Biosynthetic steroids (fermentation & biocatalytic API)

01Overview and value chain#

Markers EC: Directive 2001/83/EC + EDQM CEP / FDA DMF | OECD: Bio-pharma | Regulator: FDA (USA), EMA (European Union), NMPA (China)

Biosynthetic steroids are corticosteroid and reproductive-hormone active pharmaceutical ingredients (APIs) produced by microbial fermentation of phytosterol feedstocks into steroid precursors (androstadienedione/AD, androstadienediol/ADD, 9-hydroxyandrostenedione/9-OHAD), followed by biocatalytic and semi-synthetic finishing into cortisone, hydrocortisone, budesonide, testosterone and progesterone. The manufacture has largely moved offshore from the US to Europe, China and India. Olon partners with Ajinomoto Bio-Pharma Services on cGMP biopharmaceutical manufacturing; Farmabios markets a corticosteroid API list; Gadea Pharma supplies sterile corticoid APIs such as budesonide; Tianjin Tianyao is a leading Chinese corticosteroid API producer; Symbiotec Pharmalab is a vertically integrated steroid-API specialist (IPO 2026); and Asymchem is a biocatalysis CDMO whose enzyme-catalysed routes serve steroid synthesis.

The key directions of biosynthetic steroids are:

1. Phytosterol biotransformation (Phytosterol Biotransformation): mycobacterial (Mycobacterium) sidechain cleavage of soya/wood-derived phytosterols into AD, ADD and 9-OHAD steroid precursors — the upstream of every biosynthetic steroid.
2. Corticosteroid API manufacture (Corticosteroid API): cortisone, hydrocortisone, budesonide, prednisolone and other adrenal corticoids — Olon, Farmabios, Gadea Pharma, Tianjin Tianyao, Symbiotec.
3. Androgen and reproductive-hormone API (Reproductive Steroid): testosterone, progesterone, norgestrel and their precursors for replacement therapy and contraception.
4. Biocatalytic CDMO (Biocatalysis): enzyme-catalysed regio- and stereo-selective steroid transformations (17α-hydroxylation, Δ1-dehydrogenation) — Asymchem and CDMO peers.

Sectoral value chain#

[soya / wood phytosterol] ──> [mycobacterial fermentation → AD/ADD/9-OHAD] ──> [biocatalytic + semi-synthetic finishing]
                                              │
                                     (GMP crystallisation, CEP/DMF)
                                              │
                                              ▼
[formulation-grade API] <─── [cortisone / testosterone / budesonide] <─────┘

Value chain levels#

Cross-cutting technologies of the sector:

• Mycobacterial phytosterol degradation (Phytosterol Biotransformation): mycobacteria selectively cleave the phytosterol sidechain to yield AD/ADD/9-OHAD, the universal precursors that replaced chemical synthesis from diosgenin.
• Biocatalytic stereochemistry (Biocatalysis): enzyme-catalysed 17α-hydroxylation, Δ1-dehydrogenation and 11β-hydroxylation introduce the stereochemistry required for corticoid activity, with higher selectivity than chemical routes.
• Sterile and high-potency API CMC (API CMC): sterile corticoid APIs (Gadea) and high-potency corticosteroid GMP require dedicated particle and containment engineering.

02US#

The US is the largest consumer of steroid APIs but no longer a major producer: steroid-API manufacture has largely offshored to Europe, China and India, leaving the US tier as buyer/formulator.

offshored manufacture, FDA DMF, supply security#

• Offshored API tier: US pharmaceutical companies source corticosteroid and reproductive-hormone APIs from European (Olon, Farmabios, Gadea), Chinese (Tianjin Tianyao) and Indian (Symbiotec) manufacturers under FDA Drug Master Files, with limited US-based fermentation capacity.
• FDA DMF framework: steroid APIs enter the US supply chain under FDA Drug Master Files and cGMP inspection, with corticosteroid products reviewed as generics and branded drugs under NDA/ANDA.
• Supply security: concentrated offshore steroid-API production has made supply security a recurring US policy concern, especially for hospital-critical corticosteroids.

03CN#

China is the world’s largest steroid-API producer, with Tianjin Tianyao a leading corticosteroid manufacturer and Asymchem a global biocatalysis CDMO.

Tianjin Tianyao, Asymchem, NMPA#

• Tianjin Tianyao (天津天药药业): a leading Chinese corticosteroid API producer, manufacturing hydrocortisone, prednisolone and related adrenal-cortical APIs from phytosterol biotransformation for global supply.
• Asymchem (凯莱英): a biocatalysis CDMO whose enzyme-catalysed routes serve steroid and broader API synthesis, supporting the biocatalytic shift from traditional chemical semi-synthesis.
• Domestic cluster: China’s phytosterol-fermentation cluster (including the Zhejiang Xianju region) is the world’s largest steroid-API manufacturing base, exporting cortisone and reproductive-hormone APIs globally.
• NMPA framework: steroid APIs are produced and exported under NMPA cGMP inspection, with API dossiers filed for FDA/EDQM and other regulators.

04EU#

Europe hosts three specialist steroid-API manufacturers — Olon, Farmabios and Gadea Pharma — plus the EDQM Certification procedure.

Olon, Farmabios, Gadea, EDQM#

• Olon (Italy): a biopharmaceutical CDMO that in October 2025 announced a partnership with Ajinomoto Bio-Pharma Services, strengthening European cGMP fermentation and API capacity for steroid and other complex APIs.
• Farmabios (Italy): markets a portfolio of corticosteroid APIs, with a long-standing position in adrenal-cortical and reproductive-hormone manufacturing.
• Gadea Pharma (Spain): supplies sterile corticosteroid APIs such as budesonide (oral and respiratory) for inhalation and other sterile applications, under the Minakem group.
• EDQM CEP framework: steroid APIs enter the EU supply chain under European Directorate for the Quality of Medicines (EDQM) Certificates of Suitability (CEP) and central EU medicines regulation under Directive 2001/83/EC.

05Leading companies and research institutes#

06Tech stack and innovations#

The stack pairs mycobacterial phytosterol fermentation with enzyme-catalysed stereochemical finishing and GMP sterile API crystallisation, replacing older diosgenin-based chemical synthesis.

1. Phytosterol biotransformation (Phytosterol Biotransformation):
   • Mycobacteria selectively cleave the aliphatic sidechain of β-sitosterol/stigmasterol to yield androstadienedione (AD), androstadienediol (ADD) and 9-hydroxyandrostenedione (9-OHAD) — the universal steroid precursors that anchor the entire biosynthetic-steroid industry.
2. Corticosteroid API manufacture (Corticosteroid API):
   • Olon, Farmabios, Gadea, Tianjin Tianyao and Symbiotec convert AD/ADD/9-OHAD precursors into hydrocortisone, prednisolone, budesonide and other corticoids via regioselective hydroxylation, with Gadea specialising in sterile inhalation APIs.
3. Biocatalytic CDMO (Biocatalysis):
   • Asymchem and CDMO peers apply enzyme-catalysed 17α-hydroxylation, Δ1-dehydrogenation and 11β-hydroxylation to introduce corticoid stereochemistry with higher selectivity and lower waste than chemical routes.
4. Sterile and high-potency API CMC (API CMC):
   • Sterile corticoid APIs (Gadea budesonide) and high-potency corticosteroid GMP require dedicated crystallisation, particle and containment engineering under EDQM CEP and FDA DMF dossiers.

07Value chains and production pipelines#

Industrial pipeline of a biosynthetic steroid API (EDQM CEP / FDA DMF)#

┌───────────────────────────┐      ┌───────────────────────────┐
│ 1. Phytosterol feedstock  │ ───> │ 2. Fermentation /         │
└───────────────────────────┘      │    biotransformation      │
                                   └───────────────────────────┘
                                                   │
                                                   ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 4. API purification &     │ <─── │ 3. Biocatalytic &         │
│    GMP                    │      │    semi-synthetic finishing│
└───────────────────────────┘      └───────────────────────────┘
              │
              ▼
┌───────────────────────────┐      ┌───────────────────────────┐
│ 5. Formulation-grade      │ ───> │ 6. Supply security & PV   │
│    supply                 │      │                           │
└───────────────────────────┘      └───────────────────────────┘

Stage 1: Phytosterol feedstock

Phytosterols (β-sitosterol, stigmasterol, campesterol) are extracted from soya or wood-derived tall-oil sterol streams and purified as the carbon feedstock for steroid fermentation.

Stage 2: Fermentation and biotransformation

Mycobacterial fermentation selectively cleaves the phytosterol sidechain, producing androstadienedione (AD), androstadienediol (ADD) and 9-hydroxyandrostenedione (9-OHAD) precursors at multi-thousand-tonne scale (Tianjin Tianyao and the Chinese cluster lead globally).

Stage 3: Biocatalytic and semi-synthetic finishing

Enzyme-catalysed hydroxylations and dehydrogenations (Asymchem) plus targeted chemical steps convert the precursors into hydrocortisone, prednisolone, budesonide, testosterone and progesterone with high regio- and stereo-selectivity.

Stage 4: API purification and GMP

The steroid API is crystallised, impurity-profiled and released under cGMP, with EDQM Certificate of Suitability (CEP) and FDA Drug Master File (DMF) dossiers supporting global supply.

Stage 5: Formulation-grade supply

The GMP API is shipped to oral, sterile-inhalation, topical and injectable formulators in Europe, the US and globally, under pharmacopeial (Ph.Eur., USP) specification.

Stage 6: Supply security and pharmacovigilance

Concentrated offshore production makes supply-chain resilience and cGMP re-inspection continuous concerns, and post-market pharmacovigilance tracks steroid-product safety across the large generics and branded portfolio.