Posted by ed_uk on August 3, 2005, at 15:16:08
In reply to Re: A post for xbunny.... » ed_uk, posted by xbunny on August 2, 2005, at 18:31:27
>Does the same hold true for flupenthixol or is it weaker?
Flupenthixol is said to be similar in antipsychotic potency to haloperidol. 6mg flupenthixol is said to be approximately 'equivalent' to 6mg haloperidol. However.......... no dose of flupenthixol is truly equivalent to haloperidol because flupenthixol and haloperidol have different receptor affinities. Haloperidol is a selective D2 antagonist whereas flupenthixol antagonises D1, D2 and (less so) 5-HT2 receptors.
>What does it really mean that say 70% of the receptor sites are occupied by the drug?
At any one time, 70% of D2 (dopamine type 2) receptors in the brain are occupied by a flupenthixol molecule. Flupenthixol binds to the D2 receptors but doesn't active the receptors like dopamine would. Flupenthixol simply 'sits' on the receptors and prevents them from being activated by dopamine ie. if flupenthixol is bound to a receptor, dopamine can't bind.
>What would happen if 100% were occupied?
Marked side effects would be present eg. dystonia, dysphoria, akathisia, parkinsonism, elevated prolactin levels.
>Does the fact that I have been taking the flupenthixol for some years mean I am less likely to develop it?
Since you can tolerate flupenthixol without taking an anticholinergic, the extrapyramidal side effects must be very mild. This is a good sign. The absence of EPS suggests that TD may be less likely to occur. Watch out for involuntary movements of the tongue, jaw and mouth. Fine (involuntary) movements of the tongue can be an early sign of TD.
>I was also wondering if theres any reason why I shouldnt take my flupenthixol as a single morning dose as I have been doing?
No, that's fine. Twice daily dosing is recommended initially but most people on long term maintenace treatment can take it as a single daily dose.
>..does flupenthixol hang around long enough to build up and not require split doses like recommended in the leaflet?
Yes, it has a long half-life - about 35 hours.