Are drugs based on pregnant mare’s urine making a comeback?

Pfizer Canada increases piss purchases

         BRANDON,  Manitoba;  MONTREAL,   Quebec––Pfizer Canada is believed to have contracted with horse farmers for the first increase in pregnant mare’s urine (PMU) purchases since Pfizer took over the Premarin industry by purchasing the previous maker,  Wyeth Inc.,  in 2009.

Premarin sales had been in decline since the publication of health studies in 2002,  2003,  and 2008 that linked long-term use of PMU-based drugs to elevated risk of developing health issues including breast cancer,  heart disease,   and/or kidney stones.

Market was down by half

The market for PMU drugs,  including Premarin and PremPro,  dropped from about $2 billion in retail sales per year at peak to about $1 billion per year,  and has remained in that range.

The PMU drug sales crash approximately halved the numbers of mares used in PMU production,  mostly in western Canada,  and the numbers of foals birthed to keep the mares producing PMU.

While some of the fillies birthed in PMU production are used to replace older mares in the PMU barns,  the majority of the foals are sold to slaughter.

“A small increase,”  says Pfizer

“Pfizer would not reveal the amount of the increase,  nor would it say how much PMU it currently contracts from its 19 operations,”  reported Ron Friesen of the Manitoba Co-operator,  who first exposed the increase in February 2016.

Wrote Friesen,  “‘It will be a small increase over the current amount that we contract,’  was all Christina Antoniou, corporate affairs manager for Pfizer Canada in Montreal, would say in an email message.”

“We are currently in the process of contracting for 2016-17 and therefore cannot provide any further details,”  Antoniou told Friesen,  but added “We can confirm that we are in discussions with ranchers who have existing facilities for this type of operation.”

“Improved Premarin sales”

Said Friesen,  “Antoniou indicated some previously mothballed PMU operations could reopen as a result.  Antoniou indicated a recent improvement in Premarin sales is responsible for the increase.”

“The amount of estrogen we require from our ranchers has always been driven by product demand,”  Antoniou said.

Added Antoniou in a March email to Liz Brown of Horse Collaborative.  “We can confirm that Pfizer will be increasing our pregnant mare urine operations.”

Said Brown,  “So far,  there are no details on how much more urine will be collected,  or how many horses will be impacted.”

“Small increase” may be large

This appears to be still the case,  but the sparse available data suggests the “small increase” may be large relative to the numbers of horses involved in PMU production in recent years.

The 19 farmers currently producing pregnant mare’s urine have about 1,300 brood mares among them,  according to the North American Equine Ranching Information Council,  a Kentucky-based nonprofit front for the PMU industry.

This is about 500 more brood mares than the estimate offered by Karyn Boswell in an October 2015 article for One Green Planet entitled “Heartbreaking Truth About the Treatment of Horses Used to Produce Estrogen Replacement Drugs,”  and 240 more than could be projected from a May 2011 report by Karin Allen for Tuesday’s Horse that “The year 2010 saw the reduction in the number of farms in the North American PMU industry dwindle to a mere 26 ranches housing approximately 40 horses each.”

Big mares,  small stallions

“Quarter horses are the most common registered breed found on equine ranches,”  the North American Equine Ranching Information Council says.  “They outnumber the next most common breeds,  registered draft Percheron and Belgian horses,  by a two-to-one margin.  A variety of other less dominant breeds are also involved in the industry,  including paints,  Appaloosas,  standardbreds, and thoroughbreds.”

The traditional production pattern is that mares of large breeds,  the actual urine producers,  are inseminated with semen from stallions of small breeds,  for ease of birthing in delivering foals who historically have usually been sold to slaughter.  This parallels the practice of dairy farmers of inseminating large Holstein milk cows with semen from Herefords,  a smaller breed favored by beef producers.

Started with 1931 rat study

The PMU industry began with Samuel Leonard,  a longtime Cornell University professor who discovered through a rat study in 1931 that timed doses of the female hormone estrogen can prevent pregnancy.  Leonard,  who died at age 101 in 2007,  lived long enough to see his finding become the basis of the modern pharmacological birth control industry,  and to see the rise and much of the fall of the PMU industry that he went on to pioneer.

As rats could not produce enough estrogen to supply an industry selling hormonal supplements to humans,  Leonard turned to horses.   PMU became the active ingredient in the first birth control pills for humans,  marketed in 1941,  and soon afterward came to be used in products for the relief of menopausal symptoms,   as well.

Humane concerns began early

The humane community voiced two major concerns about the PMU industry almost from inception.  One was that it involves keeping pregnant mares artificially closely confined,  to collect their urine.  The other was that impregnating the mares year after year to collect their urine creates a surplus of foals.  Most foals born in connection with PMU production have always been sold to slaughter.

The American Humane Association published a major investigation of the PMU industry in 1947,  but as the industry grew explosively while the AHA and other humane organizations shifted their focus to dog-and-cat issues,  the next serious investigation of the humane aspects of PMU production was not done until HorseAid looked into it in 1986,  followed by the Canadian Farm Animal Care Trust in 1988-1992.

The PMU industry had meanwhile shifted northward,  first migrating from upstate New York into Quebec,  and then west,  into Alberta,  Manitoba,  and Saskatchewan.

Hub became Brandon,  Manitoba

By 1967 the hub of PMU production had become the Ayerst Organics Limited estrogen extraction facility in Brandon,  Manitoba,  still operating but since 2009 as part of the Pfizer empire.  Extracted estrogen was then processed into birth control pills and other hormonal supplements at Wyeth-Ayerst factories in Montreal and Rouse’s Point,  New York.

At peak,  in the 1990s,  Wyeth bought horse urine from 485 horse farmers,  mostly in western Canada,  but including also some in North Dakota.

While use of PMU in birth control pills faded with the introduction of soy-based hormonal drugs,  the use of PMU in drugs meant to relieve menopause boomed as the post-World War II “Baby Boom” generation reached middle age.

Sales fell 65% in one year

Sales of PMU products fell 65% in just one year,  however,  after the U.S. government-funded Women’s Health Initiative study in July 2002 reported that estrogen supplements appear to be linked to increased risk of women suffering heart attacks,  strokes,  and blood clots in their lungs.

A nine-year study involving 16,000 women altogether,  the Women’s Health Initiative warned participants that for each 10,000 women who took the PMU-based drug Prempro for one year,  there were eight more cases of invasive breast cancer than among women of the same age range and state of health who do not take the drug,  plus seven more heart attacks,  eight more strokes,  and eight more cases of blood clots in the lungs.

U.S. findings confirmed by Brits

The U.S. findings were confirmed and augmented a year later by data published in the British Medical Association journal showing that taking popular combinations of estrogen and progestin appeared to produce a 66% greater risk of developing breast cancer within five years,  and a 22% greater risk of dying from it.

Taking estrogen alone increased the risk of developing breast cancer by 30%.

The British data came from clinical observation of nearly one million women between the ages of 50 and 64,  who were surveyed at annual mammogram appointments beginning in 1996.

Product warnings

Based on the Women’s Health Initiative study results,  the U.S. Food & Drug Administration in February 2003 began requiring all estrogen product labels to carry warnings that the products might slightly increase the risk of heart attack, stroke, breast cancer,  and blood clots.

The Women’s Health Initiative breast cancer study looked at women who took the PMU-based estrogen drug Premarin in combination with progestin,  a formula sold as Prempro.   Continuing to collect and analyze the findings,  study team leader Rowan T. Chlebowski of the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center warned at the San Antonio Breast Cancer Symposium in December 2008 and in the October 20,  2010 edition of the Journal of the American Medical Association that women taking estrogen plus progestin are at greater risk from dying from the two leading causes of cancer death in women.

40% higher risk of breast cancer

Among the the 15,387 women who participated in the second phase of the Women’s Health Initiative,  the death rate from breast cancer among those who did not take estrogen plus progestin was 3.4 per 10,000;  the rate among those who did was 5.3,  or 40% higher.

Confirmation of the elevated risk of death from breast cancer associated with taking estrogen supplements came two weeks after the  October 11,  2010 edition of Archives of Internal Medicine reported the link to risk of developing kidney stones.

“Among more than 24,000 postmenopausal women taking either hormones or dummy pills,  those using hormones were 21% more likely to develop kidney stones over about five years,”  summarized Associated Press medical writer Lindsay Tanner.  “Those results suggest that over a year s time,”  assessed Tanner,   “among 10,000 postmenopausal women taking hormones,  five would develop kidney stones who wouldn’t have if they hadn’t used the pills.  The risks were similar for women taking either Prempro,  containing estrogen plus progestin,  or Premarin,   which contains only estrogen.”

Sales continued to fall like a rock

After publication of the 2002 Women’s Health Initiative findings,  the volume of prescriptions filled for PMU-based drugs reportedly fell from more than 110 million to about 40 million,  producing a parallel drop in the numbers of horses kept on PMU farms,  and the numbers of PMU farms remaining in business.

Along with falling hormone use since 2002,  “Breast cancer diagnoses started to drop,”  summarized Washington Post medical writer Rob Stein eight years later.  “That appeared to help explain one of the biggest mysteries about breast cancer:  why the number of cases rose steadily for decades.  Hormone use probably played a key role,”  subsequent study results indictated,  along with better detection by mammography and other factors.

Compounded alternatives

In place of PMU,  women appear to have turned mostly toward hormonal supplements from plant sources,  chiefly soy beans and yams,  but one recent study published  in the journal Menopause indicated a growing trend toward use of “compounded hormone therapy,”  meaning drugs that are mixed to order by pharmacists,  instead of coming from pharmaceutical manufacturers who use formulas approved by the U.S. Food and Drug Administration.

Surveying nearly 500 pharmacists,  the Menopause study authors estimated that the number of prescriptions written for unregulated compounded hormone therapy may now be in the range of 26 to 33 million per year,  “almost equal to the 36 million annual prescriptions filled for FDA-approved treatments,”  observed Lisa Rappaport of Reuters in December 2015.

Closer regulation

“Based on the survey responses,”  Rappaport wrote,  “the researchers estimated that annual sales of compounded hormones have reached $1.3 billion to $1.6 billion,”  significantly more than the sales of PMU-based drugs,   “and may grow as much as 5% to 25% over the next two years.”

The Food & Drug Administration in 2014 began attempting to more closely regulate the compounding industry.  It may be in anticipation that compounded alternatives to PMU-based drugs might become less easily available that Pfizer is again increasing PMU purchases from horse farmers.

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