DrVirgo
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An otherwise healthy 80 year old man is scheduled for endoscopy for evaluation of rectal bleeding. A standard dose of midazolam is administered intravenously when the patient is admitted to the endoscopy suite. A few minutes later, he develops cyanosis and labored respirations and requires ventilation with an oxygenated resuscitation bag. An age-related increase in which of the following is the most likely cause of these adverse effects?
A. Enterohepatic recycling
B. Metabolite formation
C. Plasma protein binding
D. Sensitivity to sedatives
E. Volume of distribution
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| manikandan
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B....
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manikandan
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| DrVirgo
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Explain please?
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| study_ing
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i think D is more likely. BDZ do form activated compounds in the liver and that is likely to decrease with age..
any ideas
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| Diego Casali
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I think D is the only possible answer.
A is not correct because midazolam is administered IV.
B is not correct because an increase in metabolite formation is not age - related.
C is not correct because benzodiazepines are lipophilic drugs that don't bind consistently to plasma proteins.
E is not correct because an increase in volume of distribution would cause a decrease of the pharmacological effect.
Do you agree with me?
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| robin082006
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I go with E
In elderly, there is an increase in fat tissue volume, resulting in the increase in volume of distribution of fat-soluble drugs therefore the patient is at high risk of intoxication of such drugs.
Sensitivity to sedatives and other drugs decreases in elderly. I studied in my college that old people are at high risk of drug intoxication because of decrease in excretion (e.g. decrease in renal or hepatic function ), decrease in metabolism, increase in distribution volume.
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| Cedrick
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let me check my book
because benzodiazepines are lipophilic,but the question does not metion if the patient is obese or not
wow I will write later good question !!!
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| Cedrick
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Midazolam "Dormicum" "Versed"
Belive it or not is lipophilic and hydrophilic !!!
The dose has to be individualized (real life )
And the question asks about AGE related Increase Fat
and decreased hepatic blood flow the P450 cytocrome does not decline with age
so Yeah
Choice E
Reference The merck manual,e-medicine
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| eytanraz
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cedrick says : the P450 cytocrome does not decline with age
First aid says: geriatric patients lose phase I first
So who' s right?
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| eytanraz
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From
https://webapp.walgreens.com/cePharmacy/programsHTML/1-pharmacokinetic.html
Another example of altered pharmacodynamics is seen with benzodiazepines. Midazolam is a short-acting benzodiazepine frequently used during diagnostic or surgical procedures. Two groups of patients, young and old, received intravenous midazolam prior to a dental procedure and pharmacokinetic and pharmacodynamic measures were obtained.17 Despite using a lower dose in the elderly group, reaction time was more blunted in the seniors and their rating of sedation was higher than the younger group. Even when the results were normalized for differences in pharmacokinetic parameters, the data clearly showed that the elderly patients were more sensitive to the central nervous system effects of midazolam. This phenomenon can be extrapolated to most medications that affect the central nervous system. Elderly patients frequently show increased sensitivity to central nervous system agents, such as benzodiazepines, antipsychotic agents, and narcotic analgesics, and this increased sensitivity is often the cause of side effects
So, right answer is D , Diego Casali was right
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| eytanraz
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https://webapp.walgreens.com/cePharmacy/programsHTML/1-pharmacokinetic.html
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| eytanraz
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I don' t know why I can't write the right link, however u find it by googling
"geriatric patient midazolam"
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| mjl1717
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After the fact--sometimes you cant read too much into the q. And just realize that the elderly are just more sensitive to just about all meds. But I must admit the pharmacokinetics and distribution of midazolam is interesting.
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| usmleasyitisnot
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mjl1717 wrote:
After the fact--sometimes you cant read too much into the q. And just realize that the elderly are just more sensitive to just about all meds. But I must admit the pharmacokinetics and distribution of midazolam is interesting.
This is perfectly stated. I'm finding that my errors on form four are mostly stemming from my obsession with scruitinizing each and every detail of the stem and from an erroneous belief that there are "trick questions" on this exam.
A question like this reminds us why there are some, keen test takers who merely understand basic science at the level of first aid (still quite an acheivment in most circumstances) and pull off amazing scores. Aside from the picky questions, most of the time they want the shortest, simplest answer.
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| DrVirgo
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My answer is E, and I agree with Robin's explanation.
P450 DOES decrease with age, and the elderly metabolize drugs at a much slower rate, thus their dosages must be adjusted. You can't give an elderly patient the same dose as a normal adult, because the levels will be too high and they will have problems metabolizing it.
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| mjl1717
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answer -d
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| robin082006
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There is similar q in Rapid Review CD and and answer is E. I'm sure.
Sensitivity to drugs does not increase in Elderly patients. This is a misunderstanding concept, they are easily intoxicated because of decreased metabolism, decreased excretion, and increased volume of distribution--> high concentration in the body. See Rapid Review.
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| mjl1717
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ok--ill change toanswer-e.. you guys are good. the pharmacokinetics is completely different in the elderly. {less muscle, more fat} /// phase1 is decreased also but not phaseII.
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| reet
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100% agreee with E
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| docswapna
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yes, E is the right choice
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