Taking promethazine while on seroquel

[paranoid android]

I am currently prescribed 300-400mg's of seroquel a day for bipolar disorder and i usually take all the dose at night. Lately after much trouble i managed to find a pharmacy that stocks Histantil (the trade name for promethazine in Canada) which i have been using both for the god awful allergies i have as well as a opiate potentiator which it works really well at. I take between 50-100mg's of promethazine orally and then take a dose of whatever opiate i am on or if i am IVing it i will wait until the promethazine kicks in to take my opiate shot.

I have read that promethazine has 1/10th the anti-psychotic effect of chlorpromazine which makes it useless as a anti-psychotic. Still tardive Dyskinesia and other EPS symptoms are listed as rare side effects. I have taken other anti-psychotics such as risperdidone and zyprexa with seroquel before for really bad mania with no problems. However i am wondering if taking the seroquel at night after taking promethazine put's me at a much higher risk of movement disorders then seroquel alone. Granted the chances of seroquel causing tardive dyskinesia are very rare. The long half life of promethazine is a bitch that's for sure.

I am just wondering if anyone else has used promethazine while on seroquel and if they did did they get any adverse effects.

 

[Rybee]

I take 100mg Quetiapine/Seroquel for sleep every night and have been taking 100mg Prometh to potentiate Oramorph/Tramadol/Dihydrocodine/Codeine for ~6 months.

How you're able to stomach 400mg of Quetiapine is beyond me. 100mg knocks me clean out within an hour 8(

Had no issues whatsoever, though that's not to say there's no risk. Tbh, the thought hadn't even crossed my mind.

I'm hoping this link shows interactions between: http://www.drugs.com/interactions-check.php?drug_list=1949-0,1979-0,1656-1027
Oramorph
Quetiapine/Seroquel
Promethazine

Morphine and Prometh says moderate: 'dizziness'
Morphine and Quetiapine says moderate: 'dizziness'
Prometh and Quetipaine says moderate:

'Talk to your doctor before using Quetiapine together with Promethazine. Combining these medications can increase the risk of an irregular heart rhythm that may be serious. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or special monitoring by your doctor to safely use both medications. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or fast or pounding heartbeats during treatment with these medications, whether together or alone. Avoid driving or operating hazardous machinery until you know how the medications affect you. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.'

Looks like there's no clear answer other than, avoid if possible.

 

[jeeves]

Seroquel actually has a potent antihistaminergic action as well as an antipsychotic action. So, essentially you will be combining two potent and very sedating antihistamines. This is not necessarily dangerous, but the sedating effect will be very pronounced. I wouldn't be worried about any tradive dyskenetic effects, these symptoms appear gradually and are much rarer in atypical antipsychotics.

 

[paranoid android]

The thing is sedation does not really increase much once you get above 100-200mg's so 400mg's is really not much more sedating then 100mg's. I know seroquel is also a potent H1 antagonist but it is certainly not good for potentiating opiates and i don't find it to be of any use in treating allergies or nausea like promethazine is. I have taken the phenothiazine anti-psychotics chlorpromazine aka Thorazine aka good ol Largactil as well as methotrimeprazine and both of those drugs do potentiate opiates. I have no idea why seroquel doesn't work like that.

I think i will just make sure to take the promethazine during the day so as to not risk any anti-cholinergic toxicity which is what kind of worries me about this mix. Quetiapine itself has very little in the way of anti-cholinergic effects but it's main metabolite norquetiapine does have potent anti-cholinergic effects.