A pharmacist once told me, that the reason we are supposed to take Tarceva 1 hour before or 2 hours after the last meal is to limit absorption to 60%.
100 % absorption would happen if you took it with food, which might be more effective against the cancer, but also would cause more severe side effects.
Is this correct and if this is indeed correct, could I increase my blood level by taking Tarceva with food ,since I have no rash and only minor gastrointestinal side effects?
Meaning I would do my own drug escalation trial and increase until side effects become bothersome?
The official way to increase absorption is to do pulsed Tarceva.
But could it also be done by taking it with food?
These are purely theoretical questions and I would of course never experiment with dosage on my own without my oncologists ok.
Just curious about the biochemical stuff
Mon, 08/17/2015 - 05:08
While it is true that taking Tarceva with food increases its absorption, as Dr. West has said "Taking tarceva with food can make the absorption of tarceva greater but is overall so variable that it’s very hard to know what kind of blood levels to expect, so the established target is 150 mg taken on an empty stomach." - http://cancergrace.org/lung/2007/04/14/tarceva-drug-food-interactions/ As a result, you really wouldn't know what your effective dosage would be on a day-to-day basis. In that sense, what you suggest would not be the same as actually escalating the dosage. And there's no evidence that a higher daily dose of Tarceva would be more effective than the standard 150 mg dose. In fact, some patients with EGFR mutations do quite well with a lower dose.
The main purpose of Tarceva pulsing is to increase the amount of the drug crossing the blood brain barrier in an effort to combat disease in the CNS, in particular leptomeningeal carcinomatosis.
Mon, 08/17/2015 - 06:36
Thank you for your explanation.
Mon, 08/17/2015 - 16:48
Tarceva is metabolized (broken down) in your liver, mainly by an enzyme called CYP3A4.
Grapefruit juice is a potent inhibitor of CYP3A4.
Taking grapefruit juice at the same time as Tarceva would significantly increase the plasma exposure to the drug. This is why grapefruit juice should be avoided with Tarceva.