Classification of autacoids MCQs With Answer

Classification of autacoids MCQs With Answer

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Introduction

Autacoids are locally acting biologically active substances that modulate vascular tone, inflammation, bronchial reactivity and platelet function. This concise guide focuses on Classification of autacoids MCQs With Answer for B. Pharm students, covering major groups — eicosanoids (prostaglandins, thromboxanes, leukotrienes), biogenic amines (histamine, serotonin), kinins (bradykinin), nitric oxide and related mediators. Emphasis is placed on biosynthesis (arachidonic acid pathways, COX and 5-LOX), receptor subtypes (H1–H4, 5-HT receptors, prostanoid receptors), pharmacological agents (NSAIDs, COX-2 inhibitors, leukotriene modifiers, antihistamines) and clinical implications in asthma, inflammation, migraine and anaphylaxis. Clear, keyword-rich questions will reinforce mechanisms, drug targets and therapeutic strategies. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which of the following best defines an autacoid?

  • A hormone released from endocrine glands traveling via blood to distant organs
  • A locally acting chemical mediator with brief duration of action
  • A long-lasting neurotransmitter stored in synaptic vesicles
  • An enzyme that degrades inflammatory mediators

Correct Answer: A locally acting chemical mediator with brief duration of action

Q2. Which of the following is NOT typically classified as an autacoid?

  • Histamine
  • Prostaglandins
  • Insulin
  • Leukotrienes

Correct Answer: Insulin

Q3. Major classes of autacoids include which of the following sets?

  • Amino acids, peptides, and steroids
  • Eicosanoids, biogenic amines, kinins, nitric oxide
  • Vitamins, minerals, and trace elements
  • Catecholamines, thyroid hormones, and glucocorticoids

Correct Answer: Eicosanoids, biogenic amines, kinins, nitric oxide

Q4. Eicosanoids such as prostaglandins and leukotrienes are biosynthesized from which precursor?

  • Cholesterol
  • Arachidonic acid
  • L-tryptophan
  • L-arginine

Correct Answer: Arachidonic acid

Q5. Which enzyme catalyzes the conversion of arachidonic acid into prostaglandin endoperoxides?

  • Lipoxygenase (5-LOX)
  • Phospholipase A2
  • Cyclooxygenase (COX)
  • Nitric oxide synthase (NOS)

Correct Answer: Cyclooxygenase (COX)

Q6. Which COX isoform is primarily inducible and upregulated during inflammation?

  • COX-1
  • COX-2
  • COX-3
  • COX-4

Correct Answer: COX-2

Q7. Prostacyclin (PGI2) mainly produces which physiological effects?

  • Vasoconstriction and platelet aggregation
  • Vasodilation and inhibition of platelet aggregation
  • Bronchoconstriction and mucus secretion
  • Increased gastric acid secretion

Correct Answer: Vasodilation and inhibition of platelet aggregation

Q8. Thromboxane A2 (TXA2) is best known for which action?

  • Inhibiting platelet aggregation and causing vasodilation
  • Stimulating platelet aggregation and causing vasoconstriction
  • Promoting bronchodilation and reducing inflammation
  • Reducing gastric mucosal blood flow

Correct Answer: Stimulating platelet aggregation and causing vasoconstriction

Q9. Which leukotriene class is primarily responsible for bronchoconstriction in asthma?

  • Leukotriene B4 (LTB4)
  • Leukotriene A4 (LTA4)
  • Cysteinyl leukotrienes (LTC4, LTD4, LTE4)
  • Prostaglandin E2 (PGE2)

Correct Answer: Cysteinyl leukotrienes (LTC4, LTD4, LTE4)

Q10. Zileuton exerts its anti-asthma effect by inhibiting which enzyme?

  • Cyclooxygenase-2 (COX-2)
  • Lipoxygenase (5-LOX)
  • Histidine decarboxylase
  • Nitric oxide synthase

Correct Answer: Lipoxygenase (5-LOX)

Q11. Which prostaglandin is widely used to induce uterine contractions and manage postpartum hemorrhage?

  • Prostaglandin I2 (PGI2)
  • Prostaglandin E2 (PGE2)
  • Prostaglandin F2α (PGF2α)
  • Thromboxane A2 (TXA2)

Correct Answer: Prostaglandin F2α (PGF2α)

Q12. The primary mechanism of action of nonsteroidal anti-inflammatory drugs (NSAIDs) is:

  • Inhibition of phospholipase A2
  • Blocking leukotriene receptors
  • Inhibition of cyclooxygenase enzymes
  • Activation of nitric oxide synthase

Correct Answer: Inhibition of cyclooxygenase enzymes

Q13. Which drug is a selective COX-2 inhibitor commonly used to reduce inflammation with less gastric toxicity?

  • Ibuprofen
  • Aspirin
  • Celecoxib
  • Acetaminophen (paracetamol)

Correct Answer: Celecoxib

Q14. Aspirin has a unique anti-platelet effect because it:

  • Reversibly inhibits COX-2
  • Irreversibly acetylates COX enzymes in platelets
  • Blocks leukotriene synthesis permanently
  • Stimulates prostacyclin production

Correct Answer: Irreversibly acetylates COX enzymes in platelets

Q15. Histamine is synthesized from which amino acid by histidine decarboxylase?

  • L-tryptophan
  • L-arginine
  • L-histidine
  • L-tyrosine

Correct Answer: L-histidine

Q16. Activation of H1 histamine receptors typically leads to which effects?

  • Gastric acid secretion and increased heart rate
  • Bronchoconstriction, vasodilation and increased vascular permeability
  • Decreased neurotransmitter release in CNS
  • Platelet aggregation and vasoconstriction

Correct Answer: Bronchoconstriction, vasodilation and increased vascular permeability

Q17. H2 histamine receptor stimulation primarily mediates which physiological response?

  • Bronchoconstriction
  • Gastric acid secretion
  • Platelet aggregation
  • Smooth muscle contraction in uterus

Correct Answer: Gastric acid secretion

Q18. Which statement about first-generation H1 antihistamines is correct?

  • They are highly selective for H2 receptors
  • They do not cross the blood–brain barrier and are non-sedating
  • They commonly cross the blood–brain barrier and cause sedation
  • They primarily inhibit cyclooxygenase enzymes

Correct Answer: They commonly cross the blood–brain barrier and cause sedation

Q19. Serotonin (5-HT) is biosynthesized from which amino acid?

  • L-histidine
  • L-arginine
  • L-tryptophan
  • L-phenylalanine

Correct Answer: L-tryptophan

Q20. Triptans used for acute migraine attacks are agonists at which serotonin receptors?

  • 5-HT2A and 5-HT2C
  • 5-HT3
  • 5-HT1B and 5-HT1D
  • 5-HT6 and 5-HT7

Correct Answer: 5-HT1B and 5-HT1D

Q21. Nitric oxide (NO), an endothelial autacoid, is synthesized from L-arginine by which enzyme?

  • Adenylyl cyclase
  • Nitric oxide synthase (NOS)
  • Monoamine oxidase (MAO)
  • Phospholipase C

Correct Answer: Nitric oxide synthase (NOS)

Q22. Bradykinin causes which of the following actions in inflamed tissue?

  • Vasoconstriction and analgesia
  • Vasodilation, increased vascular permeability and pain
  • Platelet activation and clot formation
  • Inhibition of leukocyte chemotaxis

Correct Answer: Vasodilation, increased vascular permeability and pain

Q23. The kallikrein-kinin system generates bradykinin from kininogen via which enzyme?

  • Angiotensin-converting enzyme (ACE)
  • Renin
  • Kallikrein
  • Carboxypeptidase

Correct Answer: Kallikrein

Q24. Use of ACE inhibitors can lead to a dry cough because they:

  • Increase bradykinin levels by preventing its degradation
  • Block prostaglandin synthesis in the lung
  • Stimulate leukotriene production
  • Activate histamine release from mast cells

Correct Answer: Increase bradykinin levels by preventing its degradation

Q25. Eicosanoid receptors (prostanoid and leukotriene receptors) are primarily what type of receptor?

  • Ligand-gated ion channels
  • Receptor tyrosine kinases
  • G protein-coupled receptors (GPCRs)
  • Nuclear transcription factor receptors

Correct Answer: G protein-coupled receptors (GPCRs)

Q26. Which autacoid is a potent promoter of platelet aggregation?

  • Prostacyclin (PGI2)
  • Thromboxane A2 (TXA2)
  • Nitric oxide (NO)
  • Prostaglandin E2 (PGE2)

Correct Answer: Thromboxane A2 (TXA2)

Q27. The lipoxygenase pathway of arachidonic acid metabolism primarily yields which products?

  • Prostaglandins and thromboxanes
  • Leukotrienes and hydroxyeicosatetraenoic acids (HETEs)
  • Nitric oxide and cyclic GMP
  • Bradykinin and kallidin

Correct Answer: Leukotrienes and hydroxyeicosatetraenoic acids (HETEs)

Q28. Which drug is used as a mast cell stabilizer to prevent mediators like histamine being released?

  • Montelukast
  • Cromolyn sodium
  • Propranolol
  • Zileuton

Correct Answer: Cromolyn sodium

Q29. The first-line emergency pharmacological treatment for severe anaphylaxis is:

  • Intravenous hydrocortisone
  • Intramuscular epinephrine
  • Oral antihistamine (cetirizine)
  • Inhaled salbutamol

Correct Answer: Intramuscular epinephrine

Q30. The endothelium-derived relaxing factor (EDRF) responsible for vasodilation and inhibition of platelet aggregation was identified as:

  • Prostaglandin E2 (PGE2)
  • Prostacyclin (PGI2)
  • Nitric oxide (NO)
  • Bradykinin

Correct Answer: Nitric oxide (NO)

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