drug interaction

[Ama2007]

hi,

i have a patient taken lithium 250mg(2 bd) and bendroflumethazide 2.5mg (1mane)

he is been suffering from bipolar 1 disorder for 10 years and has been diagnosed with hypertension

i think all have to do is monitor renal function and thyroid and potassium levels but what could you prescribe instead of lithium for manic patients?i dont want anything that would increase his BP.

any ideas?really need your help.

thanks for any suggestions

[Nikolai]

With all respect you have gone about this the wrong way - if he has been taking maintenance treatment for bipolar disorder for a decade and then been recently diagnosed with hypertension, you should be looking for a good treatment for BP that won't affect the Li. This scenario has been mentioned before on this forum (although I can't seem to access many of the threads) and in this patient, it would be best to avoid diuretics, ACEi's, and ARB's. Next best choice would be to start a Ca2+ blocker such as amlodipine maybe 5mg od and see how he gets on. Lithium as Liskonum, Priadel or Camcolit (presumably it is Camcolit based on the dose you have given) has the same interactions - Li salts are not interchangeable though. Regular renal and thyroid monitoring is standard, sudden withdrawal can increase the risk of bipolar relapse. And besides considering the frequent monitoring and the fact that compliance in such patients is difficult, there is no point in stopping the Li. Most evidence supports Li in prophylaxis, less so for carbamazepine.

[Ama2007]

thanks Nikolai,

1.so you would keep lithium at the same dose.
2.no need for monitoring renal and thyroid function.
3.you would give a calcium channel blocker ,what about Securon(Verapamil, better compliance as its only once daily)
4.remove bendroflumethazide.

am i right?
what extra advice would you need to give to the patient.

thanks

[Nikolai]

You only need to take amlodipine once daily, 5-10mg od. Safest option is dihydropyridine Ca2+ blocker. Continue with the Li+ and regular monitoring as usual. Patient should maintain adequate fluid intake as dehydration can lead to symptoms of Li toxicity. Make sure he has a Li+ card. Actually just looking now, 250mg 2 tab bd is a treatment dose for bipolar disorder instead of a prophylaxis dose which is usually lower.

[Ama2007]

thanks,

so you suggest the lithium to increase,he has bipolar 1 disorder for 10 years. is 250 bd too low?

[Nikolai]

From the info you've written in the first post there seems no reason to change, I was just making an observation on the treatment.

[Ama2007]

wow !
i thought you said im going the wrong way about it.anyway i hadnt considered changing until you said it and it looks a good idea to use a calcium channel blocker because there is no reason why the doctor would prescribe bendroflumethazide other than just randomly .
so i would agree with you about the change.BUT why have you changed your mind ?would Amlodipine interact with lithium?

[Nikolai]

I think you are getting too confused now When I said I was making an observation in my previous post,I meant on the dose of Li. The stuff I said earlier about changing to amlodipine is not wrong.

[Ama2007]

thanks for your help

[bobbin]

thanks Nikolai,

1.so you would keep lithium at the same dose.
2.no need for monitoring renal and thyroid function.
3.you would give a calcium channel blocker ,what about Securon(Verapamil, better compliance as its only once daily)
4.remove bendroflumethazide.

am i right?
what extra advice would you need to give to the patient.

thanks

I agree with Nikolai.

Verapamil is believed to interact with lithium. Also, verapamil is not a 1st line treatment for hypertension. Verapamil is a short-acting drug which needs to be given in divided doses. Only modified-release verapamil products such as Univer should be given once daily.

Bipolar disorder can be very difficult to stabilise. If the patient is stable on lithium, you would not want to change this.

Bobbin