Medication Mistake

My mother has accidentally been given quadruple the standard dose of Letrozole (Femara) at the nursing home she is in (recovering from a back issue) -- for about 4 weeks. So she has been getting 4 pills every morning instead of just one. Instead of 2.5mg a day (which I believe is the standard dose everyone gets), she has been getting 10mg a day. Since she has been there she has lost the ability to walk, every muscle hurts when she tries to stand up, she can't sleep and she is weakened. Of course there are other drugs and things going on too, but I was wondering if anyone knows if this high dose of letrozole can cause her side effects? I want to give her hope that once she gets back to a normal level that she will recover. Her oncologist seems to think all of the symptoms are from treatment, not the cancer. Any prescription drug error is important but I am not sure if we should make a big deal out of this or just let it go....how much is too much letrozole? Also, she is elderly.

Hi meghar:

Please be sure to raise this issue as soon as possible with her Medical Oncologist, and provide information both about the over-dose (10 mg/day) and length of time it was received (~ 4 weeks).

Meanwhile, I went to the FDA web site drug search page, searched Letrozole, chose the brand name Femara option, and downloaded the latest FDA label (01/15/2014):

FDA Search Page: http://www.accessdata.fda.gov/scripts/cder/drugsat...

Femara (Letrozole) Label: http://www.accessdata.fda.gov/drugsatfda_docs/labe...

In Section 10, "Overdosage" it states:

'In single-dose studies, the highest dose used was 30 mg, which was well tolerated; in multiple-dose trials, the largest dose of 10 mg was well tolerated."

So, in some studies, it appears that multiple doses of 10 mg were administered and were well-tolerated, which is good news for tonight. Also, Section 12.2, "Pharmacodynamics" describes administration of 5 mg doses. What is not clear is the length of time these 5 and 10 mg doses were given, since there is no citation.

Hopefully, your Mom will not be harmed by this error and the MO can confirm the above and provide more information.

BarredOwl

P.S. If you have not done so already, please also ask what steps have been taken to correct the error, and ensure that the correct dose is administered going forward. Maybe for all her meds.