Aromatase inhibitors

After menopause, the ovaries stop producing oestrogen, but small amounts are still made in other parts of the body such as the adrenal glands, fat tissue, and muscle.

This happens through an enzyme called aromatase, which converts other hormones into oestrogen. Aromatase inhibitors work by blocking this enzyme, reducing oestrogen levels in the body. This helps lower the risk of breast cancer coming back, reduces the chance of developing a new breast cancer, and can improve overall survival.

Aromatase inhibitors are most commonly used in post-menopausal women, whose ovaries are no longer producing oestrogen. In some cases, they may also be used in pre-menopausal women, along with medications like Zoladex that temporarily stop the ovaries from making oestrogen.

There are three main types of AIs: letrozole, anastrozole, and exemestane

Anastrozole (Arimidex), letrozole (Femara) and exemestane (Aromasin) all work in similar ways to reduce the amount of oestrogen made in the body.

No one drug is better than the other, your specialist doctor will explain why they have recommended a particular AI for you.

Anastrozole is used to treat oestrogen receptor (ER+) positive breast cancer in both pre-menopausal women who are having ovarian suppression, and post-menopausal women.

It can also be taken by men who have oestrogen receptor (ER+) positive breast cancer, however, tamoxifen is more commonly used.

Anastrozole (also called Arimidex) is a hormone (endocrine) therapy drug. It is used to treat oestrogen receptor (ER+) positive breast cancer.

Anastrozole works by reducing the amount of oestrogen made in the body - a process involving an enzyme called aromatase that converts other hormones into oestrogen. Anastrozole works by blocking the enzyme aromatase, preventing the breast cancer cells from getting the hormones they need to grow.

Dose of anastrozole?

In Aotearoa New Zealand, anastrozole is available as tablets (1mg).

The usual dose of anastrozole is 1 tablet (1mg) taken once a day.

Always take anastrozole exactly as your specialist team and/or GP, and pharmacist has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it, and any special instructions.

These tablets contain a type of sugar called lactose. If you have a lactose intolerance, talk to your specialist team or GP before taking this drug.

Timing:

Take anastrozole at the same time each day, you can choose to take it in the morning or evening.

With or without food:

You can take anastrozole with or without food.

What if I forget to take a dose:

If you forget to take a dose, take it as soon as you remember. But if it’s nearly time to take your next dose, just take the next dose at the right time. Do not take a double dose.

Keep taking anastrozole regularly:

It it important to take anastrozole every day for the recommended length of time (it is a long-term treatment taken over several years). Taking anastrozole everyday will reduce the amount of oestrogen made in the body, slowing or stopping the growth of cancer calls

Letrozole is used to treat oestrogen receptor (ER+) positive breast cancer in both pre-menopausal women who are having ovarian suppression, and post-menopausal women.

It can also be taken by men who have oestrogen receptor (ER+) positive breast cancer, however, tamoxifen is more commonly used.

Letrozole works by reducing the amount of oestrogen made in the body - a process involving an enzyme called aromatase that converts other hormones into oestrogen. Letrozole works by blocking the enzyme aromatase, preventing the breast cancer cells from getting the hormones they need to grow.

Dose of Letrozole?

In Aotearoa New Zealand, letrozole is available as tablets (2.5mg).

The usual dose of letrozole is 1 tablet (2.5mg) taken once a day.

Always take letrozole exactly as your specialist team and/or GP, and pharmacist has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it, and any special instructions.

These tablets contain a type of sugar called lactose. If you have a lactose intolerance, talk to your specialist team or GP before taking this drug.

Timing:

Take letrozole at the same time each day, you can choose to take it in the morning or evening.

With or without food:

You can take letrozole with or without food.

What if I forget to take a dose:

If you forget to take a dose, take it as soon as you remember. But if it’s nearly time to take your next dose, just take the next dose at the right time. Do not take a double dose.

Keep taking letrozole regularly:

It it important to take letrozole every day for the recommended length of time (it is a long-term treatment taken over several years). Taking letrozole everyday will reduce the amount of oestrogen made in the body, slowing or stopping the growth of cancer cells.

Exemestane (also called Aromasin) is used to treat oestrogen receptor (ER+) positive breast cancer in both pre-menopausal women who are having ovarian suppression, and post-menopausal women.

It can also be taken by men who have oestrogen receptor (ER+) positive breast cancer, however, tamoxifen is more commonly used.

Exemestane works by reducing the amount of oestrogen made in the body - a process involving an enzyme called aromatase that converts other hormones into oestrogen. Letrozole works by blocking the enzyme aromatase, preventing the breast cancer cells from getting the hormones they need to grow.

Dose of exemestane?

In Aotearoa New Zealand, exemestane is available as tablets (25mg).

The usual dose of exemestane is 1 tablet (25mg) taken once a day.

Always take exemestane exactly as your specialist team and/or GP, and pharmacist has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it, and any special instructions.

Timing:

Take exemestane at the same time each day, you can choose to take it in the morning or evening.

With or without food:

It’s best to take exemestane after a meal.

What if I forget to take a dose:

If you forget to take a dose, take it as soon as you remember. But if it’s nearly time to take your next dose, just take the next dose at the right time. Do not take a double dose.

Keep taking exemestane regularly:

It it important to take exemestane every day for the recommended length of time (it is a long-term treatment taken over several years). Taking exemestane everyday will reduce the amount of oestrogen made in the body, slowing or stopping the growth of cancer cells.