Prometric Questions - Yellow File - MOH | SPLE | HAAD | DHA - 21

Which of the following drugs causes water retention?
A) codeine
B) tramadol 
C) indomethacin
D) acetaminophen

The correct answer is C) indomethacin.

Indomethacin is a potent Non-Steroidal Anti-Inflammatory Drug (NSAID). Water retention (edema) is a well-known side effect of the entire NSAID class, though it is particularly pronounced with stronger agents like indomethacin.

How Indomethacin Causes Water Retention

The mechanism is tied to the inhibition of prostaglandins in the kidneys:

Prostaglandin Inhibition: NSAIDs block the COX-1 and COX-2 enzymes, which are responsible for producing prostaglandins (specifically PGE₂ and PGI₂).

Renal Vasoconstriction: In the kidneys, these prostaglandins normally help keep the afferent arterioles dilated to ensure proper blood flow.

Sodium and Water Reabsorption: When prostaglandins are suppressed, blood flow to the kidneys decreases. This triggers the body to retain sodium and, consequently, water to maintain blood pressure. This effect can be particularly dangerous for patients with pre-existing heart failure or hypertension, as the extra fluid volume increases the workload on the heart.

Analysis of Other Options:

The other medications listed do not typically cause water retention as a primary side effect:

A) Codeine & B) Tramadol: These are opioids. Their primary side effects are respiratory depression, sedation, and constipation. While they don't cause systemic water retention, they can sometimes cause urinary retention (difficulty urinating) due to effects on the bladder sphincter.

D) Acetaminophen: This is a non-opioid analgesic. It has very little effect on systemic prostaglandin synthesis in the kidneys, making it much safer for the stomach and kidneys than NSAIDs like indomethacin.

Clinical Tip: Because of its potency and side effect profile, indomethacin is often reserved for acute conditions like gout flares rather than long-term pain management.

A 7-year-old boy presents with complain of itchiness around the anus at night. Lab tests revealed Enteroblus vermicularis infection (pin worm infection).

Which of the following is the most appropriate management?

A)fluconazole

B) praziquantel

C) pantoprazole 

D) mebendazole

The correct answer is D) mebendazole.

The symptoms described—intense nocturnal anal itching (pruritus ani) in a child—are the hallmark of pinworm infection. This occurs because the female Enterobius vermicularis worm migrates out of the anus at night to lay thousands of eggs in the surrounding skin folds.

Why Mebendazole?

Mebendazole is an anthelmintic (anti-worm) medication. It works by interfering with the worm's ability to use glucose, effectively "starving" the parasite.

Dosing Strategy: It is usually given as a single dose, followed by a second dose two weeks later. The second dose is crucial because the medication kills the worms but not the eggs; the two-week gap allows any remaining eggs to hatch so the new worms can be eliminated.

Family Treatment: Because pinworms are highly contagious and easily spread via the fecal-oral route (contaminated toys, bedding, or hands), it is standard practice to treat the entire household simultaneously.

Analysis of Other Options

The other drugs listed target entirely different types of organisms or conditions:

Medication	Use Case	Why it's wrong here
A) Fluconazole	Antifungal	Used for yeast infections (Candida) or thrush; it has no effect on parasitic worms.
B) Praziquantel	Anthelmintic	While it is an anti-worm med, it is the drug of choice for tapeworms and flukes (Schistosomiasis), not pinworms.
C) Pantoprazole	Proton Pump Inhibitor	Used to reduce stomach acid in GERD or ulcers; it has no anti-parasitic properties.

Practical Advice for Pinworms

Beyond medication, hygiene is key to preventing reinfection:

• Wash all bed linens and pajamas in hot water.

• Keep fingernails cut short (to prevent eggs from lodging under nails during scratching).

• Shower in the morning to wash away eggs laid overnight.

Which of the following drugs is used for premature ejaculation?

A) atenolol 
B) dapoxetine
C) olanzapine
D) aripiprazole

The correct answer is B) dapoxetine.

While many medications in its class are used "off-label" for this condition, dapoxetine was specifically designed and marketed in many countries as a fast-acting treatment for premature ejaculation (PE).

Why Dapoxetine?

Dapoxetine is a Selective Serotonin Reuptake Inhibitor (SSRI). Unlike other SSRIs (like fluoxetine or sertraline) that take weeks to build up in the system to treat depression, dapoxetine is absorbed and eliminated very rapidly.

On-Demand Dosing: Because of its fast action, it can be taken 1 to 3 hours before sexual activity rather than daily.

Mechanism: It increases the synaptic levels of serotonin, which helps delay the ejaculatory reflex.

Analysis of Other Options

The other drugs listed serve entirely different therapeutic purposes and are generally not used for PE:

Medication	Class	Primary Use
Atenolol	Beta-Blocker	Used for hypertension, angina, and post-MI. It can actually cause sexual dysfunction as a side effect.
Olanzapine	Atypical Antipsychotic	Used for schizophrenia and bipolar disorder. Frequently associated with weight gain and sedation.
Aripiprazole	Atypical Antipsychotic	Used for schizophrenia, bipolar, and clinical depression.

Comparison to Other SSRIs

In some regions (like the US), dapoxetine is not FDA-approved, so doctors often prescribe other SSRIs off-label (such as paroxetine or sertraline). However, those usually require daily dosing to be effective, whereas dapoxetine’s unique pharmacology allows for that "as-needed" use.

Note: Common side effects of dapoxetine include nausea, dizziness, and headache.

Which of the following is the Vaughan Williams Classification for the antiarrhythmic drug procainamide?

A) class IV

B)class III

C) class II 

D) class IA

The correct answer is D) class IA.

The Vaughan Williams system classifies antiarrhythmic drugs based on their primary mechanism of action on the cardiac action potential. Procainamide belongs to Class I, which focuses on blocking sodium (Na+) channels.

Breakdown of Class IA:

Class IA drugs, including procainamide, quinidine, and disopyramide, have a "moderate" effect on the heart. They work in two main ways:

Sodium Channel Blockade: They slow the rate of depolarization (Phase 0).

Potassium Channel Blockade: They also have some Class III activity, which prolongs the repolarization phase (Phase 3). This results in an increased Action Potential Duration (APD) and a longer Effective Refractory Period (ERP).

Comparison with Other Classes: Here is how the other options in your list function within the Vaughan Williams system:

Class	Mechanism	Common Examples
Class IA	Na+ channel block (moderate); prolongs APD	Procainamide, Quinidine
Class II	Beta-Adrenergic Blockers	Metoprolol, Propranolol
Class III	K+ channel blockers; prolongs repolarization	Amiodarone, Sotalol
Class IV	Calcium (Ca2+) channel blockers (Non-DHP)	Verapamil, Diltiazem

Clinical Pearl: Lupus-Like Syndrome

A unique side effect often tested alongside procainamide is Drug-Induced Lupus Erythematosus (DILE). About 20-30% of patients on long-term procainamide therapy develop this condition, which is usually identified by the presence of anti-histone antibodies.

Which of the following drugs used in rheumatoid arthritis can be dosed once a week?

A)hydroxychloroquine 

B)methotrexate

C) sulfasalazine

D)prednisone

The correct answer is B) methotrexate.

In the context of Rheumatoid Arthritis (RA), methotrexate is the "gold standard" Disease-Modifying Antirheumatic Drug (DMARD), and its once-weekly dosing schedule is a critical safety point for patients to understand.

Why Methotrexate?

Methotrexate is a folate antimetabolite. While higher doses are used daily in chemotherapy, the low doses used for inflammatory conditions like RA are taken once per week (either orally or via injection).

Taking methotrexate daily by mistake can lead to severe toxicity, including bone marrow suppression and liver damage. This is why many clinicians also prescribe Folic Acid to be taken on the "off-days" to reduce side effects.

Comparison of Dosing Intervals

The other medications listed generally require daily (or multiple times daily) administration to maintain therapeutic levels:

A) Hydroxychloroquine: Typically taken daily. It is an antimalarial drug used in RA to reduce inflammation and has a very long half-life, but daily dosing is standard.

C) Sulfasalazine: Usually taken twice daily (BID). It is a prodrug that is broken down by gut bacteria into its active components.

D) Prednisone: Generally taken daily. As a corticosteroid, it is used for immediate symptom relief ("bridge therapy"), but stopping it abruptly or skipping days can lead to adrenal insufficiency.

Safety Note: To avoid confusion, many patients choose a specific "Methotrexate Day" (e.g., "Methotrexate Monday") to ensure they don't accidentally take it more often than prescribed.

Which medication can cause orthostatic hypotension? 

A)prazosin

B)donepezil

C)rivastigmine

D)spironolactone

The correct answer is A) prazosin.

Orthostatic hypotension (a sudden drop in blood pressure when standing up) is a classic and significant side effect of certain medications, particularly those that affect the vascular system's ability to constrict.

Why Prazosin?

Prazosin is an alpha-1 adrenergic blocker. It works by inhibiting the alpha-1 receptors on vascular smooth muscle, which causes vasodilation (widening of the blood vessels).

When a person stands up, the body normally triggers a reflex to constrict blood vessels to maintain blood flow to the brain. Prazosin blocks this reflex, leading to a "first-dose effect" where patients may experience intense dizziness or even fainting shortly after starting the medication.

While other drugs can impact blood pressure or fluid levels, they are not the primary culprits in this specific list for causing orthostatic hypotension compared to Prazosin:

Medication	Class	Common Effects
Donepezil	Cholinesterase Inhibitor	Used for Alzheimer's; more likely to cause bradycardia (slow heart rate) or GI upset.
Rivastigmine	Cholinesterase Inhibitor	Similar to Donepezil; mainly causes nausea, vomiting, and loss of appetite.
Spironolactone	Potassium-sparing Diuretic	While it can lower BP over time, it is much less likely to cause acute orthostatic shifts than an alpha-blocker.

Pro Tip: Clinical guidelines often recommend that patients take their first dose of Prazosin at bedtime to minimize the risk of injury from fainting.

To read more such exam questions with explanation visit the blog or click on Prometric Exams.