that stimulates both **alpha and beta-adrenergic receptors**. - Its diverse effects on the cardiovascular, respiratory, and other systems make it the prototypical agent for demonstrating both receptor activities. *Norepinephrine* - While norepinephrine (noradrenaline) also acts on **alpha and beta-1 receptors**, its affinity for **beta-2 receptors** is significantly lower than epinephrine. - This results in a predominant effect on **vasoconstriction** and cardiac contractility rather than bronchodilation or peripheral vasodilation. *Isoproterenol* - Isoproterenol is a **non-selective beta-adrenergic agonist**, meaning it primarily stimulates **beta-1 and beta-2 receptors**. - It has minimal or no activity at **alpha-adrenergic receptors**, differentiating it from epinephrine's mixed activity. *Dopamine* - Dopamine's effects are **dose-dependent**; at low doses, it primarily stimulates **dopamine receptors** and at moderate doses, it activates **beta-1 receptors**. - At high doses, it can stimulate **alpha-adrenergic receptors**, but its primary and distinguishing characteristic is its agonism at **dopamine receptors**, which epinephrine does not share.
Question 85: What is the effect of adding epinephrine to lignocaine (a local anesthetic)?
- A. Increases distribution of local anesthetic
- B. Decreases absorption of local anesthetic (Correct Answer)
- C. Decreases duration of local anesthetic
- D. Increases metabolism of local anesthetic
Explanation: ***Decreases absorption of local anesthetic*** - Epinephrine causes **vasoconstriction** at the site of injection, which reduces the rate at which the local anesthetic is absorbed into the systemic circulation. - This slower absorption leads to a **higher concentration of the anesthetic** at the nerve fibers, prolonging its effect and reducing systemic toxicity. - This is the primary mechanism by which epinephrine enhances local anesthetic efficacy. *Increases distribution of local anesthetic* - The primary effect of epinephrine is to **localize the anesthetic** by reducing its systemic distribution. - This localization is achieved through **vasoconstriction**, which keeps the drug at the desired site rather than allowing it to distribute widely. *Decreases duration of local anesthetic* - By slowing absorption, epinephrine effectively **increases the duration of action** of the local anesthetic. - The anesthetic remains at the site of action for a longer period, providing **extended pain relief**. *Increases metabolism of local anesthetic* - Epinephrine does not directly affect the **metabolic rate** of local anesthetics. - The primary mechanism of metabolism for amides like lignocaine is in the **liver** by cytochrome P450 enzymes.
Question 86: Which amino acid-derived neurotransmitter is primarily targeted in the pharmacological treatment of depression?
- A. Histamine
- B. None of the options
- C. Serotonin (Correct Answer)
- D. Acetylcholine
Explanation: ***Serotonin*** - **Serotonin** is an amino acid-derived neurotransmitter (from **tryptophan**) known to play a crucial role in mood regulation, sleep, appetite, and other functions, making it a primary target for **antidepressant medications**. - Medications like **Selective Serotonin Reuptake Inhibitors (SSRIs)** increase serotonin levels in the brain to alleviate symptoms of depression. *Histamine* - **Histamine** is an amino acid-derived neurotransmitter (from **histidine**) primarily involved in allergic reactions, inflammation, and regulating wakefulness. - While it has some central nervous system effects, its primary role is not directly in the treatment of **depression**. *Acetylcholine* - **Acetylcholine** is a neurotransmitter involved in muscle contraction, learning, memory, and attention, and is not derived from amino acids; it is synthesized from **choline** and acetyl-CoA. - It is not directly used for treating **depression**, although imbalances can play a role in cognitive aspects of some psychiatric disorders. *None of the options* - This option is incorrect because **Serotonin** is indeed an amino acid-derived neurotransmitter (from tryptophan) targeted for treating **depression**. - Many antidepressant drugs work by modulating **serotonergic pathways**.
Question 87: Midazolam does not cause which of the following?
- A. Anterograde amnesia
- B. Decreased cardiovascular effects as compared to propofol
- C. Causes tachyphylaxis during high dose infusions
- D. Retrograde amnesia (Correct Answer)
Explanation: ***Retrograde amnesia*** - Midazolam, a benzodiazepine, primarily causes **anterograde amnesia** [2], meaning patients have difficulty forming new memories after drug administration. - It does not significantly affect memories formed **before drug administration** (retrograde amnesia). *Anterograde amnesia* - Midazolam is well-known for its ability to induce **anterograde amnesia**, which is often a desirable effect in procedural sedation [2]. - This effect helps patients forget unpleasant or painful procedures performed while under its influence. *Causes tachyphylaxis during high dose infusions* - Prolonged or high-dose infusions of midazolam can lead to **tachyphylaxis**, requiring increased doses to achieve the same effect [1]. - This phenomenon is due to the **down-regulation or desensitization of GABA-A receptors** with continuous stimulation. *Decreased cardiovascular effects as compared to propofol* - Midazolam generally causes **less pronounced cardiovascular depression** (e.g., hypotension) compared to propofol, especially in standard sedative doses [1]. - This makes midazolam a safer option for sedation in some patients with **fragile cardiovascular statuses**.
Question 88: Drug of choice for Pneumocystis jirovecii in pregnancy?
- A. Primaquine
- B. Dapsone
- C. Pentamidine
- D. Trimethoprim-sulfamethoxazole (SMZ/TMP) (Correct Answer)
Explanation: ***Trimethoprim-sulfamethoxazole (SMZ/TMP)*** - Despite being a **folate antagonist**, SMZ/TMP is considered safe and the **drug of choice** for treating **Pneumocystis jirovecii pneumonia (PJP)** in pregnant women, particularly as the benefits outweigh the risks. - It is recommended to supplement with **folic acid** during treatment to mitigate potential teratogenic risks, although these risks are generally low. *Primaquine* - **Primaquine** is primarily used for the treatment of **Plasmodium vivax** and **Plasmodium ovale malaria**, specifically targeting hypnozoites in the liver. - It is contraindicated in pregnancy due to the risk of **hemolytic anemia** in the fetus, especially if the fetus has **glucose-6-phosphate dehydrogenase (G6PD) deficiency**. *Dapsone* - **Dapsone** is used in the treatment of **leprosy**, **dermatitis herpetiformis**, and as an alternative for **PJP prophylaxis** in HIV-positive patients. - While it can be used for PJP prophylaxis, its efficacy for **active PJP treatment** is lower than SMZ/TMP, and it carries risks of **hemolytic anemia** and **methemoglobinemia**, particularly in pregnancy. *Pentamidine* - **Pentamidine** is an alternative treatment for **PJP**, especially in patients who cannot tolerate SMZ/TMP. - It is typically reserved for **severe cases** or as a second-line agent due to its potential for **significant toxicity**, including hypotension, nephrotoxicity, and hypoglycemia, which can be particularly concerning in pregnancy.
Question 89: What is the drug of choice for malaria in pregnancy?
- A. Primaquine
- B. Chloroquine (Correct Answer)
- C. Artesunate
- D. Quinine
Explanation: ***Chloroquine*** - **Chloroquine** is the drug of choice for **uncomplicated malaria in pregnancy** caused by **chloroquine-sensitive** strains of *P. vivax*, *P. ovale*, *P. malariae*, and *P. falciparum* [1]. - It has an **established safety profile** in pregnancy across all trimesters and is considered safe by WHO and CDC. - While resistance has emerged in many areas for *P. falciparum*, chloroquine remains effective for *P. vivax* malaria in most regions including India. - For **severe malaria** or **chloroquine-resistant falciparum malaria**, alternative regimens like quinine or artesunate are used [1]. *Quinine* - **Quinine** (usually with clindamycin) is the preferred treatment for **severe malaria** or **chloroquine-resistant *P. falciparum*** malaria in pregnancy, especially in the **first trimester**. - It is safe and effective but can cause side effects like **cinchonism** (tinnitus, headache, nausea) and **hypoglycemia**. - While safe throughout pregnancy, it is not the first-line choice for uncomplicated chloroquine-sensitive malaria. *Primaquine* - **Primaquine** is **contraindicated in pregnancy** because it can cause **hemolytic anemia** in individuals with **G6PD deficiency**, and G6PD status of the fetus cannot be determined [3]. - It is used for **radical cure** of *P. vivax* and *P. ovale* to eliminate liver hypnozoites, but must be deferred until after delivery [3]. *Artesunate* - **Artesunate** and other **artemisinin-based combination therapies (ACTs)** are highly effective antimalarials [2]. - Current WHO guidelines support ACT use in all trimesters for severe malaria when benefits outweigh risks. - For **uncomplicated falciparum malaria**, ACTs are preferred in the **second and third trimesters** in areas with chloroquine resistance [2]. - However, chloroquine remains the classical "drug of choice" for uncomplicated, chloroquine-sensitive malaria in pregnancy [1].
Question 90: All of the following occurs because of prostaglandin use except?
- A. Increased motility of bowel
- B. Nausea
- C. Excess water retention (Correct Answer)
- D. Flushes
Explanation: ***Excess water retention*** - **Prostaglandins** generally promote **diuresis** and natriuresis, meaning they help the body excrete water and sodium, rather than retain them [2]. - While some prostaglandins can affect renal blood flow, direct causation of **excess water retention** as a primary side effect is not typical. *Flushes* - **Prostaglandins**, particularly **PGE1** and **PGE2**, are potent **vasodilators** and can cause cutaneous vasodilation, leading to **flushing** and a sensation of warmth [3]. - This effect is often mediated by the relaxation of vascular smooth muscle. *Increased motility of bowel* - Many **prostaglandins**, especially **PGE** and **PGF** series, stimulate **smooth muscle contraction**, including in the gastrointestinal tract [1]. - This increased contraction can lead to **enhanced bowel motility**, sometimes causing diarrhea or abdominal cramping [1]. *Nausea* - **Prostaglandins** can have various systemic effects, and activation of pathways in the central nervous system or direct irritation of the GI tract can lead to symptoms like **nausea** and vomiting [1]. - This is a common side effect, especially with systemic administration.