TCZ question

[LemonZest11]

Does anyone know for how long tocilizumab is effective in the system? I can’t find an answer and am wondering, since I have started spacing my TCZ jabs quite considerably. Might be that I don’t need to do this if it only lasts a finite time.

[Rugger]

I 'googled' 'Tocilizumab half-life' and saw anything from 6 to 21 days. The half life is the time it takes the drug to reduce by half, then half again, then half again and so on......... So it seems to stay in our system for quite a while, with the dose decreasing all the time, of course.

[LemonZest11 in reply to Rugger]

Thanks Rugger. With my spacing out the doses, I was just wondering if perhaps I no longer need it, since 4 weekly has come quite easily. My next doses will be 5 weeks apart, I still have 10 pens left so if all goes bad I can sort it. I just so want to avoid methotrexate if possible, happy to remain on 2mgs pred forever if needs be. Thanks again.

[DorsetLady PMRGCAuk volunteer]

Found this on drugs.com Q&A - - but you might not want to read the link - too scary😳 - and still doesn't give a definitive answer!

How long does it take to get actemra out of your system?

Q.

I was getting ready for my fourth infusion. no relief at all yet, the pain and the fatigue was as bad as it could be. Them I developed rashes all over my body and swelling on my legs and feet. We stopped the infusions. Now I would like to know how long it will take for Actemra to get out of my system?

A.

The half life (the time it takes for plasma levels to reduce by half) will vary depending on the dose you received and how long you had been taking it for, ranging from 10 to 13 days to 4 weeks (see link below)

It usually takes around 5.5 half lives for a drug to be completely eliminated from your system.

Other factors also need to be taken into account and include:

1. How much and how often you have taken the drug.

2. Your metabolic rate – a slower metabolism will increase the time a drug remains in your system.

3. Your age and health – older age and poor health will generally increase the time the drug stays in your system.

4. Body mass – generally the bigger you are the longer a drug will remain in your system.

Hope this is of help.

drugs.com/pro/actemra.html

[LemonZest11 in reply to DorsetLady]

Thank you DorsetLady. I haven’t understood what a half life means but Rugger has explained it. So it looks as though it remains for some time, hence why I am able to stretch to 4 weekly jabs without too much trouble. My plan is to get off it completely, I am able to just stop but don’t really have the courage. This helps.

[DorsetLady PMRGCAuk volunteer in reply to LemonZest11]

Good…

[PMRpro Ambassador in reply to DorsetLady]

"The half life (the time it takes for plasma levels to reduce by half) will vary depending on the dose you received and how long you had been taking it for"

Going to be picky here - that is rubbish. The half life is a logarithmic function if the drug is excreted by first order kinetics and a relatively constant figure for you, nothing to do with dose, The half life is how long it takes to get to half in in the blood

derangedphysiology.com/cicm...

derangedphysiology.com/cicm...

Doubling the dose will increase the time the drug is in the body by one half life - the half life doesn't change though.

[DorsetLady PMRGCAuk volunteer in reply to PMRpro]

This,

Taken from here- so maybe this information needs amending

drugs.com/answers/long-acte...

[PMRpro Ambassador in reply to DorsetLady]

Oh I know, not blaming you!! But someone doesn't understand pharmacology ...

[DorsetLady PMRGCAuk volunteer in reply to PMRpro]

No i know you weren't,...😀

[PMRpro Ambassador]

Depends - as Rugger says it is quite a variable half life. It will also depend on the disease activity and how long it takes for the inflammation to build up again IF it is still there. I'd have thought the way you are increasing the spacing is a good way to go and suggests that the course of TCZ has induced remission - which is what they hope for after all. Then what matters is how long that remission lasts.

[LemonZest11 in reply to PMRpro]

Thanks for that. You guys seem to be in a competition about who knows more. I’m just after a bit of an advice. Thanks for yours.

[DorsetLady PMRGCAuk volunteer in reply to LemonZest11]

No competition, just trying to help you…

[LemonZest11 in reply to DorsetLady]

And you do, thank you.

[PMRpro Ambassador in reply to LemonZest11]

And each of us sees a bit different aspect ... Teamwork

[LemonZest11 in reply to PMRpro]

Thank you so much for your help.

[LemonZest11]

Thanks, I always appreciate your responses, so detailed and helpful. I'm going to press on, keep stretching out the TCZ and hopefully I'll be ok. In the end, I'm still on 2mgs of the drug that works for pmr. Xx

[LemonZest11]

I will keep that in mind. I'm not stopping just yet, but I cannot get another script for TCZ and the options aren't appealing to me after reading the experiences of others. 🤞 the low dose pred will suffice in the end.