All the following drugs are reversible inhibitors of COX EXCEPT:
Correct Answer: Aspirin
Description: ANSWER: (C) AspirinREF: http://en.wikipedia.org/lviki/Cyclooxygenase, KDT 6th edition, Katzung 9th edition, Goodman Gillman manual of pharmacology and therapeutics 2008 editionRepeat from June 2010 pharmacologyMECHANISM OF ACTION OF ASPIRIN:Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and derivatives of ibuprofen, inhibit cyclooxygenase activity of PGH2 Synthase. There are two isoforms of PGH2 Synthase: COX-1 8c COX-2 (Cyclooxygenase 1 & 2)Aspirin's ability to suppress the production of prostaglandins and thromboxanes is due to its non-competitive irreversible inactivation of the cyclooxygenase (COX1 & COX2) enzyme. Cyclooxygenase is required for prostaglandin and thromboxane synthesis. Aspirin acts as an acetylating agent where an acetyl group is covalently attached to a serine residue in the active site of the COX enzyme. This makes aspirin different from other NSAIDs (such as diclofenac and ibuprofen), which are competitive reversible inhibitorsCYCLOXYGENASE: COX1COX 2ALSO KNOWN AS EXPRESSIONPGFF synthase 1Always present, in all normaltissuesPGH-, synthase 2Inducible at the site of inflammation (normally very low? levels) plus normally in brain & kidneySTIMULUSINCREASE ON STIMULUS FUNCTIONHumoral stimulation2-4 foldsHousekeeping; e.g. Gastric cytoprotection, Ductus arteriosus patencyCytokines, growth factors, tumor promoters10-20 foldsInflammatory
Category:
Pharmacology
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now