Suxamethonium is a non-competitive partial agonist. Explain what is meant by this statement using definitions of the underlined terms (50% of marks). List the advantages and disadvantages of suxamethonium within Intensive Care practice (50% of marks).
For a good answer candidates were expected to mention that an agonist is a drug that elicits a maximal response on binding to a receptor. A partial agonist has intrinsic affinity with only partial efficacy and hence is unable to elicit a maximal response. A competitive drug acts at the same binding site of a receptor as an endogenous ligand (e.g. acetylcholine at the neuromuscular junction) and its action therefore is surmountable with increasing concentrations of drug and how this conceptrelatesto suxemethonium. For the remainder of the question, Candidates were expected to mention the advantages and disadvantages of suxamethonium within Intensive Care practice. Good answers included a systematic approach and use of tables and/or well organised lists.
Non-competitive partial agonist:
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