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New! Anabolic Steroid - AVA-291

AVA-921, “Heavy Testosterone”, deuterated testosterone, or d3-testosterone (d3-T) is an androgen or androgen receptor agonist under development for treatment of women with breast cancer, sexual dysfunction, and other issues. But we can be sure men in the underground will be interested in its effects as a significantly less aromatizable form of testosterone - therefore making it “dry” or less estrogenic. In this video, I talk with Omar Hajmousa, Pharm-D, my Director of Education & Strategy for the Testosteronology Society™ about AVA-921 from a harm reduction and pharmacological standpoint.
 
Interesting. Grok says..

Key points about its structure:​

  • Base molecule: Testosterone (C₁₉H₂₈O₂), the primary male sex hormone.
    • Core structure: A steroidal framework with four fused rings (three six-membered cyclohexane rings and one five-membered cyclopentane ring).
    • Functional groups: 3-keto group (Δ⁴-3-one), 17β-hydroxyl group, and a methyl group at C19.
  • Modification in AVA-921: Incorporation of deuterium (²H or D) — typically three deuterium atoms(hence "d3-"), strategically placed to reduce or alter enzymatic breakdown (e.g., less susceptible to 5α-reductase or other metabolic pathways).
    • This isotopic substitution does not change the overall carbon skeleton or major functional groups but slightly increases molecular weight and can modify pharmacokinetics (longer half-life, potentially reduced aromatization to estrogen in some contexts, leading to descriptions as "dry" or less estrogenic).
It has been mentioned in development or research contexts for applications like treating breast cancer in women, sexual dysfunction, or other hormone-related conditions — but it also attracts interest in performance-enhancing or bodybuilding communities for its potentially favorable androgenic profile compared to standard testosterone.

No publicly available detailed chemical diagram or exact deuterium placement (e.g., positions 2,2,6 or similar common deuteration sites in steroids) appears in standard databases for "AVA-921" as a widely indexed compound — it seems to be an internal/research code or early-stage designation rather than a fully commercialized drug with a CAS number or standard PubChem entry.

If this matches what you meant (e.g., from a specific video, forum, or research context), or if you have more details like a company name or paper reference, I can refine the answer further!

For the geeks 2,2,5 substituted with deuterium.

1770896905979.png
 
what is the structure of AVA-921




AVA-921 appears to refer to a deuterated form of testosterone, specifically d3-testosterone (where three hydrogen atoms are replaced with deuterium, often at stable positions like the methyl group or elsewhere to alter metabolism).

It is described in some sources (including discussions in fitness, hormone therapy, and underground/research steroid contexts) as "Heavy Testosterone" or a modified androgen/anabolic steroid.

Key points about its structure:​

  • Base molecule: Testosterone (C₁₉H₂₈O₂), the primary male sex hormone.
    • Core structure: A steroidal framework with four fused rings (three six-membered cyclohexane rings and one five-membered cyclopentane ring).
    • Functional groups: 3-keto group (Δ⁴-3-one), 17β-hydroxyl group, and a methyl group at C19.
  • Modification in AVA-921: Incorporation of deuterium (²H or D) — typically three deuterium atoms(hence "d3-"), strategically placed to reduce or alter enzymatic breakdown (e.g., less susceptible to 5α-reductase or other metabolic pathways).
    • This isotopic substitution does not change the overall carbon skeleton or major functional groups but slightly increases molecular weight and can modify pharmacokinetics (longer half-life, potentially reduced aromatization to estrogen in some contexts, leading to descriptions as "dry" or less estrogenic).
It has been mentioned in development or research contexts for applications like treating breast cancer in women, sexual dysfunction, or other hormone-related conditions — but it also attracts interest in performance-enhancing or bodybuilding communities for its potentially favorable androgenic profile compared to standard testosterone.

No publicly available detailed chemical diagram or exact deuterium placement (e.g., positions 2,2,6 or similar common deuteration sites in steroids) appears in standard databases for "AVA-921" as a widely indexed compound — it seems to be an internal/research code or early-stage designation rather than a fully commercialized drug with a CAS number or standard PubChem entry.

If this matches what you meant (e.g., from a specific video, forum, or research context), or if you have more details like a company name or paper reference, I can refine the answer further!

Pharmacokinetics of deuterated testosterone




Pharmacokinetics of deuterated testosterone (also known as d3-testosterone or d3-T, developmental code names including AVA-291 in some sources) primarily refer to a specifically modified form of testosterone where three hydrogen atoms on the C19 methyl group are replaced with deuterium. This deuteration strategy aims to alter metabolism while preserving androgenic activity.

Deuterated testosterone is still in preclinical or early development stages (e.g., by Lennham Pharmaceuticals), with no human clinical pharmacokinetic data widely published as of the latest available information. Most data come from in vitro studies and non-clinical (animal) models.

Key Pharmacokinetic Features​

  • Primary Goal of Deuteration — The substitution targets resistance to aromatization (conversion to estradiol/E2 via the enzyme aromatase/CYP19). This reduces unwanted estrogenic effects while retaining testosterone's androgen receptor agonism.
  • Metabolic Stability (Aromatization Pathway)In vitro with recombinant human aromatase (CYP19):
    • d3-Testosterone shows substantially greater resistance to aromatization compared to regular testosterone.
    • Half-life in aromatase-containing systems: 55.9–79.9 minutes for d3-T vs. 7.7–18.5 minutes for testosterone (4–7 times longer).This kinetic isotope effect slows the rate-limiting step in aromatization due to the stronger C-D bonds compared to C-H bonds.
  • Hepatic Metabolism (General Clearance)In vitro using rat and human hepatocytes:
    • d3-Testosterone and regular testosterone are metabolized at nearly identical rates.
    • They produce similar downstream metabolite profiles.This indicates that deuteration does not broadly slow overall hepatic clearance or phase I/II metabolism pathways (e.g., via other CYPs or conjugation), but selectively blocks the aromatase pathway.
  • Pharmacodynamics (Related to PK)In vitro androgen receptor translocation assays show similar potency (EC₅₀ ≈ 0.53–0.74 nM for d3-T vs. regular testosterone), confirming that deuteration preserves core androgenic activity without altering receptor binding or activation.
  • Other Implications
    • Reduced estrogenic potential: Expected to have greatly diminished conversion to estradiol, leading to lower risks of estrogen-related side effects (e.g., gynecomastia in men, or proliferation in ER+ breast cancer contexts).
    • In cell-based assays, d3-T showed ~1,000-fold lower potential to stimulate breast cancer cell proliferation compared to testosterone.
    • No major differences in overall systemic clearance or distribution are reported from the available non-clinical data; the main PK advantage is pathway-specific (aromatase resistance).
    • Routes under consideration include oral, transdermal, or parenteral administration, but detailed absorption/bioavailability data are not publicly detailed.
In summary, deuterated testosterone exhibits selective pharmacokinetic modification: dramatically slower aromatization (leading to reduced estradiol formation) while maintaining similar overall metabolic clearance and androgenic potency as native testosterone in non-aromatase pathways. This makes it a promising candidate for applications where estrogenic side effects limit testosterone use (e.g., certain hormone therapies or cancer treatments), though full in vivo human PK (absorption, distribution, clearance rates, half-life after dosing) awaits clinical studies.
 
just reading about it i feel like my liver values took a hit already
 
www.urologytimes.com

FDA provides guidance on development pathway for testosterone therapy for women | Urology Times

AVA-291 is a differentiated formulation of testosterone designed to retain androgen activity while resisting aromatization.
www.urologytimes.com www.urologytimes.com


AVA-291’s differentiated formulation may provide a useful alternative to ordinary testosterone in these situations, which may include use as a hormone replacement therapy in menopausal women, for men on testosterone therapy who develop gynecomastia, for addressing muscle loss and/or low-libido in patients on GLP-1 therapy, and in the treatment of ER-positive breast cancer.
 
I'm guessing it will be expensive.. very expensive. It probably has to be made with in a multistep organic synthesis process, maybe with Michael addition and heavy water as part of it. I probably couldn't use it because I don't aromatize much at all.
 

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