FMGE 2017 - Pharmacology Practice Questions

Q: The shortest acting opioid is:-

Remifentanil. ***Remifentanil*** - **Remifentanil** is an **ultra-short-acting opioid** due to its unique metabolism by **non-specific plasma and tissue esterases**. - Its rapid metabolism results in a very short context-sensitive half-time, meaning its effects **terminate quickly** regardless of infusion duration. *Alfentanil* - **Alfentanil** is a **short-acting opioid** but its duration of action is longer than remifentanil. - It is eliminated primarily by **hepatic metabolism**, which is slower than esterase-based metabolism. *Fentanyl* - **Fentanyl** is a **potent synthetic opioid** with an intermediate duration of action. - Its elimination is dependent on **hepatic metabolism**, and it has a longer context-sensitive half-time compared to remifentanil. *Sufentanil* - **Sufentanil** is a **very potent opioid** with a longer duration of action than fentanyl and alfentanil. - Its metabolism is hepatic, leading to a **longer elimination half-life** and thus a more prolonged effect.

Q: Which of the following anti-diabetic drugs is associated with weight gain?

Pioglitazone. ***Pioglitazone*** - **Pioglitazone**, a **thiazolidinedione**, primarily works by improving insulin sensitivity in peripheral tissues. - Its mechanism of action can lead to **fluid retention** and **increased subcutaneous fat storage**, both contributing to weight gain. *Acarbose* - **Acarbose** is an **alpha-glucosidase inhibitor** that delays carbohydrate absorption in the gut. - This mechanism typically leads to a **neutral effect or slight weight loss**, as fewer calories are rapidly absorbed. *Metformin* - **Metformin**, a **biguanide**, reduces hepatic glucose production and improves insulin sensitivity. - It is often associated with **weight neutrality or modest weight loss**, and is not known to cause weight gain. *Sitagliptin* - **Sitagliptin** is a **dipeptidyl peptidase-4 (DPP-4) inhibitor** that enhances incretin effects. - This class of drugs is generally considered **weight-neutral** and rarely causes weight gain.

Q: All of the following are actions produced by mu receptors of morphine except:-

Hyperalgesia. ***Hyperalgesia*** - **Hyperalgesia** is not a primary physiological action of **μ-opioid receptor** activation; the fundamental role of these receptors is to produce **analgesia** by inhibiting pain transmission. - While **opioid-induced hyperalgesia** can occur with chronic use, it is a paradoxical compensatory response rather than a direct cellular action of the morphine-receptor complex. *Respiratory depression* - Activation of **μ-receptors** in the **brainstem** directly reduces the sensitivity of the respiratory center to **carbon dioxide**, leading to decreased respiratory rate. - This is one of the most clinically significant side effects and is the primary cause of death in **opioid overdose**. *Miosis* - Morphine stimulates the **Edinger-Westphal nucleus** via μ-receptors, resulting in excessive parasympathetic output to the eye. - This produces **pinpoint pupils**, a classic diagnostic sign of **opioid toxicity** that does not develop tolerance. *Decreased GI motility* - **μ-receptors** are highly expressed in the **myenteric plexus** of the gut, where their activation inhibits the release of acetylcholine and slows **peristalsis**. - This action results in **constipation**, which is a universal side effect of morphine therapy and typically requires prophylactic management.

Q: Which of the following local anesthetics is the most common cause of methemoglobinemia?

Benzocaine. ***Benzocaine***- **Benzocaine** is an ester-type local anesthetic that is the **most common cause of methemoglobinemia** among local anesthetics, especially when used in high doses or on mucous membranes due to its rapid absorption.- Its metabolic byproducts, particularly **aniline derivatives**, are potent oxidizers of hemoglobin, converting the ferrous iron (Fe2+) to ferric iron (Fe3+), thus forming methemoglobin which cannot bind oxygen.- **FDA warnings** have been issued regarding benzocaine-induced methemoglobinemia, particularly with topical spray preparations.*Lignocaine*- **Lignocaine** (lidocaine) is an amide-type local anesthetic and is **rarely associated** with methemoglobinemia.- While it can theoretically cause it in very high doses, it is significantly **less potent** in this regard compared to benzocaine.*Chloroprocaine*- **Chloroprocaine** is an ester-type local anesthetic with a very **short duration of action** due to rapid hydrolysis by plasma cholinesterases.- This rapid metabolism typically limits systemic exposure and makes it an **uncommon cause** of methemoglobinemia despite being an ester.*Prilocaine*- **Prilocaine** is an amide-type local anesthetic that can also cause methemoglobinemia, particularly at **higher doses (>600mg)** [1, 2].- It works through its metabolite, **o-toluidine**, which is an oxidizing agent [1].- However, **benzocaine** is more consistently linked to this adverse effect in clinical practice and has more documented case reports.

Q: Venlafaxine comes under which class of drugs?

Serotonin-norepinephrine reuptake inhibitor (SNRI). ***Serotonergic noradrenergic reuptake inhibitor*** - **Venlafaxine** is an antidepressant that works by inhibiting the reuptake of both **serotonin** and **norepinephrine**, making it a **Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**. - This dual mechanism contributes to its efficacy in treating **major depressive disorder**, **anxiety disorders**, and **neuropathic pain**. *Monoamine oxidase inhibitors* - **MAOIs** inhibit the enzyme **monoamine oxidase**, which metabolizes neurotransmitters like **serotonin**, **norepinephrine**, and **dopamine**. - They are associated with significant **food and drug interactions**, unlike venlafaxine. *Serotonin receptor antagonist* - These drugs *block* **serotonin receptors**, often used as **antiemetics** (e.g., ondansetron) or in some **antipsychotics**. - They do not primarily increase serotonin or norepinephrine levels via reuptake inhibition. *Selective serotonin reuptake inhibitor* - **SSRIs** (e.g., fluoxetine, sertraline) primarily inhibit the reuptake of **serotonin**, with minimal effect on other neurotransmitters. - While venlafaxine affects serotonin, it also significantly impacts norepinephrine, distinguishing it from SSRIs.

Question 1

The shortest acting opioid is:-

Accepted Answer

Remifentanil

Answer

Fentanyl

Answer

Alfentanil

Answer

Sufentanil

Question 2

Which of the following anti-diabetic drugs is associated with weight gain?

Accepted Answer

Pioglitazone

Answer

Acarbose

Answer

Metformin

Answer

Sitagliptin

Question 3

All of the following are actions produced by mu receptors of morphine except:-

Accepted Answer

Hyperalgesia

Answer

Respiratory depression

Answer

Miosis

Answer

Decreased GI motility

Question 4

Which of the following local anesthetics is the most common cause of methemoglobinemia?

Accepted Answer

Benzocaine

Answer

Lignocaine

Answer

Chloroprocaine

Answer

EMLA Cream (Lignocaine + Prilocaine)

Answer

Prilocaine

Answer

Dibucaine

Question 5

Venlafaxine comes under which class of drugs?

Accepted Answer

Serotonin-norepinephrine reuptake inhibitor (SNRI)

Answer

Monoamine oxidase inhibitors

Answer

Serotonin receptor antagonist

Answer

Selective serotonin reuptake inhibitor

FMGE 2017 — Pharmacology