INI-CET 2021 - Pharmacology Practice Questions

Q: A patient is on phenytoin for a seizure disorder. He was prescribed sucralfate 4 times a day for peptic ulcers. What should be the minimum duration of time between consumption of these drugs?

120 minutes. **_120 minutes_** - **Sucralfate** forms a protective barrier in the stomach and can **adsorb other medications**, significantly reducing their absorption. - A minimum separation of **2 hours (120 minutes)** is recommended between sucralfate and other oral medications to prevent drug interactions. *90 minutes* - While a longer interval is beneficial, **90 minutes** may not be sufficient to completely avoid the significant reduction in **phenytoin absorption** caused by sucralfate. - Given the narrow therapeutic index of phenytoin, a more conservative approach with a longer separation is preferred. *60 minutes* - A **60-minute interval** is generally considered too short to prevent the **adsorption of phenytoin** by sucralfate. - This short duration increases the risk of **subtherapeutic phenytoin levels** and potential seizure recurrence. *30 minutes* - A **30-minute interval** is entirely inadequate and would almost certainly lead to a significant **reduction in phenytoin absorption**. - This would place the patient at high risk of **seizure recurrence** due to insufficient drug levels.

Q: What is the mechanism of action of cyclosporine?

Inhibition of calcineurin. ***Inhibition of calcineurin*** - Cyclosporine forms a complex with **cyclophilin**, which then inhibits the phosphatase activity of **calcineurin**. - This inhibition prevents the dephosphorylation and subsequent nuclear translocation of **NFAT (nuclear factor of activated T-cells)**, thereby blocking the transcription of **IL-2** and other cytokines essential for T-cell activation. *Dihydro-orotate dehydrogenase inhibition* - This is the mechanism of action of **leflunomide**, another immunosuppressant, which works by inhibiting *de novo* pyrimidine synthesis. - Leflunomide primarily affects rapidly proliferating cells, such as T-lymphocytes, by depriving them of essential pyrimidine nucleotides. *AMP kinase stimulation* - **AMP-activated protein kinase (AMPK)** is a cellular energy sensor that plays a role in metabolism and cellular growth. - While AMPK activation has various cellular effects, it is not the primary mechanism of action for cyclosporine or other calcineurin inhibitors. *IMP dehydrogenase inhibition* - This is the mechanism of action of **mycophenolate mofetil**, an immunosuppressant that selectively inhibits *de novo* guanosine nucleotide synthesis. - By depleting guanosine nucleotides, mycophenolate specifically inhibits the proliferation of T and B lymphocytes.

Q: Which of the following is the most effective drug in smoking cessation?

Varenicline. ***Varenicline*** - **Varenicline** is a **partial agonist** of the **nicotinic acetylcholine receptor (nAChR)**, reducing cravings and withdrawal symptoms while blocking the pleasurable effects of nicotine. - It has been shown to be more effective than other pharmacological interventions, including bupropion and nicotine replacement therapies, in achieving **long-term abstinence**. *Nicotine gum* - **Nicotine gum** is a form of **Nicotine Replacement Therapy (NRT)** that provides nicotine to reduce withdrawal symptoms. - While effective, NRTs (including gum) are generally less effective than varenicline in achieving sustained smoking cessation. *Buspirone* - **Buspirone** is an anxiolytic drug primarily used to treat generalized anxiety disorder. - It does not have a primary indication or significant evidence of effectiveness for smoking cessation. *Rimonabant* - **Rimonabant** is a **cannabinoid receptor 1 (CB1) antagonist** that was once explored for smoking cessation and weight loss. - It was withdrawn from the market due to significant psychiatric side effects, including depression and suicidal ideation, and is not used for smoking cessation.

Q: Which of the following is a centrally acting non-opioid antitussive?

Dextromethorphan. ***Dextromethorphan*** - **Dextromethorphan** is a **centrally acting non-opioid antitussive** that suppresses the cough reflex by acting on the cough center in the medulla oblongata [1], [2]. - It is an **NMDA receptor antagonist** and a **sigma-1 receptor agonist**, which are the primary mechanisms responsible for its antitussive effects [2]. - Unlike opioid antitussives (codeine, hydrocodone), it does **not bind significantly to opioid receptors** at therapeutic doses and therefore lacks addiction potential, respiratory depression, and other opioid side effects [1], [3]. - It is a synthetic morphine analog (dextro-isomer) but is pharmacologically distinct from opioids [1]. *Ambroxol* - **Ambroxol** is a **mucolytic agent** that helps to thin and clear mucus from the respiratory tract. - It works by stimulating serous gland secretion and breaking down mucopolysaccharide fibers, which is different from suppressing the cough reflex centrally. *Guaifenesin* - **Guaifenesin** is an **expectorant** that increases the volume and reduces the viscosity of respiratory tract secretions. - This action helps to make coughs more productive, rather than directly suppressing the cough reflex. *Diphenhydramine* - **Diphenhydramine** is a first-generation **antihistamine** with significant sedative and anticholinergic properties. - While it has some antitussive effects, these are primarily due to its anticholinergic actions causing drying of respiratory secretions and its sedative properties, rather than direct central action on the cough center.

Question 1

A patient is on phenytoin for a seizure disorder. He was prescribed sucralfate 4 times a day for peptic ulcers. What should be the minimum duration of time between consumption of these drugs?

Accepted Answer

120 minutes

Answer

90 minutes

Answer

60 minutes

Answer

30 minutes

Question 2

What is the mechanism of action of cyclosporine?

Accepted Answer

Inhibition of calcineurin

Answer

Dihydro-orotate dehydrogenase inhibition

Answer

AMP kinase stimulation

Answer

IMP dehydrogenase inhibition

Question 3

Which of the following is the most effective drug in smoking cessation?

Accepted Answer

Varenicline

Answer

Nicotine gum

Answer

Buspirone

Answer

Rimonabant

Question 4

Which of the following is a centrally acting non-opioid antitussive?

Accepted Answer

Dextromethorphan

Answer

Ambroxol

Answer

Guaifenesin

Answer

Diphenhydramine

INI-CET 2021 — Pharmacology