Expert: Dr Ian Jackson - please note UK based - 2/12/2004

Question
When someone consumes, in excess, most recreational drugs or drugs used legitamtely to treat chronic pain, why can the medication  manifest itself in the consumers eyes and face?  I understand why speech can become slurred and physical reaction time increased but why do the eyes turn red, face sometimes become blushed, and the always "obvious sign" of glazed or glossy eyes?  What exactly does alcohol, pain and anxiety meds (vicodin, percocet, and benzodiazapines etc..) do to the eyes (not the vision, but the outward apperance to someone else)?

Secondly, as a user becomes tolerant of a pain med, Vicodin as an example, more and more of the narcotic is needed to satisfy the "craving".  Some people are sound asleep after taking one vicodin 5/500 while others take 5 Vicodin 10/660 and hit the dance clubs, albeit a bit more "glazed and glossy".  The question is:  As the body becomes tolerant of the medication does the amount of the drug one would consume to "overdose" or harm the body (i.e. respiratory arrest, etc)  increase proportionately to the amount needed to produce the "high"?  Is the LD 50 usually the same for everyone? ( I do understand that the real threat of Vicodin overdose is the acetomenaphin on the liver, but lets assume for arguments sake its just the hydrocodone thats doing the damage)

Thanks, JM

Answer
Jason

Though I am an anaesthetist I and have lots of experience with many drugs - this does not include 'abuse' of these substances. However that known I will try and answer as best I can.

Your body becomes tolerant of drugs in several ways. To a degree the body can increase it ability to metabolise drugs it is exposed to regularly. However that is not the reason for loss of effect of recreational drugs. The body can also 'down regulate its receptors'. Now these drugs act on receptors in your body to produce their effects. The body can reduce the number of these receptors or make them more difficult to 'trigger' and this is what happens. So people have to take more and more of the drug.
Consequently the lethal dose required also increases and so is totally different for someone who has not been exposed to the drug.

On top of all this there is huge variation in how each of us handle drugs and so some people are very sensitive and others not so. This is all part of natural variation.

You are right that it is the acetomenaphin that would kill you if you take too much - basically everyones liver can only cope with a limited amount of that drug. The main problem being once you swamp the liver with too much it carries on metabolising it and the first stage of this pathway produces a toxic product. Ironically it is the second stage of this pathway (that gets rid of this toxic product) that can't keep up and so the liver ends up being damaged.

Glazed look is direct effect due to the fact you are 'spaced out' You might feel in control but you are not.

Red eyes (chemosis) - direct effect of the abuse I'm afraid. Probably combination of things - lack of sleep, less control over blinking which lubricates the eyes, may even reduce tear formation.

Hope this helps a bit, please take care and seek help to break the cycle you are in.

Ian Jackson