Novo Nordisk A/S and Sanofi are facing an investigation in South Africa over concerns about potential anti-competitive practices in the human insulin pen market.

South Africa’s Competition Commission said it has started a probe and is talking to the local units of both drugmakers. Further investigation is expected to explore if multiple device patents and proprietary designs are being used to exclude competition and prevent the entry of alternative suppliers.

Danish drugmaker Novo said it welcomes the opportunity to provide information to the authorities. The company complies with all relevant laws and “strongly supports a competitive market,” it added in an emailed statement.

Diabetes is a major problem in South Africa and is the leading underlying cause of death among women in the country, which has overburdened public facilities.

After a decade of being the primary supplier of human insulin pens in South Africa, Novo decided against bidding for the 2024 tender. Instead it decided to phase out the easy-to-use pens and tendered for an older form of the drug that comes in a vial, where patients have to administer the treatment via a syringe themselves.

The decision was made after “thorough discussion” with the South African Department of Health and “we ensured the public sector had adequate access to insulin through this route,” Novo said.

However, hundreds of people marched to the South African headquarters of Novo in Johannesburg last year demanding greater access to its human insulin and lower prices and protesting the phasing out of pens.

Sanofi also chose not to respond to the government tender seeking bids to supply insulin pens, according to Doctors Without Borders, also known as MSF. The lack of a bulk buying agreement forced South Africa to directly procure a limited number of insulin analogue pens outside the tender from Sanofi at a higher price, the advocacy group added. Insulin analogue pens can adjust their speed of absorption and are generally more expensive than human insulin.

Sanofi did not respond to requests for comments.

Aspen Pharmacare Holdings Ltd, Africa’s largest drugmaker, has a deal with Novo to make human insulin vials in South Africa, with local commercial production starting soon.

“We are just trying to get these medicines out to South Africa and emerging markets,” Aspen Chief Executive Officer Stephen Saad said by phone on Monday. “There’s been a real shortage of these products, particularly since they share production with, for example, the diabetes and weight-loss products.”

Aspen is adding the ability to make pens and may yet get rights to manufacturer insulin pens, Saad added.

South Africa’s regulator has also been called on by advocacy groups to examine whether Novo’s focus on manufacturing injectable weight-loss drugs has contributed to insulin pen supply problems.

- With assistance from Ashleigh Furlong.