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 direct effect of **μ-opioid receptor activation**; in fact, μ-receptor activation causes **analgesia**.- While chronic opioid use can lead to **opioid-induced hyperalgesia**, this is a complex phenomenon involving adaptations to long-term exposure, not an acute action of the receptor itself.*Respiratory depression*- Activation of **μ-opioid receptors** in the **brainstem** leads to a dose-dependent decrease in respiratory rate and depth [1].- This effect is mediated by reduced sensitivity of respiratory centers to **CO2 levels**, making it a major concern in opioid overdose [1].*Miosis*- **Miosis** (pinpoint pupils) is a classic sign of **opioid intoxication** and results from excitatory actions of μ-opioid receptor activation on the **Edinger-Westphal nucleus** of the oculomotor nerve [1, 3].- This effect is mediated through inhibition of **GABAergic neurons**, leading to increased parasympathetic outflow to the iris sphincter.*Decreased GI motility*- Activation of **μ-opioid receptors** in the **gastrointestinal tract** reduces peristalsis, increases water reabsorption, and decreases secretions [1, 2].- This leads to **constipation**, a very common and persistent side effect of opioid use [1, 2].

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: Disulfiram is a type of:-

Aversion therapy. **Aversion therapy** - **Disulfiram** works by inhibiting aldehyde dehydrogenase, leading to the accumulation of acetaldehyde when alcohol is consumed, which causes unpleasant symptoms like flushing, nausea, and vomiting. - This creates an **aversive reaction** to alcohol, which discourages further drinking, making it a form of aversion therapy. *Anticraving therapy* - While disulfiram can indirectly reduce cravings by making alcohol consumption unpleasant, its primary mechanism is not to directly modulate craving pathways in the brain. - Drugs like **naltrexone** or **acamprosate** are more commonly categorized as specific anticraving agents for alcohol dependence. *Detoxification* - **Detoxification** refers to the supervised withdrawal from a substance to manage acute withdrawal symptoms and stabilize the patient. - Disulfiram is used after detoxification to help maintain abstinence, not during the acute withdrawal phase. *Opioid management therapy* - **Opioid management therapy** involves medications like **methadone** or **buprenorphine** used to treat opioid dependence. - Disulfiram is specifically used for **alcohol use disorder** and has no role in managing opioid dependence.

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

Disulfiram is a type of:-

Accepted Answer

Aversion therapy

Answer

Anticraving therapy

Answer

Detoxification

Answer

Opioid management therapy

Question 6

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