Direct acting sympathomimetics – Naphazoline MCQs With Answer

Direct acting sympathomimetics – Naphazoline MCQs With Answer
Direct acting sympathomimetics such as naphazoline are important alpha-adrenergic agonists frequently covered in B.Pharm pharmacology and pharmaceutics. This concise, Student-friendly post examines naphazoline’s mechanism of action, receptor selectivity, ocular decongestant uses, pharmacokinetics, adverse effects like rebound hyperemia and ischemia, contraindications, drug interactions, and formulation considerations. B.Pharm students will benefit from targeted MCQs that reinforce clinical relevance, dosing, toxicity management, and quality-control issues such as preservatives in eye drops. Mastery of these concepts aids safe dispensing, patient counseling, and exam success. The following questions are designed to deepen understanding and prepare you for university and licensure exams. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the primary pharmacological action of naphazoline?

• Beta-adrenergic blockade
• Direct acting alpha-adrenergic agonism
• Indirect catecholamine release
• Muscarinic receptor antagonism

Correct Answer: Direct acting alpha-adrenergic agonism

Q2. Naphazoline is most commonly used clinically as which formulation?

• Oral tablet for nasal congestion
• Topical cream for dermatitis
• Ocular (eye) drops for conjunctival decongestion
• Intravenous infusion for hypotension

Correct Answer: Ocular (eye) drops for conjunctival decongestion

Q3. Which receptor subtype does naphazoline predominantly stimulate?

• Beta-2 adrenergic receptors
• Alpha-1 adrenergic receptors
• Muscarinic M2 receptors
• Dopamine D2 receptors

Correct Answer: Alpha-1 adrenergic receptors

Q4. The vasoconstrictive effect of naphazoline on conjunctival vessels primarily reduces which symptom?

• Eye pain from corneal abrasion
• Redness and hyperemia
• Tear production
• Intraocular pressure

Correct Answer: Redness and hyperemia

Q5. Which adverse effect is classically associated with prolonged topical use of naphazoline eye drops?

• Rebound congestion (rebound hyperemia)
• Systemic bradycardia
• Excessive lacrimation
• Increased tear film stability

Correct Answer: Rebound congestion (rebound hyperemia)

Q6. Tachyphylaxis to naphazoline refers to:

• Development of allergic dermatitis
• Rapid loss of drug effect after repeated use
• Enhanced potency over time
• Delayed drug absorption

Correct Answer: Rapid loss of drug effect after repeated use

Q7. Which preservative commonly found in naphazoline eye formulations can cause ocular surface toxicity with chronic use?

• Sodium chloride
• Benzalkonium chloride
• Phenylephrine

Correct Answer: Benzalkonium chloride

Q8. Systemic absorption of topical naphazoline is most likely to produce which effect?

• Bronchospasm
• Peripheral vasoconstriction and hypertension
• Hypoglycemia
• Prolonged QT interval

Correct Answer: Peripheral vasoconstriction and hypertension

Q9. Which patient group requires caution when using naphazoline due to risk of severe cardiovascular effects?

• Patients with glaucoma
• Patients with hypertension or ischemic heart disease
• Patients with hypothyroidism
• Adolescents under 16

Correct Answer: Patients with hypertension or ischemic heart disease

Q10. Naphazoline’s onset of action when used as eye drops is typically:

• Within seconds to a few minutes
• Several hours
• 24 to 48 hours
• After 7 days of continuous use

Correct Answer: Within seconds to a few minutes

Q11. Which mechanism explains rebound hyperemia after stopping naphazoline?

• Upregulation of adrenergic receptors causing vasodilation
• Local allergic immune reaction
• Excessive lacrimal gland stimulation
• Permanent destruction of conjunctival vessels

Correct Answer: Upregulation of adrenergic receptors causing vasodilation

Q12. Which of the following is a contraindication or relative contraindication to naphazoline use?

• Controlled asthma
• Angle-closure glaucoma
• Mild seasonal allergies
• Dry eye syndrome

Correct Answer: Angle-closure glaucoma

Q13. Naphazoline belongs to which chemical class of sympathomimetics?

• Imidazolines
• Phenylethylamines
• Aminoglycosides
• Phosphodiesters

Correct Answer: Imidazolines

Q14. Compared to phenylephrine, naphazoline is generally considered to have:

• Shorter duration of action
• Longer duration and greater alpha selectivity
• Stronger beta-2 agonist activity
• No vasoconstrictive effect

Correct Answer: Longer duration and greater alpha selectivity

Q15. Which monitoring parameter is most relevant after accidental systemic overdose of naphazoline?

• Serum creatinine
• Blood pressure and heart rate
• Blood glucose
• Liver enzymes

Correct Answer: Blood pressure and heart rate

Q16. The primary route of elimination for systemically absorbed naphazoline is:

• Renal excretion
• Fecal elimination unchanged
• Exhalation through lungs
• Metabolism followed by biliary excretion

Correct Answer: Renal excretion

Q17. In pediatric patients, topical naphazoline carries increased risk due to:

• Small ocular surface area
• Higher systemic absorption and immature metabolic pathways
• Increased tear production
• Rapid hepatic clearance

Correct Answer: Higher systemic absorption and immature metabolic pathways

Q18. Which co-administered drug class could potentiate systemic hypertension when combined with naphazoline?

• ACE inhibitors
• MAO inhibitors
• Calcium channel blockers
• Loop diuretics

Correct Answer: MAO inhibitors

Q19. A pharmacist counseling a patient about naphazoline eye drops should advise to:

• Use continuously for at least 4 weeks
• Avoid driving immediately after use due to permanent vision loss
• Limit use to short courses to prevent tachyphylaxis and rebound
• Store in a freezer

Correct Answer: Limit use to short courses to prevent tachyphylaxis and rebound

Q20. Which pharmacokinetic property explains the rapid ocular effect of naphazoline?

• High oral bioavailability
• High lipophilicity and local absorption across conjunctiva
• Slow distribution to target tissues
• Extensive first-pass metabolism

Correct Answer: High lipophilicity and local absorption across conjunctiva

Q21. Naphazoline’s effect on pupil size is best described as:

• Miosis (pupil constriction)
• Mydriasis (pupil dilation) via alpha-1 receptor stimulation of iris dilator
• No effect on pupil size
• Cycloplegia

Correct Answer: Mydriasis (pupil dilation) via alpha-1 receptor stimulation of iris dilator

Q22. Which laboratory test is most likely to be useful in severe systemic toxicity from naphazoline?

• Serum troponin for myocardial injury
• Serum electrolytes and glucose for metabolic disturbances
• Complete blood count for neutropenia
• Serum amylase for pancreatitis

Correct Answer: Serum electrolytes and glucose for metabolic disturbances

Q23. Naphazoline’s duration of action when applied topically to the eye is approximately:

• 5–10 minutes
• Several hours (up to 6–12 hours)
• 2–3 days
• One month

Correct Answer: Several hours (up to 6–12 hours)

Q24. Which pathological condition could be masked by naphazoline use because it reduces redness?

• Bacterial conjunctivitis
• Glaucoma due to increased intraocular pressure
• Retinal detachment
• Corneal ulcer signs

Correct Answer: Bacterial conjunctivitis

Q25. Which statement about naphazoline pharmacodynamics is true?

• It acts indirectly by releasing norepinephrine from nerve terminals
• It directly stimulates alpha receptors leading to vasoconstriction
• It is a selective beta-1 agonist used for heart failure
• It blocks cholinergic receptors to produce effect

Correct Answer: It directly stimulates alpha receptors leading to vasoconstriction

Q26. What is the recommended action if a patient develops severe local irritation after using naphazoline eye drops?

• Continue treatment and increase dose
• Discontinue the drops and seek medical evaluation
• Switch to higher concentration of the same drug
• Apply warm compresses and continue the medication

Correct Answer: Discontinue the drops and seek medical evaluation

Q27. Which pharmacological property differentiates imidazoline derivatives like naphazoline from catecholamines?

• Greater oral bioavailability but no topical activity
• Longer duration and resistance to COMT metabolism
• Exclusive beta receptor activity
• They are peptide-based

Correct Answer: Longer duration and resistance to COMT metabolism

Q28. During formulation development of naphazoline eye drops, what is a key consideration?

• Ensuring isotonicity and appropriate pH for ocular comfort
• Maximizing oral absorption
• Using high sugar content to stabilize the drug
• Avoiding sterile manufacture

Correct Answer: Ensuring isotonicity and appropriate pH for ocular comfort

Q29. Which symptom would suggest systemic alpha-adrenergic overactivation after topical exposure?

• Flushing and low blood pressure
• Palpitations, hypertension, and headache
• Excessive salivation and sweating
• Bradykinesia

Correct Answer: Palpitations, hypertension, and headache

Q30. For safe dispensing, which instruction is important for patients using naphazoline eye drops?

• Use continuously until bottle is empty
• Do not share eye drops and follow recommended dosing intervals
• Combine with other OTC ocular vasoconstrictors daily
• Administer internally for nasal congestion

Correct Answer: Do not share eye drops and follow recommended dosing intervals

Q31. Which of the following best describes tachyphylaxis seen with topical imidazolines?

• Slow onset of therapeutic effect with increasing dose
• Rapid diminution of effect after repeated short-term use
• Immunologic allergy causing rash
• Permanent vasoconstriction despite stopping therapy

Correct Answer: Rapid diminution of effect after repeated short-term use

Q32. Which management is appropriate for rebound hyperemia caused by prolonged naphazoline use?

• Continue naphazoline at higher dose
• Gradual discontinuation and use of artificial tears or topical steroid under supervision
• Switch to systemic sympathomimetics
• Immediate surgical intervention

Correct Answer: Gradual discontinuation and use of artificial tears or topical steroid under supervision

Q33. Incompatibility studies for an eye drop formulation would primarily assess:

• Color and taste
• Chemical stability, preservative compatibility, and sterility
• Oral bioavailability
• Evaporation rate at 100°C

Correct Answer: Chemical stability, preservative compatibility, and sterility

Q34. When counseling a pregnant patient, naphazoline use is generally classified as:

• Completely safe with no precautions
• Use with caution; consider risk-benefit and minimize systemic exposure
• Recommended to increase dosage
• Contraindicated in all trimesters

Correct Answer: Use with caution; consider risk-benefit and minimize systemic exposure

Q35. Which ocular condition is a relative contraindication for naphazoline because it may worsen the disease?

• Allergic conjunctivitis
• Angle-closure glaucoma due to potential mydriasis
• Bacterial conjunctivitis responding to antibiotics
• Dry eye treated with lubricants

Correct Answer: Angle-closure glaucoma due to potential mydriasis

Q36. Which is a common over-the-counter combination product involving naphazoline?

• Naphazoline with topical antibiotic for systemic infections
• Naphazoline plus antihistamine for allergic eye symptoms
• Naphazoline with insulin for diabetes
• Naphazoline combined with oral decongestant tablets

Correct Answer: Naphazoline plus antihistamine for allergic eye symptoms

Q37. In quality control of naphazoline drops, assay of active ingredient is usually performed by:

• UV spectrophotometry or HPLC
• Microbial culture only
• Physical observation of clarity alone
• pH paper strip exclusively

Correct Answer: UV spectrophotometry or HPLC

Q38. Which pharmacological interaction is least likely with topical naphazoline?

• Potentiation of systemic vasoconstriction with MAO inhibitors
• Increased intraocular pressure with anticholinergics
• Direct inhibition of CYP450 leading to drug accumulation
• Exacerbation of hypertension with systemic sympathomimetics

Correct Answer: Direct inhibition of CYP450 leading to drug accumulation

Q39. What is an important sterility consideration for ophthalmic naphazoline formulations?

• They can be non-sterile if refrigerated
• They must be sterile to prevent ocular infections
• Sterility is optional for multi-dose containers
• Oral preservatives ensure sterility

Correct Answer: They must be sterile to prevent ocular infections

Q40. Which adverse systemic effect might occur in neonates after exposure to topical naphazoline?

• Hyperactivity
• Apnea and hypotonia due to central nervous system depression
• Improved feeding
• Enhanced growth rate

Correct Answer: Apnea and hypotonia due to central nervous system depression

Q41. Resistance to degradation by catechol-O-methyltransferase (COMT) makes imidazoline drugs like naphazoline:

• More susceptible to inactivation in synapses
• Longer-acting than catecholamines when applied locally
• Completely inactive in humans
• Restricted to intravenous administration

Correct Answer: Longer-acting than catecholamines when applied locally

Q42. Which of the following is a sign of severe systemic alpha-adrenergic toxicity requiring emergency care?

• Mild ocular irritation
• Severe hypertension with bradycardia and decreased perfusion
• Temporary blurred vision only
• Minor headache that resolves

Correct Answer: Severe hypertension with bradycardia and decreased perfusion

Q43. For stability, naphazoline eye drops should be stored:

• At extreme heat above 40°C
• In a cool, dark place within recommended temperature range
• Exposed to light to activate the drug
• Frozen solid to prolong shelf life

Correct Answer: In a cool, dark place within recommended temperature range

Q44. Which formulation factor can increase ocular residence time of naphazoline?

• Adding a mucoadhesive polymer to the formulation
• Reducing viscosity to near water consistency
• Increasing volatile solvent content
• Using large particle suspensions

Correct Answer: Adding a mucoadhesive polymer to the formulation

Q45. Which educational point is important for patients using naphazoline for allergic red eyes?

• It treats the underlying allergic inflammation completely
• It relieves redness but underlying allergy may need antihistamines or steroids
• Doubling the dose improves allergy control
• Systemic antibiotics are always required

Correct Answer: It relieves redness but underlying allergy may need antihistamines or steroids

Q46. Which laboratory animal study finding would support ocular safety of a new naphazoline formulation?

• Corneal epithelial erosion at therapeutic concentrations
• No structural ocular damage and minimal irritation at intended dose
• Systemic organ failure after topical application
• Severe conjunctival necrosis in all animals

Correct Answer: No structural ocular damage and minimal irritation at intended dose

Q47. Which pharmacological property would be prioritized when designing a preservative-free single-use naphazoline product?

• Ensuring maximum excipient variability
• Maintaining sterility and isotonicity in single-dose format
• Adding alcohol to increase shelf life
• Increasing benzalkonium chloride to compensate

Correct Answer: Maintaining sterility and isotonicity in single-dose format

Q48. Which clinical scenario warrants immediate discontinuation of naphazoline eye drops and ophthalmic evaluation?

• Mild transient stinging on instillation
• Onset of severe eye pain, vision loss, or corneal changes
• Temporary improvement in redness
• Slight dryness after prolonged use

Correct Answer: Onset of severe eye pain, vision loss, or corneal changes

Q49. Which statement about naphazoline metabolism is correct?

• It is primarily metabolized by hepatic CYP3A4 to active metabolites
• It undergoes minimal systemic metabolism due to local application, with renal excretion of absorbed fraction
• It is converted to dopamine in the eye
• It is exclusively exhaled unchanged

Correct Answer: It undergoes minimal systemic metabolism due to local application, with renal excretion of absorbed fraction

Q50. For exam preparation, which study strategy best helps B.Pharm students master naphazoline pharmacology?

• Memorize only trade names without mechanism
• Integrate mechanism, clinical uses, adverse effects, formulation and QC questions with practice MCQs
• Ignore clinical scenarios and focus on manufacturing only
• Rely solely on anecdotal patient stories

Correct Answer: Integrate mechanism, clinical uses, adverse effects, formulation and QC questions with practice MCQs

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