Menopause hormone patches are in short supply. What are they? And how do they compare with other therapies?

The federal government yesterday released its response to the Senate inquiry into issues related to menopause. The inquiry recommended the government examine options to make menopause hormone therapy (MHT, or sometimes called hormone replacement therapy) more affordable and accessible, and address drug shortages.

In response, three MHT products will be added to the Pharmaceutical Benefits Schedule (PBS): Estrogel and Estrogel Pro (gels) and Prometrium (a tablet). From March 1, this will bring the cost down to A$31.60 a month ($7.70 concession).

Some MHT skin patches are already subsidised on the PBS, but they’re in short supply globally. This is due to a combination of factors including manufacturing issues, unexpected increases in demand and the discontinuation of the Climara brand of patch.

When patients can’t access their MHT patches, they may be prescribed alternative brands that aren’t listed on the PBS, potentially costing more. Others will switch to different formulations, combinations and or strengths to try to get the same effect.

So what are MHT patches? And how do they compare with gels, tablets and other formulations?

First a quick recap of menopause

During the transition to menopause, the ovaries gradually produce less oestrogen until they stop altogether.

This hormonal change can lead to a range of symptoms, including hot flushes, night sweats, sleep disturbances, mood swings, memory problems and vaginal dryness.

Over time, the reduction in oestrogen also increases the risk of health problems such as osteoporosis.

To help reduce the sometimes-debilitating symptoms, some women may be prescribed hormone therapy. This typically includes an oestrogen hormone (such as oestradiol or conjugated oestrogens) and, for women with an intact uterus, a progestogen. Therapy with both hormones is known as combination therapy.

If taken alone, oestrogen stimulates endometrial growth, increasing the risk of endometrial hyperplasia (irregular thickening of the uterine lining) and cancer. Progestogens counteract this by promoting regular shedding.

Women without a uterus (after a hysterectomy, for example) do not require progestogens as there is no endometrium to protect.

What are the different MHT formulations?

Early MHT, used in the 1940s, used oestrogens extracted from the urine of pregnant mares. Oral formulations derived from this source, such as conjugated equine oestrogens (such as Premarin, short for PREgnant MARes’ urINe), are still available.

These days, MHT can be broken down into two types of formulations:

1. ‘Systemic’ treatments such as tablets, patches or gels

Tablets and capsules are swallowed, while patches and gels are applied to the skin.

These treatments affect the whole body and are usually best for the vasomotor symptoms such as hot flashes and night sweats, as well as to prevent bone loss.

2. ‘Localised’ treatments, such as creams and pessaries

These are inserted into the vagina, and act on the vagina and surrounding tissues. They are absorbed in very small amounts into the bloodstream, much lower than systemic treatments, and are unlikely to have significant effects on the rest of the body.

Creams and pessaries contain oestrogen alone, and are the best option for treating dryness and discomfort in the vagina.

They can also help prevent frequent urinary tract infections and improve some bladder problems, such as urinary urgency and urge incontinence.

It is possible for women to use different forms of oestrogen and progestogen in their hormone therapy regimen. They might use an oestradiol patch to deliver oestrogen, for example, and take oral progesterone to provide the necessary progestogen component.

Potential MHT side effects include oestrogen-related, headaches, breast tenderness or pain, nausea, leg cramps, mood changes, vaginal bleeding or spotting, bloating, swelling of the hands or feet, indigestion, and skin irritation with patches.

Patches vs tablets and gels

MHT patches, which have been available since the 1990s, are now more widely used and often preferred.

Patches deliver a consistent dose of hormones directly into the bloodstream through the skin, bypassing the liver. This mimics the natural release by the ovaries and provides steady hormone levels into the bloodstream.

Gels, like patches, bypass the liver. They are associated with less skin irritation than patches, making them a preferable option for people sensitive to adhesives or prone to skin irritation.

In contrast, oral formulations must be absorbed by the gut and then pass through the liver, where the drug gets processed. Some will be broken down, some will be converted to active metabolites, before entering the bloodstream. This can result in fluctuating oestrogen levels and more side effects than the more consistent delivery provided by patches.

When oral oestrogen goes through the liver, there is also an increase in the production of clotting factors. For this and other reasons, oestrogen patches have a lower risk of blood clots compared to oral tablets and capsules. Women with an elevated risk of blood clots – including those who are obese, smoke, or have a history of clotting disorders – often prefer patches.

Patches, which are applied once or twice weekly, are designed to make it easier to stick to than tablets and gels MHT, which requires daily dosing.

What if you need to switch?

Currently, both oestrogen and combination skin patches are in short supply in Australia.

The differences in absorption and metabolism between formulations mean that switching directly from one dosage form to another might not maintain the same level of symptom control or could cause new side effects.

MHT guidelines provide prescribers with information on dose equivalence between formulations – for example, switching from an oestrogen-containing patch to a gel or tablet – ensuring women have a range of options available and for treatment to be tailored to their individual needs.

To address the shortages, the Therapeutic Goods Administration (TGA) has enabled pharmacists to dispense alternative brands or strengths of estradiol patches without requiring a new prescription. This might mean, for example, two lesser strengths that add up to the strength prescribed.

The TGA also temporarily approved the supply of MHT patches from the United States in June, and listed them on the PBS, but these are now also in short supply.

What if you’re new to MHT?

The TGA is advising prescribers to consider current shortages when initiating patients on MHT.

First-time MHT patients may be prescribed readily available formulations to avoid therapy changes and to preserve stock for those already using patches.

The TGA expects some patches to be out of stock until December 2025 and provides regular updates about the estimated dates the patches will be available again.