Anaesthesia and elective surgery: the aspiration question — does this still hold?

Anaesthesia and elective surgery: the aspiration question — does this still hold? I have a specific reason for asking rather than idle curiosity, and the context is below.

Practical question with the units stated, because I have seen how quickly these go wrong without them.

I have a 2 mg vial of retatrutide and I am working to a 0.5 mg step. My syringes are U-100 insulin syringes, 0.5 mL barrel.

I can do the arithmetic and I have done it twice, getting the same answer both times, but I would like someone to check the reasoning rather than the number — specifically whether I have thought about the residual volume correctly, and whether the graduation I am landing on is one a person can actually read.

Thyroid medications: semaglutide is associated with a slowing of gastric emptying, which might affect thyroid medication absorption if they are taken very close together. Separating them by a few hours is the conservative approach.

I read the opening post twice before replying, because I had assumed the opposite.

Separation timing versus clinically important interaction: a separation timing inconvenience (taking one medication 2 hours before or after another) is not the same as a clinically important interaction. Both can reduce absorption of one or the other, but only true interactions require active management.

SGLT2 inhibitors: frequently co-administered and relevant to renal and cardiovascular discussion, not to interactions. There is no pharmacokinetic interaction of concern.

Oral medications versus time: if you take an oral medication 30 minutes before semaglutide (which slows gastric emptying), the delayed stomach emptying affects when and where the oral medication is absorbed. Separating by a larger interval (1 to 2 hours) usually resolves this.

Coming back to post #5, because the follow-up matters more than the original answer.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

Picking up post #5: that is the part I would want checked first.

Supplements and herbs: many have no established interaction. Some do. If you are taking something unusual, checking a reference (like a pharmacist) is more useful than guessing from forum discussion.

Worth separating two things that post #5 runs together.

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.

post #9 is right about the mechanism and I think understates the practical bit.

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.

post #10 answers the question as asked. The question underneath it is different.

Insulin interaction: semaglutide and tirzepatide are not contraindicated with insulin but the combination carries hypoglycemia risk if insulin doses are not adjusted. That is a reason for close monitoring, not for avoiding the combination.

Metformin: commonly co-administered and relevant to gastrointestinal tolerability. Gastrointestinal side effects can overlap and additive. Taking them separately or adjusting one if tolerability is poor are reasonable approaches.

Food interactions: most interactions are absorption interactions. Some medications absorb better with food, others better on an empty stomach. With an incretin agonist that already slows gastric emptying, food effects interact with the drug effect as well.

Coming back to post #12, because the follow-up matters more than the original answer.

Two things before anyone answers the substance.

First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.