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rinueA few days ago, I came down with a UTI, which has only happened to me once before, and which, like last time, only took three hours to go from asymptomatic to pissing alarming amounts of blood. And since it was late, and a long weekend, I had to go to the emergency room. First time ever.
In any case, the antibiotic I'm on is 500mg of Levaquin daily for ten days. Levaquin is the trade name for levofloxacin, which is a third-generation fluoroquinolone. Since I am already feeling much better (although sleepy, dizzy, and unable to handle bright sunlight - all side-effects of the medication), I am quite reasonably trying to figure out whether there is any drug interaction between Levaquin and my birth control pill (Microgynon30, which is 150 micrograms levonorgestrel and 30 micrograms ethinyl estradiol).*
The literature has not been helpful, partly because the female reproductive system, like the minds of the mentally ill, seems to be viewed with fear and superstition by most doctors; and mainly because pharmaceutical companies are (sensibly but infuriatingly) more concerned about minimizing their legal risk than finding the truth of the matter, and so will always suggest the most extreme precautions possible with no care for whether they are necessary. Pharmacists and doctors are the same way. Although we treat medicine as though it is a science, more often the methodology is "well, this can't hurt, so we might as well just in case it helps something." In a life-and-death situation, one understandably attempts to minimize all risks, but the unwanted side effect is blooming medical costs and doctoring that can be a bit too witch-doctor for my tastes.
Thus far, I have uncovered two items which are scientifically useful, and one which is dubious but provides clues.
useful:Swedish researchers performed a clinical trial to see whether fluoroquinolone in any way altered the effects of oral contraceptives. They found that it did not: none of the 20 women in the study ovulated during any of six contraceptive pill cycles. For this study, they were using the very same contraceptive I do, but were using a second-generation form of fluoroquinolone (oxoflacin), which is only half as strong as levaquin (which I am taking). I am also not positive it included enough subjects to be statistically sound. The pill's failure rate without antibiotics is 1-3% per year, and they tested only 20 women for half a year.
useful: Three recent peer-reviewed articles suggesting that birth control failure rates while on antibiotics are no different than birth control failure rates when not on antibiotics. The three articles cited appear to be meta, in that instead of conducting new studies they review other studies and report statistical data. This kind of number crunching is not my favorite form of science, and makes me naturally wary, but the second article in particular provides an excellent evidence summary, and I find it persuasive. [The articles also suggest that a small subset of women with uncommonly low steroid hormone levels may be susceptible to higher failure rates, but I am not one of those women (or at the very least have never displayed such symptoms.)] Considering I questioned the earlier study's sample size, I'm almost obligated to go with the weight of numbers in these metareviews from respectable sources (one by the generally conservative American Medical Association).
clueful: When reading the literature on Microgynon, it lists a number of drugs which definitely compromise The Pill. Among them are rifampicin and rifabutin, which were also mentioned in other studies as antibiotics that really do require a backup non-hormonal birth control method, because they speed up the breakdown of hormones in the liver. Both are part of the rifamycin family, an early and classic antibiotic group used widely in the 1960s, when the pill first came out. I suspect it is for this reason that the link was made between birth control failure and antibiotics - when one said antibiotic, one probably meant rifmyacin.
Reading further in the literature, we hit the dubious part:
It's the twice-repeated "very low" that gets to me, with no statistic attached and no explanation for why there would be an interaction. Birth control itself, as mentioned earlier, already has its own very low conception risk. So what this sounds like to me is a company or pharmacist covering its ass, just in case, because they want to make sure you think it's your fault and not theirs if your contraception fails, even though it does fail for 1-3% of pill-using women a year, even under laboratory conditions.
(Along the same lines, most pill manufacturers will stress the importance of taking the pill at the exact same time every day, even though, really, what with how different livers metabolize at different rates, half an hour is not going to make a difference, other than that if it then does fail - as it will a certain percentage of the time - you'll be able to blame yourself. And if you take it at exactly the same time every day, you'll probably still be able to come up with a reason that it's your fault instead of bum luck.**)
Because I am a completist, I went ahead and called the pharmacy, even though I was pretty sure they would just give me the company line. I'd rather have called the emergency room doctor, who I liked, and who seemed to be on top of things, and who explained to me the history of cranberries, vinegar, etc. My type of guy. However, I suspect he's busy. I would also like to talk to a gynecologist I trust, but didn't want to call Texas long distance. (I might still do it, though. Completist.)
Surprise surprise, the pharmacist said "use a backup." Without pause. Without considering that I take my pills continually and have not had a gap in two months - so that even if Levaquin prevented all absorption of birth control hormones, I would still be in the clear for a week (although not after the week was up), just as though I was taking the usual monthly break.*** There would be cause to worry if Levaquin was a fertility drug and caused ovulation on its own, but it is not and does not. I can't find any instance of it being used for follicle stimulation, etc. If it had such an effect, drug companies would certainly capitalize on it - the market in fertility drugs is huge right now. But, no, it's an antibiotic.
Basically, it looks like the reputed link between contraceptive failure and antibiotics is an urban legend founded on the real interaction of hormones and rifamycin. It may be widely dissiminated in contraceptive literature, but this is probably to satisfy a nervous legal department. Chemistry, research, and statistics are all on my side.
What makes me furious is that I'm probably going to have to use a condom anyway.
I know - I am positive - that if I were to get pregnant now, it would simply be a normal failure of the pill and nothing whatever to do with Levaquin. By a similar token, my UTI, the first in five or six years, happened to occur at the same time that Mom got one, the first in three years. There is no way I got it from her, as it is not communicable - it is a function of E-coli bacteria moving up the urethra, and is a self-infection. Wildly against the odds, Mom and I both got it at the same time while in the same house, and so when I first suspected I had it, I knew my sister would not believe me and would assume I was being a hypochondriac - which she would not have done had my mom not also had it.
So if I got pregnant now, it would always be my fault, growing from my own orneriness, and I would never be forgiven. Even though the odds weren't any greater than they ever were.
Thinking about it makes me so angry I start crying.
*Coincidentally, Microgynon and Levaquin are made by the same pharmaceutical company. This has no effect other than that it makes it harder to Google both at the same time - I get a lot of stock reports mixed in.
**Possibly this is connected many people's willingness to play roulette - they must believe they actually have an influence over the odds. The sound of the roulette ball and wheel spinning is pretty great, though. Why isn't that sampled all over the place?
***I would also immediately notice this was happening, because I'd bleed.
In any case, the antibiotic I'm on is 500mg of Levaquin daily for ten days. Levaquin is the trade name for levofloxacin, which is a third-generation fluoroquinolone. Since I am already feeling much better (although sleepy, dizzy, and unable to handle bright sunlight - all side-effects of the medication), I am quite reasonably trying to figure out whether there is any drug interaction between Levaquin and my birth control pill (Microgynon30, which is 150 micrograms levonorgestrel and 30 micrograms ethinyl estradiol).*
The literature has not been helpful, partly because the female reproductive system, like the minds of the mentally ill, seems to be viewed with fear and superstition by most doctors; and mainly because pharmaceutical companies are (sensibly but infuriatingly) more concerned about minimizing their legal risk than finding the truth of the matter, and so will always suggest the most extreme precautions possible with no care for whether they are necessary. Pharmacists and doctors are the same way. Although we treat medicine as though it is a science, more often the methodology is "well, this can't hurt, so we might as well just in case it helps something." In a life-and-death situation, one understandably attempts to minimize all risks, but the unwanted side effect is blooming medical costs and doctoring that can be a bit too witch-doctor for my tastes.
Thus far, I have uncovered two items which are scientifically useful, and one which is dubious but provides clues.
useful:Swedish researchers performed a clinical trial to see whether fluoroquinolone in any way altered the effects of oral contraceptives. They found that it did not: none of the 20 women in the study ovulated during any of six contraceptive pill cycles. For this study, they were using the very same contraceptive I do, but were using a second-generation form of fluoroquinolone (oxoflacin), which is only half as strong as levaquin (which I am taking). I am also not positive it included enough subjects to be statistically sound. The pill's failure rate without antibiotics is 1-3% per year, and they tested only 20 women for half a year.
useful: Three recent peer-reviewed articles suggesting that birth control failure rates while on antibiotics are no different than birth control failure rates when not on antibiotics. The three articles cited appear to be meta, in that instead of conducting new studies they review other studies and report statistical data. This kind of number crunching is not my favorite form of science, and makes me naturally wary, but the second article in particular provides an excellent evidence summary, and I find it persuasive. [The articles also suggest that a small subset of women with uncommonly low steroid hormone levels may be susceptible to higher failure rates, but I am not one of those women (or at the very least have never displayed such symptoms.)] Considering I questioned the earlier study's sample size, I'm almost obligated to go with the weight of numbers in these metareviews from respectable sources (one by the generally conservative American Medical Association).
clueful: When reading the literature on Microgynon, it lists a number of drugs which definitely compromise The Pill. Among them are rifampicin and rifabutin, which were also mentioned in other studies as antibiotics that really do require a backup non-hormonal birth control method, because they speed up the breakdown of hormones in the liver. Both are part of the rifamycin family, an early and classic antibiotic group used widely in the 1960s, when the pill first came out. I suspect it is for this reason that the link was made between birth control failure and antibiotics - when one said antibiotic, one probably meant rifmyacin.
Reading further in the literature, we hit the dubious part:
Other antibiotics do not affect the breakdown of the pill by the liver. However, if you are prescribed another antibiotic medicine (eg amoxicillin, doxycycline) while taking this contraceptive, there is a very low risk that the antibiotic may make your pill less effective at preventing pregnancy. Although the risk of this is very low, the personal and ethical consequences of an unwanted pregnancy can be very serious. For this reason, it is recommended that you use an extra method of contraception (eg condoms) while you are taking the antibiotic and for seven days after finishing the course.
It's the twice-repeated "very low" that gets to me, with no statistic attached and no explanation for why there would be an interaction. Birth control itself, as mentioned earlier, already has its own very low conception risk. So what this sounds like to me is a company or pharmacist covering its ass, just in case, because they want to make sure you think it's your fault and not theirs if your contraception fails, even though it does fail for 1-3% of pill-using women a year, even under laboratory conditions.
(Along the same lines, most pill manufacturers will stress the importance of taking the pill at the exact same time every day, even though, really, what with how different livers metabolize at different rates, half an hour is not going to make a difference, other than that if it then does fail - as it will a certain percentage of the time - you'll be able to blame yourself. And if you take it at exactly the same time every day, you'll probably still be able to come up with a reason that it's your fault instead of bum luck.**)
Because I am a completist, I went ahead and called the pharmacy, even though I was pretty sure they would just give me the company line. I'd rather have called the emergency room doctor, who I liked, and who seemed to be on top of things, and who explained to me the history of cranberries, vinegar, etc. My type of guy. However, I suspect he's busy. I would also like to talk to a gynecologist I trust, but didn't want to call Texas long distance. (I might still do it, though. Completist.)
Surprise surprise, the pharmacist said "use a backup." Without pause. Without considering that I take my pills continually and have not had a gap in two months - so that even if Levaquin prevented all absorption of birth control hormones, I would still be in the clear for a week (although not after the week was up), just as though I was taking the usual monthly break.*** There would be cause to worry if Levaquin was a fertility drug and caused ovulation on its own, but it is not and does not. I can't find any instance of it being used for follicle stimulation, etc. If it had such an effect, drug companies would certainly capitalize on it - the market in fertility drugs is huge right now. But, no, it's an antibiotic.
Basically, it looks like the reputed link between contraceptive failure and antibiotics is an urban legend founded on the real interaction of hormones and rifamycin. It may be widely dissiminated in contraceptive literature, but this is probably to satisfy a nervous legal department. Chemistry, research, and statistics are all on my side.
What makes me furious is that I'm probably going to have to use a condom anyway.
I know - I am positive - that if I were to get pregnant now, it would simply be a normal failure of the pill and nothing whatever to do with Levaquin. By a similar token, my UTI, the first in five or six years, happened to occur at the same time that Mom got one, the first in three years. There is no way I got it from her, as it is not communicable - it is a function of E-coli bacteria moving up the urethra, and is a self-infection. Wildly against the odds, Mom and I both got it at the same time while in the same house, and so when I first suspected I had it, I knew my sister would not believe me and would assume I was being a hypochondriac - which she would not have done had my mom not also had it.
So if I got pregnant now, it would always be my fault, growing from my own orneriness, and I would never be forgiven. Even though the odds weren't any greater than they ever were.
Thinking about it makes me so angry I start crying.
*Coincidentally, Microgynon and Levaquin are made by the same pharmaceutical company. This has no effect other than that it makes it harder to Google both at the same time - I get a lot of stock reports mixed in.
**Possibly this is connected many people's willingness to play roulette - they must believe they actually have an influence over the odds. The sound of the roulette ball and wheel spinning is pretty great, though. Why isn't that sampled all over the place?
***I would also immediately notice this was happening, because I'd bleed.
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(no subject)
Date: 2007-09-05 01:01 am (UTC)(no subject)
Date: 2007-09-05 09:33 pm (UTC)P.S. Am excited about the Sigur Ros doc you sent Ciro the link to.
P.P.S. Glad your first week of school was a thorough success. Wow!
(no subject)
Date: 2007-09-23 08:46 pm (UTC)I went through the same damn thing. Thankfully, one of my doctors (I think it was my urologist, but then when i try to picture him saying it, I can't, so maybe it was pulmonary or gynecology?), though less specifically than your research found, that the chance of it affecting it was very low, and that besides, that specific antibiotic should not affect it. I can't remember if I was on Levaquin or the mic-something - actually, I think I was on both? - but at any rate, very similar findings. I was really surprised, myself!
(no subject)
Date: 2007-09-23 08:54 pm (UTC)And I'm extra extra extra angry that there are still people who don't think female ejaculation exists.
Women's bodies aren't that mysterious, goddamnit!
Honestly this kind of fuzzy thinking is a problem I have with medicine at large, it's just that with the woman stuff you're also supposed to be ashamed for asking about it.
Incidentally, have continued to read Julie/Julia in spurts. Am in mid-April currently.