Dosages for prophylactic antibiotics?

[acs80.livejournal.com]

Hi there!

I take a prophylactic antibiotic (50 mg of Nitrofurantoin, which is generic for Macrodantin) when I have sex to prevent UTIs, as ordered by my urologist. My boyfriend and I had sex today around 10:30 a.m., and I took the antibiotic immediately afterward. Then we had sex again a few hours later, around 1:30 p.m. I didn't take another pill after that, figuring the one I took earlier in the day would still be in my system. Was that stupid of me? Should I have taken another antibiotic after I had sex for the second time? Does anyone know anything about this? The Wikipedia article on Nitrofurantoin said the half-life of the drug is 20 minutes, but I really don't know what that means.

I'd be really grateful for any help you can give me! I'm going on a trip in a few days and can't afford to get a UTI right now.

Comments

[arularia.livejournal.com]

I'd call your provider and ask them explicitly how you should handle days in which you have sex multiple times.

[acs80.livejournal.com]

Thanks -- but it's Sunday, and they're not in their office. I figured I should take action before tomorrow, since a UTI can develop kind of rapidly.

[pushi5236.livejournal.com]

To my understanding, the half-life of an antibiotic is the time it takes for half of the medication to be flushed from your blood stream. I've read (if I'm interpreting it correctly) that it takes four cycles of the half-life for it to be fully removed (according to this website: http://bipolar.about.com/od/glossary/g/gl_medhalflife.htm).

That being said, even if it did take 80 minutes to leave your system completely, you had sex 180 minutes after. I don't think the medication was in your system any longer when you had sex the second time, but this doesn't mean that you definitely have a UTI. Watch the color and pay attention to the frequency and sensation of urination for the next few days (you probably already know to do that, though).

Also, I have had problems with UTIs and found a cranberry supplement which strengthens the integrity of the bladder, should bacteria make its way up. It's kind of like a built in defense system. It's pretty cheap and obviously over the counter. I got mine at Wal-Mart! I've not had a UTI since taking two per day, every day. You probably already know about the water and peeing thing, so I'm not going to elaborate any more.

I hope this helps, and really hope you don't feel badly for your trip. Maybe run and get a script from your doctor for some ciprofloxacin (or your antibiotic of choice) just in case.

[acs80.livejournal.com]

Thanks. I also took some cranberry, hoping that it would make a difference if I were going to develop a UTI.

[pushi5236.livejournal.com]

http://www.mayoclinic.com/health/drug-information/DR601017

MayoClinic rocks with medical questions. Read the dosage portion, and see if it corresponds to yours. It looks like you only need to take it once a day. I think you will be fine!

[acs80.livejournal.com]

I appreciate you doing that homework for me! Let's hope you're right! Thank you!

[pushi5236.livejournal.com]

No problem! Hope all is well. Nobody likes pee that burns, haha :)

[kuangning]

Y'know, a prophylactic antibiotic sounds like an awfully good way to develop antibiotic-resistant infections to me. As bad as urinary tract infections can be, MRSA is many times worse -- and communicable to other people, unlike the UTI. I'm kind of surprised at your urologist, though I suppose if you do come down with MRSA, s/he's not going to be the one who has to treat it...

[acs80.livejournal.com]

I think using antibiotics prophylactically is a fairly common practice for preventing UTIs, actually.

[kuangning]

That doesn't negate the problem, though. Things like this (and the wonderful cost-cutting measure of "half-courses" of antibiotics) is why we have rising rates of antibiotic-resistant infections in the wild, when they used to only be seen in hospital settings.

[acs80.livejournal.com]

Right, I understand. But I think that the logic is, better to take one very small-dose antibiotic to prevent an infection than take a larger dose of a more powerful antibiotic for a longer period to treat one.

Also, nitrofurantoin is only used to prevent (and in some cases, treat, though it's not the preferred drug for an active UTI) uncomplicated UTIs, while Cipro, for example, one of the most common antibiotics to treat cystitis, can be used to treat a number of infections. I think by prescribing prophylactic antibiotics, urologists are trying to reserve Cipro and other more potent broad spectrum antibiotics for treatment.

[kuangning]

It's primarily used for that now, because it's not as effective as the other drugs. However, with resistance rates to the other drugs increasing, it is being looked at as a fallback for a few other drugs, such as the pretty-common metronidazole. I guess your urologist isn't worried, and is the one I should really have this discussion with to do any good, but what happens if/when we do> need it as a fallback and there's already immunity to it as well?

[christemo.livejournal.com]

Can I please see your medical degree?
Exactly. I'm on oral antibiotics for a year. For the first two months, it was to kill a bacteria, for the next ten, it's to prevent it EVER from growing back. It's the only way to treat some diseases/prevent them. This is also my second time of being on amoxil for a year, and well, I'm still not resistant to it. ;)

[kuangning]

Please don't be disingenuous; it is not like antibiotic resistance is a deep trade secret known only to doctors. I have two family members currently in health professions (nursing) and am planning to take up a different health profession (midwifery) myself. Even fifteen years ago when I was doing clinicals in an RN program though, they were warning us about antibiotic resistance. Here, have a link on nitrofurantoin as a replacement for metronidazole. Have another on those resistant to nitrofurantoin being resistant to metranidazole too: the abstract is so neatly put you don't even have to do the free signup. I hope the Oxford Journal at least is authoritative source enough for you? I mean, since you don't believe anything unless it comes from someone with a medical degree, regardless of whether they're telling you truth a ten-year-old could verify in a twenty-second Google search.

There is also a huge difference between a continuous course of antibiotics strong enough to actually kill the bacteria and small, weak, intermittent doses. The former doesn't leave any half-treated bacteria behind to become resistant; the latter does. Also, no matter how long you take the antibiotic, once you stop taking it, the bacteria can come back. An antibiotic is not an inoculation against the bacteria. The original use of preventative antibiotics is before a surgical procedure where they don't want you to contract a nosocomial infection and they know once you go home you're not likely to come in contact with the same bacteria you'd find in the hospital. Giving small, intermittent doses for a bacteria you come in contact with all the time is a fairly sure recipe for eventual bad.

[frolicnaked.livejournal.com]

At the same time, though, we're talking about a decision reached by a particular individual and her health care provider. Given that antibiotic resistance isn't a big secret, it's entirely possible that both the OP and her doctor made informed and carefully weighed decisions to prescribe and use this treatment. I'm lucky enough not to be prone to frequent UTIs, but it's my understanding that for some people, this is the only thing that works to avoid them.

Either way, it seems like the OP's intent in posting was to get input on prophylactic antibiotic in a specific set of circumstances. Second-guessing the OP's choice of medical treatment isn't likely to answer that question or to be of help to her.

[kuangning]

That's a fair point, and is the reason I said above that I should probably be having this discussion with the health care provider instead. That would be the comment right before someone else came along to suggest in a really flippant way that nothing I said had validity because I didn't wave a medical degree around. ;)

[cyberpurple.livejournal.com]

When I was on prophylactic nitrofurantoin for UTI (six in seven months) my dosage was 50mg daily for three months.