General Pharmacology — MCQs

General Pharmacology Indian Medical PG Practice Questions and MCQs

Question 601: What is the iodine content percentage in amiodarone?

A. 10 - 20%
B. 20 - 40% (Correct Answer)
C. 40 - 60%
D. 60 - 80%

Explanation: ***20 - 40%*** - **Amiodarone** is highly lipophilic and contains a significant amount of **iodine**, typically comprising around **37.5%** of its molecular weight. - This high iodine content is responsible for many of its **adverse effects**, particularly those related to thyroid dysfunction. *10 - 20%* - This range is too low; the actual iodine content in **amiodarone** is considerably higher, making it a prominent feature of the drug's chemical structure. - A lower iodine percentage would likely result in fewer **thyroid-related side effects**. *40 - 60%* - While amiodarone has a high iodine content, 40-60% is slightly above the generally accepted range. - Iodine constitutes a substantial but not an overwhelming majority of the drug's molecular mass. *60 - 80%* - This range is significantly higher than the actual iodine content in **amiodarone**. - Such a high percentage would imply an even greater propensity for **iodine-induced adverse effects**.

Question 602: What is the standard amount of diphtheria toxoid in the DT vaccine?

A. 5 Lf
B. 10 Lf
C. 15 Lf
D. 30 Lf (Correct Answer)

Explanation: ***30 Lf*** - The **DT vaccine** (pediatric diphtheria-tetanus vaccine) contains **30 Lf** of **diphtheria toxoid** per dose according to traditional formulations, along with tetanus toxoid. - This higher diphtheria toxoid content is standardized for vaccines administered to children younger than 7 years. - Note: Modern vaccine standards often express potency in **International Units (IU)** where ≥30 IU corresponds to approximately 15-25 Lf, though 30 Lf was the traditional specification. *5 Lf* - This reduced amount of diphtheria toxoid is present in adult formulations like **Tdap vaccine** and **Td vaccine** (typically 2-5 Lf). - The lower diphtheria toxoid content in adult vaccines is sufficient to maintain immunity in individuals with pre-existing immunity from childhood vaccination. *10 Lf* - This amount of diphtheria toxoid is not a standard specification for DT, Td, or Tdap vaccines. - Standard diphtheria toxoid amounts are typically 15-30 Lf for pediatric formulations (DT/DTP) and 2-5 Lf for adult formulations (Td, Tdap). *15 Lf* - While approximately 15 Lf may correspond to the minimum potency when measured in International Units (≥30 IU), the traditional standard specification for DT vaccine is **30 Lf**. - Vaccine formulations are precisely standardized to ensure optimal immunogenicity and safety.

Question 603: What is Dinoprost?

A. Prostaglandin E2 (PGE2)
B. Prostaglandin F2α (PGF2α) (Correct Answer)
C. Prostaglandin I2 (PGI2)
D. Prostaglandin E1 (PGE1)

Explanation: ***Prostaglandin F2α (PGF2α)*** - **Dinoprost** is the generic name for **Prostaglandin F2α**. - It works by stimulating **myometrial contractions** and promoting cervical ripening, making it useful in obstetrics. *Prostaglandin E2 (PGE2)* - **PGE2** is known as **Dinoprostone** and is also used for cervical ripening and labor induction. - While similar in function, **Dinoprostone** (PGE2) is distinct from **Dinoprost** (PGF2α). *Prostaglandin I2 (PGI2)* - **PGI2** is also known as **Prostacyclin** and acts as a potent **vasodilator** and **inhibitor of platelet aggregation**. - Its primary therapeutic uses are in conditions like **pulmonary hypertension**, which differs from Dinoprost's obstetric uses. *Prostaglandin E1 (PGE1)* - **PGE1** is also known as **Alprostadil** and is used to maintain the **patency of the ductus arteriosus** in neonates with certain congenital heart defects. - It is distinct from Dinoprost and has different clinical applications.

Question 604: Opium is derived from which part of the opium poppy?

A. Leaf
B. Root
C. Poppy seed
D. Unripe capsule (Correct Answer)

Explanation: ***Unripe capsule*** - **Opium** is collected from the **latex** that seeps out of incisions made in the **unripe seed capsules** of the opium poppy (*Papaver somniferum*). - This milky latex contains various **alkaloids**, including **morphine**, **codeine**, and **thebaine**, which are responsible for its medicinal and psychoactive properties. *Leaf* - The leaves of the opium poppy do not contain significant amounts of the **therapeutic alkaloids** found in opium. - They are not used for the production or extraction of **opium**. *Root* - The root of the opium poppy is not the part where **opium alkaloids** are concentrated or harvested. - The primary site of alkaloid synthesis and storage is within the **capsule**. *Poppy seed* - **Poppy seeds** themselves contain very low levels of opium alkaloids, typically negligible after processing. - They are primarily used in cooking and baking, and while they can test positive for **opiates** in drug screens, they do not yield opium.

Question 605: What type of compound is Tibolone?

A. Natural steroidal estrogen
B. Natural non-steroidal estrogen
C. Synthetic steroidal estrogen (Correct Answer)
D. Synthetic non-steroidal estrogen

Explanation: ***Synthetic steroidal estrogen*** - **Tibolone** is a **synthetic steroid** that acts as a selective tissue estrogenic activity regulator (STEAR), mimicking some effects of estrogen, progesterone, and androgens. - Its **steroidal structure** means it is derived from the basic steroid nucleus, setting it apart from non-steroidal compounds. *Natural steroidal estrogen* - **Natural steroidal estrogens** like estradiol are produced endogenously in the body and have a specific chemical structure. - **Tibolone** is a man-made compound developed in a laboratory, not found naturally. *Natural non-steroidal estrogen* - **Natural non-steroidal estrogens** would refer to compounds found in nature (e.g., phytoestrogens) that do not possess a steroid backbone. - **Tibolone** is synthetic and has a **steroidal structure**. *Synthetic non-steroidal estrogen* - **Synthetic non-steroidal estrogens** are man-made compounds (e.g., diethylstilbestrol) that mimic estrogen but lack the steroid nucleus. - **Tibolone**, however, possesses a **steroidal structure**, making this option incorrect.

Question 606: Finasteride is classified as a:

A. 5-alpha reductase inhibitor (Correct Answer)
B. Phosphodiesterase inhibitor
C. Alpha-1 blocker
D. Androgen receptor antagonist

Explanation: ### ***5-alpha reductase inhibitor*** - **Finasteride** specifically inhibits the enzyme **5-alpha reductase**, preventing the conversion of **testosterone** to **dihydrotestosterone (DHT)** [2], [4]. - This reduction in DHT is clinically useful for treating conditions like **benign prostatic hyperplasia (BPH)** and **androgenetic alopecia** [4]. ### *Phosphodiesterase inhibitor* - **Phosphodiesterase inhibitors** (e.g., sildenafil) typically work by increasing levels of **cyclic GMP**, leading to **vasodilation** and are used for **erectile dysfunction** [3]. - Their mechanism of action is distinct from finasteride's effect on **hormone metabolism**. ### *Alpha-1 blocker* - **Alpha-1 blockers** (e.g., tamsulosin) primarily relax **smooth muscle** in the prostate and bladder neck, improving **urine flow** in BPH [3], [5]. - They act on **adrenergic receptors** and do not affect **hormone synthesis** or **metabolism** [3]. ### *Androgen receptor antagonist* - **Androgen receptor antagonists** (e.g., flutamide) directly block the binding of **androgens** (like testosterone and DHT) to their receptors [1], [4]. - While they also affect androgen action, their mechanism is different from finasteride's **enzyme inhibition** [4].

Question 607: Which of the following is NOT caused by Prostaglandin E2 (PGE2)?

A. None of the options (Correct Answer)
B. Water retention
C. Flushing
D. Uterine contraction

Explanation: ***None of the options*** - All three listed effects (water retention, uterine contraction, and flushing) **ARE caused by Prostaglandin E2 (PGE2)**, making this the correct answer to the question asking what is NOT caused by PGE2. - Since PGE2 actually causes all the listed effects, "None of the options" is the accurate response. *Water retention* - PGE2 **stimulates ADH (vasopressin) release** from the posterior pituitary gland. - PGE2 also **enhances ADH action** on renal collecting ducts, promoting water reabsorption. - While PGE2 has complex renal effects including natriuresis, its net effect includes **promoting water retention** through the ADH mechanism. - This is an important effect of PGE2 on fluid balance. *Uterine contraction* - PGE2 is a **potent stimulator of uterine smooth muscle contraction**. - It is used clinically for **labor induction** and **cervical ripening** (dinoprostone). - PGE2 plays a crucial role in **parturition** and is involved in **dysmenorrhea**. *Flushing* - PGE2 causes **peripheral vasodilation**, particularly in cutaneous blood vessels. - This vasodilatory effect leads to **increased skin blood flow**, manifesting as **flushing** and warmth. - This is commonly seen as part of the **inflammatory response** and contributes to erythema.

Question 608: What is the name of the mumps vaccine?

A. Jeryl Lynn (Correct Answer)
B. Moraten
C. Edmonston-Zagreb
D. Schwarz

Explanation: ***Jeryl Lynn*** - The **Jeryl Lynn strain** is a widely used and highly effective **live attenuated mumps vaccine virus** found in many combined MMR (measles, mumps, rubella) vaccines. - It was developed by **Maurice Hilleman** and is known for its **low reactogenicity** and good safety profile. *Edmonston-Zagreb* - The **Edmonston-Zagreb strain** is a specific type of **live attenuated measles vaccine virus**, not mumps. - It is used in some combinations of the **MMR vaccine** but is distinct from the mumps component. *Schwarz* - The **Schwarz strain** is another variant of **live attenuated measles vaccine virus**, primarily distinguished by its passage history. - Like Edmonston-Zagreb, it targets **measles prevention** and is not used for mumps. *Moraten* - The **Moraten strain** is a specific **live attenuated measles vaccine virus** that is derived from the **Edmonston B strain**. - It is one of the most common measles vaccine strains, also used in **MMR vaccines**, but it does not protect against mumps.

Question 609: Which of the following is a guanosine analogue?

A. Abacavir (Correct Answer)
B. Bromodeoxyuridine
C. Allopurinol
D. Acyclovir

Explanation: ***Abacavir*** - **Abacavir** is a nucleoside reverse transcriptase inhibitor (NRTI) used in HIV treatment. - It is a **carbocyclic analogue of guanosine** (specifically, a 2'-deoxyguanosine analogue). - Structurally, it contains a modified cyclopentane ring instead of the ribose sugar, but retains the guanine base, making it a guanosine analogue. *Acyclovir* - **Acyclovir** is also a **guanosine analogue** - specifically an acyclic guanosine analogue. - It is an antiviral drug used to treat herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. - Note: Both Abacavir and Acyclovir are technically guanosine analogues; in this PYQ context, Abacavir is the expected answer. *Bromodeoxyuridine* - **Bromodeoxyuridine** is a **pyrimidine analogue**, specifically a thymidine analogue. - It is incorporated into DNA during replication and is used in research and as a radiosensitizer. *Allopurinol* - **Allopurinol** is a purine analogue (hypoxanthine analogue) that inhibits xanthine oxidase. - It is primarily used to treat **gout** and prevent kidney stones by reducing uric acid production. - While it's a purine derivative, it is not specifically a guanosine analogue.

Question 610: What is the classification of Buprenorphine in terms of its action on opioid receptors?

A. Pure agonist
B. Pure antagonist
C. Partial agonist (Correct Answer)
D. Mixed agonist-antagonist

Explanation: ***Partial agonist*** - **Buprenorphine** acts as a **partial agonist** at the **mu-opioid receptor**, meaning it binds to the receptor and produces some but not all of the effects of full opioid agonists. - This property contributes to its **ceiling effect** for respiratory depression and analgesic effects, making it safer in overdose compared to full agonists. - It has **high receptor affinity** but **lower intrinsic activity** compared to full agonists. *Pure agonist* - A **pure agonist** would fully activate opioid receptors, producing the maximum possible effect at the receptor. - Examples include **morphine** and **fentanyl**, which carry a higher risk of respiratory depression and overdose at higher doses. - These lack the ceiling effect seen with buprenorphine. *Pure antagonist* - A **pure antagonist** would block opioid receptors without activating them, reversing or preventing the effects of agonists. - An example is **naloxone**, which is used to treat opioid overdose by competitive inhibition. *Mixed agonist-antagonist* - **Mixed agonist-antagonists** (e.g., **pentazocine**, **nalbuphine**) act as agonists at some opioid receptors (kappa) and antagonists at others (mu). - Unlike buprenorphine, which is a partial agonist at mu receptors, mixed agonist-antagonists have different actions at different receptor subtypes. - They can precipitate withdrawal in opioid-dependent patients.

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