Clinical Pharmacology and Drug Toxicity Practice Questions

Q: A 19-year-old man at a rave party is brought to the ED with agitation, temperature of 107°F (41.7°C), severe hypertension (180/110 mm Hg), tachycardia, dilated pupils, and diaphoresis. His friends report he took 'Molly.' Despite aggressive cooling, his temperature remains dangerously elevated and he develops rhabdomyolysis. Evaluate the most appropriate additional pharmacologic intervention.

Benzodiazepines to reduce CNS and muscular hyperactivity. ***Benzodiazepines to reduce CNS and muscular hyperactivity*** - **Benzodiazepines** are the first-line pharmacologic treatment for **MDMA (Molly)** toxicity as they help control agitation, reduce **sympathetic outflow**, and decrease heat production from muscle hyperactivity. - They facilitate **GABAergic inhibition**, which helps manage hypertension and tachycardia while secondarily reducing the risk of further **rhabdomyolysis**. *Dantrolene sodium to reduce muscle hypermetabolism* - While used in **malignant hyperthermia**, dantrolene has limited evidence and is not the primary treatment for **serotonin syndrome** or stimulant-induced hyperthermia. - It does not address the underlying **central nervous system** agitation or sympathetic surge caused by MDMA. *Antipyretics to reduce hypothalamic set point* - **Antipyretics** (like Acetaminophen) are ineffective because the hyperthermia in MDMA toxicity is due to excessive **muscle activity** and heat production, not a change in the **hypothalamic set point**. - Fever in this context is **environment and activity-driven** rather than an inflammatory cytokine-mediated response. *Bromocriptine as a dopamine agonist* - **Bromocriptine** is specifically used for **Neuroleptic Malignant Syndrome (NMS)** to counteract dopamine blockade. - It is not indicated for MDMA toxicity, where the primary neurotransmitter imbalance involves **serotonin** and **norepinephrine** excess. *Beta-blockers to control hypertension and tachycardia* - **Beta-blockers** are generally avoided in stimulant-induced emergencies due to the risk of **unopposed alpha-adrenergic stimulation**, which can worsen hypertension. - They may further impair **peripheral vasodilation**, hindering the body’s ability to dissipate heat through the skin.

Q: Which of the following is NOT characteristic of severe barbiturate poisoning?

Hypertension. **Explanation:** Severe barbiturate poisoning is characterized by generalized **Central Nervous System (CNS) and cardiovascular depression**. **1. Why Hypertension is the Correct Answer:** Barbiturates cause profound **hypotension**, not hypertension. This occurs due to a combination of direct myocardial depression, peripheral vasodilation (loss of vasomotor tone), and depression of the medullary vasomotor centers. In severe toxicity, this can lead to circulatory collapse and shock. **2. Analysis of Other Options:** * **Hypothermia (A):** Barbiturates depress the hypothalamic thermoregulatory center and reduce the metabolic rate, leading to a significant drop in body temperature. * **Coma (C):** As GABA-A receptor agonists, barbiturates increase the duration of chloride channel opening, leading to global CNS depression. This typically manifests as a deep, unresponsive coma. * **Non-reactive pupils (D):** While pupils may initially be constricted (miotic), in severe or terminal stages of barbiturate poisoning, hypoxic brain damage often results in paralytic dilatation and non-reactive pupils. **High-Yield Clinical Pearls for NEET-PG:** * **Respiratory Depression:** The most common cause of death in acute barbiturate poisoning is respiratory failure. * **Bullous Lesions:** The presence of **"Barbiturate blisters"** (clear vesicles/bullae) on pressure points is a characteristic, though not pathognomonic, skin finding. * **Management:** There is **no specific antidote**. Treatment is supportive (ABC). For long-acting barbiturates (e.g., Phenobarbital), **Urinary Alkalinization** with Sodium Bicarbonate is used to enhance excretion (ion trapping). Hemodialysis is reserved for extreme cases.

Q: Which of the following is NOT a common or well-known manifestation of an adverse drug reaction?

Leukaemia. **Explanation:** In clinical pharmacology, **Adverse Drug Reactions (ADRs)** are typically categorized into predictable (Type A) and unpredictable/idiosyncratic (Type B) reactions. While many drugs can cause acute bone marrow suppression or blood dyscrasias, they rarely act as direct carcinogens to induce malignancy like **Leukaemia**. **Why Leukaemia is the correct answer:** Leukaemia is a neoplastic transformation of hematopoietic stem cells. While certain cytotoxic chemotherapy agents (like alkylating agents or etoposide) can cause "secondary leukaemia" years after treatment, it is considered a **long-term complication or secondary malignancy** rather than a common or classic manifestation of a standard ADR. In the context of competitive exams, blood dyscrasias (A, B, and C) are the hallmark examples of drug-induced hematotoxicity. **Analysis of incorrect options:** * **Agranulocytosis:** A classic idiosyncratic ADR. Common culprits include **Clozapine, Antithyroid drugs (Methimazole, PTU), and Dipyrone.** * **Aplastic Anaemia:** A life-threatening ADR characterized by pancytopenia. The most high-yield association is with **Chloramphenicol** (idiosyncratic type), but it is also seen with Phenylbutazone and Gold salts. * **Haemolysis:** A frequent ADR, especially in individuals with **G6PD deficiency** when exposed to oxidative drugs like **Primaquine, Sulfonamides, and Nitrofurantoin.** **High-Yield Clinical Pearls for NEET-PG:** * **Chloramphenicol** causes two types of bone marrow suppression: 1. Dose-dependent (reversible) and 2. Idiosyncratic aplastic anaemia (irreversible and fatal). * **Clozapine** monitoring requires mandatory weekly WBC counts due to the risk of agranulocytosis. * **Drug-induced SLE** is another common ADR question; remember **HIP** (Hydralazine, Isoniazid, Procainamide).

Q: Alkalinization of urine is required to treat toxicity of all except:

Amphetamine. ### Explanation The principle underlying this question is **Ion Trapping**, which is based on the **Henderson-Hasselbalch equation**. To enhance the renal excretion of a drug, the urine pH must be adjusted to ensure the drug remains in its **ionized (charged) form**, preventing its reabsorption across the renal tubular membrane. **1. Why Amphetamine is the Correct Answer:** Amphetamine is a **weak base**. According to the principle of ion trapping, weak bases are ionized in an **acidic environment**. Therefore, to treat amphetamine toxicity, **acidification of urine** (using Ammonium Chloride) is required to trap the drug in the renal tubules and promote excretion. Alkalinization would keep a weak base in its non-ionized form, increasing its reabsorption. **2. Why the other options are incorrect:** * **Salicylates (A) and Barbiturates (B):** These are **weakly acidic** drugs. Alkalinization of urine (using Sodium Bicarbonate) converts them into their ionized (salt) form, trapping them in the urine and accelerating clearance. This is a standard treatment for Aspirin and Phenobarbital overdose. * **Methotrexate (D):** Methotrexate is also an acidic drug. Alkalinization is crucial here not only to increase excretion but also to **prevent crystalluria** and subsequent acute kidney injury, as methotrexate is more soluble in alkaline urine. ### NEET-PG High-Yield Pearls: * **Alkalinization of Urine:** Used for **Acidic drugs** (Salicylates, Barbiturates, Methotrexate, Sulfonamides, Fluoride). Target urine pH is usually 7.5–8.5. * **Acidification of Urine:** Used for **Basic drugs** (Amphetamines, Phencyclidine, Quinine). *Note: Clinically, acidification is rarely performed now due to the risk of metabolic acidosis and worsening rhabdomyolysis.* * **Forced Alkaline Diuresis:** Involves the administration of IV fluids + Sodium Bicarbonate + Loop diuretics (like Furosemide).

Question 1

A 19-year-old man at a rave party is brought to the ED with agitation, temperature of 107°F (41.7°C), severe hypertension (180/110 mm Hg), tachycardia, dilated pupils, and diaphoresis. His friends report he took 'Molly.' Despite aggressive cooling, his temperature remains dangerously elevated and he develops rhabdomyolysis. Evaluate the most appropriate additional pharmacologic intervention.

Accepted Answer

Benzodiazepines to reduce CNS and muscular hyperactivity

Answer

Dantrolene sodium to reduce muscle hypermetabolism

Answer

Antipyretics to reduce hypothalamic set point

Answer

Bromocriptine as a dopamine agonist

Answer

Beta-blockers to control hypertension and tachycardia

Question 2

Which of the following is NOT characteristic of severe barbiturate poisoning?

Accepted Answer

Hypertension

Answer

Hypothermia

Answer

Coma

Answer

Non-reactive pupils

Question 3

Which of the following is NOT a common or well-known manifestation of an adverse drug reaction?

Accepted Answer

Leukaemia

Answer

Agranulocytosis

Answer

Aplastic anaemia

Answer

Haemolysis

Question 4

A 65-year-old female with ovarian cancer is being treated with cisplatin-based chemotherapy. Which of the following is NOT used to limit the toxicity of cisplatin?

Accepted Answer

N-acetylcysteine

Answer

Slow rate of infusion

Answer

Chloride diuresis

Answer

Amifostine

Question 5

Alkalinization of urine is required to treat toxicity of all except:

Accepted Answer

Amphetamine

Answer

Salicylates

Answer

Barbiturates

Answer

Methotrexate

Clinical Pharmacology and Drug Toxicity — MCQs

Clinical Pharmacology and Drug Toxicity — MCQs

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