CB-03-01 (Clascoterone, CAS 19608-29-8) 99% Powder | Topical Androgen Receptor Antagonist for Hair Loss & Acne Research

CB-03-01 (Clascoterone) CAS 19608-29-8
Topical Androgen Receptor Antagonist, 99% Powder

Name: CB-03-01 (Clascoterone)
Brand: Nutrabiotech Chem
SKU: CB03-19608
Price: Inquiry USD
Availability: InStock

CB-03-01 - also known as clascoterone or cortexolone 17alpha-propionate (C17P) - is a high-affinity androgen receptor (AR) antagonist purpose-designed for topical, peripherally selective anti-androgen activity. Applied to skin it competes with dihydrotestosterone (DHT) at AR in sebaceous glands and dermal papilla cells, suppressing DHT-driven sebum lipogenesis, inflammatory cytokine output and follicular miniaturization, then is rapidly hydrolysed by cutaneous esterases to inactive cortexolone - delivering local potency with minimal systemic androgen blockade. It is the reference compound for modern topical anti-androgen research in androgenetic alopecia and acne vulgaris.

AR Antagonist Topical Anti-Androgen Androgenetic Alopecia Acne Vulgaris Sebocyte Biology DHT Blockade Peripherally Selective 99% HPLC

Request a Quote Technical Specs

402.52

MW (C24H34O5)

≥99%

Purity (HPLC)

AR / NR3C4

Primary Target

Molecular Information

Name: CB-03-01 (Clascoterone)
CAS: 19608-29-8
Formula: C24H34O5
MW: 402.52 g/mol
SMILES: CCC(=O)O[C@@]1(CC[C@@H]2
[C@@]1(C)CC[C@H]3[C@H]2CCC4=
CC(=O)CC[C@]34C)C(=O)CO
InChIKey: GPNHMOZDMYNCPO
-PDUMRIMRSA-N
Purity: ≥99% (HPLC)
Appearance: White to off-white powder
Solubility: DMSO; ethanol; insoluble in water
Synonyms: Clascoterone / C17P /
Cortexolone 17alpha-propionate
Storage: 2-8°C or -20°C, dry and dark

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CAS Number

19608-29-8

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Molecular Weight

402.52

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Primary Activity

Topical AR Antagonist

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Purity

≥99%

CB-03-01 (Clascoterone) Technical Specifications & QC Release Data

Complete physicochemical properties and quality control parameters for 99% CB-03-01 powder (clascoterone, CAS 19608-29-8)

📋 Physicochemical Properties

Product NameCB-03-01 (Clascoterone)
IUPAC Name[(8R,9S,10R,13S,14S,17R)-17-(2-Hydroxyacetyl)-10,13-dimethyl-3-oxo-1,2,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-17-yl] propanoate
Common SynonymsClascoterone; Cortexolone 17alpha-propionate; C17P; CB-03-1
CAS Number19608-29-8
Molecular FormulaC24H34O5
Molecular Weight402.52 g/mol
SMILESCCC(=O)O[C@@]1(CC[C@@H]2[C@@]1(C)CC[C@H]3[C@H]2CCC4=CC(=O)CC[C@]34C)C(=O)CO
InChI1S/C24H34O5/c1-4-21(28)29-24(20(27)14-25)12-9-19-17-6-5-15-13-16(26)7-10-22(15,2)18(17)8-11-23(19,24)3/h13,17-19,25H,4-12,14H2,1-3H3/t17-,18+,19+,22+,23+,24+/m1/s1
InChIKeyGPNHMOZDMYNCPO-PDUMRIMRSA-N
Chemical Class17alpha-ester of cortexolone (11-deoxycortisol); steroidal antiandrogen
AppearanceWhite to off-white / light beige powder
MDL NumberMFCD18384978
UNIIXN7MM8XG2M
Trade Names (reference)Winlevi (acne) / Breezula (alopecia)

🔬 Quality Control & Handling

Purity (HPLC)≥99%
FormFine crystalline powder
Identity1H-NMR / 13C-NMR / LC-MS conforming
Related SubstancesCortexolone ≤0.5%; total impurities ≤1.0%
Loss on Drying≤0.5%
Residual SolventsMeets ICH Q3C limits
Storage Condition2-8°C (long term -20°C), sealed, dry, protect from light
Solution Storage-80°C 6 months / -20°C 1 month in DMSO
SolubilityDMSO and ethanol soluble; propylene glycol / PEG compatible; practically insoluble in water
Stability NoteEster bond hydrolyses in the presence of esterases and at extreme pH
QC DocumentationCOA / HPLC / NMR / MS / MSDS
Pack Sizes1g / 5g / 10g / 100g / 1KG
Stock StatusIn Stock
Use StatementResearch use only; not for human or clinical use

Molecular Target: The Androgen Receptor (AR / NR3C4) in Skin

CB-03-01 was engineered for high-affinity AR binding in cutaneous target cells combined with rapid local inactivation - the defining features of a peripherally selective topical anti-androgen

🧬 Androgen Receptor (AR / NR3C4) 🛡️ DHT-AR Competitive Antagonism 🧠 Sebaceous Gland Sebocytes 🧠 Dermal Papilla Cells (hair follicle) 💧 Sebum Lipogenesis Pathway 🔥 IL-6 / IL-8 Inflammatory Output ✂️ Cutaneous Esterase Hydrolysis (to cortexolone) ❌ No 5-alpha-Reductase Inhibition

How CB-03-01 Works: Local AR Blockade Without Systemic Anti-Androgen Load

A steroidal 17alpha-propionate ester designed to act where it is applied and to be inactivated before it can act anywhere else

1. Cutaneous Penetration

The lipophilic 17alpha-propionate ester penetrates the stratum corneum efficiently and partitions into the pilosebaceous unit - sebaceous glands, sebocytes and the dermal papilla - which are the anatomical sites where androgen signalling drives acne and androgenetic alopecia.

2. High-Affinity AR Binding

CB-03-01 binds the androgen receptor (AR, NR3C4) with high affinity and acts as a competitive antagonist, displacing dihydrotestosterone (DHT) and testosterone. In hamster flank organ assays it showed local anti-androgenic potency comparable to cyproterone acetate and greater than finasteride, flutamide or progesterone.

3. Blocked AR Transcriptional Programme

With AR occupied by antagonist, receptor dimerisation, nuclear translocation and binding to androgen response elements are suppressed. Testosterone-stimulated reporter transcription is inhibited, and downstream androgen-dependent gene expression in sebocytes and dermal papilla cells is turned down.

4. Reduced Sebum and Inflammation

In human sebocyte culture, CB-03-01 inhibits DHT-induced lipid synthesis and the production of inflammatory cytokines such as IL-6 and IL-8 (Rosette et al., J Drugs Dermatol 2019). This dual anti-sebogenic and anti-inflammatory action addresses two of the four pillars of acne pathogenesis simultaneously.

5. Protection of the Hair Follicle

In androgenetic alopecia, DHT-AR signalling in dermal papilla cells shortens anagen and drives progressive follicular miniaturization. Blocking AR locally is intended to interrupt that cascade at the receptor level - downstream of 5-alpha-reductase and therefore independent of DHT synthesis inhibition.

6. Rapid Local Inactivation ('Soft Drug' Design)

Cutaneous and plasma esterases hydrolyse the 17alpha-propionate ester to cortexolone (11-deoxycortisol), which has no meaningful AR antagonist activity. Any compound reaching the circulation is therefore largely deactivated, which is the mechanistic basis for the low systemic anti-androgenic burden that distinguishes topical CB-03-01 from oral anti-androgens.

Research Applications of CB-03-01 in Dermatology and Androgen Pharmacology

From hair follicle organ culture to sebocyte lipidomics and topical formulation science

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Androgenetic Alopecia (Hair Loss) Research

The most-searched application. CB-03-01 is used in dermal papilla cell culture, ex vivo human hair follicle organ culture and hair-cycle rodent models to test whether local AR blockade can prolong anagen and reverse DHT-driven follicular miniaturization without systemic feminising effects. It has been advanced clinically as a topical solution for male and female pattern hair loss.

Hair Loss

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Acne Vulgaris & Sebaceous Gland Biology

CB-03-01 became the first genuinely new topical mechanism approved for acne in decades. In SZ95 and primary human sebocytes it suppresses DHT-induced neutral lipid accumulation and cytokine release, making it the standard positive control for anti-sebogenic screening.

Acne / Sebum

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Androgen Receptor Pharmacology

As a steroidal competitive AR antagonist with a clean profile, CB-03-01 is used in AR binding assays, AR-driven luciferase reporter systems (e.g. testosterone-stimulated transcription), coactivator recruitment studies and AR-antagonist structure-activity work.

Target Biology

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Topical Formulation & Percutaneous Absorption

Its lipophilic ester structure makes CB-03-01 a model compound for cream, gel, solution, liposome and nanocarrier development, Franz diffusion cell permeation studies, and skin-versus-plasma partitioning experiments in topical drug delivery research.

Drug Delivery

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Soft Drug / Antedrug Design

The 17alpha-propionate ester is a textbook example of antedrug design: potent at the application site, hydrolysed to an inactive metabolite thereafter. Widely used to teach and test local-selectivity strategies in medicinal chemistry.

Med Chem Strategy

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Hidradenitis Suppurativa & Other Androgen-Driven Skin Disease

Androgen-dependent adnexal disorders - hidradenitis suppurativa, seborrhoea, hirsutism and folliculitis models - are active exploratory areas for topical AR antagonism, with CB-03-01 as the benchmark tool compound.

Dermatology

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Comparative Anti-Androgen Benchmarking

Head-to-head studies against finasteride and dutasteride (5-alpha-reductase inhibitors), spironolactone, flutamide, bicalutamide, cyproterone acetate and RU-58841 use CB-03-01 to separate receptor-level from synthesis-level androgen blockade.

Comparative Pharmacology

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Endocrine Safety & HPA Axis Studies

Because cortexolone is a corticosteroid precursor, studies of clascoterone examine systemic exposure, cortisol suppression and hypothalamic-pituitary-adrenal axis effects - important endpoints for any high-surface-area topical steroid ester.

Endocrinology

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Analytical Method Development

As a well-characterised steroid ester with a defined degradation product (cortexolone), CB-03-01 is used for HPLC/UPLC-MS assay development, forced-degradation studies and stability-indicating method validation.

Analytical Chemistry

Key Publications on CB-03-01 (Clascoterone) and Topical Androgen Antagonism

Peer-reviewed literature spanning the original pharmacology of CB-03-01 through pivotal Phase 3 dermatology trials

Authors & Title	Journal	Year	DOI / PMID
Celasco G, Moro L, Aloisi AM, et al. Biological profile of cortexolone 17alpha-propionate (CB-03-01), a new topical and peripherally selective androgen antagonist.	Arzneimittelforschung (Drug Research)	2004	PMID: 15646375
Trifu V, Tiplica GS, Naumescu E, Zalupca L, Moro L, Celasco G. Cortexolone 17alpha-propionate 1% cream, a new potent antiandrogen for topical treatment of acne vulgaris: a pilot randomized, double-blind comparative study versus placebo and tretinoin 0.05% cream.	British Journal of Dermatology	2011	10.1111/j.1365-2133.2011.10332.x
Rosette C, Agan FJ, Mazzetti A, Moro L, Gerloni M. Cortexolone 17alpha-propionate (clascoterone) is a novel androgen receptor antagonist that inhibits production of lipids and inflammatory cytokines from sebocytes in vitro.	Journal of Drugs in Dermatology	2019	PMID: 31141847
Hebert A, Thiboutot D, Stein Gold L, et al. Efficacy and safety of topical clascoterone cream, 1%, for treatment in patients with facial acne: two phase 3 randomized clinical trials.	JAMA Dermatology	2020	10.1001/jamadermatol.2020.0465
Dhillon S. Clascoterone: first approval.	Drugs	2020	10.1007/s40265-020-01417-6

Available Pack Sizes & Ordering

Research-grade CB-03-01 (clascoterone, CAS 19608-29-8) at ≥99% HPLC purity with full QC documentation - from 1 g research packs to 1 KG bulk batches

Pack sizes: 1 g / 5 g / 10 g / 100 g / 1 KG

Tier	Pack Size	Stock Status	Suitable For	Shipping & Lead Time
Standard	1 g	In Stock	Sebocyte and dermal papilla cell assays, AR binding and reporter studies	Same/next-day dispatch, ambient with ice pack
Medium	5 g	In Stock	Ex vivo hair follicle organ culture, small-scale topical formulation trials	Same/next-day dispatch, ambient with ice pack
Large	10 g	In Stock	Rodent and hamster flank-organ in vivo programmes, permeation studies	Same/next-day dispatch, double-bagged foil pouch
Bulk	100 g	In Stock	Pilot topical formulation batches, stability and scale-up development	2-5 business days, drum/foil pack, quote to confirm
Industrial	1 KG	Made to order	Production-scale supply for cosmetic-science and CDMO programmes	Batch delivery, quote to confirm lead time

💡 Reference sizes shown above; for exact pricing and availability please contact us for a quote. Bulk orders qualify for tiered discounts.

Frequently Asked Questions (FAQ)

Answers to the most common questions on CB-03-01 purity, mechanism, RU-58841 comparisons and formulation

What is CB-03-01 (clascoterone, CAS 19608-29-8)?

CB-03-01 is clascoterone, chemically cortexolone 17alpha-propionate (C17P), with molecular formula C24H34O5 and molecular weight 402.52 g/mol. It is a steroidal, high-affinity androgen receptor (AR/NR3C4) antagonist developed specifically for topical use in androgen-dependent skin disorders - androgenetic alopecia and acne vulgaris. This product is supplied as a ≥99% HPLC purity powder.

Is CB-03-01 structurally related to RU-58841?

No - and this is a common misconception. They are structurally unrelated. CB-03-01 is a steroidal molecule, a 17alpha-propionate ester of cortexolone (11-deoxycortisol). RU-58841 is a non-steroidal anilide of the nilutamide/flutamide chemical family. What they share is a design philosophy: both are intended as topically active, peripherally selective anti-androgens that block AR in skin while being rapidly degraded or cleared so that systemic androgen blockade is minimised. In that functional sense CB-03-01 can be described as an improved-generation topical anti-androgen, but it is not a chemical analogue of RU-58841.

How does CB-03-01 differ from finasteride and dutasteride?

They act at completely different points in the pathway. Finasteride and dutasteride are 5-alpha-reductase inhibitors - they reduce the synthesis of dihydrotestosterone from testosterone, and taken orally they do so systemically. CB-03-01 blocks the androgen receptor itself, downstream of DHT production, and it does so locally in the skin. Receptor-level blockade means the effect does not depend on how much DHT is present, and topical application plus rapid esterase inactivation means the systemic hormonal footprint is far smaller than with oral 5-alpha-reductase inhibition.

Why is CB-03-01 called a peripherally selective or 'soft' anti-androgen?

The 17alpha-propionate ester is the key. It is stable enough to reach and act on AR in sebaceous glands and dermal papilla cells, but is rapidly hydrolysed by cutaneous and plasma esterases to cortexolone (11-deoxycortisol), which lacks meaningful AR antagonist activity. Drug that escapes into the circulation is therefore largely pre-inactivated. This antedrug (soft drug) strategy is what allows high local potency with a much lower systemic anti-androgenic burden than oral agents such as flutamide, bicalutamide or cyproterone acetate.

What evidence supports CB-03-01 in acne vulgaris?

A pilot randomised double-blind study found 1% cortexolone 17alpha-propionate cream superior to placebo and at least comparable to tretinoin 0.05% cream in acne (Trifu et al., Br J Dermatol 2011). Two large Phase 3 randomised trials subsequently demonstrated efficacy and safety of clascoterone cream 1% in facial acne (Hebert et al., JAMA Dermatology 2020), leading to approval in the United States in August 2020 as the first topical androgen receptor inhibitor for acne. Mechanistically, Rosette et al. (2019) showed suppression of DHT-induced sebocyte lipogenesis and IL-6/IL-8 release.

What is the evidence for CB-03-01 in androgenetic alopecia?

Androgenetic alopecia is driven by DHT-AR signalling in dermal papilla cells, causing progressive follicular miniaturization and shortened anagen. Because CB-03-01 antagonises AR directly within the follicle, it has been developed clinically as a topical solution for male and female pattern hair loss and has progressed through controlled clinical studies. In the laboratory it is used in dermal papilla cell culture, ex vivo human hair follicle organ culture and hair-cycle models to quantify AR-dependent growth-factor changes such as DKK-1 and TGF-beta1.

What is the purity and appearance of your CB-03-01 powder?

We supply CB-03-01 at ≥99% purity by HPLC as a white to off-white (occasionally light beige) fine crystalline powder. Release testing includes HPLC assay and related substances (with cortexolone controlled as the principal degradant), 1H/13C-NMR identity, LC-MS confirmation, loss on drying and residual solvents to ICH Q3C. A full Certificate of Analysis accompanies every lot.

How should CB-03-01 be dissolved and formulated for experiments?

For in vitro work prepare stock solutions in DMSO and dilute into medium keeping final DMSO at or below 0.1% v/v; ethanol also works well. For topical research formulations, the compound is compatible with ethanol/propylene glycol, PEG and lipid-based vehicles, and is practically insoluble in water. Because the active moiety is an ester, avoid strongly alkaline or acidic vehicles and esterase-rich biological buffers during storage, and confirm assay stability if incubations exceed a few hours in serum-containing media.

How should CB-03-01 be stored?

Store the powder sealed at 2-8°C for routine use, or at -20°C for long-term storage, protected from light and moisture. Prepared DMSO stock solutions should be aliquoted and kept at -80°C for up to 6 months or -20°C for up to 1 month; avoid repeated freeze-thaw cycles, which can accelerate ester hydrolysis and generate cortexolone as a degradant.

What pack sizes are available and what documentation is included?

Pack sizes are 1 g, 5 g, 10 g and 100 g in stock, with 1 KG available made to order for formulation development and manufacturing programmes. Each shipment includes a COA with HPLC, NMR and MS data, plus MSDS/SDS and Certificate of Origin on request. Material is supplied strictly for research use. Please contact us for pricing, lead times and bulk discounts.

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CB-03-01 (CAS 19608-29-8) - topical androgen receptor antagonist, C24H34O5, MW 402.52, purity ≥99% HPLC with COA
Available in 1g / 5g / 10g / 100g / 1KG - request your quote today

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Clascoterone CB‑03‑01 99% Purity Powder CAS 19608‑29‑8 Androgen Receptor Antagonist Biochemical Research Reagent