Bringing active life back to patients

About us

Synartro AB

Synartro is a Swedish life science company developing local injection treatments to provide superior and sustained efficacy without systemic side-effects. This is achieved by chemically binding existing proven drugs to the base compound in our novel local injection technology.

Our lead program focuses on a novel therapy using our compound SYN321 for the treatment of symptomatic osteoarthritis (OA). This disease leaves up to 50% of patients without adequate pain relief.


Bengt Lindqvist, part of the team behind the hyaluronic acid substance Healon from Pharmacia, is one of the inventors of our patented hyaluronan-based local injection technology. After the initial discovery, he teamed up with other skilled chemists to commence development of the compound SYN321, where diclofenac is linked to the technology platform. In 2013, an animal study showed that SYN321 provided a sustained release of diclofenac in horse joints, without observed side effects.

In 2020, a US patent was granted for the local injection platform and drug candidate SYN321. Since then, development activities have intensified.

Technology & Development

Unique local injection technology

Synartro develops local injection treatments using a patented local injection technology that enables a sustained drug release. By locally injecting the treatment, a very low dose of the active substance is needed. For other indications where local slow release of compounds with systemic safety concerns is beneficial, our technology could provide significant improvement.  

Lead program, SYN321

Drug candidate SYN321 is an intraarticular injection in development for the treatment of symptomatic knee OA. It is the slow release of diclofenac inside the joint that enables therapeutic benefits of SYN321 such as reduced side effects, prolonged pain relief as well as reduction of inflammation and pain. Further, SYN321 will also provide lubrication to the joint.

SYN321 has the potential to become the preferred second line treatment for knee OA.

Preclinical development

In the preclinical stage of SYN321 a study in horses at the Swedish University of Agricultural Sciences (SLU) compared SYN321 joint injections to a mixture of unbound hyaluronic acid and diclofenac. Diclofenac remained in the joint 10 times longer with SYN321 than with the unbound version. Minimal systemic exposure (plasma and urine) was observed, demonstrating excellent tolerability and favorable pharmacokinetics. You can find the publication here.

Efficacy for SYN321 was confirmed in an in vitro miniaturized model of human OA cartilage on a chip (uKnee®), in collaboration with BiomimX. The study revealed that SYN321 decreased the OA inflammatory response, slowed matrix-degrading events, and importantly, caused no damage to the cartilage.

The preclinical program also involved various GLP-Tox studies, which demonstrated favorable safety and local tolerability. Other steps that have been performed are manufacturing the substance under Good Manufacturing Practice (GMP).


The next step for SYN321 is a first-in-human trial in osteoarthritis patients (phase 1/2a). This trial will focus on safety and exploratory efficacy of SYN321, but will also provide indicative efficacy data. Synartro plans to manufacture trial product and start the clinical trial in 2024. The clinical trial approval was received in 2023.


The patent filed by Synartro in 2015 was initially approved in the US in May 2020, in Europe in 2021 and Canada in 2022. The patent is a compound patent, covering the unique platform of hyaluronan and a linker, that can be connected to different pharmaceutical active substances. Thus, the patent protects not only SYN321, but also other compounds based on the platform.

The patent is valid until 2035, with a possible extension of five years. It is the company’s assessment that the patent provides strong immaterial protection. Two PCT applications for the manufacturing method were filed in 2023.

About knee OA

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OA is a chronic, slowly progressive, joint disease caused by the breakdown of joint cartilage, which leads to pain, stiffness, and reduced motion. OA is generally diagnosed in people over 40 years of age and mainly affects the knees, hips, and hands. Women have a higher risk of becoming affected by OA, as well as individuals with physically stressful jobs or those affected by obesity.



Around 500 million people are affected by osteoarthritis globally, a number which is expected to increase due to the ageing population. The global prevalence of osteoarthritis is 23% in individuals aged 40 and over). Roughly 24 million patients are estimated to receive drug treatment for knee OA. An early diagnosis generally yields best treatment outcomes. There are four disease stages: minor, mild, moderate and severe.

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There is no cure for osteoarthritis. At diagnosis, knee OA is commonly treated with mild analgesics and physiotherapy where the key focus is pain relief and increasing mobility. The second treatment approach includes the use of analgesics (NSAIDs and opioids), intraarticular steroids, and hyaluronan injections.

With 50% of treated patients left with inadequate pain relief or side effects from the treatment, there is a huge unmet clinical need for novel drugs that can increase the level and duration of pain relief without causing systemic side effects.

Based on the current standards, SYN321 with demonstrated favorable safety profile, extended release of diclofenac and decrease of inflammatory response in preclinical trials is well-positioned as a preferred second line treatment for OA.

Current treatment steps

Step 1

At early diagnosis of mild knee osteoarthritis, the patient receives instruction to do physical therapy and use paracetamol (rescue analgesic). If symptoms remain, topical NSAIDs and regular exercise are prescribed.

Step 2 – novel SYN321 therapy

As a second-line treatment intermittent or continuous oral NSAIDs (non-selective, COX-2 selective, naproxen, etc.) are given as symptom reliever. If additional treatment is needed, the patient can receive either intraarticular hyaluronan or intraarticular corticosteroids. This step is where use of SYN321 could be initiated.

Step 3

For the moderate progression stage of knee osteoarthritis, the symptoms and pain from the breakdown of joint cartilage can be relieved with weak and short-term opioids and continued injections as in step 2.

Step 4

Once the disease has reached the point of completely broken-down joint cartilage, none of the previous treatment steps can reduce the symptoms enough. The final treatment option for severe osteoarthritis is joint replacement surgery.

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Market size

The market for osteoarthritis treatments is growing rapidly and is expected to be $15.8 billion in 2030. Roughly 80% of this is generated from treatment of knee osteoarthritis.

Unmet needs

There is currently a major demand for osteoarthritis treatments with improved safety and efficacy profiles within the medical community as well as a strong desire to avoid surgery and opioids. The increasing interest in intraarticular combinations offering these benefits is making the SYN321 a great candidate for future treatments.

Our solution

SYN321 has shown beneficial properties with a favorable side effect profile and potential for long-term pain relief in animal studies. The novel therapy of SYN321 could provide patients the ability to live an active life again. A patent has been approved for the unique binding between diclofenac and hyaluronan in SYN321, which offers several competitive advantages including a better side-effect profile compared to competing injectables, opioids, oral diclofenac and other NSAIDs.


There is a clear trend towards injection treatments instead of opioids and NSAIDs due to their side effects. Injections with longer duration are gaining market share. The number of treated osteoarthritis patients are growing with the aging society and an increasingly overweight population.  


The estimated annual revenue potential for SYN321 is estimated at $600M, looking solely at six major markets: The US, France, Germany, Italy, Spain, and the UK. These markets are also Synartro’s primary focus. In addition, the underlying secular growth in demand means even further long-term revenue potential.

Board of Directors

Fredrik Lehmann

PhD, founder & chairman

Fredrik is founder of OT Chemistry, board member at Sprint Bioscience and venture partner at Industrifonden. Entrepreneur-in-Residence at Sound Bioventures and previous Head of Research and CMC at Oncopeptides.

Mats Persson


Mats has extensive experience from the pharma and Medtech industry. Currently chairman of Exocure Sweden AB. Former Executive Senior Vice President Business Development and partner at SHL Group.

Lars Jansson


Lars has more than 30 years’ experience in reg. affairs and drug development. Previously Swedish MPA, Schering and Kabi Pharmacia. Founder and manager of Scandinavian Regulatory Services.

Contact us

Magnus Hurst

CFO & acting CEO

+46 (0)76 027 44 27

Antonio Bermejo Gómez

Head of R&D and CMC

+46 (0)76 034 25 78

Mia Brundin

(on sick leave)


Synartro is a Swedish life science company developing local injection treatments that provide superior and sustained efficacy without systemic side-effects. This is achieved by chemically binding existing proven drugs to our local injection technology.

The initial focus area is knee osteoarthritis, a disease with significant demand for treatments with improved efficacy and safety profiles for the growing patient population.  

The company is ready to start the clinical phase for the lead compound SYN321 with a phase 1/2a trial in osteoarthritis patients.  

The company is seeking investments to enable continued development of its promising lead program SYN321.

For further information, please get in touch with Magnus Hurst, CFO & Investor Relations.


BioStock: Synartro ready for clinical trials

31 May 2024 – Synartro has initiated a capital raise of between SEK 38 and 75 million to conduct a clinical study of the osteoarthritis candidate SYN321. In addition, it is in the final phase to secure an EU grant of EUR 2.5 million.

The combination of a long-lasting effect from the well-known substance diclofenac and the minimised side effect profile that a local administration entails, will give us a unique position in the market,’ says the company’s acting CEO Magnus Hurst

Read full BioStock article (Swedish) here

Dr. Ali Mobasheri joins Synartro as Senior Scientific Advisor

28 February 2024 – Synartro welcomes Dr. Ali Mobasheri to the team as a Scientific Advisor. Dr. Mobasheri is a Professor of Musculoskeletal Biology in the Research Unit of Health Sciences and Technology within the Faculty of Medicine at the University of Oulu. He is a globally renowned authority within musculoskeletal physiology and brings invaluable expertise in cartilage biology and OA biomarkers to the company. In addition, he brings extensive experience of working with pharmaceutical companies in developing OA treatments. His prominent roles in organisations such as OARSI, ESCEO, WHO Collaborating Center, and ICRS, further solidify his distinguished reputation in musculoskeletal health research.

Read Dr. Mobasheri’s bio here

Synartro has been granted regulatory and ethical approval for the first clinical trial of lead compound SYN321 for treatment of symptomatic knee osteoarthritis

27 April 2023 – Synartro announces that the company has been granted approval from the Swedish Medical Products Agency and the Swedish Ethical Review Authority to start the phase 1/2a first-in-human clinical study of the investigational drug candidate SYN321.

Read full press release

Synartro prepares for first clinical trial of lead compound SYN321 for treatment of symptomatic knee osteoarthritis

31 January 2023 – Synartro announced today that the company has submitted a clinical trial application to the Swedish Medical Products Agency and the Swedish Ethical Review Authority, for a phase 1/2a first-in-human clinical study of investigational drug candidate SYN321.

Read full press release

Synartro granted European patent

17 February 2022 – Synartro’s patent application for its drug delivery platform has been granted by the European Patent Office. The patent strengthens the position of the company’s lead candidate SYN321, which is developed for treatment of knee osteoarthritis. The granted patent also protects further development within other areas and indications based on the platform.

Read full press release

Synartro tar in 34 Mkr inför studie på patienter med knäartros

25 oktober 2021 – Synartro, som utvecklar nytt läkemedel mot artros har tagit in 34 Mkr i en nyemission. Bolagets största aktieägare, investmentbolaget Linc, utökade sin ägarandel ytterligare. Kapitalet ska användas till att genomföra den första kliniska studien i människa med bolagets läkemedelskandidat SYN321. 

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Goda inledande resultat i Synartros prekliniska utveckling av SYN321

5 oktober 2021 – Synartro, som utvecklar ett nytt läkemedel för behandling av artros, meddelar att de inledande toxikologi- och säkerhetsstudierna för läkemedelskandidaten SYN321 har genomförts med goda resultat. Utvecklingsarbetet fortsätter därmed för att påbörja klinisk prövning under 2022. 

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Synartro rekryterar CFO och förstärker projektteamet inför start av kliniska studier

15 maj 2021 – Bioteknikbolaget Synartro växlar upp inför nästa steg i utvecklingen av bolagets kandidat SYN321 och rekryterar Magnus Hurst som CFO samt Eva Arlander som har gedigen erfarenhet från läkemedelsbranschen och kliniskt utvecklingsarbete. 

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Synartro har fått positivt besked inför toxikologiska säkerhetsstudier i höst

31 mars 2021 – Synartro har efter vetenskaplig rådgivning med Läkemedelsverket beslutat att under hösten 2021 inleda toxikologiska säkerhetsstudier med läkemedelskandidaten SYN321 för behandling av knäartros. Studierna kan vara tillräckliga för att starta nästa fas i läkemedelsutvecklingen – kliniska studier med SYN321 i patienter.   

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Synartro rapporterar positivt utfall från effektstudie av SYN321

22 December 2020 – Synartro, som utvecklar ett nytt läkemedel för behandling av artros, har framgångsrikt slutfört en preklinisk effektstudie av kandidaten SYN321 i råtta med knäartros. Studieresultaten visar effekt av SYN321 avseende smärta och viktuppgång trots väsentligt lägre dos diklofenak. Bolaget går därmed vidare med säkerhetsstudier för att därefter kunna göra en första studie i människa.

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Synartro presents at Redeye and Sciety Life Science Unlisted 2020

On 2nd of December, Synartro was invited to present at Redeye and Sciety Life Science Unlisted 2020. Please click here to access our presentation by Mia Brundin, CEO of Synartro.

Fulltecknad nyemission om 17 MSEK genomförd

Synartro meddelar att bolaget har genomfört en fulltecknad nyemission om 17 miljoner kronor tillsammans med investeringsnätverket Sciety. Emissionen fulltecknades den 2 oktober på endast fyra dagar. Kapitaltillskottet ska användas för att slutföra det prekliniska arbetet med kandidaten SYN321 för behandling av knäartros, och innefattar bland annat CMC (kemi, tillverkning och kvalitetskontroll av kandidaten) och toxikologiska studier.

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Synartro får nytt patent i USA

29 september 2020 – Synartros patentansökan avseende bolagets plattform för läkemedelsadministration beviljas i USA. Med patentet stärker bolaget sin position för kandidaten SYN321 som utvecklas för behandling av knäartros i människa men också möjligheterna till utlicensiering inom andra områden och indikationer.

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Synartro genomför fulltecknad nyemission inför artrosstudie

5 maj 2020 – Synartro, ett svenskt bioteknikföretag fokuserat på utveckling av en patentsökt teknologiplattform för att förbättra effekt och säkerhet av beprövade substanser, med målsättning att kunna erbjuda artrospatienter en lokal och säker behandling som alternativ till behandling med opioider, injicerad hyaluronsyra samt orala NSAID-preparat, meddelade idag att bolaget genomfört en fulltecknad nyemission.

Synartro har genomfört en nyemission tillsammans med life science investerarnätverket Sciety. Kapitalet syftar till att färdigställa tillverkningen av SYN321 hos bolagets tillverkningspartner Recipharm för att inleda en artrosstudie tillsammans med ett externt, oberoende kontraktslabb i en industrivaliderad sjukdomsmodell. Studien besvarar en rad viktiga utvecklingsfrågor och underleverantören har kontrakterats efter en systematisk utvärdering av olika artrosmodeller.

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Mia Brundin announced as new CEO of Synartro

20 April 2020 – Mia Brundin has over 20 years of leadership experience from international business development and commercial roles at companies such as AstraZeneca, Recip and Meda. Today, Mia is the Country Manager Sweden for Mylan, one of the largest global healthcare companies. Mia holds a Master of Science in Business Administration and Economics, International Business Program, from Linköping University. 

“It is with great excitement and enthusiasm that the Board today announces that Mia Brundin has accepted the role as CEO of Synartro,”  says Fredrik Lehmann, Synartro Chairman of the Board. “Mia has led several successful development projects as well as international launches and, with her impressive track record and broad experience in international commercialization and leadership, we look forward to continuing the development of our lead program SYN321 as well as exploring further opportunities for Synartro.”

Mia Brundin will start her new leadership position as the CEO of Synartro on August 1, 2020. Until that time, Monika Vedin, current CEO, will remain in her position.