Are prescriptions for heparin – derived from the viscera of pigs – worth the planetary cost?

Included in the WHO’s Model List of Essential Medicines, use of the anticoagulant is rising, with global sales projected to grow from US $9.38 in billion in 2021 to US $12.06 billion by 2028.

Besides increased demand for treatment of rising cardiovascular disease and thrombosis in ageing populations, it has also been making headlines in recent months as a treatment for COVID-19.

But there are calls for clinicians to think twice before drawing up their next script, given the vast numbers of pigs required in its manufacture.

In a commentary last week for The Lancet Haematology, experts have pointed out that crude heparin has been almost exclusively extracted from porcine intestinal mucosa since 1999.

Usage of bovine heparin ceased in 1999 because of the risks of possible contamination with bovine spongiform encephalopathy (BSE).

Unfortunately, pig farming carries a massive carbon footprint, with approximately 6.1 kg of CO₂ produced for every kilogram the pig grows, according to a paper co-authored by Dr Emmanuel Favaloro of the Department of Haematology, Westmead Hospital, Sydney.

The authors say only a tiny amount of crude heparin can be extracted from each carcass: typically between 160–260mg per kilogram of intestinal mucosa.

As a result, the offal of around 1.1 billion pigs will be required annually to meet projected demand by 2028, the authors say.

The authors note that the 668 million ton carbon footprint of the porcine industry through procurement of fresh porcine intestines is a major contributor to the 52 megatonnes of CO₂ emissions by the pharmaceutical industry,  greater than the 46 megatonnes of CO₂ emissions generated by the automotive industry.

“The irony that the production of life-saving medications, such as heparin, poses a long-term threat to planetary health and climate change should not be lost in the pursuit of value-based health care,” they write.

“Urgent policy change and clinical leadership are required to address and escalate these initiatives to mitigate the high carbon cost of heparin.”

They suggest clinicians consider alternatives including direct oral anticoagulants as well as emerging novel agents such as the oral factor XIa inhibitor asundexian (also known as BAY2433334).

“Notably, the synthetic heparin fondaparinux, which has not been favoured for clinical use because of the associated high costs from complicated manufacturing processes, now has a new potentially scalable and programmable one-pot synthesis method that could result in a lower carbon footprint and cost,” they say.

Besides that, drug companies should be required to publish the carbon footprints for every medication on the product information sheet as part of moves to encourage emission reductions where possible, the authors argue.