AboutDr Alan Galbraith Expertise I can answer most questions on drugs, both medical and "recreational". Answers can be given in either technical or layperson terminology. My main areas of interest are psychiatric, gastrointestinal and cardiovascular drugs.
Experience I have been a university lecturer/head of department for almost thirty years, but am now retired. My research interests were alcohol, smoking and cardiovascular disease.
Organizations Institute of Biology, London.
Publications Principal author of "Fundamentals of Pharmacology" 4th Edition published in November 2003 by Pearson Education, Australia.
Question QUESTION: why has suxamethonium a short duration of action of around 2-3 minutes in most patients? (5 marks) please be scientific.
ANSWER: Dear Mahria
Quite simple. This drug is metabolised by the enzyme pseudocholinesterase, naturally present in the bloodstream at a fast rate. Persons deficient in this enzyme show a marked increase in duration (ie skeletal muscle paralysis) of this neuromuscular blocking agent.
Regards
Dr Alan Galbraith
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QUESTION: please could you be more scientific and more detailed. thnks
Answer Dear Mahria
Difficult to be more specific but I'll give you a bit more detail and feel there is nothing much more to say without giving the actual molecular structures and chemical equation.
Pseudocholinesterase (aka butyrylcholinesterase) is an esterase found in tissues and the blood therefore suxamethonium can be metabolised without hepatic (or renal) metabolism hence the rapidity of its metabolism. Suxamethonium (aka succinylcholine) is hydrolysed to choline and succinic acid whish are booth pharmacologically inert.
I would not expect more than this from a student with such a question except the chemical equation showing the hydrolysis.
