Side effects - Methadone Toxicity Symptom Query

[ladydragon]

Hi All...

I'm after a little bit of information on the symptoms of methadone toxicity in a hypothetical scenario...

A minor is hypothetically prescribed Fentanyl (25mg 72hr patch), Voltarol (50mg am / 50mg pm) and Carbamazapine (100mg am / 200mg pm) as a core drug concoction for pain relief in a terminal condition... In addition, this hypothetical minor is also prescribed Methadone and Ibuprufen for breakthrough pain relief... The methadone would have been hypothetically prescribed at 5ml when required with a minimum of 3hrs between dosages with it anticipated that the required doses might vary between 0 - 3 per day as a 'top up' analgesia...

It might be fair to say that the hypothetical doctor was planning on replacing Methadone with Ketamine once the need for Methadone became regular 4 or more doses daily rather than intermittent...

After a few months on this regime, the hypothetical minor has a week to ten days of needing the methadone at three doses per 24hrs so that each day sees 15ml - 20ml being introduced into their system... We can presume the minor's body weight to be around 44kg...

Which leads me to wonder what the symptoms of methadone toxicity might initially present as? Given the hypothetical minor has a terminal condition which might in itself also present with excessive sleepiness as their condition progresses, would there be any advice on how to differentiate between sleep brought on by early stage methadone toxicity and excess sleep brought on by progression of a debilitating medical condition? Is there more than just sleepiness to indicate early toxicity? By excessive sleepiness, we can presume the hypothetical minor has dropped from being awake for approximately 12hrs per day to between 5 and 8 during the same week...

How variable is an individual's ability to deal with methadone build up when used in a prolonged situation? Would it be affected at all by the other medications listed above?

We can consider that the hypothetical prescribing doctor is on leave and therefore the parent of the minor wants a little more information if they have to deal with a doctor they have yet to build up a relationship of trust with whilst their usual doc is away..

Thank you for taking the time to read and perhaps reply to this query... Apologies for the length of post...

LD