NEET-PG 2013 - Pharmacology Practice Questions

Q: Which local anaesthetic is known to cause methemoglobinemia?

Prilocaine. ***Prilocaine*** - **Prilocaine** is metabolized into **ortho-toluidine**, which can oxidize hemoglobin to **methemoglobin**, especially at higher doses or in susceptible individuals. - **Methemoglobinemia** symptoms include **cyanosis**, **dyspnea**, and in severe cases, central nervous system depression, due to reduced oxygen-carrying capacity of blood. *Procaine* - **Procaine** is an ester-type local anesthetic. It is metabolized to **para-aminobenzoic acid (PABA)**, which can cause allergic reactions, but it is not associated with methemoglobinemia. - It has a relatively **short duration of action** and is less commonly used now compared to amide-type local anesthetics. *Etidocaine* - **Etidocaine** is an amide-type local anesthetic that is known for its **long duration of action** and high potency. - While it can cause systemic toxicity with high doses due to its cardiac and neurological effects, **methemoglobinemia** is not a characteristic side effect. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic similar to bupivacaine, known for its **motor-sparing effect** and use in regional anesthesia. - It is associated with a lower risk of **cardiotoxicity** compared to bupivacaine but does not cause methemoglobinemia.

Q: Which of the following medications is not typically used for the treatment of erectile dysfunction?

Beta blockers. ***Beta blockers*** - **Beta blockers** are primarily used to treat conditions like **hypertension** and **heart disease**. - While they can cause ED as a side effect, they are **not used for its treatment**. *Sildenafil* - **Sildenafil** is a **PDE5 inhibitor** that works by increasing **blood flow to the penis**, facilitating an erection. - It is a **first-line oral medication** widely prescribed for erectile dysfunction. *PG-E* - **PG-E** refers to **Prostaglandin E1** (alprostadil), which can be administered via **intracavernosal injection** or **urethral suppository**. - It directly causes **vasodilation** in the penis, leading to an erection, and is used when oral medications are ineffective or contraindicated. *Papaverine* - **Papaverine** is a **non-specific vasodilator** that can be used as an **intracavernosal injection** for ED. - It works by relaxing **smooth muscle** in the penile arteries, increasing blood flow and inducing an erection, often used in combination with phentolamine.

Q: Which drug would be most appropriate for treating a patient with suspected chlamydia-gonorrhea coinfection?

Doxycycline. ***Doxycycline*** - **Doxycycline** is a highly effective treatment for **chlamydia**, and its broad-spectrum activity also covers potential **gonorrhea coinfection** when used as part of a dual therapy regimen. - It is often prescribed alongside a **single dose of ceftriaxone** for presumed gonorrhea coinfection, as ceftriaxone targets gonorrhea while doxycycline targets chlamydia. *Ciprofloxacin* - **Ciprofloxacin** is a **fluoroquinolone** antibiotic, which is generally not recommended as first-line treatment for uncomplicated **gonorrhea** or **chlamydia** due to increasing resistance. - It has activity against *Neisseria gonorrhoeae*, but its effectiveness against *Chlamydia trachomatis* is suboptimal compared to macrolides or tetracyclines. *Norfloxacin* - **Norfloxacin** is another **fluoroquinolone** with a narrower spectrum of activity than ciprofloxacin and is primarily used for **urinary tract infections**. - It has **poor efficacy against chlamydia** and is not a recommended treatment for either organism in this context. *Nalidixic acid* - **Nalidixic acid** is a first-generation **quinolone** with a very limited spectrum, used mainly for **gram-negative urinary tract infections**. - It has **no significant activity against chlamydia** or gonorrhea and is therefore inappropriate for treating this suspected coinfection.

Q: In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?

Prilocaine. **Local anesthetics are classified into two chemical groups: esters (aminoesters) and amides. Allergies to esters typically do not cross-react with amides.** ***Prilocaine*** - **Prilocaine** is an **amide-type local anesthetic**, and allergies to **aminoesters** typically do not cross-react with **amides**. - It is a safe alternative in patients with a known allergy to **ester-type local anesthetics**. *Cocaine* - **Cocaine** is an **ester-type local anesthetic**, sharing a similar chemical structure with **aminoesters**. - Patients allergic to **aminoesters** are likely to experience a **cross-reaction** with **cocaine**. *Procaine* - **Procaine** is a classic **ester-type local anesthetic** (an aminoester). - An allergy to aminoesters directly implies an allergy to **procaine** due to its chemical classification. *Tetracaine* - **Tetracaine** is also an **ester-type local anesthetic** (an aminoester). - It is contraindicated in patients with an allergy to **aminoesters** due to the high risk of **allergic reaction**.

Q: The mechanism by which ergometrine stops postpartum hemorrhage is that it:

Increases tone of uterine muscle. ***Increases tone of uterine muscle*** - **Ergometrine** is an **ergot alkaloid** that directly stimulates **uterine smooth muscle contractions**. - These sustained contractions lead to **compression of blood vessels within the myometrium**, thereby reducing blood flow and controlling **postpartum hemorrhage**. *Causes vasoconstriction of uterine arteries* - While ergometrine does have some generalized **vasoconstrictive effects**, its primary mechanism of action in controlling postpartum hemorrhage is not mainly through direct vasoconstriction of large uterine arteries. - The crucial effect is the **sustained uterine contraction** which mechanically occludes blood vessels, rather than chemical constriction of the vessels themselves. *Induces platelet aggregation* - Ergometrine does not primarily act by inducing **platelet aggregation**; this is a function of specific clotting factors and platelet activators. - Its therapeutic effect against hemorrhage is mediated through its action on **uterine contractility**, not on the cellular components of coagulation. *Promotes coagulation* - Ergometrine does not directly promote the **coagulation cascade** or enhance the formation of fibrin clots. - Its mechanism of action is distinct from agents that affect intrinsic or extrinsic pathways of coagulation.

Q: What is the treatment for Trichomonas vaginalis?

Metronidazole. ***Metronidazole*** - **Metronidazole** is the **first-line drug** for treating *Trichomonas vaginalis* infection. - It is effective against this **anaerobic protozoan** and can be administered as a single dose or a 7-day course. *Azithromycin* - **Azithromycin** is a **macrolide antibiotic** primarily used to treat bacterial infections, such as **chlamydia** or certain **respiratory tract infections**. - It is **not effective** against *Trichomonas vaginalis*, which is a parasitic protozoan. *Ciprofloxacin* - **Ciprofloxacin** is a **fluoroquinolone antibiotic** used for bacterial infections, especially **urinary tract infections** and complicated **gastrointestinal infections**. - It has **no activity** against *Trichomonas vaginalis*. *None of the options* - This option is incorrect because **Metronidazole** is a highly effective and widely accepted treatment for *Trichomonas vaginalis* infections.

Q: In pseudocholinesterase deficiency, which drug should be used cautiously?

Succinylcholine. ***Succinylcholine*** - **Succinylcholine** is primarily metabolized by **pseudocholinesterase** (also known as butyrylcholinesterase). - In individuals with **pseudocholinesterase deficiency**, the metabolism of succinylcholine is significantly delayed, leading to **prolonged neuromuscular blockade** and extended paralysis. *Barbiturates* - **Barbiturates** are mainly metabolized by the **hepatic cytochrome P450 system** and do not depend on pseudocholinesterase for their breakdown. - Their metabolism would not be significantly affected by pseudocholinesterase deficiency. *Halothane (an inhalational anesthetic)* - **Halothane** is primarily metabolized by the **hepatic cytochrome P450 system** and excreted via the lungs. - Its metabolism is unrelated to **pseudocholinesterase activity**. *Gallamine (a neuromuscular blocker)* - **Gallamine** is a **nondepolarizing neuromuscular blocker** that is primarily eliminated by **renal excretion** as an unchanged drug. - Its metabolism and elimination are independent of **pseudocholinesterase**.

Q: Which drug is most commonly associated with causing exanthema?

Sulfonamide. ***Sulfonamide*** - **Sulfonamides** are among the **most common causes** of drug-induced exanthema (maculopapular/morbilliform rash). - They account for a significant proportion of cutaneous adverse drug reactions, with exanthema being the most frequent presentation. - The mechanism typically involves a **delayed hypersensitivity reaction** (Type IV) to the drug or its metabolites. - **Classic presentation:** Symmetrical, erythematous, maculopapular rash appearing 7-14 days after drug initiation. *Phenytoin* - **Phenytoin** can cause exanthematous eruptions, but it is more notably associated with **severe cutaneous adverse reactions** such as: - **DRESS syndrome** (Drug Reaction with Eosinophilia and Systemic Symptoms) - **Stevens-Johnson syndrome (SJS)** and **Toxic Epidermal Necrolysis (TEN)** - While exanthema can occur, **sulfonamides** are more frequently implicated in simple morbilliform rashes. *Atropine* - **Atropine** is an anticholinergic agent primarily causing **predictable pharmacological effects**: - Dry mouth, mydriasis, tachycardia, urinary retention - **Allergic skin reactions** with atropine are rare and not a characteristic adverse effect. - Atropine is **not recognized** as a common cause of exanthema. *All of the options* - This is incorrect because **atropine** is not commonly associated with exanthema. - While both sulfonamides and phenytoin can cause exanthema, only **sulfonamides** are considered among the **most common** causes.

Q: Depot preparations are administered by ?

Both subcutaneous and intramuscular route. ***Both subcutaneous and intramuscular route*** - **Depot preparations** are designed for **sustained release** of medication over an extended period - This is achieved by forming a 'depot' in the tissue, often facilitated by a viscous vehicle or sparingly soluble form of the drug - Both **subcutaneous** and **intramuscular** tissues can sustain depot formulations effectively - **SC depot examples:** Insulin glargine, contraceptive implants (Nexplanon), leuprolide acetate - **IM depot examples:** Haloperidol decanoate, medroxyprogesterone acetate (Depo-Provera), paliperidone palmitate, long-acting risperidone *Subcutaneous route* - While some **depot preparations** are administered **subcutaneously**, it is not the *only* route for all depot formulations - The **subcutaneous tissue** offers relatively low blood flow, suitable for slow absorption - Alone, this option is incomplete as many depot preparations require IM administration *Intramuscular route* - Many **depot preparations** are given **intramuscularly** due to the muscle tissue's vascularity and tissue volume - The **muscle tissue** provides an excellent site for drug reservoir formation - Alone, this option is incomplete as some depot preparations are given subcutaneously *Intravenous route* - **Intravenous administration** is used for immediate and rapid drug delivery directly into the bloodstream - This route is **unsuitable for depot preparations** which require sustained release over time - No 'depot' can be formed with IV route as the drug is immediately diluted and distributed throughout the body

Question 1

Which local anaesthetic is known to cause methemoglobinemia?

Accepted Answer

Prilocaine

Answer

Procaine

Answer

Ropivacaine

Answer

Etidocaine

Question 2

Which of the following medications is not typically used for the treatment of erectile dysfunction?

Accepted Answer

Beta blockers

Answer

Papaverine

Answer

Sildenafil

Answer

PG-E

Question 3

Which drug would be most appropriate for treating a patient with suspected chlamydia-gonorrhea coinfection?

Accepted Answer

Doxycycline

Answer

Ciprofloxacin

Answer

Nalidixic acid

Answer

Norfloxacin

Question 4

In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?

Accepted Answer

Prilocaine

Answer

Procaine

Answer

Cocaine

Answer

Tetracaine

Question 5

The mechanism by which ergometrine stops postpartum hemorrhage is that it:

Accepted Answer

Increases tone of uterine muscle

Answer

Induces platelet aggregation

Answer

Promotes coagulation

Answer

Causes vasoconstriction of uterine arteries

Question 6

What is the treatment for Trichomonas vaginalis?

Accepted Answer

Metronidazole

Answer

Azithromycin

Answer

Ciprofloxacin

Answer

None of the options

Question 7

Which of the following statements about Selective Estrogen Receptor Modulators (SERMs) is correct?

Accepted Answer

Some SERMs can act as both agonists and antagonists on estrogen receptors.

Answer

Act as agonists on estrogen receptors.

Answer

Used to reduce the risk of hot flushes and thromboembolism.

Answer

Act as antagonists on estrogen receptors.

Question 8

In pseudocholinesterase deficiency, which drug should be used cautiously?

Accepted Answer

Succinylcholine

Answer

Barbiturates

Answer

Gallamine

Answer

Halothane

Question 9

Which drug is most commonly associated with causing exanthema?

Accepted Answer

Sulfonamide

Answer

Atropine

Answer

Phenytoin

Answer

All of the options

Question 10

Depot preparations are administered by ?

Accepted Answer

Both subcutaneous and intramuscular route

Answer

Subcutaneous route

Answer

Intravenous route

Answer

Intramuscular route

NEET-PG 2013 — Pharmacology