Premedication — MCQs
Premedication is prescribed to – a) Allay anxiety b) Make the patient asleep before coming for operation c) Reduce the dose of induction agents d) Produce amnesia
Midazolam does not cause which of the following?
Choose the correct options regarding the route of administration and bioavailability. A- Intravenous =1 B- 0.75< Oral <1 C-0.75 <IM ≤ 1 D- 0.75<SC ≤ 1 IM - Intramuscular SC- Subcutaneous
Anticholinergic which can be used as sedative and antiemetic premedication is
Diazepam poisoning is treated by:
Which anxiolytic acts through 5-HT1A receptor partial agonism without exhibiting significant anticonvulsant or muscle relaxant properties?
When do we have to start antibiotics to prevent post-operative infection?
Regarding propofol, which one of the following statements is false?
Which of the following is the FIRST-LINE antiemetic drug most commonly used for post-operative nausea and vomiting (PONV) prophylaxis?
The commonly used muscle relaxant with quickest onset of action and spontaneous recovery is :
Premedication Indian Medical PG Practice Questions and MCQs
Question 1: Premedication is prescribed to – a) Allay anxiety b) Make the patient asleep before coming for operation c) Reduce the dose of induction agents d) Produce amnesia
- A. Reduce the dose of induction agents
- B. Allay anxiety (Correct Answer)
- C. Produce amnesia
- D. Make the patient asleep before coming for operation
Explanation: ***Allay anxiety*** - Premedication frequently includes anxiolytic agents like **benzodiazepines** to calm the patient before surgery. - Reducing anxiety helps in achieving a smoother induction of anesthesia and can improve the patient's overall experience. *Reduce the dose of induction agents* - While some premedication agents like **opioids** or sedatives can have an anesthetic-sparing effect, this is a secondary benefit, not the primary goal. - The main aim is patient comfort and psychological preparation, not primarily dose reduction. *Produce amnesia* - Amnesia, particularly **anterograde amnesia**, is a desirable side effect of some premedication drugs like **midazolam**. - However, it's a consequence of the anxiolytic effect rather than the sole or primary reason for prescribing premedication. *Make the patient asleep before coming for operation* - While some premedication agents can cause **somnolence** or light sleep, the goal is not to have the patient fully asleep before entering the operating room. - The primary aim is to make the patient relaxed and comfortable, not unconscious.
Question 2: 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 3: Choose the correct options regarding the route of administration and bioavailability. A- Intravenous =1 B- 0.75< Oral <1 C-0.75 <IM ≤ 1 D- 0.75<SC ≤ 1 IM - Intramuscular SC- Subcutaneous
- A. A and D
- B. A and C
- C. A, C, D (Correct Answer)
- D. A, B, D
Explanation: ***A, C, D*** - Intravenous (IV) administration has **100% bioavailability** because the drug enters the systemic circulation directly, bypassing any absorption barriers. - Intramuscular (IM) and subcutaneous (SC) routes generally have **high bioavailability**, often between 75% and 100%, as drugs are absorbed directly into the bloodstream without first-pass metabolism. *A and D* - While options A and D are correct, this choice is incomplete as option C is also a correct statement regarding bioavailability. - IM administration typically results in high systemic bioavailability, similar to SC, making its exclusion here incorrect. *A and C* - While options A and C are correct, this choice is incomplete as option D is also a correct statement regarding bioavailability. - Subcutaneous administration also generally results in high bioavailability, as absorption tends to be complete. *A, B, D* - While options A and D are correct, option B is typically incorrect for oral bioavailability. - Oral bioavailability of many drugs is often less than 0.75 (75%) due to factors like **first-pass metabolism** and incomplete absorption in the gastrointestinal tract.
Question 4: Anticholinergic which can be used as sedative and antiemetic premedication is
- A. Atropine
- B. Hyoscine (Correct Answer)
- C. Promethazine
- D. Glycopyrrolate
Explanation: ***Hyoscine*** - **Hyoscine** (scopolamine) is a muscarinic antagonist that readily crosses the **blood-brain barrier**, allowing it to exert central effects such as **sedation** and potent **antiemetic** actions. - Its ability to reduce secretions and prevent **nausea and vomiting** makes it a suitable anticholinergic for premedication. *Atropine* - **Atropine** is primarily used to increase **heart rate**, reduce **salivary and bronchial secretions**, and as an antidote for cholinesterase inhibitors. - While it is an anticholinergic, its central effects are less pronounced at clinical doses compared to hyoscine, making it less suitable as a sole sedative or antiemetic. *Promethazine* - **Promethazine** is an antihistamine with significant **anticholinergic, sedative**, and **antiemetic** properties. - However, it is primarily classified as an **H1-receptor antagonist** rather than a pure anticholinergic for premedication, although it is often used for these effects. *Glycopyrrolate* - **Glycopyrrolate** is a quaternary ammonium anticholinergic that does not readily cross the **blood-brain barrier**. - Its action is largely peripheral, making it effective for reducing secretions but without significant **sedative** or **antiemetic** effects.
Question 5: Diazepam poisoning is treated by:
- A. Resins
- B. Hemofiltration
- C. Charcoal
- D. Flumazenil (Correct Answer)
Explanation: ***Flumazenil*** - **Flumazenil** is a **benzodiazepine receptor antagonist** that competitively binds to the benzodiazepine binding site on the GABA-A receptor, reversing the effects of diazepam. - It is used in cases of severe benzodiazepine overdose causing **respiratory depression** or **severe sedation**. *Resins* - **Resins**, such as **cholestyramine**, are typically used to bind toxins or drugs in the **gastrointestinal tract** that undergo enterohepatic recirculation. - They are generally not effective for reversing the central nervous system depression caused by a benzodiazepine overdose. *Hemofiltration* - **Hemofiltration** is a form of renal replacement therapy used to remove small and middle molecular weight substances from the blood. - While it can remove some drugs, **diazepam** is highly **lipophilic** and extensively **protein-bound**, making it poorly amenable to removal by hemofiltration. *Charcoal* - **Activated charcoal** is used to prevent the absorption of ingested toxins from the gastrointestinal tract. - It is effective when administered soon after ingestion but does not reverse the established effects of an absorbed drug like diazepam in an overdose situation.
Question 6: Which anxiolytic acts through 5-HT1A receptor partial agonism without exhibiting significant anticonvulsant or muscle relaxant properties?
- A. Diazepam
- B. Zolpidem
- C. Phenobarbitone
- D. Buspirone (Correct Answer)
Explanation: ***Buspirone*** - **Buspirone** is a unique anxiolytic that primarily acts as a **partial agonist at 5-HT1A receptors**. - Unlike benzodiazepines, it lacks significant **anticonvulsant**, **muscle relaxant**, or **sedative-hypnotic properties** and does not lead to physical dependence or withdrawal. *Diazepam* - **Diazepam** is a **benzodiazepine** that acts by enhancing the effect of **GABA** at GABA-A receptors, leading to significant anxiolytic, sedative, muscle relaxant, and anticonvulsant effects. - It does not primarily act via **5-HT1A receptor partial agonism**. *Zolpidem* - **Zolpidem** is a **non-benzodiazepine hypnotic** that selectively binds to the **GABA-A receptor** subunit, primarily mediating sedative effects. - While it's used for insomnia, it doesn't primarily act as a **5-HT1A partial agonist** and is not typically used for its anxiolytic properties in the same way as buspirone. *Phenobarbitone* - **Phenobarbitone** is a **barbiturate** that acts by prolonging the opening of **chloride channels** associated with GABA-A receptors, leading to strong sedative, hypnotic, and anticonvulsant effects. - Its mechanism of action is distinct from **5-HT1A receptor partial agonism**, and it carries a high risk of dependence and overdose.
Question 7: When do we have to start antibiotics to prevent post-operative infection?
- A. 1 week before surgery
- B. 2 days before surgery
- C. After surgery
- D. 30-60 minutes before incision (up to 24 hours post-op) (Correct Answer)
Explanation: ***30-60 minutes before incision (up to 24 hours post-op)*** - Surgical antibiotic prophylaxis (SAP) should be administered **30-60 minutes before surgical incision** to ensure adequate tissue and serum concentrations at the time of incision. - This timing allows optimal drug distribution to surgical tissues, which is crucial for preventing surgical site infections (SSIs). - For most clean and clean-contaminated surgeries, prophylaxis should be limited to a **single dose** or continued for **maximum 24 hours post-operatively** as per WHO and CDC guidelines. - Prolonged post-operative antibiotics beyond 24 hours do **not** reduce infection rates and increase the risk of **antibiotic resistance** and **adverse effects**. *1 week before surgery* - Administering antibiotics this far in advance is **unnecessary** and **ineffective** for surgical prophylaxis. - It increases the risk of **antibiotic resistance** and does not guarantee adequate drug levels at the time of incision. - Pre-operative antibiotic use should be avoided unless treating an active infection. *2 days before surgery* - This timeframe is too early to achieve prophylactic benefit during the surgical procedure. - Prolonged pre-operative use promotes **bacterial resistance** without providing additional protection. - Drug levels will not be optimal at the time of incision due to metabolism and excretion. *After surgery* - Starting antibiotics **after surgical incision** is **too late** for prophylaxis as contamination has already occurred. - Post-operative initiation is considered **therapeutic treatment** for established infection, not prevention. - The critical window for prophylaxis is the period from skin incision to wound closure.
Question 8: Regarding propofol, which one of the following statements is false?
- A. It is painful on injecting intravenously
- B. It has no muscle relaxant property
- C. It is used as an intravenous induction agent
- D. It causes severe vomiting (Correct Answer)
Explanation: ***It causes severe vomiting*** - Propofol is actually known for its **antiemetic properties**, meaning it helps *prevent* rather than cause nausea and vomiting. - This makes it a preferred anesthetic for procedures where **postoperative nausea and vomiting (PONV)** are a concern. *It is used as an intravenous induction agent* - **Propofol** is a widely used **intravenous anesthetic** for the **induction and maintenance of general anesthesia**. - It provides a rapid onset of unconsciousness due to its high lipid solubility. *It is painful on injecting intravenously* - Injection of propofol can often cause **pain at the injection site**, particularly when administered into smaller veins. - This pain can be mitigated by co-administering **lidocaine** or using larger veins. *It has no muscle relaxant property* - Propofol does **not possess intrinsic muscle relaxant properties**; patients require additional neuromuscular blocking agents for surgical relaxation. - It facilitates intubation by causing **loss of consciousness** and **reducing airway reflexes**, but does not directly relax skeletal muscles.
Question 9: Which of the following is the FIRST-LINE antiemetic drug most commonly used for post-operative nausea and vomiting (PONV) prophylaxis?
- A. Lorazepam
- B. Metoclopramide
- C. Promethazine
- D. Ondansetron (Correct Answer)
Explanation: ***Ondansetron*** - **Ondansetron** is a **5-HT3 receptor antagonist** and is considered a first-line agent due to its high efficacy and favorable side effect profile in preventing PONV. - It works by blocking serotonin receptors in the **chemoreceptor trigger zone** and the **gastrointestinal tract**, reducing the sensation of nausea and vomiting. *Lorazepam* - **Lorazepam** is a **benzodiazepine** primarily used for its **anxiolytic** and **sedative effects**, and sometimes as an adjunct for refractory nausea, but not as a first-line antiemetic for PONV prophylaxis. - While it can help indirectly by reducing anxiety, it does not directly target the key pathways involved in PONV as effectively as 5-HT3 antagonists. *Phenytoin* - **Phenytoin** is an **anticonvulsant** medication used to prevent seizures and has no role in the direct treatment or prophylaxis of PONV. - It primarily acts on voltage-gated sodium channels in neurons and does not possess antiemetic properties. *Metoclopramide* - **Metoclopramide** is a **dopamine D2 receptor antagonist** and a **prokinetic agent** that can be used for PONV, particularly when gastric stasis is a concern. - However, it is generally considered a second-line agent due to the risk of **extrapyramidal side effects**, especially with higher doses or prolonged use. *Promethazine* - **Promethazine** is a **first-generation antihistamine** with **antidopaminergic** and **anticholinergic properties** that can be effective for nausea and vomiting. - It is often used as a rescue antiemetic or in combination therapy, but its sedative effects and potential for extrapyramidal symptoms make it less preferable as a first-line prophylactic agent compared to ondansetron.
Question 10: The commonly used muscle relaxant with quickest onset of action and spontaneous recovery is :
- A. Vecuronium
- B. Rocuronium
- C. Suxamethonium (Correct Answer)
- D. Atracurium
Explanation: ***Suxamethonium*** - Suxamethonium (succinylcholine) is a **depolarizing neuromuscular blocker** with the most rapid onset of action (30-60 seconds) due to its unique mechanism. - Its short duration of action and **spontaneous recovery** are due to its rapid hydrolysis by **plasma pseudocholinesterase**, making it ideal for rapid sequence intubation. *Vecuronium* - Vecuronium is an **intermediate-duration non-depolarizing neuromuscular blocker** with an onset of action typically around 3-5 minutes, which is slower than suxamethonium. - It does not undergo spontaneous recovery as rapidly as suxamethonium and often requires administration of a **reversal agent**. *Rocuronium* - Rocuronium is a **non-depolarizing neuromuscular blocker** known for its relatively rapid onset of action (60-90 seconds) among non-depolarizing agents, but it is still slower than suxamethonium. - While it can be reversed quickly with sugammadex, its **spontaneous recovery** is much slower than suxamethonium. *Atracurium* - Atracurium is an **intermediate-duration non-depolarizing neuromuscular blocker** with an onset of action (3-5 minutes) that is slower than suxamethonium. - Its metabolism involves **Hofmann elimination** and ester hydrolysis, providing a degree of organ-independent elimination, but its recovery is not as rapid or spontaneous as suxamethonium.
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