I need some pharmacology advice med students. I'm abusing a certain drug. If I take one dose of 200 mg...

I need some pharmacology advice med students. I'm abusing a certain drug. If I take one dose of 200 mg, then according to the half life(I'm a mathematician, I'm using a mathematical model which I assume has to be somewhat inaccurate but in general accurate) after some hours I have 100 mg in my system, if I redose with 100 mg will I feel the same effects like the first time I took it a couple hours ago? Or will the new 100mg not act additively with the old 100mg in my system? I assume the onset will be faster as the last time 200mg were gradually absorbed while the second one it will start from 100 then go up from there but is there any other difference?

good night sweet Prince

I'm not Hamlet.

>pharmacology
>med-students

They don't take up a course?

[A]t = [A]0 • e^(-k • t)

T1/2 = ln2/k

also look up michaelis menten equation. It depends on the substance and concentration. Im on mobile so sorry for shitty equations

I already know that, that's how I calculated how to get 200 mg by redosing x amount after y hours. The question is different.

In general you can expect to need about 1.1x-1.25x more, e,g, you'd have to take 110-125mg, to overcome the body's tolerance now that the drug has been in your system a while, in order to feel as if you are at 200mg again. This rapid tolerance is called tachyphylaxis, its why redosing will never quite feel as good as the first time you get high that day.

BUT it depends on the drug a lot. And what effects you are going for. If this is amphetamines, what i said holds true. If this is opiates, then yes you will take 100mg exact, because the overdose is more severe so you should err on the side of caution.

Yes it will act additively assuming you are not at 100% receptor saturation for that drug (very unlikely)

I'm taking modafinil, it doesn't exactly get me high. Well it does because I actually feel awake and myself after months but that's irrelevant to the action of the drug. Really? I thought tolerance builds up after chronic use. 12.5% more seems a damn lot for just taking a single dose.

The effects I'm going for are the godlike alertness and wakefulness I get for 3 hours during the peak of 200mg. The peak is 2-5 hours after I take it so I guess at 5 hours I could redose 50 more mg(158 has to be in my system after 5 hours if the half life is 15 hours) and get a second 3 hour peak?

Oh I also take 200mg caffeine with the morning dose, should I redose that too if I want the same peak? Because modafinil by itself doesn't do a lot but it combines perfectly with caffeine.

"Feel the same effect" is a very complex and subjective thing when talking psychoactive drugs, and may not be the same as attaining the same tissue concentration.

Also if it is not going IV all your calculations are probably shite

Neurotransmitter receptors and transporters are some nextlevel fuckery and up and down regulate relatively fast.

I studied this shit years ago, dont remember it well.

Go download a pdf pharma book and read.

PS: Mathematical autismo will probably lead you nowhere. Have you looked for studies on modafinil dosage or some controlled dosage records or something of the like?

PSS: Never fucking ever trust a med student on anything medicine related. Me included. Go read that book boi

Link me a book and I'll read it.
Well my calculations are approximations that I hope have a margin of error less than 25%. The bioavailability of the drug can't be determined because it's insoluble in water(which I took from wikipedia and have no idea why it matters, can't you docs just test a large sample with different routes of administration each time taking peak blood level of the drug and conclude on the average?) but that shouldn't matter if I use the same route of administration for the redose. I am perfectly capable of searching math articles but my med game is bad. I have no idea where to look and how to judge which study is the one I want.

Sorry man but im sleepy and i dont really feel like browsing piles of shit. Plus publishers are fucking jews and you need an account to access the full works most of the times.
There was a site by a russian qt neurosurgeon in which you can paste the link to gain full access but i dont remember it.

Go to your favorite torrent tracker, search pharmacology and download a couple of books (as up to date as posible)

Ctrl+f modafinil those fuckers, rage because they will probably tell you different, partial or confuse shit and draw your conclusions.

Bioavailability changes with route of administration, taking an average would be useless.

Stay away from wikipedia, the editors copypaste shit they dont understand to fill pages. The result is a clusterfuck at best and nonsense at worst.

The math articles on wikipedia are not half bad, just really bad if you don't already know the subject. It's good if you just need a quick formula reminder or theorem. I can access everything, I'm still enrolled in my uni. I feel you, math academia is fucked up as well but you don't get contradictory stuff in different studies on the same subject unless you expect to.

What I meant was take one large sample of patients, give them dose X via route Y1, test their peak blood concentrations, take the average of those and conclude on route Y1 bioavailability. Then dose X, route Y2 etc.

Will do, thanks for your honestly on the shittiness of doctors.

>PSS
>Post Scriptum Scriptum

Take in account that blood concentration may not mean much in the case of a drug acting on the NS.
Read the pages on pharmacodynamics and farmacokinetics of any of the books, they are the first chapters usually.

The problem is that pharmacology books rarely include studies, and vary from autor to autor. Different autors might give different orientations to the same subject or highlight different concepts. It can really get tiring if you are looking for an specific answer sometimes.

Of course all info about drugs is very carefully tested and recorded before release for use, drugs dont work as you may think they do at first, read about pharmacokinetics/dynamics and everything will be much clearer

PSSS: you got it boy

It usually gets a lot foggier the more I know but at least I actually know stuff on the subject. Pic related is so true.

Pharmfag here.
Agreed with this guy. Most drugs' bioavailability changes significantly based on route of administration.

Even if you shitty little drug is insoluble in water, doesn't mean your intestines are going to absorb all 100mg of it.

>if I redose with 100 mg will I feel the same effects like the first time I took it a couple hours ago?

No. Because your brain is now in a different state after several hours of influence of the first dose.

>Med-students
>Pharmacology
If it's amphetamines were talking about, you need to take into account pH. More acidic pH would mean more substance needed to reach the same effect. Down-regulation, first-pass metabolism blah blah blah


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you take 200 mg half life of 1 day

next day you have 100 and then 200 dose puts you at 300

it takes 3 half lives to reach maximum plasma concentrations

i know this cuz i do steroids

too general to say tolerance

besides things like clenbuterol are cycled to allow the beta receptors to down regulate

its like having adrenaline coursing through 24x7 youll reach a point where the nervous system has run out of steam and it wont do anything

what i mean by this is "tolerance" is too vague and a load of shit

the actual mechanisms behind it vary so actual reasons need to be examined on a per substance basis