My boyfriend is on warfarin and is currently suffering from heartburn. I gave him some of my Tums but checked online before giving him my ranitidine. I found that they should not be mixed.
I told him to suck it up and wait for it to get better. He gets heartburn so rarely that it’s not going to kill him to deal with it for one night. It is definitely food related so there’s no concern that he’s suffering from a bleeding ulcer or anything.
But, we’d still like to know what ranitidine can do to someone on warfarin that makes it a bad combo. Is this just one of those situations where a drug trial showed a .01% chance of problems so they have to report it?
Preface: I am not a real doctor, this is not real medical advice.
Interestingly enough, I have a pharmacology exam on Monday, so let me check my notes.
Says that little ranitidine is bound to plasma protein (so as to displace the warfarin) and it is a minor inhibitor of CYP enzymes (which metabolize warfarin). My interaction checker lists an increase in INR (a measure of the extrinsic clotting cascade) when the two are mixed, which is attributed to an inhibition of hepatic metabolism (the aforementioned CYPs).
So what appears to happen is that warfarin is normally broken down by enzymes in the liver. Ranitidine slows that process down, making the concentration of warfarin go up in the blood, thus potentiating its effects.
Once again, the Dope comes through. Thank you very much - for the details and the layman’s translation. I was pretty sure I got the gist of the long part and the short part confirmed it.
And bravo to you, for checking on the drug combo before anyone took it. Not everyone thinks to do that. Good habit, may prevent a serious problem in the future.
I don’t know about your antacid, but I know quite a bit about warfarin. I take it every day. It inhibits the clotting of blood by being a Vitamin K antagonist. The difference between a dose too small to be therapeutic and a dangerously large dose is a small window. To complicate matters, people vary widely in their ability to clear the drug, so that dosage varies from 1 mg/day to (in my case), 6.125mg/day and maybe some people use even more. I get normally tested every six weeks. But if I am prescribed an antibiotic, I must reduce my dose of warfarin by about 1/3. A friend of mine, also on warfarin, was prescribed an antibiotic by a doctor who neglected to warn him of the interaction and ended up in the hospital with a hemorrhagic stroke. He has recovered, but it was not pleasant.
Not to complicate the issue, various foods also interact, mainly by providing large doses of vitamin K which reduces the effect of the warfarin. Broccoli and other brassica are the worst, but most green leafy vegetables as well as soybeans also provide loads of vitamin K.
I’ve got patients on both ranitidine and warfarin. It’s not an absolute contraindication by any means, or even a strong relative contraindication. Some extra monitoring is needed when a patient either goes on or goes off ranitidine while on warfarin.
Now, we’re not even talking about prescription ranitidine or even frequent use. So I’m assuming that taking one OTC ranitidine when he makes unwise food decisions is probably safe. But, it’s better to be safe than sorry. Since it’s so unusual for him to have heartburn bad enough even for Tums (lucky bastard), I think he’ll survive on those rare occasions. He seems to agree. Broomstick: I wish I could take the credit for being cautious but it was him. I was the one who said I doubted it was an issue but I checked just to make him happy. He has only been on the warfarin since October so he’s really paranoid and unsure what he can and can’t do.
Yes, rat poison is basically warfarin at massive overdose levels.
I agree - better safe than sorry, especially when one is not a doctor. I used to go to my dad the pharmacist for help on things like that, but he’s been retired long enough he won’t give that sort of advice anymore as his knowledge is way out of date.
Though he still freaks out his local pharmacist when he inspects his own scripts and can usually tell what factory the stuff was made in. Still, a lot of new things have come out since he was active in the profession so he just doesn’t know some of the new stuff.
I just want to point out that there are over-the-counter alternatives to ranitidine (Zantac). There are also cimetidine (Tagament) and famotidine (Pepcid), which are the same class of medicine–H2 blockers. (I don’t believe the PPIs work quickly enough for occasional use.) Nizatidine (Axid) is also supposedly available OTC, but I haven’t seen it.
Actually, this was how warfarin first got its use. It was discovered originally when some cows who ate moldy feed died of acute hemorrhages. It was then put into rat poison. Then, many years later, a U.S. Navy sailor tried to commit suicide by ingesting large quantities of warfarin (as rat poison), but he survived. And the rest, as you can say, is history!
Cimetidine (Tagament) is actually worse to take with Warfarin then ranitidine. Famotidine or Nizatidine are the two H2 receptor blockers that are recommended for patients taking warfarin, since they haven’t shown any interactions.
Oh, congodwarf, you should show this youtube video to your boyfriend. It will tell him all about warfarin, in a nice fun rap song.
Amazing what the people in my class at Pharmacy School can make when they aren’t distracted by tests!
We have ranitidine because it is what works best for me. When my reflux was at it’s worst, even when multiple prescriptions wouldn’t control my reflux, 150mg of OTC Zantac would work (of course I had to take 150mg twice a day but it still worked).
We do actually have Pepcid in the bathroom though. The ER Vet told us to give it to our dogs after they ate a soda can. It doesn’t work for me so it has just been sitting there. I told him he can take it in the future.
You guys are awesome. Thanks for all the info.
That’s why it sounds so funny to me when people (my wife is one) casually refer to “taking Warferin.” Watch out, rat, it might just be dangerous. Hey, I’ll bet those rats just bleed out internally, because it has the same blood-thinning/anti-clotting effect as in humans!
A big part of the U of Wisconsin’s profile is the Warferin that came from the brains in the WARF building on campus. In fact, I’ll bet it stands for something like the Wis. Alumni Research Foundation.
The mechanism of action for coumarin derivatives is disruption of the body’s (mostly, the liver’s) ability to synthesize Vitamin K-dependent clotting factors. In this case, addition of ranitidine can alter that balance. It will do so 100% of the time (it’s pretty much always metabolized the same way in every patient), although with markedly different net effect, depending on the patient.
As such, the interaction you reference is not really a contraindication per se. What’s important is that the combination of medications be accounted for. In the short-term, this is done by measuring blood tests (such as the INR) to determine the level of net anti-coagulation, so to speak, and over the longer term, adjustments can be made in the patient’s dose of warfarin to account for the addition of a second drug.
Folks on Coumadin will have the easiest time regulating their anti-coagulation if they maintain a stable diet (particularly for Vitamin K-containing foods such as spinach) and a stable suite of medications. That way, the metabolic processes can stay in balance. A short-term addition of an interfering medication such as ranitidine can throw that balance off. Ranitidine doesn’t present a problem for a monitored patient on it long-term; where it might be an issue is when you pop some every now and then.
And now, trivia time: I have read that Stalin was actually murdered by poisoning with warfarin, which triggered a hemorragic stroke. Doctors didn’t see Stalin until many, many hours after his stroke, and that apparently is what sealed his fate.
Whether this was coincidence, or whether whoever poisoned Stalin made sure to delay the arrival of doctors as much as possible, is open for debate.
If Stalin was poisoned with warfarin in the first place, of course.
From Wikipedia:
"In 2003, a joint group of Russian and American historians announced their view that Stalin ingested warfarin, a powerful rat poison that inhibits coagulation of the blood and which predisposes the victim to hemorrhagic stroke (cerebral hemorrhage). Since it is flavorless, warfarin is a plausible weapon of murder. The facts surrounding Stalin’s death will probably never be known with certainty.
His demise arrived at a convenient time for Lavrenty Beria and others, who feared being swept away in yet another purge. It is believed that Stalin felt Beria’s power was too great and threatened his own. According to Molotov’s memoirs, Beria claimed to have poisoned Stalin, saying, ‘I took him out.’ Whether Beria or anyone else was directly responsible for Stalin’s death, it is true that the Politburo did not summon medical attention for Stalin for more than a day after he was found."
And this is true of *many *of the hundreds of drug interactions with warfarin, so the OP may as well get used to it! Don’t freak out if his doctor prescribes something that the drug checker says can’t be taken with warfarin - but do make sure his doctor *knows *he’s on warfarin. If he knows, he can check levels and use (some) interacting drugs safely. If he doesn’t know, well… see Post 5.
And when in doubt, you can always call a pharmacist. They’re actually far better to call than a doctor in drug cases, as they’ve got a lot more training in pharmacology in most cases. (Plus, they tend to answer their phones and return calls more quickly!)
Don’t freak out if his doctor prescribes something that the drug checker says can’t be taken with warfarin - but do make sure his doctor *knows *he’s on warfarin. If he knows, he can check levels and use (some) interacting drugs safely. If he doesn’t know, well… see Post 5.