This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Grapefruit is worth one more sentence than it usually gets, and the sentence is the one about how the number was arrived at.
I read post #92 twice before replying, because I had assumed the opposite.
SGLT2 inhibitors: frequently co-administered and relevant to renal and cardiovascular discussion, not to interactions. There is no pharmacokinetic interaction of concern.
Reading it back, the second half matters more than the first.
This follows post #94 rather than contradicting it.
Anticoagulants: no direct interaction with the compounds in this class. Weight loss and body composition changes might affect the clearance or effect of warfarin if you are on it; monitoring INR more frequently during weight loss is reasonable.
The uncertainty is in the assumption, not in the calculation.
Where I would push back on the grapefruit consensus is the confidence, not the direction. The direction looks right. The confidence is borrowed.
Coming back to post #96, because the follow-up matters more than the original answer.
The most defensible general position in this subcategory: identify the plausible mechanism, check whether it has been studied, and where it has not, say that rather than filling the gap.
Post #97 is the version of this I will quote in future. One addition.
I would keep grapefruit and the decision it usually gets used for separate in this thread. They are related and they are not the same question, and merging them is why the last one went badly.
Where I part company with post #96, and it is a narrow parting.
Grapefruit looks different depending on whether you are reading the primary literature or the summaries of it, and the difference is not in our favour.
Building on post #100 rather than restating it.
A pharmacist can answer most questions in this subcategory in a few minutes with access to a proper interaction database, and that access is the thing a forum does not have.
Not the whole picture, but the part of it I can speak to.
Post #99 put the caveat in the right place and I want to underline it.
Adding a null result on grapefruit. I looked, carefully, and found nothing, and null results deserve posting precisely because they never are.
Reading rather than contributing, but this is the most useful thread I have found on it.
Anticoagulants: no direct interaction with the compounds in this class. Weight loss and body composition changes might affect the clearance or effect of warfarin if you are on it; monitoring INR more frequently during weight loss is reasonable.
Written in the hope of being told what I have missed.
Oral contraceptive absorption has been studied specifically for some compounds in this class and the findings are compound-specific. Generalising from one to another is not supported.
I am reporting what happened, not recommending it.
Where I part company with post #102, and it is a narrow parting.
Distinguishing three things in the grapefruit discussion that keep getting used interchangeably: the observation, the proposed mechanism, and the recommendation that gets attached to both.
The arithmetic in post #104 is right; the assumption feeding it is the part to check.
The strongest argument against my own position on grapefruit, stated as well as I can state it, since nobody else has yet.
Trying to state the grapefruit position in a way that someone who disagrees would recognise as fair, because I do not think the version in this thread passes that test.
Confirming post #109 from a second method, which matters more than confirming it from a second person.
Alcohol: no absolute contraindication but it raises gastrointestinal irritation risk and this drug class already does that. The conservative position during titration is to limit it.
The conclusion is tentative; the arithmetic underneath it is not.
Two sentences on grapefruit and then I will stop, because the rest is speculation and the thread is better without mine.
What is documented is narrow. What is inferred from it is broad. The gap between them is where every argument here lives.
Where I part company with post #113, and it is a narrow parting.
A pharmacist can answer most questions in this subcategory in a few minutes with access to a proper interaction database, and that access is the thing a forum does not have.
That distinction has done more work for me than anything else in this category.
Agreed on all of that, and I have nothing to add to it.
My understanding of grapefruit is a few years old and may have been superseded. If it has been, I would genuinely like to know rather than keep repeating it.
Anticoagulant questions come up regularly and are the clearest case for professional advice rather than discussion, because the consequence of being wrong is not gradual.
Adding what did not work for me on grapefruit, since the failures never get written up and they are half the useful information.