Clinical Pharmacology and Drug Toxicity — MCQs

Clinical Pharmacology and Drug Toxicity Indian Medical PG Practice Questions and MCQs

Question 781: Seal like limbs i.e. phocomelia is a specific side effect of -

A. Doxorubicin
B. Thalidomide (Correct Answer)
C. Cyclophosphamide
D. Terazosin

Explanation: ***Thalidomide*** - **Phocomelia**, characterized by severely shortened or absent limbs resembling those of a seal, is a classic and well-documented **teratogenic effect** of thalidomide. - This drug, when taken during early pregnancy (especially between weeks 4 and 8), disrupts limb bud development. *Doxorubicin* - **Doxorubicin** is an **anthracycline antibiotic** used in cancer chemotherapy, known for its significant **cardiotoxicity**, leading to dilated cardiomyopathy. - While it has various side effects, **phocomelia** is not a reported teratogenic effect of doxorubicin. *Cyclophosphamide* - **Cyclophosphamide** is an **alkylating agent** used in chemotherapy and immunosuppression, with notable side effects including **hemorrhagic cystitis** and **myelosuppression**. - Although it is a teratogen and can cause various fetal malformations, it is not specifically associated with **phocomelia**. *Terazosin* - **Terazosin** is an **alpha-1 blocker** primarily used to treat hypertension and benign prostatic hyperplasia (BPH). - Its main side effects include **orthostatic hypotension** and dizziness; it is not known to be teratogenic or associated with **phocomelia**.

Question 782: In snake envenomation, antivenom treatment is started by giving a dose of:

A. 4 vials
B. 10 vials (Correct Answer)
C. 2 vials
D. 20 vials

Explanation: ***10 vials*** - The initial dose of **antivenom** for significant snake envenomation is commonly **10 vials** given intravenously. - This dosage aims to quickly neutralize the circulating **venom toxins** and halt the progression of envenomation effects. *4 vials* - While a smaller dose might be considered in mild cases, **4 vials** is generally insufficient for the initial treatment of moderate to severe snake envenomation. - Underdosing can lead to ongoing **tissue damage** and systemic effects. *2 vials* - An initial dose of **2 vials** of antivenom is typically too low to effectively counteract the venom in clinically significant snakebites. - This dosage would likely result in continued **toxemia** and worsening of symptoms. *20 vials* - An initial dose of **20 vials** is an exceptionally high amount and is generally reserved for extremely severe cases or when there is a poor response to the standard initial dose. - Administering an unnecessarily large dose can increase the risk of **adverse reactions** to the antivenom.

Question 783: A patient of biliary colic presented to hospital. Intern gave an injection and the pain worsened. Which is the most likely injection given?

A. Morphine (Correct Answer)
B. Diclofenac
C. Etoricoxib
D. Nefopam

Explanation: *Morphine*- **Morphine** and other opioids can cause **spasm of the sphincter of Oddi**, leading to increased pressure in the **biliary tree** and worsening of biliary colic.- This effect is mediated through **mu-opioid receptors** on the smooth muscle of the sphincter.*Diclofenac*- **Diclofenac** is a non-steroidal anti-inflammatory drug (NSAID) which is an excellent choice for **biliary colic** because it reduces inflammation and relaxes smooth muscle.- It works by inhibiting **prostaglandin synthesis**, thus reducing pain and spasm of the gallbladder.*Etoricoxib*- **Etoricoxib** is a selective COX-2 inhibitor [1], another type of NSAID, which would typically alleviate pain in biliary colic.- It reduces inflammation and pain [1] without the **sphincter of Oddi spasm** concerns associated with opioids.*Nefopam*- **Nefopam** is a non-opioid analgesic that acts as a centrally acting **serotonin-norepinephrine-dopamine reuptake inhibitor (SNDRI)**. It would typically help with pain relief.- It is not known to cause **sphincter of Oddi spasm** and would therefore not usually worsen biliary colic.

Question 784: Which drug increases bone formation in osteoporosis?

A. Teriparatide (Correct Answer)
B. Calcitonin
C. Risedronate
D. Denosumab

Explanation: ***Correct Option: Teriparatide*** - **Teriparatide** is a recombinant form of **parathyroid hormone (PTH)** that, when administered intermittently, stimulates **osteoblast activity** to increase bone formation. - It is an **anabolic agent** specifically designed to build new bone, making it unique among osteoporosis treatments that primarily inhibit bone resorption. - Administered as a **daily subcutaneous injection** for up to 2 years. *Incorrect Option: Calcitonin* - **Calcitonin** is a hormone that inhibits **osteoclast activity**, thereby reducing bone resorption, but does not directly stimulate bone formation. - It may be used for pain relief in acute vertebral fractures but has a minor role in increasing bone density. *Incorrect Option: Risedronate* - **Risedronate** is a **bisphosphonate** that works by inhibiting **osteoclast-mediated bone resorption**, preventing bone breakdown. - It does not directly promote new bone formation; its primary action is to reduce bone turnover. *Incorrect Option: Denosumab* - **Denosumab** is a **monoclonal antibody** that targets and binds to **RANKL**, thereby inhibiting **osteoclast formation, function, and survival**, leading to decreased bone resorption. - Like bisphosphonates, its main mechanism is anti-resorptive, not anabolic.

Question 785: All of the following can be used to decrease intraocular pressure in glaucoma except?

A. Mannitol
B. Clonidine
C. Dexamethasone (Correct Answer)
D. Methazolamide

Explanation: ***Dexamethasone*** - **Corticosteroids** like dexamethasone are known to **increase intraocular pressure** by reducing the outflow of aqueous humor, thus exacerbating glaucoma. - This effect is often dose-dependent and can lead to **steroid-induced glaucoma** in susceptible individuals. *Mannitol* - **Mannitol** is an osmotic diuretic used to **rapidly decrease intraocular pressure** by drawing fluid out of the vitreous humor. - It is often used in acute angle-closure glaucoma or before ocular surgery. *Clonidine* - **Clonidine** is an alpha-2 adrenergic agonist that can **decrease aqueous humor production**, thereby reducing intraocular pressure. - While it has been studied for glaucoma, its systemic side effects often limit its use. *Methazolamide* - **Methazolamide** is a **carbonic anhydrase inhibitor** that reduces the production of aqueous humor. - This reduction in fluid production directly leads to a decrease in intraocular pressure, making it a common glaucoma treatment.

Question 786: Glucosamine is used in which of the following conditions?

A. Niemann-Pick disease
B. Alzheimer's disease
C. Arthritis (Correct Answer)
D. Cancer

Explanation: ***Arthritis*** - **Glucosamine** is a naturally occurring compound found in healthy cartilage and is often used as a supplement to help with **joint pain** and inflammation associated with arthritis, particularly **osteoarthritis**. - It is believed to help in the formation and repair of **cartilage**, reducing symptoms like pain and improving joint function. *Niemann-Pick disease* - This is a rare, inherited metabolic disorder characterized by the accumulation of **fatty substances** (lipids) in cells, leading to liver, spleen, and brain damage. - **Glucosamine** has no established role in the treatment or management of Niemann-Pick disease. *Alzheimer's disease* - This is a progressive neurological disorder causing brain cells to degenerate and die, leading to memory loss and cognitive decline. - There is currently **no scientific evidence** to support the use of glucosamine in the prevention or treatment of Alzheimer's disease. *Cancer* - Cancer is a disease characterized by the uncontrolled **growth and spread of abnormal cells** in the body. - While some research explores the potential effects of various compounds on cancer cells, **glucosamine is not a recognized treatment** and may even interact with certain cancer therapies.

Question 787: Z tracking technique is used in?

A. Administering long acting antipsychotic (Correct Answer)
B. Carbamazepine monitoring
C. Lithium monitoring
D. Nicotine patch

Explanation: ***Administering long acting antipsychotic*** - The **Z-track technique** is a method of intramuscular injection used to prevent medication from leaking back into the subcutaneous tissue, which is particularly important for irritating or discoloring medications like **long-acting antipsychotics**. - This technique involves pulling the skin and subcutaneous tissue to one side before injection, then releasing it after the needle is withdrawn, creating a **zigzag path** that seals the medication within the muscle. *Carbamazepine monitoring* - **Carbamazepine monitoring** involves regularly checking blood levels of the drug to ensure therapeutic efficacy and avoid toxicity. - This is a **laboratory process**, not an administration technique, and does not involve Z-tracking. *Lithium monitoring* - **Lithium monitoring** requires periodic blood tests to maintain therapeutic levels and prevent adverse effects due to its narrow therapeutic index. - Like carbamazepine monitoring, this is a **laboratory-based task** and not related to drug administration methods. *Nicotine patch* - A **nicotine patch** is a transdermal delivery system applied to the skin, which releases nicotine slowly into the bloodstream. - This is a **topical application method** and does not involve injections or the Z-track technique.

Question 788: A voluntary donor underwent apheresis for platelet donation for the first time after which he developed perioral tingling and numbness. This is seen because:

A. Due to fluid depletion
B. He underwent apheresis for the first time
C. Due to citrate based anticoagulant (Correct Answer)
D. His platelet count was low for donation

Explanation: ***Due to citrate based anticoagulant*** - **Citrate** is commonly used as an anticoagulant during apheresis procedures and can chelate **ionized calcium**. - A decrease in ionized calcium levels can lead to symptoms like **perioral tingling** and **numbness** (paresthesias) due to increased neuromuscular excitability. *Due to fluid depletion* - While fluid shifts can occur during apheresis, **hypovolemia** is more likely to cause symptoms like dizziness, lightheadedness, or syncope rather than specific paresthesias. - **Fluid depletion** alone does not typically directly explain perioral tingling and numbness. *He underwent apheresis for the first time* - The novelty of the procedure does not inherently cause physiological symptoms like **perioral tingling** and **numbness**. - This is a psychological factor, not a direct cause of a specific physiological response seen in this scenario. *His platelet count was low for donation* - A donor's **low platelet count** would typically contraindicate donation or lead to a less efficient collection, but it does not cause **perioral tingling** or **numbness** during or after the procedure. - The symptoms described are related to the **anticoagulant** used, not the donor's baseline platelet levels.

Question 789: All are drugs which lower IOP except:

A. Mannitol
B. Clonidine
C. Acetazolamide
D. Dexamethasone (Correct Answer)

Explanation: ***Dexamethasone*** - Dexamethasone is a **corticosteroid** that is known to increase **intraocular pressure (IOP)**, particularly with prolonged use, in susceptible individuals. - This increase in IOP is a significant side effect and can lead to **steroid-induced glaucoma**. *Mannitol* - **Mannitol** is an osmotic diuretic that rapidly reduces IOP by creating an osmotic gradient, drawing water out of the eye. - It is often used in acute settings for rapid reduction of **high IOP**, such as in acute angle-closure glaucoma. *Clonidine* - **Clonidine** is an alpha-2 adrenergic agonist that lowers IOP by reducing aqueous humor production and possibly increasing uveoscleral outflow. - While not a primary glaucoma medication, it has been shown to have an **IOP-lowering effect**. *Acetazolamide* - **Acetazolamide** is a carbonic anhydrase inhibitor that significantly reduces IOP by decreasing the production of aqueous humor. - It is a cornerstone medication for managing **glaucoma** and other conditions requiring IOP reduction.

Question 790: Which drug is not given in Wilson disease?

A. Trientine
B. Zinc
C. Penicillamine
D. Calcium (Correct Answer)

Explanation: ***Calcium*** - **Calcium** is not used in the management of **Wilson disease**. - Its role is primarily in bone health and metabolic functions not directly related to **copper chelation** or **absorption**. *Trientine* - **Trientine** is a **chelating agent** that binds to **copper** and is used as a first-line treatment for **Wilson disease**, especially in patients intolerant to **penicillamine**. - It helps remove excess copper from the body, reducing its toxic effects on organs. *Zinc* - **Zinc** is used as maintenance therapy in **Wilson disease** by inducing metallothionein in the intestinal cells, which sequesters copper and prevents its absorption. - It works by blocking the **absorption of copper** from the diet [1]. *Penicillamine* - **Penicillamine** is a well-established **chelating agent** used to bind and remove excess **copper** in patients with **Wilson disease**. - It is often the initial treatment but can have significant side effects, leading to the use of alternative agents like **trientine**.

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