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How long for interferons?
Posted: Fri May 23, 2008 12:39 pm
by Punchy
How long do interferons remain in our systems?
I can't seem to find any information to find how long it takes for our bodies to be clear of it. I would imagine there must be variances with methods (subcutaneous vs. intramuscular) and type and of course we all have different metabolisms.
I have been off of Rebif for two months now. I read somewhere recently that it takes up to 6 months for Rebif and Avonex to reach full level in the blood. Not sure how reliable the source was.
Posted: Fri May 23, 2008 2:18 pm
by Sandrine
I think it means 6 month to "fully modulate" your immune system. I've heard around 4 month btw
Half-life of interferon beta is quite short. It is normally, as you probably know, a reaction of your body to several viral infections. It's a cytokine, so it's tightly regulated. i can't imagine it stays for month. Maybe some side effects last.
Because of the short half life of interferons, interferon alpha for hepatitis c-therapy is PEGylated. As far as I know they were experiments for interferon beta as well. I don't know the results.
Intravenously interferon beta lasts only for a few hours. For subcutaneous injections the peak is after 1-8 hours, half life maybe 10 hours?? (my personal estimation). It should be cleared after around 60 hours, this is why you have to inject 3x/week.
I could ask some interferon guys from my institute, but we work with mice - and mice tell lies, at least they don't remind me of MS patients
But some people here measure interferon levels or reaction on interferon/viral infection with so-called reporter mice. It doesn't last long.
Sandrine
Posted: Fri May 23, 2008 10:12 pm
by RuSmolikova
Punchy,
due to The Outcome Measures for the Firategrast Clinical Trial I think that three month are enough:
"Exclusion Criteria:
· Subjects receiving corticosteroids within 4 weeks of Screening for treatment of MS.
· Use of an ß-interferon product, glatiramer acetate or azathioprine within 3 months of Screening, or use of Mitoxantrone within 12 months of Screening."
Btw: I had to stop Avonex I to be able to start Fir three month later.