Diphenylpyraline hydrochloride MCQs With Answer

Diphenylpyraline hydrochloride MCQs With Answer

Diphenylpyraline hydrochloride is a first‑generation H1 receptor antagonist widely discussed in B.Pharm pharmacology for its antihistaminic, anticholinergic and sedative properties. This topic covers mechanism of action, clinical indications (urticaria, allergic rhinitis), pharmacokinetics, adverse effects, drug interactions, formulation as the hydrochloride salt, and analytical assay methods. Understanding diphenylpyraline’s lipophilicity, blood–brain barrier penetration, and risks in the elderly is essential for safe therapy and counselling. These MCQs are designed to deepen your knowledge of therapeutic use, toxicity management, and pharmaceutical considerations relevant to B.Pharm students. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which pharmacological class does diphenylpyraline hydrochloride belong to?

• Beta blocker
• First‑generation H1 antihistamine
• Selective serotonin reuptake inhibitor
• ACE inhibitor

Correct Answer: First‑generation H1 antihistamine

Q2. The primary therapeutic action of diphenylpyraline is mediated through antagonism of which receptor?

• M3 muscarinic receptor
• H2 histamine receptor
• H1 histamine receptor
• D2 dopamine receptor

Correct Answer: H1 histamine receptor

Q3. Why does diphenylpyraline commonly cause sedation?

• It selectively blocks peripheral H1 receptors only
• It is a strong inhibitor of acetylcholinesterase
• It is highly lipophilic and crosses the blood–brain barrier
• It increases central norepinephrine release

Correct Answer: It is highly lipophilic and crosses the blood–brain barrier

Q4. Which of the following is a common anticholinergic adverse effect of diphenylpyraline?

• Diarrhea
• Excessive salivation
• Dry mouth
• Increased sweating

Correct Answer: Dry mouth

Q5. The hydrochloride salt form of diphenylpyraline is used mainly to:

• Decrease water solubility
• Increase photodegradation
• Enhance aqueous solubility and stability
• Make the molecule more lipophilic

Correct Answer: Enhance aqueous solubility and stability

Q6. Which patient group requires extra caution when using diphenylpyraline due to anticholinergic effects?

• Pediatric patients only
• Patients with narrow‑angle glaucoma
• Patients on thyroid hormone replacement
• Those receiving insulin therapy

Correct Answer: Patients with narrow‑angle glaucoma

Q7. Which drug interaction is most clinically relevant with diphenylpyraline?

• Reduced effect with proton pump inhibitors
• Potentiation of CNS depression with alcohol and benzodiazepines
• Antagonism of beta‑blockers
• Reduced anticoagulant effect of warfarin

Correct Answer: Potentiation of CNS depression with alcohol and benzodiazepines

Q8. Which laboratory method is commonly used for quantitative assay of diphenylpyraline in formulations?

• Thin‑layer chromatography only
• High‑performance liquid chromatography (HPLC)
• Gram staining
• pH titration

Correct Answer: High‑performance liquid chromatography (HPLC)

Q9. Overdose of diphenylpyraline is most likely to produce which of the following acute signs?

• Profound miosis and hypersalivation
• Marked sedation, delirium, and anticholinergic signs
• Severe hypoglycemia
• Excessive lacrimation and bradycardia

Correct Answer: Marked sedation, delirium, and anticholinergic signs

Q10. In case of acute oral overdose of diphenylpyraline within 1 hour, which management step is appropriate in many cases?

• Immediate forced diuresis
• Administration of activated charcoal if indicated
• Routine use of flumazenil
• Hemodialysis as first‑line

Correct Answer: Administration of activated charcoal if indicated

Q11. Diphenylpyraline’s antihistaminic effect is useful in treating which condition?

• Congestive heart failure
• Urticaria (hives)
• Type 1 diabetes
• Bacterial meningitis

Correct Answer: Urticaria (hives)

Q12. Which pharmacokinetic property explains once‑ or twice‑daily dosing potential for many first‑generation antihistamines?

• Very high renal excretion unchanged
• Short half‑life of minutes
• Variable oral bioavailability and moderate to long half‑life
• Complete inability to be absorbed orally

Correct Answer: Variable oral bioavailability and moderate to long half‑life

Q13. Diphenylpyraline should be used cautiously in elderly patients because it may cause:

• Increased bone density
• Enhanced cognitive function
• Confusion, falls, and urinary retention due to anticholinergic burden
• Severe hypokalemia

Correct Answer: Confusion, falls, and urinary retention due to anticholinergic burden

Q14. Which statement about diphenylpyraline and second‑generation antihistamines is true?

• Diphenylpyraline has less propensity for sedation than second‑generation agents
• Second‑generation antihistamines are generally less sedating and more selective for peripheral H1 receptors
• Both classes have identical CNS penetration
• Second‑generation agents are more anticholinergic than diphenylpyraline

Correct Answer: Second‑generation antihistamines are generally less sedating and more selective for peripheral H1 receptors

Q15. Which contraindication is most appropriate for diphenylpyraline use?

• History of narrow‑angle glaucoma
• Controlled allergic rhinitis
• Mild seasonal allergies in adults
• History of uncomplicated otitis media

Correct Answer: History of narrow‑angle glaucoma

Q16. Co‑administration of diphenylpyraline with which class of drugs increases risk of additive anticholinergic effects?

• Cholinesterase inhibitors
• Anticholinergic agents like tricyclic antidepressants and some antipsychotics
• Proton pump inhibitors
• Topical emollients

Correct Answer: Anticholinergic agents like tricyclic antidepressants and some antipsychotics

Q17. From a pharmaceutical perspective, why is the hydrochloride salt often chosen for formulating basic amine drugs like diphenylpyraline?

• To make the drug volatile
• To reduce hygroscopicity dramatically
• To increase solubility in aqueous media and ease tablet/capsule formulation
• To convert it into an acidic molecule

Correct Answer: To increase solubility in aqueous media and ease tablet/capsule formulation

Q18. Which adverse cardiovascular effect may be seen with overdose or in susceptible patients taking diphenylpyraline?

• Bradyarrhythmia with prolonged PR interval only
• Tachycardia and possible hypotension due to anticholinergic and vasodilatory effects
• Marked hypertension and acute left ventricular failure
• Immediate myocardial infarction in all users

Correct Answer: Tachycardia and possible hypotension due to anticholinergic and vasodilatory effects

Q19. Which mental status effect is commonly associated with therapeutic doses of diphenylpyraline?

• Insomnia and hyperactivity
• Drowsiness and impaired psychomotor performance
• Mania
• Improved concentration

Correct Answer: Drowsiness and impaired psychomotor performance

Q20. For analytical quality control of diphenylpyraline tablets, which impurity-related test is typically important?

• Microbial bioburden only
• Assay and related substances (impurities) by validated HPLC method
• Odor profile comparison only
• Colorimetric pH strip test exclusively

Correct Answer: Assay and related substances (impurities) by validated HPLC method

Q21. Which clinical scenario would make diphenylpyraline a less suitable choice compared with a second‑generation antihistamine?

• A patient needing relief of urticaria at night
• A professional driver requiring alertness during work
• Short‑term treatment of acute allergic reaction at home
• Situations where anticholinergic effects are desired

Correct Answer: A professional driver requiring alertness during work

Q22. Which symptom is least likely to be caused by diphenylpyraline’s anticholinergic activity?

• Urinary retention
• Dilated pupils (mydriasis)
• Excessive sweating
• Constipation

Correct Answer: Excessive sweating

Q23. Which metabolic consideration is relevant for diphenylpyraline in hepatic impairment?

• Hepatic impairment has no effect on clearance of lipophilic drugs
• Hepatic metabolism may be reduced, requiring caution and dose adjustment
• The drug is entirely excreted unchanged in urine
• The drug activates hepatic CYP enzymes to lower its own level

Correct Answer: Hepatic metabolism may be reduced, requiring caution and dose adjustment

Q24. Which monitoring advice is appropriate when counselling a patient starting diphenylpyraline?

• Avoid driving or operating heavy machinery until you know its sedative effects
• Take with grapefruit juice to enhance effect
• Stop all other medications immediately
• Expect improved wakefulness and report insomnia

Correct Answer: Avoid driving or operating heavy machinery until you know its sedative effects

Q25. Structural features of many first‑generation antihistamines, including diphenylpyraline, that contribute to CNS penetration include:

• High polarity and low lipophilicity
• Large polar surface area only
• Marked lipophilicity and relatively low molecular polarity
• Presence of charged quaternary ammonium at physiologic pH

Correct Answer: Marked lipophilicity and relatively low molecular polarity

Q26. Which of the following is a desirable pharmaceutical property when developing a tablet of diphenylpyraline HCl?

• Poor batch‑to‑batch content uniformity
• Good dissolution profile in physiologic media
• Excessive hygroscopicity that ruins stability
• Uncontrolled release with variable bioavailability

Correct Answer: Good dissolution profile in physiologic media

Q27. Which statement about use of diphenylpyraline in pregnancy is most appropriate for B.Pharm counselling?

• It is universally safe and can be used without medical advice
• Safety is not fully established; use only if clearly needed and under medical supervision
• It is a proven teratogen and absolutely contraindicated in all trimesters
• It should be used to treat labor pain

Correct Answer: Safety is not fully established; use only if clearly needed and under medical supervision

Q28. Which of the following best describes diphenylpyraline’s role in modern allergy treatment?

• First‑line chronic therapy for seasonal allergic rhinitis due to no sedation
• Occasionally useful but often replaced by less sedating second‑generation antihistamines for daytime use
• Primarily an antibiotic
• Used as a primary bronchodilator in asthma

Correct Answer: Occasionally useful but often replaced by less sedating second‑generation antihistamines for daytime use

Q29. Which patient history finding would prompt avoidance of diphenylpyraline?

• History of seasonal allergic rhinitis only
• History of narrow‑angle glaucoma and significant urinary retention
• Occasional tension headaches
• Well‑controlled hypothyroidism

Correct Answer: History of narrow‑angle glaucoma and significant urinary retention

Q30. In formulation development, which excipient property is important to control for a hygroscopic HCl salt like diphenylpyraline hydrochloride?

• Use of moisture‑protective packaging and suitable desiccants
• Exclusion of fillers to reduce tablet mass
• Deliberately increasing water content in the tablet core
• Avoiding any coating to allow moisture ingress

Correct Answer: Use of moisture‑protective packaging and suitable desiccants

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com