General Pharmacology Practice Questions

Q: Live influenza vaccine is given by which route?

Intranasal. ***Intranasal*** - The **live attenuated influenza vaccine (LAIV)** is specifically designed for **intranasal administration**, allowing it to mimic natural infection in the respiratory tract. - This route promotes a robust **mucosal immune response**, which is crucial for respiratory pathogens. *Intradermal* - **Intradermal vaccines** are typically administered into the dermis, beneath the epidermis. - While some influenza vaccines (e.g., Fluzone Intradermal) exist, the **live influenza vaccine** is not given via this route. *Subcutaneous* - **Subcutaneous injection** delivers the vaccine into the fatty tissue just under the skin. - While some vaccines are given subcutaneously, the **live attenuated influenza vaccine** is not. *Intramuscular* - Most **inactivated influenza vaccines** are administered intramuscularly, depositing the vaccine into muscle tissue. - The **live attenuated influenza vaccine** is not given via this route as it is designed to replicate in the upper respiratory tract.

Q: What is the role of magnesium [Mg] in the Inactivated Polio Vaccine (IPV)?

Stabilizer. ***Stabilizer*** - Magnesium (Mg) is included in IPV formulations primarily to **maintain the integrity and potency** of the viral antigens. - It helps prevent the **degradation of the inactivated poliovirus** particles, ensuring a consistent immune response upon vaccination. *Adjuvant* - Adjuvants are substances that **enhance the immune response** to an antigen, often by creating a depot effect or stimulating immune cells. - While essential in some vaccines, magnesium's role in IPV is not primarily to boost immunogenicity but to protect the antigen itself. *Preservative* - Preservatives are added to multi-dose vaccine vials to **prevent microbial contamination** after the vial has been opened. - Common preservatives include 2-phenoxyethanol or thimerosal (though less frequently used now), which have antimicrobial properties not shared by magnesium. *Antiinfective* - An antiinfective agent's primary function is to **kill or inhibit the growth of infectious microorganisms**. - Magnesium does not possess significant antiinfective properties at the concentrations used in vaccines and is not intended to treat or prevent infections in this context.

Q: Rasburicase is a recombinant form of which enzyme?

Urate Oxidase. ***Urate Oxidase*** - **Rasburicase** is a recombinant **urate oxidase** enzyme that catalyzes the oxidation of uric acid into allantoin. - This conversion makes uric acid more soluble and easier to excrete, thereby lowering serum uric acid levels, which is crucial in managing or preventing **tumor lysis syndrome** [2]. *Xanthine oxidase* - **Xanthine oxidase** is involved in the catabolism of purines, converting xanthine to uric acid [1]. - **Allopurinol**, a common drug for hyperuricemia, inhibits xanthine oxidase, but rasburicase does not act as an analogue or inhibitor of this enzyme [3], [4]. *IMP dehydrogenase* - **IMP dehydrogenase** is an enzyme involved in the de novo synthesis of guanine nucleotides from inosine monophosphate (IMP). - It is not directly involved in the catabolism of uric acid, and rasburicase has no known functional analogy to it. *Adenosine Deaminase* - **Adenosine deaminase** is an enzyme that catalyzes the deamination of adenosine to inosine. - Its deficiency is associated with a severe combined immunodeficiency (SCID), and it plays no direct role in uric acid metabolism related to rasburicase's action.

Q: What is the mechanism of action of Iloprost?

PGI 2 analogue. ***Thromboxane receptor antagonist*** - This statement is incorrect. **Iloprost** is an analogue of **prostacyclin (PGI2)**, not a thromboxane receptor antagonist. - It works by mimicking the effects of natural prostacyclin, leading to **vasodilation** and **inhibition of platelet aggregation**. *Thromboxane synthetase antagonist* - **Thromboxane synthetase inhibitors** prevent the production of thromboxane A2, a potent vasoconstrictor and platelet aggregator. - While this is a different mechanism from iloprost, drugs like **dazoxiben** act this way to achieve similar clinical effects of reduced vasoconstriction and platelet aggregation. *PGE 1 analogue* - **PGE1 analogues** (like **alprostadil**) are primarily used to maintain patent ductus arteriosus in neonates or for erectile dysfunction. - While PGE1 also has vasodilatory and antiplatelet effects, **iloprost** specifically mimics **PGI2**. *PGI 2 analogue* - This is the **correct mechanism of action** for **Iloprost**. Iloprost is a stable synthetic analogue of **prostacyclin (PGI2)**. - By activating **prostacyclin receptors**, it causes **vasodilation** (especially in the pulmonary and systemic vasculature) and potent **inhibition of platelet aggregation**.

Q: What is the typical maintenance dose of Levetiracetam in pediatric patients?

30 - 40 mg/kg/day. ***30 - 40 mg/kg/day*** - Levetiracetam is often initiated with a lower dose (e.g., 10-15 mg/kg/day) and **titrated upwards** to achieve seizure control. - The typical maintenance dose for Levetiracetam, especially in pediatric patients, is generally considered to be in the range of **30-40 mg/kg/day** administered in two divided doses. *10 - 20 mg/kg/day* - This range is more typical for the **initial starting dose** of Levetiracetam, rather than the maintenance dose. - While sometimes used as a maintenance dose in specific adult cases or for mild seizure control, it is often considered **sub-therapeutic** for many patients. *20 - 30 mg/kg/day* - This dose range can be an **intermediate dose** during titration, or a maintenance dose for some patients, but it is generally at the lower end of the effective maintenance range. - Many patients require a higher dose to achieve **optimal seizure control** without intolerable side effects. *40 - 50 mg/kg/day* - Doses in this range are often associated with an **increased risk of side effects**, such as somnolence, asthenia, and behavioral changes [1]. - While some patients may require these higher doses under careful supervision, they are generally **above the typical maintenance dose** and should be considered only when lower doses are ineffective.

Q: Which drug acts primarily as a selective 5HT4 receptor agonist?

Renzapride. ***Renzapride*** - **Renzapride** is a **selective 5-HT4 receptor agonist** used to stimulate gut motility, particularly in conditions like chronic constipation. - It enhances the release of acetylcholine in the enteric nervous system, promoting **gastrointestinal motility**. - Unlike metoclopramide, renzapride's **primary mechanism** is 5-HT4 receptor agonism. *Loxiglumide* - **Loxiglumide** is an antagonist of the **cholecystokinin-A (CCK-A) receptor**, not the 5-HT4 receptor. - It is used experimentally to inhibit the effects of CCK, such as gallbladder contraction and pancreatic enzyme secretion. *Atractiloside* - **Atractiloside** is a plant toxin that interferes with mitochondrial function by inhibiting the **adenine nucleotide translocase (ANT)**. - It is not a pharmacological agent targeting serotonin receptors, but rather a mitochondrial poison. *Metoclopramide* - **Metoclopramide** primarily acts as a **D2 dopamine receptor antagonist**, which is its main mechanism for prokinetic effects. - While it has **some 5-HT4 agonistic activity**, this is a **secondary mechanism**, and its primary action is dopamine antagonism. - It is also a **5-HT3 antagonist** at higher doses, making it a mixed-mechanism drug rather than a selective 5-HT4 agonist like renzapride.

Q: Tachyphylaxis is seen with which of the following drugs?

Ephedrine. ***Ephedrine*** - **Ephedrine** is an indirectly acting sympathomimetic that releases stored norepinephrine from nerve terminals [1, 3]. This can lead to **tachyphylaxis** (rapidly decreasing response to repeated doses) as **norepinephrine stores** become depleted [2, 3]. - Due to the depletion of **neurotransmitter stores**, subsequent doses become less effective until stores are replenished [2, 3]. *Pethidine* - **Pethidine** is an opioid analgesic; its primary mechanism of action involves agonizing opioid receptors. - It does not typically exhibit **tachyphylaxis** through neurotransmitter depletion, but rather can lead to tolerance with chronic use. *Phenoxybenzamine* - **Phenoxybenzamine** is a non-selective, **irreversible alpha-adrenergic receptor blocker**. - Its mechanism involves long-lasting blockade of receptors, and **tachyphylaxis** is not a characteristic feature of its pharmacodynamics. *Phentolamine* - **Phentolamine** is a non-selective, **reversible alpha-adrenergic receptor blocker**. - While it has a shorter duration of action compared to phenoxybenzamine, its effects are reversible and it does not typically cause **tachyphylaxis** through neurotransmitter depletion.

Q: Mechanism of action of Niclosamide is:

Inhibition of mitochondrial oxidative phosphorylation. ***Inhibition of mitochondrial oxidative phosphorylation*** - **Niclosamide** is an **uncoupler of oxidative phosphorylation**, leading to **ATP depletion** in the parasite. - This effectively starves the parasite of energy, particularly **tapeworms**, which are highly dependent on this pathway. *Inhibition of substrate level phosphorylation* - **Substrate-level phosphorylation** is a metabolic pathway that directly phosphorylates ADP to ATP using high-energy intermediate molecules, not the primary target of niclosamide. - While it contributes to ATP production, its inhibition is not the primary mechanism of action for **niclosamide**. *Inhibition of proton efflux pumps* - **Proton efflux pumps** (e.g., proton pumps in gastric cells) are generally not the direct target for anthelmintic drugs like niclosamide. - This mechanism is characteristic of drugs like **proton pump inhibitors** (PPIs) used to reduce stomach acid. *Increase production of free radicals* - Some antiparasitic drugs act by increasing **oxidative stress** and **free radical production**, leading to parasite death. - However, for **niclosamide**, the primary mechanism is the disruption of **ATP synthesis** through uncoupling.

Q: What is the mechanism of action of metyrosine?

Tyrosine hydroxylase. ***Tyrosine hydroxylase*** - **Metyrosine** acts as a **competitive inhibitor** of **tyrosine hydroxylase**, which is a crucial enzyme in the **catecholamine synthesis pathway**. - By blocking this rate-limiting step, metyrosine reduces the production of **dopamine**, **norepinephrine**, and **epinephrine**. *Phenylethanolamine N-methyltransferase* - This enzyme converts **norepinephrine to epinephrine** and is not the primary target of metyrosine. - While metyrosine indirectly affects downstream products, its direct action is not on this enzyme. *Phenylalanine hydroxylase* - This enzyme converts **phenylalanine to tyrosine** and is associated with conditions like **phenylketonuria**. - It is not involved in the direct synthesis of catecholamines from tyrosine, nor is it the target of metyrosine. *Tyrosinase* - **Tyrosinase** is involved in the synthesis of **melanin**, not catecholamines. - Inhibition of this enzyme would primarily affect pigmentation, which is unrelated to metyrosine's therapeutic use.

Q: What is the active principle of the plant Calotropis?

Calotropin. ***Calotropin*** - **Calotropin** is the primary **cardiac glycoside** found in the latex of the *Calotropis* plant, responsible for its toxic and medicinal properties. - This compound exerts its effects by inhibiting the **Na+/K+-ATPase pump**, leading to increased intracellular calcium and potentially cardiotoxicity. *Plumbagin* - **Plumbagin** is a **naphthoquinone** derivative found in plants like *Plumbago zeylanica*, known for its antimicrobial and anticancer activities. - It is not associated with *Calotropis* and has a different chemical structure and mechanism of action compared to cardiac glycosides. *Ricin* - **Ricin** is a highly potent **protein toxin** derived from the seeds of the **castor bean plant** (*Ricinus communis*). - Its mechanism involves inhibiting protein synthesis, which is distinct from the cardiac glycoside action of *Calotropis*. *Emodin* - **Emodin** is an **anthraquinone** derivative commonly found in plants such as **rhubarb** and **aloe**, known for its laxative and anti-inflammatory properties. - It is structurally and functionally different from the cardiac glycosides found in *Calotropis*.

Question 1

Live influenza vaccine is given by which route?

Accepted Answer

Intranasal

Answer

Intradermal

Answer

Subcutaneous

Answer

Intramuscular

Question 2

What is the role of magnesium [Mg] in the Inactivated Polio Vaccine (IPV)?

Accepted Answer

Stabilizer

Answer

Adjuvant

Answer

Preservative

Answer

Antiinfective

Question 3

Rasburicase is a recombinant form of which enzyme?

Accepted Answer

Urate Oxidase

Answer

Xanthine oxidase

Answer

IMP dehydrogenase

Answer

Adenosine Deaminase

Question 4

What is the mechanism of action of Iloprost?

Accepted Answer

PGI 2 analogue

Answer

Thromboxane synthetase antagonist

Answer

Thromboxane receptor antagonist

Answer

PGE 1 analogue

Question 5

What is the typical maintenance dose of Levetiracetam in pediatric patients?

Accepted Answer

30 - 40 mg/kg/day

Answer

10 - 20 mg/kg/day

Answer

20 - 30 mg/kg/day

Answer

40 - 50 mg/kg/day

Question 6

Which drug acts primarily as a selective 5HT4 receptor agonist?

Accepted Answer

Renzapride

Answer

Loxiglumide

Answer

Atractiloside

Answer

Metoclopramide

Question 7

Tachyphylaxis is seen with which of the following drugs?

Accepted Answer

Ephedrine

Answer

Pethidine

Answer

Phenoxybenzamine

Answer

Phentolamine

Question 8

Mechanism of action of Niclosamide is:

Accepted Answer

Inhibition of mitochondrial oxidative phosphorylation

Answer

Inhibition of substrate level phosphorylation

Answer

Inhibition of proton efflux pumps

Answer

Increase production of free radicals

Question 9

What is the mechanism of action of metyrosine?

Accepted Answer

Tyrosine hydroxylase

Answer

Phenylethanolamine N-methyltransferase

Answer

Phenylalanine hydroxylase

Answer

Tyrosinase

Question 10

What is the active principle of the plant Calotropis?

Accepted Answer

Calotropin

Answer

Emodin

Answer

Ricin

Answer

Plumbagin

General Pharmacology — MCQs

General Pharmacology — MCQs

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