When to take Venlafaxine?

[numberWang]

Hi,

I've been taking Venlafaxine for Anxiety for about 5 weeks now and have been on 150mg for a few days. I have just moved to slow release and have started out taking 75mg when I wake and 75mg just before bed. I have had major issues with insomnia in the past and have found that the Venlafaxine has not helped with this at all. However, I feel that my sleep is improved with the slow release tablets, possibly because they are less likely to induce spikes in side effects.

Although I am still trying to find the best therapeutic dose for me, my main question is about half life of the drug. If I take 75mg just before bed, will the effects of the drug be wearing off just as I wake in the morning? And if that's the case, why would I bother taking at this time? If I avoid taking before bed then I feel I may sleep better and just do 75mg slow release in the morning to get me through the day. Of course this would mean an effective reduction to 75mg in total as my dosage. I'm possibly not thinking this through right but I'm just not clear as to when the effects of the drug will be at their peak - I want that to be during the day when I have to do stuff!

Thanks in advance

[nicola1980]

Hi if your taking the slow release you only need to take it once a day, I take mine in the morning. The effects won't wear off as the slow release has a longer half life than the standard release and is meant to be only took once a day, if your splitting your slow release doses then I would imagine your levels of ven in your system are all over the place. I can't take mine at night as unfortunately it does effect my sleep if I do that but morning suits me better anyway.

[MyNameIsTerry]

Firstly, I hope you are not splitting an extended release med. I mean actually splitting the pill/capsule. This is 100% not advised as it can cause the entire dose to be delivered without a timed release element.

I agree with Nicola, you will be all over the place doing this with Ven XR. Whilst it has a longer half life, it's not 24 hours and you are having an overlapping dose here but it won't ever be at 150mg, so you are not getting 150mg.

The elimination half life is 5±2 (drug) and 11±2 (major metabolite) hours. Usually it takes 5 half lives for a drug to reach <5% in elimination (using the standard pharmacokinetic calculation) but Ven is faster to both reach it's "steady-state" (as much going in as coming out) but seems to be slower to be eliminated. About 87% of the drug is eliminated in urine within 48 hours. You don't need to worry about the elimination though if you take it the correct way and that's once a day but even with your overlapping routine, you are still taking far below the max dose so the elimination won't be a problem anyway.

The problem is going to be in the Distribution phase (when it is being absorbed). About 92% gets absorbed according to studies. However, due to the fast elimination half life (5+2 hours for the drug and 11+2 hours for the major metabolite) you will be losing one half life by the time you take your next dose easily and that means a 50% drop in that previous dose. Does that make sense?

BUT, and this is something Nicola & co can help with, someone taking this once a day will see a greater fall in the amount of the drug in their body by the 24 hour mark. So, whilst you are not perhaps getting a full 150mg at the same time, I think you could be getting a greater volume of dose over the same 24 hours.

What do you think, Nicola? You would normally take it every 24 hours around the same time but a great deal of that drug is out of your system by then on the XR. So, is the OP perhaps getting more than you despite not reaching the full 150mg?

apparent elimination half-life is 5±2 and 11±2 hours, respectively

[numberWang]

Hi both,

Thank you so much for the replies, very much appreciated.

Terry, I will come back to your advice in the morning when I have a clear head but it looks very useful - I really want to get to know the in's and out's of this drug to give it the best chance of success. But, I do confess to being a bit ignorant of some of the terminology you use - this gives me a good excuse to do some research.

Basically, I want the drug to have maximum effect during the day - naturally really as I want to be at the peak of my powers then. Conversely, I want to have as little as possible in my body (so far as possible) when I go to sleep as I already have enough issues with sleep as it is.

I really wish the GP could have been as informative as you both!

---------- Post added at 21:10 ---------- Previous post was at 21:08 ----------

Oh, and to confirm, no, I am not splitting - I take 75mg as I wake and 75mg just as I go to sleep which seems a little sub-optimal to me.

Another thing the Dr said to me - the more you take the lower the side effects! I'm sure it's not quite that simple and sounds very counter intuitive.

[MyNameIsTerry]

Your GP has just won my "Dumb things GP's say" award for this week. It's totally the opposite. It's even more the opposite with SNRI's because they operate as SSRI's until they reach a certain dosage and then the "N", the adrenaline element, starts to be impacted. For Ven this is 150mg. At that point you see an even greater range of side effects because of the additional neurotransmitter it is affecting but before this point it is pretty weak so it's really more like SSRI side effects.

I went on Duloxetine at 30mg and then up to 60mg. This is the correct way to start the med for GAD according to the manufacturer. The adrenaline kicks in at 60mg for this one and boy did I know it. The 30mg felt like the usual minor side effects of SSRI's but the "N" element was very different and very hard for me.

Not everyone suffers though and some people can start on higher doses but no doctor can really say for sure as it's completely individual. So, some GP's now taper up from the half minimum therapeutic dose to allow the patient to experience some of the med which should theoretically make the full dose easier to tolerate. Even then some people struggle though, again it's totally individual but this tapered route is safer. The downside is that it prolongs the side effect window as each time you increase, you can go through it again.

Did your GP tell you to take it in a split dose? Given the lack of knowledge of one of the most basic concepts, I would question it, if so.

However, it is an interesting question. My Duloxetine doesn't run the full 24 hours eithers and has a half life similar to the Ven XR. I've often wondered whether this plays a factor in how much of the med is really helping me (and the med has never really helped me much anyway, but it did cause me a lot of new problems) and with it reducing so quicker over the day, am I getting enough?

How you split your dose says to me you are getting more than Nicola is but she reaches a higher max than you do because her's dips a lot lower. I don't believe any GP could answer this one, it's a specialist question, but I would love to know the answer.

Just shout if you need an explanation of anything, I knew none of this either until the last couple of years so just researched it all. It certainly pays to understand your meds.

A question to consider is the one you posed about when you want to feel it at it's peak. Taking it before bed is going to mean it will reach that peak whilst asleep although you will never reach that 150mg because of the split dose method. If you took it all in the morning, you will reach peak in the day instead and given the short half life it will decreasing a lot by bedtime. GP's usually won't think about things like this as to them it's just about taking the med itself but in someone like me who suffers their anxiety more in the morning, I may differ in my approach unless I see insomnia. If the side effects are like agitation, it can help when you take it.

[Istherehope?]

This is all very interesting...I'm currently taking Venlafaxine (standard not slow release) 75mg at 7am and 7pm. Also taking Mirtazapine 30mg approx 10pm. This seems to be working quite well for me but I do like the idea of taking the Ven all at once like Nicola as I often forget to take the evening dose until i take Mirt at 10pm...tbh it doesn't seem to make much difference but I have wondered about switching to XR if I can persuade a doctor I'm worth extra cost that is! Did you have a particular reason for switching to slow release numberwang? Terry would I have less of a dip if I stick with the two normal doses 12 hours apart or if I did slow release all in one go - my maths doesn't feel up to the task right now!

Maybe though I should just stick with what's working seeing as it's taken five months to get somewhere near being stable.

Hope it's working out ok for you numberWang and hope your sleep improves too.

[nicola1980]

You definitely should only be taking it once a day if it's the slow release version, my physc told me this, splitting the slow release to twice daily will have your levels going haywire, I certainly wouldn't do it personally. I've known people take their ven morning or night, it really just is personal preference as to what suits you best, if I take mine at night it interferes tremendously with my sleep so I stick to the morning and that works for me but like I said I have a friend who takes hers at night and that works for her. It's only the standard release you need you need to take twice daily as that has a half life of approx 6 hours but the slow release will certainly see you through for 24 hours as it's mechanism is released slowly throughout your body until your next dose.

[numberWang]

I've been taking Venlafaxine now since mid December. I am now on extended release at 75mg which I take every morning. I tried 150mg but found the side effects too unpleasant to bear but probably need to give it a longer run to see if they become more tolerable.

I have to say that I think I am finally starting reap rewards with this drug. On one hand, I feel more resilient, more capable and less anxious in general which is a big deal. My sleep is now much better and I my mind seems much much sharper than before I started on it. I'm not sure if this sharpening effect is purely the drug, or the fact that somewhat strangely, it has made my appetite for alcohol disappear overnight.

On the downside, it does make me quite jittery and I still get really bad hot flushes. This is embarrassing as situations which are mildly stressful now trigger flushing/blushing and sometimes excessive sweating.

I had considered that upping the does to 150mg might help with the latter problem but then again I suspect it will simply exacerbate it, given the Noradrenaline is likely to be kicking in at this dosage. This does lead me to the conclusion that perhaps taking an SNRI is no better for me than an SSRI and maybe I went down the wrong route, given that my major problem is GAD.

Any thoughts on any of this welcome.