The Gender Pain Gap

simple meter illustrating pain relief on a scale from low to high

Pain management is an important part of patient care for LTC facilities. As with most areas of healthcare, providers can’t afford to take a one-size-fits-all approach to prescribing or administering pain relief drugs. Specifically, pain medications must be tailored to the individual: and gender in particular is an important factor to be taken into account.

For most of the 20th Century, pharmaceutical research has largely used biological male anatomy as its standard for new drug testing. But numerous studies are raising awareness that men and women have a gender pain gap because many pain medications have a different level of effectiveness on women.

Morphine, for example, is one of the most common painkillers in use, yet it does not have the same effect on both sexes. A study cited in the October 2008 issue of the American Association of Nurse Anesthetists (AANA) Journal found female surgery patients undergoing general anesthesia required 30 percent more morphine than males. Another study showed nalbuphine–a pain medication given to women during childbirth–is not nearly as effective on men.

Scientists attribute these effects to variations in the neurological physiology of male and females. Both morphine and nalbuphine relieve pain by activating opioid receptors in the brain. Opioid receptors are molecular sites on the outer membrane of a cell that can cause a chemical reaction inside the cell when they come in contact with an opioid. Specifically, opioid receptors block neurons from transmitting pain signals.

Opioid receptors come in a variety of subclasses. The three primary classes are: mu, kappa and delta. Morphine binds to mu receptors while nalbuphine binds to kappa receptors. PET scans have shown mu receptors play a dominant role for pain relief in men while kappa receptors dominate in females.

To complicate matters further, pain transmission for women can be affected by the level of estrogen in their system. Specifically, when estrogen levels are higher the female body responds more dramatically by releasing more endorphins and enkephalins. This could explain why postmenopausal women with low estrogen suffer more from chronic painful conditions.

Older women are more likely than men to report common chronic pain conditions such as back pain, fibromyalgia, arthritis, and osteoarthritis. Women with these conditions also report greater pain severity and pain-related disability than their male counterparts.

A recent study reviewing VA health records revealed women with a higher menopause symptom burden may be the most vulnerable for developing chronic pain. More specifically, women with menopause symptoms had nearly twice the chance of having chronic pain and multiple chronic pain diagnoses.

“Changing levels of hormones around menopause have complex interactions with pain modulation and pain sensitivity, which may be associated with vulnerability to either the development or exacerbation of pain conditions,” says Dr. JoAnn Pinkerton, executive director of the North American Menopause Society (NAMS). “This study suggests the menopause symptom burden may also be related to chronic pain experience.”

Long-term care facilities would do well to keep these gender differences in mind when prescribing or administering pain medication to their patients.

logo for Blue Ridge Pharmacy