When does diarrhea start when taking Nerlynx?

Q: When does diarrhea start when taking Nerlynx?

Diarrhea can start as soon as you start taking Nerlynx – 93% of women experienced diarrhea within the first month of treatment (average time to the onset of diarrhea was 8 days) in trials that did not require anti-diarrheal medication to be taken at the same time. However, the risk of diarrhea developing is greatly reduced in those who take loperamide, an antidiarrheal medication, at the same time as Nerlynx.

Medically reviewed by Carmen Pope, BPharm. Last updated on Aug 14, 2024.

Official Answer by Drugs.com

Diarrhea is a common side effect of Nerlynx (neratinib) and diarrhea was experienced by 95% of women in clinical trials that did not receive anti-diarrhea medications while taking Nerlynx. 93% experienced diarrhea within the first month of treatment and the average time to the onset of diarrhea was 8 days.

However, the risk of this side effect can be greatly reduced if loperamide (brand names include Imodium, Kaopectate 1-D) is started on the same day as Nerlynx is started, instead of just waiting to see if you develop diarrhea or not.

The usual starting dose of Nerlynx is 240mg once daily. Loperamide should be started on the same day Nerlynx is started and the recommended dose is:

Days 1 to 14: loperamide 4mg by mouth 3 times per day
Days 15 to 56: loperamide 4mg by mouth 2 times per day
Days 57 to 365 (or until Nerlynx is stopped): loperamide 4mg when needed so that only one or two bowel motions per day are experienced, but do not take more than 16mg per day.

To minimize your risk of diarrhea:

Always take loperamide exactly as your health care provider has told you to take it
If you have more than two bowel movements in one day, or you have diarrhea that doesn’t go away, tell your health care provider
Call your health care provider immediately if you have severe diarrhea or experience weakness, dizziness, or fever at the same time as diarrhea
If you develop severe diarrhea, fluid and electrolytes will also be needed. Ensure you drink about 2 liters of fluid a day anyway, to avoid dehydration.
You may be able to decrease the dose of your loperamide after two weeks of Nerlynx treatment, and then again after 56 days of Nerlynx treatment
If you develop diarrhea but your diarrhea resolves to Grade 0-1 in one week or less, your doctor may resume Nerlynx treatment at the same dose
If you develop diarrhea, but it takes longer than one week for diarrhea to resolve, then Nerlynx should be resumed at a reduced dose
With Grade 4 diarrhea, Nerlynx should be permanently discontinued.

Why does Nerlynx cause diarrhea?

It is not known exactly why Nerlynx causes diarrhea; however, experts have suggested it may be due to epidermal growth factor receptor inhibition in cells lining the intestinal tract, which may disrupt the protective mucosal lining. In addition, Nerlynx use may also result in some inflammation within the GI tract as well as reducing the reabsorption of bile acids in the small part of the intestine.

93% of patients taking Nerlynx who were not prescribed anti-diarrhea medication experienced diarrhea within the first month of Nerlynx treatment. Grade 3 diarrhea occurred in 40% and Grade 4 diarrhea occurred in 0.1% of patients.

The average time to the first onset of Grade 3 or greater diarrhea was 8 days (range was one day to 350 days) and the average length of time the grade 3 or greater diarrhea persisted for was 5 days (range one day to 139 days).

References

Manage Diarrhea in Patients Receiving Nerlynx® (Neratinib) Tablets May 11, 2018, Puma Biotechnology https://voice.ons.org/news-and-views/manage-diarrhea-in-patients-receiving-nerlynxr-neratinib-tablets#:~:text=Severe%20diarrhea%20and%20sequelae%2C%20such,epidermal%20growth%20factor%20receptor%20inhibition
Nerlynx (neratinib) https://www.drugs.com/pro/nerlynx.html
Nerlynx (neratinib) Nerlynx.com https://nerlynx.com
Nerlynx Breastcancer.org 2020 https://www.breastcancer.org/treatment/targeted_therapies/nerlynx#:~:text=Nerlynx%20is%20a%20pill%20taken,take%20Nerlynx%20for%201%20year

Can you drink alcohol with Nerlynx?

Although there is no direct interaction between alcohol and Nerlynx, you should not drink excessive quantities of alcohol while you are taking Nerlynx, because it may increase the risk of side effects such as diarrhea, dehydration, dizziness, and liver problems; as well as increase your cancer risk. It is OK to have a glass of alcohol every now and then while taking Nerlynx. Continue reading

Does Nerlynx cause hair loss?

Hair loss has not been reported as a side effect of Nerlynx. Hair loss is also not an anticipated side effect of Nerlynx because of the targeted way that it works, so if hair loss were to occur, it is probably due to other causes. Continue reading

How does Nerlynx (neratinib) work?

Nerlynx is a type of targeted treatment that works by irreversibly binding to and inhibiting specific receptors on the surface of cancer cells called HER2, HER4, and EGFR receptors. These receptors receive signals that tell cancer to grow and spread. By inhibiting HER2 and EGFR receptors, Nerlynx prevents HER2 positive breast cancer cells from growing and multiplying. Continue reading

When does diarrhea start when taking Nerlynx?

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