Great News (Tobra and Breastfeeding)

On Monday night, Greg asked me why I can't nurse Lillian while I'm on IV tobra. I told him I wasn't sure and went to Dr. Google. Everything I found online said that it Tobra was a pregnancy category D medication, but that it was safe for breastfeeding. Dr. Google said that, because Tobra is poorly absorbed when taken orally (and hence the reason it's not available orally), it is not a breastfeeding risk.

I know not to trust what I find on the internet, but it made me want a second opinion. So, yesterday morning I spent about three hours on the phone.

I called Lily's pediatrician's office, and the nurse seemed confused as to why my CF doctor said I couldn't nurse. She said that it was fine to nurse while on Tobra. I called my lactation consultant. She looked up the drug in Dr. Hale's book and read that it was safe for nursing. She then referred me to Dr. Hale's Infant Risk Center. The Infant Risk Center has a hotline you can call to find out about the safety of a drug while pregnant or breastfeeding. The Infant Risk Center told me the following (I was typing while the woman spoke):

Tobra is considered a lactation risk L3, (on a scale of L1 to L5, which L1 being the safest and L5 meaning do not nurse while on this mediation). They said that levels in milk are low but could cause changes in a baby's gut flora. They quoted a study where a woman was given 150 mg three times a day. Tobra was not detectable in any milk samples, and no side effects were noted in infant. In another study, a woman was given 80 mg every 8 hours and the Tobra was detected in her milk at very low levels. They also explained that 2.6% of what I get ends up in my milk and that Tobra has a 2-3 hr half life. Based on this, they suggested waiting 3 hours until I nurse so that half of the Tobra would be out of my system.

Both studies and one additional one are listed on this site: http://www.drugs.com/breastfeeding/tobramycin.html, which the pharmacist at the home infusion company printed out for me.

After getting all of this information, I called my brother (an MD) and sister-in-law (a pedi NP). My sister-in-law suggested that I pump and dump about three hours after administering the Tobra, just to be extra safe. This is based on what they recommended to nursing women who were taking illicit drugs (apparently not all drugs are re-absorbed back into the bloodstream the way alcohol is, so the levels in my breastmilk may not be the same as the levels in my blood).

I also passed the information on to my CF doctor. He confirmed that his recommendation was based on the pregnancy category. He said he was okay with me nursing as long as I had done my research, but wanted to make sure that I knew that the affect of doing so is unknown (as it is the case for most drugs!).

Based on all of this, here is the plan: Because I only have to administer Tobra once a day, I will do it at 5:30pm and won't nurse Lily before bed. I will pump and dump at 9:30, (I rented a hospital-grade pump because I haven't been responding well to my Medela Freestyle). And that will give us at least 12 hours (4-6 half-lives) between administering the Tobra and nursing.

This is what we did last night and it went surprisingly well. The last time I nursed her was 4:00. After that, we tried to give her formula, but she rejected it. Instead, we gave her an early dinner at 5:30 and a snack at 7:30. Greg put her to bed at 8:00 and she cried for a few minutes and went to sleep! During the night she only woke up a couple of times and cried for a few minutes, but that was it. MUCH easier than I thought it would be!

I am so relieved and so happy that we can continue nursing!