Ld99

[Step1Hash]

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I took the prometric free 150 a while ago and they had a question about the LD99/ED1 ratio (I think those were the abbreviations, it was something not in First Aid) and I didn't know how to answer it. If you did the prometric test and remember that question do you mind explaining the concept to me? I understand what LD99 and ED1 mean but the question was worded in a specific way that was confusing to me. I would hate it if it was on my test and I could have known it ahead of time. Thanks!

 

[Vagus08]

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[Step1Hash]

I took the prometric 150 today. I think the answer was 4. My logic is as follows: the question stated that each of the four unique drugs was being used at it's maximally effective dose (ED99). So, I basically looked for the drug which had the highest TD1/ED99 ratio value, as the one that would be most toxic out of the four. I'm not sure the left column could be used to derive any benefit in solving the problem, but my approach could be wrong.

it was TD1/ED99! lol thanks. So I think I put A or B (the lowest TD1/ED99). I thought that if the Toxic Dose that killed 1% was way higher than the effective dose that treated 99% then you would need ALOT of drug to kill just a few people and thus it has a wide therapeutic window? So if the TD1 was 100, and the ED99 was 10 -- 10 units would treat 99% of people and kill only 1/10th of a person. And if TD1 was 1000 then it would kill only 1/1000th of a person. Is my thinking correct?

I was more confused with the left column-- I think it was talking about potency or something? I thought it may affect it but I wasn't sure.

 

[waterlilly]

They had the same question on the 2003 Free150 and the answer was whatever the lowest TD1/ED99 was.....ur answer was correct

 

[Step1Hash]

They had the same question on the 2003 Free150 and the answer was whatever the lowest TD1/ED99 was.....ur answer was correct

damn, how many free 150s did you do? lol

So does the 1st column affect anything or was it unnecessary?

 

[coralis]

to the OP:

LD = lethal dose and the number after always how many deaths. So LD99 = lethal dose for 99%

TD = toxic dose (ie where you see toxicity symptoms)

ED = efficiency dose at which you see clinical benefits

 

[waterlilly]

damn, how many free 150s did you do? lol

So does the 1st column affect anything or was it unnecessary?

Lol. I happened to have a friend with past Free150s so I did them all and according to Kaplan explanations that year, the first column is a distractor

 

[richse]

I took the prometric 150 today. I think the answer was 4. My logic is as follows: the question stated that each of the four unique drugs was being used at it's maximally effective dose (ED99). So, I basically looked for the drug which had the highest TD1/ED99 ratio value, as the one that would be most toxic out of the four. I'm not sure the left column could be used to derive any benefit in solving the problem, but my approach could be wrong.

Wouldn't the highest TD1/ED99 ratio mean that the drug was the least toxic? If it takes 1000 mg to be toxic and 1 mg to treat 99% of people then that's a ratio of 1000. If it takes 10 mg to be toxic and 1 to treat then the ratio is 10 and the drug is much more toxic with a lower ratio.

 

[Vagus08]

Wouldn't the highest TD1/ED99 ratio mean that the drug was the least toxic? If it takes 1000 mg to be toxic and 1 mg to treat 99% of people then that's a ratio of 1000. If it takes 10 mg to be toxic and 1 to treat then the ratio is 10 and the drug is much more toxic with a lower ratio.

Your explanation is definitely correct. I think I misinterpreted the question.

 

[nitpick]

Wouldn't the highest TD1/ED99 ratio mean that the drug was the least toxic? If it takes 1000 mg to be toxic and 1 mg to treat 99% of people then that's a ratio of 1000. If it takes 10 mg to be toxic and 1 to treat then the ratio is 10 and the drug is much more toxic with a lower ratio.

Nicely explained!!!! thanx...